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Kobi

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You can cut and paste these GD&T symbols into your drawing:

To load the symbols:

1. Download and open the symbol library.

2. Cut and paste to your drawing.

Custom Machining

If you need custom mechanical parts machined - we would be pleased to quote your job using conventional CAD files or you can use our unique free CAD software where you can: design your part quickly and easily, get instant pricing, and order online.

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GD&T CAD symbols | eMachineShop CAD | eMachineShop

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You can cut and paste these GD&T symbols into your drawing: To load the symbols: Download and open the symbol library. Cut and paste to your drawing. If you need custom mechanical parts machined - we would be pleased to quote your job using conventional CAD files or you can use our unique free CAD software where you can: design your part quickly and easily, get instant pricing, and order online.

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Fernando

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Kobi

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Engineers use CAD software to design all the necessary parts and components for the project. In the digital realm, it is easy to attain perfection. In real life, manufacturing is never 100% accurate.

Sometimes, deviations of a few millimetres from the basic dimensions can be absolutely fine. At the same time, two mating components could require extremely high accuracy.

To keep the expected deviation in a predefined range, it is possible to use engineering tolerances. Dimensional tolerances are very common but lack ways to communicate some very important aspects of manufacturing. This is where GD&T, or geometric dimensioning & tolerancing, steps in.

It is a form of describing dimensions and tolerances in a wholly new way. Using a common language of engineering symbols, it helps to pinpoint all the necessary information easily.

It is a system of symbols and standards used by engineers to provide manufacturing information to the production team.

The reasons for using Geometric Dimensioning and Tolerancing (GD&T) are:

1. It ensures that mating parts fit together well

2. The universal language works regardless of who you are working with

3. Tolerances give a limit to the worst-case conditions

4. Defines production and inspection processes

Stanley Parker is credited for being the engineer behind the development of the GD&T system in 1938.

Before that, all features used only X-Y axes to determine the position of a hole, for example. Giving a positional tolerance on that scale means that the circular hole's position can deviate in a rectangular pattern from the intended spot.

However, we would actually want the tolerance zone to be a circle, as this allows for a uniform measurement in all angles, whereas a rectangle is longer towards the corners and shorter towards the sides.

So as Parker realized that, he started working on the new concept which was adopted as a military engineering standard in the 50s.

Today, GD&T is an important part of engineering, especially when creating parts that require CNC machining services. The American standard describing the features is ASME Y14.5-2018 and the European equivalent is ISO 1101-2017.

GD&T focuses solely on the geometry of the product. Linear dimensions, surface roughness, threads, etc. are not part of this standard.

Why Implement GD&T?

We do have traditional methods of denoting dimensions and tolerances. So what is the need for geometric dimensioning and tolerancing?

Geometric dimensioning and tolerancing (GD&T) offers some unique advantages over regular methods. Let's see what these are.

Perfect assembly

The most important drawback of using traditional dimensioning and tolerancing is that they denote individual part and part feature information. It does not guarantee how well our parts will fit and function at the assembly level.

This is important because most parts are not useful by themselves. Consider the example of a connecting rod. By itself, it doesn't provide us with any benefit. But when we connect it to the crankshaft and the piston, it becomes a bit more useful, as it converts the linear motion of the piston into rotational motion of the crankshaft.

When this assembly becomes a part of a larger assembly such as a diesel engine, it can end up as a part of a generator that provides us with many uses.

Thus, it is crucial that our parts mate well with each other. This is why we need GD&T. Using it, we can be 100 per cent certain that our parts will fit together and function exactly as needed.

Common system to explain the design intent

GD&T also provides the designer with a platform to convey his design intent to all the relevant departments. These include:

Manufacturing

Inspection

Future designers in the design department who will pick up work if the initial design team is not available

The definitions, vocabulary and rules are straightforward and universally understandable. This makes the symbols easy to translate for every engineer and a great way of conveying the designer's intention.

Saves time and money

This is the most important benefit of using GD&T. Using this system reduces wastage as it cuts down the number of design-manufacturing-test fit cycles.

This is because manufactured parts fit well at the first attempt and consequently, the number of rejects will be low. Using a common language also reduces the effort necessary for inspection.

What to Consider?

Geometric dimensioning and tolerancing is a more powerful system compared to traditional tolerances. But it only works if all departments (design, engineering, manufacturing) are well versed in reading and interpreting the information.

Therefore, while creating engineering drawings and tolerancing various part features, it is important to follow the recommended guidelines/conventions for the benefit of everyone who will interact with the drawing at any stage of product development.

Observing them ensures that the drawing is standardised and everyone is on the same page when it comes to drawing specifics. Some of these good practices are as follows.

Intelligibility of the drawing

This is arguably the most important quality of a drawing. The intelligibility refers to the clarity with which part features are drawn and tolerances are shown in the drawing. Some ways to improve the intelligibility of a drawing are:

Draw true profiles for all part features.

Label dimensions and tolerances outside the drawing (not on top). Use white space effectively.

Reading direction must be constant. A reader should be able to read all dimensions while holding the drawing upright.

Space out dimensions of parallel part features.

Explain the part and its function briefly.

Specify angles only when they are not right angles (90°).

Tight tolerances only when necessary

Unless a part fit/function demands it, tolerances must be kept as loose as possible. This reduces the manufacturing cost and turnaround time. We recommend leaving the choice of manufacturing method to the machinists.

The designer must also mention the general tolerance for a drawing. This acts as the standard tolerance for all part features. For part features with a different tolerance limit, the designer must mention them at appropriate positions.

These specific tolerance limits will override the general tolerances. When specifying special tolerance limits, prefer functional features over other features.

GD&T Features & Symbols

The GD&T language is able to define pretty much any qualities that are necessary for ensuring a perfect assembly.

The system uses a number of symbols for this purpose. To use these engineering symbols on drawings correctly, we must first be familiar with some basic building blocks of this system.

We can start with the various definitions, terminologies, and rules before we get to GD&T symbols.

Nominal dimensions

A nominal dimension is the feature size of the true profile. It is the exact dimension which we would like to achieve ideally. Feature specifics such as size, orientation, the location from a reference point have a nominal size that machinists target.

On a drawing, they are shown within a box. It may be shown as a number or from a popular standard such as ASME.

Feature control frame

This frame contains information about part specifics. It contains various compartments where each compartment defines a specific attribute of the part feature. In one look, the feature control frame conveys the information required for machining and inspection.

The feature control frame can be divided into 4 main parts as follows.

Leader arrow

This arrow marks the part feature under control. If it leads to a surface, the surface is under geometric control. If it marks a diametric dimension, then GD&T controls the axis. This arrow may not be present in some cases.

Geometric characteristic symbol

The first compartment (starting from the left) contains the geometric characteristic symbol. This is where we specify the geometric characteristic. In total, there are 14 types of geometric tolerances based on the number of symbols, and 15 when classified.

The different types of geometric characteristics are form control, profile control, location control, orientation control, etc. We will dive deeper into each category later on.

Feature tolerance compartment

The 2nd block contains a maximum of 3 (sometimes 2 or 1) different symbols.

The first symbol shows the type of tolerance zone. A diameter symbol (⌀) signifies a diametric zone (cylindrical tolerance zone). To specify a spherical zone, the symbol is the letter 'S' followed by the diameter symbol (⌀). In the absence of a symbol, we assume a total wide zone.

The second symbol in the 2nd block gives the value of the tolerance zone in mm. This value must always be present in the 2nd block.

The third symbol in this block is the modifier for tolerance. This material modifier is only present when the feature has a size, for instance, a hole. Examples of material modifiers are MMC (Maximum material condition) and LMC (Least material condition). More information on the various modifiers available will be discussed further in the article.

The third block gives information about the datum(s) with a minimum of 1 and a maximum of 3 datums. In the case of 3 datums, they are referred to as primary, secondary, and tertiary datums with each being shown enclosed in a different box (the image above has 2, for example). This block may also contain a material modifier.

All the information above helps us to understand how to read a feature control frame. In order to better understand how tolerance can be adjusted using material condition modifiers, we need to be familiar with the different options.

Material Condition Modifiers

Material condition modifiers convey the intent when tolerance applies to a feature at a specific feature size. Whenever we give tolerances to any feature, it establishes two material conditions

Maximum material condition

Least material condition

Consider a shaft of diameter 100 mm. When manufacturing, if we give it tolerance of ±0.2 mm, then at 100.2 mm, the shaft will contain the maximum amount of material. This is what we mean by the maximum material condition.

On the other hand, the same shaft, when manufactured with a diameter of 99.8 mm, will contain the least amount of material. These limits are called material conditions.

The geometric tolerances can be applied to a feature in 3 different ways. These are as follows:

Maximum material condition

Least material condition

Regardless of feature size

Maximum material condition modifier

We represent this condition by a circled "M" after the tolerance value in the feature control compartment. The feature contains the maximum material at this feature size.

For external FOS (Feature Of Size), such as the diameter of a shaft, MMC represents the largest size. For internal FOS, such as the diameter of a hole, MMC represents the smallest possible size within stated tolerance limits because a smaller hole means that more material will be left.

When we need to apply geometric tolerance at the maximum material condition, we mention this condition in the feature control frame.

Least material condition modifier

LMC is the condition where the material contains the least amount of material.

For external FOS, it will be the smallest possible size within stated limits. And for internal FOS, it will be the largest possible size.

We represent this modifier with the letter "L" in a circle. This feature removes excessive material and thus weight. To apply geometric tolerances at this condition, we use its symbol in the feature control frame.

Regardless of Feature Size (RFS)

When the given geometric tolerances are applied at any increment of size of FOS, we indicate this by RFS. The symbol for RFS was the letter "S" enclosed in a circle but it is no longer needed as RFS is considered the default condition now, and does not need a symbol.

Datums and Feature Callouts

Datums are reference points for measuring dimensional tolerances. It could be a point, a line, or a plane. With the help of a datum, we establish Datum Reference Frames (DRF). The DRF is basically a 3D coordinate system that helps us define the positions of all other features with respect to the DRF.

There are 6 degrees of freedom (3 translational and 3 rotational) that we need to control to manufacture and inspect parts effectively. We use DRF to establish these degrees of freedom.

Datum features are the actual part features such as holes and slots. They can show variation from desired positions.

Among all the datum features, we give the highest preference to those that mate with other parts in the assembly. We can mention more than one datum in our feature control frame. As per the sequence of the DRFs in the feature control frame, the parts are mated to the DRFs in decreasing order of importance.

GD&T Symbols

Up to 14 GD and T symbols are available to represent different geometric characteristics of features. These symbols help us to specify these characteristics as requirements for the final product.

We place these symbols in the first compartment of the feature control frame. We shall look at these types of tolerance control.

Form control

As the name suggests, form control relates to the final form or shape of the feature. We define form controls to limit the deviation of the geometric tolerance from its ideal form. Some popular form control characteristics are as follows.

Straightness

To indicate the straightness characteristic of a feature (such as an axis or a surface), we use its symbol (a straight horizontal line) in the first compartment.

Surface straightness can apply to flat surfaces like a side of a block or curved surfaces like a side of a cylinder along the direction of the axis. It defines the allowable variation of a line (2 dimensions) on the surface within a specified tolerance.

Axial straightness usually applies to the axis of a shaft or a hole, for example. Go/no go gauge is the inspection tool used in the process of making sure the part conforms to the demands.

We use this characteristic for features such as the face of a part. The symbol for flatness is a parallelogram tilted to the right. The difference between the highest and lowest point of a flat surface is its flatness.

The flatness symbol does not require any datums, as it only shows a tolerance range within which the whole surface of a part must conform to in 3 dimensions.

A height gauge is used for checking the results. It touches upon different areas of the surface to determine that all the points are inside the tolerance zone.

Circularity

The circularity (GD&T) of a feature shows how close the circumference of the part should be to a perfect circle. It uses 2 concentric circles on a plane perpendicular to the part axis to define the suitable tolerance range in 2D. Each point of the final measurements has to fall between the circles.

This characteristic is shown as a circle in the first compartment of the feature control frame.

Cylindricity

Cylindricity is basically circularity in 3D, meaning that it runs along the whole length of the part.

This feature also describes other cylindrical characteristics such as its taper, straightness, and roundness. This is why this feature is also expensive to inspect.

Profile Controls

We use profile controls to control the 3D tolerance zone around the feature. This feature helps us to give tolerance limits to advanced curves and shapes.

A feature that is good for advanced curves must naturally work well with simpler curves as well. This makes profile controls extremely versatile. This is why some designers recommend abandoning all other controls and working only with profile controls.

These controls form a tolerance limit around the advanced curve by mimicking it on both sides. It then prevents any point on the feature curve from going outside the tolerance limit. Profile controls are of two types.

Line profile

Line profile establishes a tolerance zone around varying 2D cross-sections of the part. It controls individual line elements of a part feature.

The line profile control traces the ideal curve at the tolerance limits on both sides. All points on the part's curve must lie within these limits.

Surface profile

Surface profile control is more popular compared to line control. Instead of a two-dimensional tolerance zone, the surface profile control creates a 3D zone around a surface.

All points on the table's surface must lie within the two virtual planes.

Orientation Controls

Orientation tolerance controls the orientation of a feature with respect to a defined datum. There are three types of orientation controls in GD&T.

Angularity

The angularity control keeps the angle of a feature with respect to the datum in check. We can use it to control a 2D line, but it is more popular with keeping surfaces (3D) under control.

This kind of tight control keeps the angle and the surface flatness in check and is recommended for part features that mate with other parts through the angled surface.

It is important to note that the angularity feature controls the angle indirectly, not being essentially the same as an angular tolerance (e.g. +/- 2°). Rather, the necessary angle is a result of keeping to the dimensional requirements laid out by this control.

Parallelism

Parallelism is a refined form of angularity. Here, the datum is the surface we need to imitate and the angle is set to 0°. There are 2 types of parallelism: surface parallelism and axis parallelism.

We can choose an axis or a surface as a reference. This becomes our datum and we reference it in the 3rd block of the feature control frame as the datum for the feature.

Similarly to angularity, it does not control the actual angle but rather secures it by laying out the requirements in the form of a tolerance zone.

Perpendicularity

Perpendicularity is also a specific form of angularity where the angle is set to 90°. It is a tricky control since it can mean two very different types of requirements.

There's surface perpendicularity ( Symbol:⟂), and then there's axis perpendicularity (Symbols: ⟂+⌀).

Surface perpendicularity specifies that a surface or line needs to be perpendicular to a datum surface or line much like angularity. Two virtual planes/lines are assumed around the target surface for control.

Axis perpendicularity specifies how perpendicular an axis needs to be to the mentioned datum. This is done by erecting a virtual cylinder around the target axis on a surface exactly parallel to the datum surface.

Location Controls

The Location tolerance control is used for tight control on a feature's position with respect to a datum. There are four main types of location controls.

Concentricity

Concentricity, also known as coaxiality (even though not exactly the same thing), control maintains the concentricity of circular as well as cylindrical features.

It fixes the axis of a part to the axis of a referenced feature (datum axis). The axes of both parts are determined to be at the median points of the parts.

This control can lead to some confusion because the axes derive from outside measurements, rather than their actual placement.

Coaxiality creates a 3D tolerance zone based on surface measurements that the part must lie in.

The symmetry callout establishes a central plane around which the two parts of the feature are placed at equal distance. The midpoint of the two points on either side must lie within the tolerance zone set around the central plane.

The symmetry callout is not very common. It has very limited uses and is also difficult to inspect. We need a CMM to inspect the final symmetry.

True position

True position (popularly known as position) is a very useful callout and finds extensive use in GD&T.

Position defines how much the actual position of a feature can vary from its intended position. The definition includes the datum plane which the measurement relates to.

It often includes a diametrical sign (⌀) to highlight that the tolerance zone is a circle, rather than just X and Y axis (which we talked about at the start of the article as being the reason for creating GD&T in the first place).

Here is a great video showing how to use the tolerances on a drawing, using true position:

Runout Controls

We use the runout controls to measure the deviation of a part feature from its assigned position with respect to an established datum. This control is used for circular features. It essentially measures its wobble by rotating the feature about the fixed datum.

There are two types of runout control.

Circular runout

Circular runout works in two dimensions to control the form, location, and orientation of various part features. This 2D callout needs us to assign it a datum axis to check these features.

In GD&T jargon, circular runout is commonly known as runout. Runout measures the deviation in the surface elements by rotation.

Meaning that the shaft, for example, is rotated by its datum axis and the featured element is measured for tolerance. In essence, it limits the vibration of a working shaft to ensure a longer lifetime for connected parts like bearings.

Total runout

Total runout is the 3D counterpart of circular runout. It controls form, location, and orientation as well. But instead of checking individual cross-sections (as in circular runout), it checks the entire surface. Thus, using total runout gives us stricter control on the feature's characteristics.

Inspection

In all industries, the failure of the manufacturing process to meet design specifications can be problematic. While in some cases, customers' lives may be at risk, in other cases, a product recall could lead to huge monetary losses.

Even if the results are not that bad, a company's reputation relies heavily on the quality of its products and services.

GD&T standardises the inspection process by bringing inspectors in on the same platform as the designer. This eliminates a lot of obstacles. But GD&T is a vast subject.

As we have seen, there are a number of different geometric characteristics, each very different from another, that can be controlled with GD&T. Due to this disparity, the inspection of each characteristic requires a specific method, tool, and skill.

Some of these characteristics can be measured with the simplest of tools while others are impossible to measure without advanced equipment such as a coordinate-measuring machine (CMM).

Inspectors will need the knowledge and skill to use various measurement tools such as dial gauges, micrometres, vernier callipers, surface plates, and coordinate-measuring machines to inspect the accuracy of parts satisfactorily.

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Geometric Dimensioning & Tolerancing (GD&T) Symbols & Basics

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Engineers use CAD software to design all the necessary parts and components for the project. In the digital realm, it is easy to attain perfection. In real life, manufacturing is never 100% accurate. Sometimes, deviations of a few millimetres from the basic dimensions can be absolutely fine.

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Before GD&T, manufacturing features were specified by X-Y areas. For example, when drilling a mounting hole, the hole had to be within a specified X-Y area.

An accurate tolerancing specification, however, would define the position of the hole in relation to the intended position, the accepted area being a circle. X-Y tolerancing leaves a zone in which inspection would have produced a false negative because while the hole is not within the X-Y square, it would fall within the circumscribed circle.

Stanley Parker, an engineer who was developing naval weapons during World War II, noticed this failure in 1940. Driven by the need for cost-effective manufacturing and meeting deadlines, he worked out a new system through several publications. Once proven as a better operational method, the new system became a military standard in the 1950s.

Currently, the GD&T standard is defined by the American Society of Mechanical Engineers ( ASME Y14.5-2018) for the USA and ISO 1101-2017 for the rest of the world. It concerns mostly the overall geometry of the product, while other standards describe specific features such as surface roughness, texture, and screw threads.

With functional assemblies, multi-part products, or parts with complex functionality, it is crucial that all components work well together. All relevant fits and features need to be specified in a way that impacts the manufacturing process and its related investments the least, while still guaranteeing functionality. Tightening tolerances by a factor two can raise the costs twofold or even more, due to higher reject rates and tooling changes. GD&T is the system that allows developers and inspectors to optimize functionality without increasing cost.

The most important benefit of GD&T is that the system describes the design intent rather than the resulting geometry itself. Like a vector or formula, it is not the actual object but a representation of it.

For example, a feature standing at 90 degrees to a base surface can be toleranced on its perpendicularity to that surface. This will define two planes spaced apart, that the center plane of the feature must fall within. Or, when drilling a hole, it makes the most sense to tolerance it in terms of alignment to other features.

Describing product geometry related to its intended functionality and manufacturing approach is ultimately simpler than having to describe everything in linear dimensions. It also provides a communication tool with manufacturing vendors, customers, as well as quality inspectors.

When performed well, GD&T even allows statistical process control (SPC), reducing product reject rates, assembly failures, and the effort needed for quality control, saving organizations substantial resources. As a result, multiple departments are able to work more in parallel because they have a shared vision and language for what they want to achieve.

Engineering drawings need to show the dimensions for all features of a part. Next to the dimensions, a tolerance value needs to be specified with the minimum and maximum acceptable limit. The tolerance is the difference between the minimum and maximum limit. For example, if we have a table that we would accept with a height between 750 mm and 780 mm, the tolerance would be 30 mm.

However, the tolerance for the table implies that we would accept a table that is 750 mm high on one side and 780 mm on the other, or has a waved surface with 30 mm variation. So to appropriately tolerance the product, we need a symbol communicating the design intent of a flat top surface. Therefore we have to include an additional flatness tolerance in addition to the overall height tolerance.

Similarly, a cylinder with a toleranced diameter will not necessarily fit into its hole if the cylinder gets slightly bent during the manufacturing process. Therefore it also needs a straightness control, which would be difficult to communicate with traditional plus-minus tolerancing. Or a tube that has to seamlessly match a complex surface that it's welded to requires a surface profile control.

GD&T establishes a library of symbols to convey such design intents, which we discuss in the following section.

The art of tolerancing means to specify just the right variations for all specific design features in order to maximize product approval rate within the limits of the manufacturing processes and depending on the part's visual and functional purpose.

In the metric system, there are International Tolerance (IT) grades that can also be used to specify tolerances by means of symbols. The symbol 40H11, for example, means a 40 mm diameter hole with a loose running fit. The manufacturer then only needs to look up the basis table for hole features to derive the exact tolerance value.

Besides individual tolerances, engineers must take into account system-level effects. For example, when a part comes out with all dimensions at their maximum allowed value, does it still meet overall requirements such as product weight and wall thicknesses? This is called the Maximum Material Condition (MMC), while its counterpart is the Least Material Condition(LMC).

Tolerances also stack up. If we create a chain link where each hole has a 0.1 mm plus tolerance and each shaft a 0.1 mm negative tolerance, that means we will still accept a 20 mm length difference at 100 links. When installing repeated elements such as a perforated hole pattern, first position the pattern and then specify interrelated distances rather than referencing elements to a fixed edge or plane of the part.

The standards do not only pertain to designers and engineers but also to quality inspectors by informing them how to measure the dimensions and tolerances. Using specific tools such as digital micrometers and calipers, height gauges, surface plates, dial indicators, and a coordinate measuring machine (CMM) are important to tolerancing practice.

When measuring and defining a part, the geometry exists in a conceptual space called the Datum Reference Frame (DRF). This is comparable to the coordinate system at the origin of a space in 3D modeling programs. A datum is a point, line or plane that exists in the DRF and is used as a starting place for measuring. Make sure to define the datum features relevant to the functionality of your part. Unless you are mating features of one part to those of others in an assembly, you can often use a single datum. Always make sure that the primary datum has a reliable location to derive other measurements from, for example, where the final part will have little unpredictable variation.

An engineering drawing has to accurately convey the product without adding unnecessary complexity or restrictions. The following guidelines are helpful to consider:

Clarity of a drawing is the most important, even more so than its accuracy and completeness. To improve clarity, draw dimensions and tolerances outside of the part's boundaries and applied to visible lines in true profiles, employ a unidirectional reading direction, convey the function of the part, group and/or stagger dimensions, and make use of white space.

Always design for the loosest feasible tolerance to keep costs down.

Use a general tolerance defined at the bottom of the drawing for all dimensions of the part. Specific tighter or looser tolerances indicated in the drawing will then supersede the general tolerance.

Tolerance functional features and their interrelations first, then move on to the rest of the part.

Whenever possible, leave GD&T work to the manufacturing experts and do not describe manufacturing processes in the engineering drawing.

Do not specify a 90-degree angle since it is assumed.

Dimensions and tolerances are valid at 20 °C / 101.3 kPa unless stated otherwise.

GD&T is feature-based, with each feature specified by different controls. These tolerancing symbols fall into five groups:

Form controls specify the shape of features, including:

Straightness is divided into line element straightness and axis straightness.

Flatness means straightness in multiple dimensions, measured between the highest and lowest points on a surface.

Circularity or roundness can be described as straightness bent into a circle.

Cylindricity is basically flatness bent into a barrel. It includes straightness, roundness, and taper, which makes it expensive to inspect.

Profile controls describe the three-dimensional tolerance zone around a surface:

Line Profile compares a two-dimensional cross-section to an ideal shape. The tolerance zone is defined by two offset curves unless otherwise specified.

Surface Profile creates through two offset surfaces between which the feature surface must fall. This is a complex control typically measured with a CMM.

Orientation controls concern dimensions that vary at angles, including:

Angularity is flatness at an angle to a datum and is also determined through two reference planes spaced the tolerance value apart.

Perpendicularity means flatness at 90 degrees to a datum. It specifies two perfect planes the feature plane must lie in between.

Parallelism means straightness at a distance. Parallelism for axes can be defined by defining a cylindrical tolerance zone by placing a diameter symbol in front of the tolerance value.

Location controls define feature locations using linear dimensions:

Position is the location of features relative to one another or to datums and is the most used control.

Concentricity compares the location of a feature axis to the datum axis.

Symmetry ensures that non-cylindrical parts are similar across a datum plane. This is a complex control typically measured with a CMM.

Runout controls define the amount by which a particular feature can vary with respect to the datums:

Circular Runout is used when there is a need to account for many different errors, such as ball-bearing mounted parts. During inspection, the part is rotated on a spindle to measure the variation or 'wobble' around the rotational axis.

Total Runout is measured on multiple points of a surface, not just describing the runout of a circular feature but of an entire surface. This controls straightness, profile, angularity, and other variations.

The Feature Control Frame is the notation to add controls to the drawing. The leftmost compartment contains the geometric characteristic. In the example above, it is a location control but it can contain any of the control symbols. The first symbol in the second compartment indicates the shape of the tolerance zone. In this example, it is a diameter as opposed to a linear dimension. The number indicates the allowed tolerance.

Next to the tolerance box, there are separate boxes for each datum feature that the control refers to. Here, the location will be measured related to datum B and C. Next to the tolerance or a datum feature is an optional encircled letter, the feature modifier.

The following possibilities can occur:

M means that the tolerance applies in the Maximum Material Condition (MMC)

L means that the tolerance applies in the Least Material Condition (LMC)

U indicates an unequal bilateral tolerance, i.e. for a 1 mm tolerance it may specify it as minus 0.20 and plus 0.80.

P means that the tolerance is measured in a Projected Tolerance Zone at a specified distance from the datum.

No symbol installs the tolerance regardless of feature size (RFS)

For this example, if the part is not in MMC, a bonus tolerance can be added proportionally to the deviation from MMC. So if a part is at 90% MMC, the tolerance will also loosen by 10%.

Many product designers and engineers use 3D printing during prototyping and product development to produce cost-effective prototypes and custom parts that would otherwise require significant investment in tooling.

Tolerancing in 3D printing differs from traditional manufacturing tools because 3D printing is a single automated process. Tighter tolerances may require more effort in the design stage, but can yield significant time and costs savings in prototyping and production.

Most CAD tools aimed at mechanical engineering such as SolidWorks, Autodesk Fusion 360, AutoCAD, SolidEdge, FreeCAD, CATIA, NX, Creo, and Inventor offer GD&T integration when creating engineering drawings. However, designers still have to install tolerances manually, taking into account the possible deviations that occur during the manufacturing process. In the following case study, we show an example of GD&T in use in SolidWorks.

This specific project aims to produce 50,000 bottle caps through injection molding. We want to control the feel and force with which the caps will fit onto the bottle and therefore require good tolerancing specification. We want to prevent that some caps are larger in outer diameter than the bottle, while others are smaller, and retain a consistent running fit instead.

The bottle's thread has an outer diameter of 36.95 +/- 0.010 mm. That means the limits of the cap's inner diameter are 36.985 and 37.065 mm, with a mean value of 37.0 mm.

The cap also has specific hole connections to an axle that is mounted underneath a flat surface. This allows the bottle to be opened with one hand while it hangs underneath the surface of a storage cabinet. The axle is a standard OEM stainless steel component with a 4mm diameter and 0.13mm (0.005") tolerance. For a snug connection, we require a force fit with an allowance between -0.0375 and 0.0125 mm. Here we find a range of 3.99 to 4.01 mm for the hole diameter that results in a force fit for all axle sizes. Because this is such a narrow range we decide to specify the hole at 3.85 mm then drill it to an exact 4.00 mm which also controls concentricity of the two holes.

To control our dimensions properly, we need to make use of a datum. A datum needs to represent mating features and function of the assembly, plus it needs to be stable, repeatable, and accessible. In this case, the mating of the cap and bottleneck are most important, so we choose the cap's inner cylindrical surface as the primary datum. The secondary function is the mating with the mounting surface, so we pick the flat top of the cap as the secondary datum.

After considering the requirement, implementing GD&T tolerancing in Solidworks works as follows. Indicate the datums in DimXpert > Auto Dimension Scheme and select the Geometric option as opposed to Plus/Minus tolerancing. Then select the datums and features to control based on the datums. With the Dimension Scheme completed, add individual Geometric Tolerances and GD&T symbols. The software automatically generates dimensions for features-of-size (FOS), such as holes and bosses. Make sure to select 'bilateral' or 'limit' as tolerance type for features where the plus and minus limit are unequal.

To import these tolerances into an engineering drawing, first, check the FeatureManager for which planes are used in the 'Annotations' folder. When importing the views from these planes into a drawing, check 'Import annotations' and 'DimXpert annotations'. Adding an appropriate section view will greatly clarify the drawing.

In this guide, we have discussed the system of Geometric Dimensioning and Tolerancing (GD&T), which brings tremendous benefits for designers and engineers working on complex products where dimensions need to be tightly controlled. We have seen how GD&T conveys not only linear dimensions but also design intent, which helps communicate the engineering design more clearly to project stakeholders.

With just over a dozen symbols, the datum feature, and feature control frame, it is possible to highly enrich production drawings and ensure that engineering fits remain consistent across product assemblies. GD&T also invites developers to think about how to optimally tolerance their parts for the chosen manufacturing process, since different production techniques bring along different characteristic deviations.

Companies across aerospace, automotive, defense, consumer goods, medical, and more are adopting digital manufacturing tools to take steps towards the promise of Industry 4.0. 3D printing is a catalyst for efficiency, giving staff from production engineer to machinist the tools to tighten supply chains, improve production, and get to market faster-saving hundreds of thousands of dollars and weeks to months of time along the way.

Learn more about how leading manufacturers like Tesla, General Electric, and Dyson leverage 3D printing to save money and shorten lead times from design to production.

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The Basics of Geometric Dimensioning and Tolerancing (GD&T)

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Before GD&T, manufacturing features were specified by X-Y areas. For example, when drilling a mounting hole, the hole had to be within a specified X-Y area. An accurate tolerancing specification, however, would define the position of the hole in relation to the intended position, the accepted area being a circle.

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1.5 PRINT FOLDING FORMAT

SECTION 2 - Unigraphics Practices

SECTION 3 - AutoCAD PRACTICES

SECTION 4 - PREFERRED LIMITS AND FITS FOR CYLINDRICAL PARTS

4.5 RECOMMENDED TOLERANCE SYSTEM

SECTION 5 - DRAWING NUMBERS AND REVISIONS

SECTION 6 - GENERAL DIMENSIONING AND TOLERANCING

6.3 GENERAL DIMENSIONING RULES

6.4 UNITS OF MEASUREMENT

6.5 APPLICATIONS OF DIMENSIONS

6.7 GENERAL TOLERANCING RULES

SECTION 7 - SURFACE FINISH

7.1 INTRODUCTION AND SCOPE

7.2 APPLICABLE DOCUMENTS

7.3 DEFINITIONS AND TECHNICAL ISSUES

SECTION 8 - WELDS AND WELD SYMBOLIZATION

SECTION 9 - SCREWS, NUTS AND WASHERS

9.6 DRAWING REPRESENTATIONS

9.7 SUSPECT/COUNTERFEIT PARTS

SECTION 10 - FACILITIES DESIGN STANDARD

10.4 DRAWING SCALE PROVISIONS/NOMENCLATURE

10.8 MANUAL DRAWN DETAILS, SECTIONS, ELEVATIONS, FLOOR PLANS, ETC.

10.11 CADD COMPATIBILITY

10.15 REVISIONS AND MODIFICATIONS

10.16 FACILITY DOCUMENT NUMBER

10.18 SECTION AND DETAILING NOMENCLATURE

10.20 ELECTRONIC DRAWING REVIEW

10.21 FINAL SUBMITTAL OF DRAWINGS

SECTION 11 - DETAILED CHECKING PROCEDURE

11.2. Checking practice will be as follows:

This section defines general rules and practices to be followed by all
designers and drafters to produce design drawings of consistent and
professional quality. The contents of this section are intended to be
consistent with various American national standards listed in . Because of the broad scope of the design and drafting activities and
the need for an accurate interpretation of the drawings produced, any use of
special or local practices is strongly discouraged.

1.2.1 All drawings shall comply with rules and guidelines for
dimensioning and tolerancing given in Section 6.

1.2.3 Each detail shall be drawn on a separate sheet except for
tooling, weldments, and architectural drawings.

(a) Specific materials called for by name,
identifying number, and specification.

(b) Material hardness and hardness depth.

(c) Annealing or stress relieving.

(d) Surface finish symbols.

(e) Weld symbols with joint sizes and other
requirements (See Section 8).

(f) Testing specifications, such as pressure
tests, vacuum tests, dye penetrant tests, magna-flux tests, radiographic tests,
etc.

(g) Finish specifications such as painting,
plating, etc.

(h) Brazing specifications.

(i) Calculated weight for heavy components. In
special cases add provisions for lifting.

(j) Identification of all assemblies with the
drawing number.

1.2.5 Sub-assemblies, in general, are to be drawn in the same
orientation as their assembly.

1.2.6 Dimensions given are to be the ones used to fabricate, inspect,
and match other parts.

1.2.8 All drawings are to be brought up to date and revisions noted
in the revision block (see Section 7).

1.2.11 The use of multiple sheet drawings should be avoided if
possible. If multiple sheet drawings must be used they must all have the same
log number and document number listed in title blocks. All sheets must have the
same title listed in title blocks. All sheets must be of the same size and
scale. When revising multiple sheet drawings, the revision levels (i.e., the
last two (2) digits of the log number and document number) must be updated on
all sheets.

1.2.14 No symbols are to be used unless otherwise approved or
specified in national standards.

1.2.15 All characters height will be .13. All sectionals, views, and
identifiers text will be .25 in height and may be in BOLD characters.

1.2.16 All title block titles will reflect the W. B. S. titles
description on the first four (4) or less of the title block.

1.3.1 All drawings shall be produced using the "third angle
orthographic projection" system. The third angle system is preferred as
the American standard because the views are the same as those obtained by
observing the object from the front, top, side, or rear as indicated by
directional arrows in . The arrangement of typical views is shown in . A minimum number of views, necessary to completely describe the
object, shall be used.

1.3.2 Sectional views shall be placed as close as practical behind
the arrows, showing the shape and construction of the object at the cutting
plane (see ).

If it becomes necessary to rotate a sectional view, the degree of rotation
and direction are specified.

A sectional view must be identified by its title consisting of the full word
SECTION followed by the pair of letters; for example, SECTION A-A, SECTION
B-B, etc. Avoid use of letters I, O, Q, S, X, Y and Z for sectional views.
Lettering shall be upper case.

1.3.3 Detail views shall be shown in the same plane and in the same
arrangement as in the principal view. Two ways of identifying the area of
detail are shown in . The view scale is specified directly below the view (and its title).

For general use a cross-section lining symbology depicting cast iron (see ) shall be used on detail and assembly drawings, regardless of actual
material. When two or more materials must be identified individually in a
drawing, use the material-specific symbology of the latest ANSI Standards
wherever applicable.

For ease of handling and filing, prints shall comply with the folding format
depicted in . Final folded will be approximately 8.5 inch vertical x 11.0 inch
horizontal.

1.6.1 In general, drawings will be reviewed for general compliance
with the following:

a. Established standards

b. Manufacturing feasibility

c. Dimensional tolerance considerations

d. General Safety practice

e. Simplicity

f. Economy

g. View alignment

h. Scale

i. Materials

j. Fit of mating parts

The purpose of this section is to outline general AutoCAD practices that
have been implemented to promote drafting efficiency, and access and
portability of the design drawings.

3.2.1 All drawings produced on the AutoCAD system shall comply with
the applicable ANSI standards and the standards not included in this manual.
3.2.2 Access to the AutoCAD system will be unless specifically exempted by the
Supervisor, or the responsible engineer.

3.2.3 A new drawing shall be initiated by downloading a standard
formatted blank drawing (via AutoEDMS) containing APS-designated title block
and border. An appropriate size FORMAT scaled to fit the drawing's requirements
shall be used. Do not explode the FORMAT.

3.2.4 Use of multiple sheets in a single electronic file should be
avoided. See Section 1.2.11.

3.2.5 Drawings shall be created with all features in full size, drawn
at 1:1 scale.

3.2.6 The drawing coordinates x,y = 0,0 shall be on lower left corner
of the screen.

3.2.7 Associative dimensioning shall be used. The only exception will
be when the parts must show break lines.

3.2.8 All text shall be in ROMANS vertical font, (not slanted).
Character height will be .13 or multiples of dependent on drawing scale.

3.2.9 All dimensioning symbols will be of standard shapes and sizes.
An electronic file of the symbols will be provided by the D&D Supervisor.
Refer to latest ANSI Standards in Dimensioning and Tolerancing Book, Appendix
C, Figure C-1.

3.2.10 Hatch patterns available in the standard version of AutoCAD
shall be used. (C.I. is preferred when nothing else applies).

3.2.11 Colors and line types shall be assigned by layers in all new
drawings. The layers shall be identified by names, rather than by numbers as in
the existing drawings. This will ensure the layers' uniformity in the new
drawings without causing conflict when old drawings are imported. The layers
shall be identified as follows:

3.2.12 Color number 0 (zero) shall be reserved for transporting files
and inserting blocks.

3.2.13 The line width for each layer shall remain fixed. Refer to
latest ANSI Standards for more information. (see Figure 3.3).

3.2.15 Dimension styles and its variables have built-in default
values. These values should not be changed or modified except for the length
scale factor, which may be modified for auxiliary views and section views,
depending on their scale.

A tolerance is the total by which a specific dimension may
vary.

The basic size is that diameter to which allowances and
tolerances are applied to achieve the limits of size for shaft and hole.

A clearance fit is one having limits of size so
prerscribed that a clearance always results when mating parts are assembled.

4.4.1
RC Running or Sliding Fits: (
RC 2. Sliding Fits are intended for
accurate location but with greater maximum clearance than class RC 1. Parts
made to this fit move and turn easily but are not intended to run freely and in
the larger sizes may seize with small temperature changes.

RC 3. Precision Running Fits are about the
closest fits which can be expected to run freely. They are intended for
precision work at slow speeds and light journal pressures, but are not suitable
where appreciable temperature differences are likely to be encountered.

RC 5. Medium Running Fits are intended for
higher running speeds or heavy journal pressures or both.

RC 6. Medium Running Fits are intended for
applications where more play than RCS is required.

LC 1 through LC 11 Transition Fits are intended for parts which are
normally stationary but which can be freely assembled or disassembled. They run
form snug fits for parts requiring accuracy of location, through the medium
clearance fits for parts such as spigots, to the looser fastener fits where
freedom of assembly is of prime importance.

LN 2 and LN 3 Locational Interference Fits are used where accuracy
of location is of prime importance, and for parts requiring rigidity and
alignment with no special requirements for bore pressure. Such fits are not
intended for parts designed to transmit frictional loads from one part to
another by virtue of the tightness of fit, as these conditions are covered by
force fits.

FN 3 Heavy Drive Fits are suitable for heavier steel parts or for
shrink fits in medium sections.

FN 4 Force Fits are suitable for parts which can be highly stressed
or for shrink fits where the heavy pressing forces required are impractical.

The unilateral system of tolerance is recommended, in which the tolerance on
each part (shaft and hole) is disposed in only one direction from the design
size, plus for the hole and minus for the shaft. See
Example

_________________________

This section describes various drawing numbers and their use on the student
drawings. The drawing numbers are assigned and controlled by the system
specified by the instructor.

5.2 DRAWING NUMBERS
The following drawings numbers are presently in use: 5.2.1 Number A log number is a seven (7) digit number preceded by a letter (letter A
at present), that is assigned to the drawing by the DCC upon written request.
This number is assigned sequentially to the drawings as well as other APS
documents. The log numbers often appear to be at random on related drawings
when the requests for numbers are not submitted at the same time. Once a log
number is assigned to a drawing, it never changes except for its revision level
designation, (i.e., its last two (2) digits). (The last two (2) digits are for
revision designation and should coincide with the revision level of the
document number). 5.2.2 Document Number The multiple-digit WBS number, explained in "Document Control Center, Hands-on Guide for APS Users," identifies a major component assembly of
the APS Project. The six-digit LDN is composed of three (3) two-digit sequences
(see ), representing (from left to right) a sub-assembly, a sub-sub-assembly,
and a part. Figure 5.1 illustrates how this hierarchical breakdown is used for
a photon shutter assembly. In order to avoid any conflict with the old design numbers not based on
LDN, the number zero is not allowed in the first digit (left most) of the LDN.
This ensures that the assigned number will always be different from the old
numbers which contained only five (5) digits. 5.2.3 Prototype Drawing Number
and incrementing the revision number.
5.2.4 Sketch Number The use of sketch numbers on the APS production drawings is not to be
used. Asof January 1996 sketch numbers will no longer be used. 5.2.5 Electronic File Number The Experimental Facilities Division (XFD) uses electronic file numbers
in its Design Exchange System, which is being set-up to exchange design
drawings of standard components between XFD, beamline users, and other outside
organizations. An electronic file number consists of a descriptive identifier
of field length two (2) followed by the logical numbering sequence (LDN)
explained above in sub-section 5.2.2. The descriptive identifier essentially
replaces the long WBS number. Its first field is a letter which represents a
component group, and the second field is a number assigned sequentially to
different components of that group. As an example, an existing APS Drawing Number 1415972-810000-00,
consisting of WBS 1.4.1.5.9.7.2, LDN 810000, and revision 00, is identified as
V2810000 in the Design Exchange System.
5.3.4 Revision Symbol - A revision symbol is an identifying
number, enclosed in an equilateral triangle as shown in . Revision symbols shall be used to locate the revision in the field of
the drawing. To avoid crowding of revision symbols, a single revision symbol
may be used to identify the changes if they are properly identified and
described in the (DCN).

5.3.7 Revising a Change - Whenever a change is revised, a
new symbol shall be placed next to the previous one.

5.3.8 Revision Block - Each revision shall be recorded in
the revision block of the drawing (see ) showing (1) revision symbol, (2) the DCN number, (3) initials of the
person making the change, (4) signed initials of the person authorizing the
change, and (5) date of the revision.

Excerpts of ANSI Y14.5M-82 are included in this design manual as Appendix
6-A. For a quick reference, only the most commonly used dimensioning and
tolerancing requirements are outlined below.

6.2.4 Basic Dimension. A numerical value used to describe
the theoretically exact size, profile, orientation, or location of a feature or
datum target. It is the basis from which permissible variations are established
by tolerances on other dimensions, in notes, or in feature control frames.
Basic dimensions are shown on the drawing in enclosed rectangle.

A datum is the origin from which the location
or geometric characteristics of features of a part are established.NOT
A CENTERLINE.

6.2.10 Feature. The general term applied to a physical
portion of a part, such as a surface, hole, or slot.

6.3.1 Dimensioning of parts must convey enough information to define
clearly the engineering intent, so that no scaling of drawings is required, nor
any assumptions need to be made. Functional dimensional values is the preferred
method.

6.3.4 Dimensions shall be selected and arranged to avoid accumulation
of tolerances.

6.3.5 Dimensions are shown on the view that most clearly represents
the form of the feature being dimensioned.

6.3.6 Dimensions are shown outside the outline of the part unless
clarity is impaired.

6.3.7 Dimensioning to hidden lines shall be avoided.

6.3.8 Dimensions must be selected to give the required information
directly so that no calculations are needed to arrive at usable figures.

6.3.10 Dimensions out of scale shall be avoided.

6.3.11 Unidirectional dimensioning is to be used, that is, all
dimensions and notes should be aligned with the bottom of the drawing.

6.4.1 All drawings produced by students shall use the inch as the
unit of measurement as per ANSI Y14.5.

Dimensions are applied with dimension lines or as notes with leaders.
Dimension lines indicate linear distance between feature centers or surfaces
directly or by the use of extension lines (see ).

Dimensional tolerances may be expressed as follows:

6.6.1 Title Block Tolerancing - The tolerances are specified
in the title block and depend on the number of decimal places used in the basic
dimension ().

6.6.2 Limit Tolerancing - The high (maximum) value of a
dimension is placed above the low (minimum) value as shown in .

6.6.3 Plus and Minus Tolerancing - The basic dimension is
followed by plus and minus tolerance values ().

6.6.4 Geometric Tolerancing - The tolerances are defined by
means of a Feature Control Frame () which specifies dimensional limits for an individual geometric feature
such as location, orientation, form, profile and runout. The Feature Control
Frame is divided into several compartments containing (1) geometric
characteristic symbol (which is, when applicable, preceded by a diameter
symbol), and (3) datum references as needed.

Symbols used for geometric tolerances are shown in . These symbols can be down-loaded from a CAD file available from the
design room supervisor.

shows typical uses of geometric tolerances on a drawing.

6.7.1 Tolerances shall be assigned, directly or as default values, to
all dimensions in a drawing.

6.7.2 Title block default tolerances shall be used whenever feasible
or modified for the drawing requirements.

6.7.6 Tolerances shall have the same number of decimal places as the
base dimensions, and have the same character height as the dimensions.

ANSI B46.1 and ANSI Y14.36 must be stated on all drawings when surface irregularities
need to be controlled.

All terms related to the surfaces of solid material shall be defined per
ANSI B46.1 and ANSI Y14.36. These terms are summarized in Figures 7.1,
7.2,
7.3,
and 7.4.

Some commonly used terms are outlined as follows:

Surface- The surface of an object is the boundary
which seperates that object from another object. Substance or space and
produced by such means as abrading, casting, coating, cutting, etching, plastic
deformation, sintering, wear, erosion, etc.

Roughness- Roughness is the surface feature of
random and repetitively spaced minute or smaller from the center line.
Roughness height is the measured profile height deviation taken within sampling
length. The average spacing between adjacent peaks is known as the roughness width
spacing.

Waviness- Waviness is a more global surface feature
than roughness. It is the mean surface upon which roughness can be
superimposed. Waviness height is the peak-to-valley height of the modified
profile from which roughness and flaws have been removed. The average spacing
between adjacent peaks of such a surface is known as the waviness width
spacing.

Thus, waviness refers to the larger mean surface upon which roughness is
superimposed. However, the roughness number defined deviation from mean centerline.

Lay- Lay defines the direction of the predominant
surface pattern. This surface pattern or tool mark is determined by the
production method used. This feature may be necessary in sealing of joints and
sliding applications of mating surfaces.

It is important to note that these numerical values have dimensions. In APS,
the dimensions shall be micro-inches for roughness height and inches for
waviness height, waviness width and roughness width unless otherwise stated.
Most standard and common machining operations are good for roughness height
about 63 micro-inches. A summary of the roughness height of other machining
practices are included in one of the attached.

So do not specify surface finish control in metric format whenever it
can be done. Finally, better surface finish is very costly. So
care must be taken not to request better surface finish than required.

In communicating with metric dimensions, these dimensions and their meaning
are going to be quite different.

8.2.2 Welding Processes - Welding processes may be
classified into the following main categories:

8.2.3 Weld Symbols - Weld symbols are ideographs used to
represent the type of weld specified. shows the most commonly used weld symbols and examples of their use.
Refer to ANSI/ASW A2.4 for a complete list of weld symbols.

8.2.4 Supplementary Weld Symbols - Supplementary weld
symbols, shown in , are used to provide additional information about the extent of the
weld, where and how welding is performed, and the contour of the weld bead.

8.2.5 Welding Symbols - Welding symbols are graphical
symbols made up of up to eight elements that convey explicit welding
instructions. The eight elements, shown in are: reference line, arrow, basic weld symbols, dimensions and other
data, supplementary weld symbols, finish symbols, tail and specification, and
process or other reference.

The dimensions of the various fastener elements are given in the respective
American national Standards Institute standards cited in . Plain washer dimensions are tabulated in . The "TAD DATA" Screw Data Slide Calculator shall serve as
the dimensional reference for the standard screws and lock washers. This slide
gives data on screw sizes #0 - 1 in. diameter which probably represents 95% of
our requirements. For other sizes, refer to the respective standards.

The materials covered by this standard are limited to steel, stainless steel
and brass. These are identified by the respective ASTM standards or as noted in
. Material call out shall follow examples shown in Table 9.1.

Although this standard does not restrict choice of sizes, and 9.4

list the sizes that are commercially available. However, preference should be
given to sizes listed in the Argonne Stores Catalog. It is recommended that the
UNC series be specified for machine screws because coarse threads make up the
bulk of production. The notable exception is size #10-32 where a full selection
of lengths is available. Recommended tap drill sizes are given in .

The U.S. Department of Energy and the Argonne National Laboratory are
concerned that Suspect/Counterfeit parts and materials are not incorporated
into APS systems and components. A list of Suspect/Counterfeit parts will be
provided to the successful bidder of goods and services. The awarded seller of
items and services to the APS will assure that none of the indicated
Suspect/Counterfeit parts and materials are incorporated or installed on or
within components or equipment. These special requirements will be noted within
drawings, specifications, statements of work, and general instructions.
Typical Notification Statement on APS Drawings
This drawing/application requires the use of high-strength fasteners such as
grade 5 or grade 8 bolts. In an effort to prevent the introduction of
Suspect/Counterfeit parts into components, a list denoting unfavorable fastener
manufactures will be provided by your instructor. The Suspect/Counterfeit
fasteners, (as noted by their headmarkings), are not to be used in the
construction or installation of items identified within this drawing.

Consistent with the objective of this standard is the need to discuss with
and achieve with the above mentioned firms agreement as to the particular
drafting methods employed.

Floor plans are to be oriented with north arrow pointing either up or to the
right - never down or to the left.

10.3 DRAWING SCALES
10.3.1 Plans
All floor plans for construction drawings will be drawn at a scale of
1/4″ per ft. If this is not feasible, downsizing is permitted to 1/8″

of 1/16″ upon approval of the Project Manager.

Increasing size of the floor plans is permissible by a factor of 1/8″
per ft. (Example, 3/8″, 1/2″).

Group details and sections as much as possible to maintain uniform scale on
individual sheets. Do no combine details of one scale with a floor plann of a
different scale on the same sheet.

Building elevations, interior elevations and building cross sections shall
be drawn at a minimum of 1/4″ per ft. (Preferred).

Increasing or decreasing size of building elevations, interior elevations,
and building cross sections is acceptable at a rate scale of 1/8″ per ft.
(Example, 3/8″, 1/2″, 1/4″, 1/8″).

All deviations must be approved prior to usage by your instructor.

If drawings are reduced from their original size for publication, etc., the
following note must appear on the drawing: "Warning - This Drawing
Has Been Reduced."

All dimensions shown on drawings will be true dimensions to the graphic
representation shown, if not, dimensions will be accompanied by the following:
Example:
A plotting schedule will be provided on each drawing defining screen
colors and pen weights used to create the drawing. See for further information.
10.8 MANUAL DRAWN DETAILS, SECTIONS,
ELEVATIONS, FLOOR PLANS, ETC.

Manual drawn details, sections, elevations, etc. shall be avoided.

All drawings shall include both a standard scale and a graphic scale.

Final original drawings shall be presented on plain bond paper (standard
printer paper).

Standard sheet sizes shall be as shown below. Select size to maximize
drawing efficiency. All drawing sets/packages shall be of one size only.
Standard Sheet Sizes (Inches)
Standard text fonts will be used. These are as provided in AutoCad and
Unigraphics. Deviations in font styles will be submitted for approval prior to
usage. See for further information.

Insofar as all drawings are drawn to scale, i.e., limits, text must also be
drawn to the appropriate scale. See Example #5 for further information.

All students shall provide their instructor with electronic drawing data
compatible with the lab CAD Systems. The following is a list of CADD computer
programs being used at this time:

AutoCad - Version 2004 or earlier

Unigraphics NX5 or earlier

Symbols shall be as per the standard systems in the latest versions of
AutoCad and Unigraphics. Should non-standard symbols be required, prior written
approval shall be obtained from the instructor.

Layering shall be as per the standard layering system in the latest versions
of AutoCad, and Unigraphics. Should non-standard layers be required, prior
written approval shall be obtained by the APS Project Manager or CADD System
Manager. (See ).

Abbreviations shall be used only when their meanings are unquestionably
clear and shall be per ANSY Y1.1, "Abbreviations for Use on Drawings and
in Text," of the American Society of Mechanical Engineers.

When abbreviations are used, the words and/or terms and their abbreviations
shall be defined in a legend.

Revisions and modifications to CADD files must be done electronically, no
hand changes will be accepted, this includes reversional changes in the title
block.
10.16.1 General description of identification system.
A technical document shall be identified by the assignment of an
alphanumeric designation consisting of a Project Identifier, Document Status
Identifier, and Document Identifier (sheet number) as follows:

The project identifier is assigned by the Document Control Center upon request of the ANL Project Manager.

The document status identifier shall denote the project phase in which the
document was originated and shall have one of the following alpha codes:

"P" - Pre-Conceptual or Feasibility

"S" - Conceptual Design

"D" - Preliminary Design - Title I

"W" - Final Design - Title II

"T" - Tenant Layout

"G" - General

The document identifier shall identify the type of document and the
corresponding assigned number. This shall be an alpha code to denote the
document type, i.e., drawing or non-drawing.

A drawing-type document shall be denoted by the particular discipline
associated with the drawing as follows:

"A" - Architectural

"C" - Civil

"E" - Electrical

"F" - Fire Protection

"G" - General

"I" - Interiors

"L" - Landscaping

"M" - Mechanical

"S" - Structural

"T" - Non-Drawing Document

Each drawing document shall be numbered sequentially within its associated
discipline.

J0046-101-D-A001

J0046-101-D-E001

J0046-101-D-T001

J0046-101-W-T001

A CADD file shall be identified by a 12-character name. It shall consist of
an 8-character file name, a period, and a 3-character file extension.

a. Characters 1 thru 3 shall reflect the building number or utility.
Example:

XXX XXXXX . XXX

400 - Experiment Hall

410 - Control Center

500 - Site Utilities

a. The following information shall also be provided along with the
electronic files.*

1. Listing of all WBLOCKS and BLOCKS incorporated.

2. Customized LISP routines.

3. Drawings List.

4. Linetypes, symbols, etc.

a. Electronic file name and
drawing

"J" - number and title.

b. Manual drawing title and "J" -
number*

Listing of all text fonts and styles used other than the
stock font files offered in AutoCador ASG.

b. The 5-digit code shall be a unique number sequentially assigned
throughout the project and each sheet will be uniquely numbered.

c. File Extension.

The 3-character file extension shall always be DWG for AutoCAD files.

40000001.DWG

40000002.DWG

40000010.DWG

40100001.DWG

40100102.DWG

10.18 SECTION AND DETAILING
NOMENCLATURE

The letters for sections will be in sequential order beginning with the
letter A through Z. If more letters are required, a double-lettering system
will be employed, such as AA, BB, etc.

The numbers for details will be in sequential order beginning with the
number one and so on. (See ).

A title block for each project shall be provided to the A/E and D/B firms
for their use in either an AutoCad DWG or DXF format. A sample is enclosed.
(See ).

The electronic files will be reviewed for the standards listed and the
following generally accepted CADD practices.

1. Unnecessary fragmented lines.

2. Improper layering as described.

3. Improper text size and fonts.

4. Scale.

5. Dimensioning Scale.

6. Unnecessary electronic files.

a. Pieces or blocks outside the
electronic border.

Multiple blocks, lines, text inserted on top of each
other, etc.

Drawings shall be presented on plain bond paper. No grayscale or colors are
permitted on detail views. Grayscale and color are permitted for rendered
pictorial views.

This section defines general rules and practices to be followed to check
drawings for consistency and professional quality.

11.2. Checking practice will be as
follows:

a. Final checked drawings must be signed by all persons designated in the
title block.

b. Detailing Checklist:

Inspect the drawing to see
that the projections and sections are made in such a way as to show most
clearly the form of the piece and the work to be done on it. Make sure
that any workman looking at the drawing will understand what the shape of
the piece is and how it is to be molded or machined. Make sure that the
delineation is correct in every particular, and that the information
conveyed by the drawing as to the form of the piece is complete.

Check all dimensions to see
that they are correct.

Scale all dimensions and see
that the drawing is to scale and that dimensions are associated
dimensions.

See that the dimensions on the
drawing agree with the dimensions on the layout.

Wherever any dimensions is out
of scale, see that the dimension is so marked. ( XX ).X.XXX this
practice is not recommended.

Investigate any case where the
dimension, the scale of the drawing, and the scale of the layout do not
agree.

See that all figures are
correctly formed and that they will print clearly, so that the Shop can
easily read them correctly.

See that the overall dimensions
are given.

See that all dimension
extension lines go to the correct part of the drawing.

See that all arrow points go
to the correct dimension extension lines.

See that proper allowance is
made for all fits.

See that the tolerances are
correctly given where necessary. Ask if you don't know the tolerances to
be applied.

See that all dimensions given
agree with the corresponding dimensions of adjacent parts.

Be sure that the dimensions
given on a drawing are those that the machinist will use and that the
worker will not be obliged to calculate in order to obtain the necessary
measurements for machining or checking his work.

Avoid strings of dimensions
where errors and tolerance can accumulate. It is generally better to give
a number of dimensions from the same reference surface or center line.

When holes are to be located
by boring on a horizontal spindle boring machine or other similar machines
give dimensions to the centers of bored holes in rectangular coordinates
and from the center lines of the first hole to be bored, so that the
operator will not be obliged to add measurements or transfer gages.

Give all weld sizes, show
proper weld symbols, and insure accessibility for all welds.

Show weldment cuttings only
when necessary.

Provide "breather"
holes on closed weldments.

Study the sequences of
operations in machining, and see that all finish marks are indicated. Try
to make the part in your mind with the information shown on the drawing.

See that the finish marks are
placed on the lines to which dimensions are given.

See that methods of machining
are indicated where necessary.

Insure adequate stock for
machining.

Give all drill, ream, and tap
sizes.

Insure proper use of geometric
tolerancing symbols.

Avoid special taps, drills,
reamers, etc. unless such tools are specially authorized.

Where parts are right- and
left-handed, be sure that the hand is correctly designated. No drawing
should contain both parts.

When possible, make parts
symmetrical, as to avoid making them right- and left-handed, but do not
sacrifice correct design or satisfactory operation to accomplish this.

When heat treatment is
required, the heat treatment should be specified. Ask, if uncertain, of
the proper heat treat process.

Verify the title, the scale,
the drawing number, and series on both the drawing and the drawing record
sheet.

Note required finishing
operations, i.e., amoloy, electroless nickel, black oxide, etc.

Utilize 1/16, 1/8, 1/4, 1/2,
and full-scale only, for details. Consult with the standard design
supervisor for exceptions.

Consider the kind of material
required for the part and the various possibilities of casting, forging,
welding, or otherwise forming the part from this material. Then consider
the machining operations to see whether changes in form or design will
reduce the number of operations or the cost of machining.

See that parts are detailed
with reference to the economical use of material, and whenever possible,
utilize standard sizes of stock and material readily obtainable. In the case
of alloy steel, special bronze, and similar materials, be sure that the
material can be obtained in the size required.

Insure that the Bill of
Material on assembly drawings properly calls out the type of material,
stock size, quantity required, vendor part number, and source.

When preparing assembly
drawings, see that the part can readily be assembled with the adjacent
parts.

Make sure that in being
assembled, the piece will not interfere with other pieces already in place
and that the assembly can be taken apart without difficulty.

When specifying purchased
components, insure complete information for ordering, including correct
catalog numbers.

When using purchased
components, insure proper interfacing with fabricated parts, i.e., tapped
holes, bearing fits, shaft diameters, mounting feet, etc.

Utilize standard hardware
whenever possible.

When detailing a new casting,
assign a new pattern number.

Insure proper application of
standard drawing note stamps.

Obtain from the design
engineer, and note on the assembly drawing, any applicable information
regarding motor speeds, traverse rates, pulley ratios, specification
number, technical information, etc.

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Design and Drafting Standards for Students

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1.5 PRINT FOLDING FORMAT SECTION 2 - Unigraphics Practices SECTION 3 - AutoCAD PRACTICES SECTION 4 - PREFERRED LIMITS AND FITS FOR CYLINDRICAL PARTS 4.5 RECOMMENDED TOLERANCE SYSTEM SECTION 5 - DRAWING NUMBERS AND REVISIONS SECTION 6 - GENERAL DIMENSIONING AND TOLERANCING 6.3 GENERAL DIMENSIONING RULES 6.4 UNITS OF MEASUREMENT

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Kobi

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The vast majority of engineered products have multiple components that need to fit together. Sometimes you need components to slip together easily, while other times, you need components to press together and not come apart. There's a systematic way to design parts so they fit together exactly the way you want on the first try, every time, and in this video, we show you how!

The engineering term for this consideration is "fits and tolerances". Let's define these terms. Most of the time, especially in CAD, we just type single, exact numbers into the computer for our dimensions. That's called a "nominal" dimension. But when it comes time to actually make that part, we won't be able to manufacture the features to exactly those dimensions. Each feature might be slightly larger or smaller than the number we originally typed into the computer. So, we need to specify a "tolerance" which tells the person manufacturing the part how much of a variation from our nominal dimension is acceptable.

Different manufacturing processes are capable of different tolerances. It's important to remember that tolerance capability corresponds to a large production run, where factors like tool and machine wear, deflection, sharpening, and the natural variation of different processes apply. A very common mistake that new engineers make is selecting tolerances that are far tighter than necessary. As the tolerances become tighter, the cost to manufacture the part grows exponentially.

So how tight of a tolerance do you need? Tolerances typically come into play when designing fits. In some cases, you might want components to slip easily together, but not have a lot of perceptible play. In other cases, lots of relative movement is okay. You might even need to have two components come together permanently and not come apart. These different cases are called "fits".

Machinery's Handbook is the go-to reference for designing fits. Fits have a particular naming convention of a two-letter abbreviation followed by a number.

The letters denote the type of fit, and the number corresponds to the tolerance class of the fit, with larger numbers representing looser tolerances. This video deals primarily with ASME fits in the inch system, but there is a similar convention for metric. The naming convention is different, but the general concept is the same. For more information, you can reference Machinery's handbook, or ISO 286-2.

Be sure to watch the video to see examples of six different types of common fits, and some general guidelines for how to manufacture them.

# data[].attributes.attachment_link.title
Fits and Tolerances: How to Design Stuff that Fits Together

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The vast majority of engineered products have multiple components that need to fit together. Sometimes you need components to slip together easily, while other times, you need components to press together and not come apart. There's a systematic way to design parts so they fit together exactly the way you want on the first try, every time, and in this video, we show you how!

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Edited to answer comment down below also:
http://www.eng-tips.com/viewthread.cfm?qid=228088

This was written by someone else (link at end) but does a very well job of defining the differences between the two:

The American National Standards Institute (ANSI, /ˈænsi/ an-see) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States.

The organization also coordinates U.S. standards with international standards so that American products can be used worldwide.

ANSI accredits standards that are developed by representatives of other standards organizations, government agencies, consumer groups, companies, and others. These standards ensure that the characteristics and performance of products are consistent, that people use the same definitions and terms, and that products are tested the same way. ANSI also accredits organizations that carry out product or personnel certification in accordance with requirements defined in international standards.

[4]

The organization's headquarters are in Washington, DC. ANSI's operations office is located in New York City. The ANSI annual operating budget is funded by the sale of publications, membership dues and fees, accreditation services, fee-based programs, and international standards programs...

he Institute administers nine standards panels:
*ANSI Homeland Defense and Security Standardization Collaborative (HDSSC)
*ANSI Nanotechnology Standards Panel (ANSI-NSP)
*ID Theft Prevention and ID Management Standards Panel (IDSP)
*ANSI Energy Efficiency Standardization Coordination Collaborative (EESCC)
*Nuclear Energy Standards Coordination Collaborative (NESCC)
*Electric Vehicles Standards Panel (EVSP)
*ANSI-NAM Network on Chemical Regulation
*ANSI Biofuels Standards Coordination Panel
*Healthcare Information Technology Standards Panel (HITSP)

where as ISO!!

The International Organization for Standardization (ISO) is an international standard-setting body composed of representatives from various national standards organizations.

Founded on 23 February 1947, the organization promotes worldwide proprietary, industrial and commercial standards. It is headquartered in Geneva, Switzerland,

[5]

and as of 2015 works in 163 countries.

[6]

It was one of the first organizations granted general consultative status with the United Nations Economic and Social Council.

ISO, the International Organization for Standardization, is an independent, non-governmental organization, the members of which are the standards organizations of the 163

member countries. It is the world's largest developer of voluntary international standards and facilitates world trade by providing common standards between nations. Nearly twenty thousand standards have been set covering everything from manufactured products and technology to food safety, agriculture and healthcare.

Use of the standards aids in the creation of products and services that are safe, reliable and of good quality. The standards help businesses increase productivity while minimizing errors and waste. By enabling products from different markets to be directly compared, they facilitate companies in entering new markets and assist in the development of global trade on a fair basis. The standards also serve to safeguard consumers and the end-users of products and services, ensuring that certified products conform to the minimum standards set internationally.

IT depends upon where you are working and whom you are working!!

If you are working for American based product then ANSI will come first and rest ISO will come

Credit due to:
https://www.quora.com/What-is-the-difference-between-ANSI-and-ISO

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What is the difference between ANSi and ISo drafting Standard?

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Edited to answer comment down below also: http://www.eng-tips.com/viewthread.cfm?qid=228088 This was written by someone else (link at end) but does a very well job of defining the differences between the two: The American National Standards Institute (ANSI, /ˈænsi/ an-see) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States.

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https://images.app.goo.gl/Sra83JJ1oP5VJVoc6

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https://images.app.goo.gl/VgXcpJJGvdda3Avg8