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Epilog Laser Beam Alignment for Fusion & FusionM2

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Making a laser-cut box/case with elastic clips

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Make a laser-cut box/case of any size that uses elastic clips, without needing any glue or screws. Downloadable plans. Ideal for acrylic (Perspex) or MDF.

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Hershey Text is an Inkscape extension that can render a line of text in one of several stroke-based "engraving" fonts. This extension solves a persistent problem, and one which we have come across in many different contexts: How to easily create simple and readable vector representations of text.

Quick start: Download and install the EggBot extensions for Inkscape, which now include Hershey Text. Much more information follows.

Huh? What's this all about? Why are you doing this?

It's kind of a long story. But it goes to the heart of who we are and what we're doing.

Neither the problem nor the fundamental solution are new. Creating simple representations of text was an important problem in early computer graphics, for both vector displays and pen plotters. Good solutions- sets of "engraving" fonts -were developed. But then along came "outline" fonts, dot matrix monitors, high-resolution printers and personal computers. And that was that.

Thirty years later, low-cost and easily available computer-controlled manufacturing tools have created an exciting realm for exploration that's even open to most hobbyists: Laser engravers, 3D printers, CNC routers, vinyl cutters, embroidery machines, and (yes) pen plotters. If you design for any of these on a regular basis, you're likely to come across a case where you'd like to efficiently create some readable text with your tool, and "engraving" fonts are often the best choice. For this very reason, many professional-level CAD tools include some form of engraving font.

The trouble is, many CAD packages and most illustration packages (including our favorite, Inkscape) do not come with engraving font support, because it's such a specialized requirement. We'd like to fix that.
Outline fonts versus Engraving fonts

We've mentioned outline fonts and engraving fonts, but let's clear on these. Most modern font systems (truetype, postscript, opentype, etc.) are examples of outline fonts. In these, the font file describes a filled vector shape. That is to say, the visible part of a character in an outline font is the area enclosed by the shape. Fonts like these are appropriate for use in laser printers or other high-resolution devices.
By contrast, an engraving font (sometimes called a "stroke" font) is one where each visible character is defined by the stroke itself, not the area enclosed by it. Fonts like these are appropriate for pen plotters, machine tools, and other circumstances where the pen width itself is significant.
Here are examples of text written in an outline font versus written in engraving font:

In the upper box, both lines of text are drawn with a solid black fill, and no stroke (outline). The outline font is legible; it looks as it is intended.

The engraving font is basically illegible, since the enclosed area is not meaningful. In the lower box, both lines of text are drawn without any color fill, but instead with a solid black stroke. This renders the engraving text correctly.
Now, there's a time and place for both types of font face.

Outline fonts are perfect for use with high-resolution raster imaging devices, like LCD screens and laser printers. In these cases there's no significant penalty for filling in large regions.

But, if you use any of the physical fabrication methods that we've already mentioned, then there is usually a significant time cost to filling in large regions. For example with a pen plotter, it's much faster to draw the outline of the engraving font than to raster back and forth to fill in the entire outline font area. The higher the pen resolution (the smaller the tip), the slower it will be. The same goes for text areas cut with a milling cutter on a CNC machine, certain types of laser-engraving, embroidery machines, and so on.

A second reason (besides speed) to use engraving fonts with physical fabrication is that the tool size is often significant. The tool size could be the pen width (for a plotter), the cutter width for a milling machine, or the thread width for embroidery. You certainly can use an outline font and just trace its outline, but that can create legibility issues, especially if your tool is wide. By contrast, engraving fonts rely on the tool width to create the legibility. In the example above (shown with and without a realistic thick pen stroke), it is the pen width that creates the intended character.

Other examples where we've come across good uses for engraving fonts include production laser engraving (where a single-stroke font lead to a huge speedup), printed circuit board design, where the minimum silkscreen and copper widths led to better looking graphics when we used engraving fonts, extrusion-based 2D and 3D printers (including cake decorators and MakerBot), and genuine pen plotting with 2D machines and the EggBot.
Getting and Installing the extension
NOTE ADDED: As of version 0.91.0, the Hershey Text extension is included with Inkscape. If you already have Inkscape 0.91 or newer installed, skip these instructions and simply look in the "Render" submenu of the Extensions menu in Inkscape.

Download the latest version of this extension as part of the EggBot extensions for Inkscape (or as source code in the repository). You will need to have a recent copy of Inkscape installed as well.

The easiest way to install them is to copy the three files from the ZIP file into your Inkscape extensions directory. (The exact location of this directory depends upon your operating system and version of Inkscape.)

Once you copy the files into that folder, restart Inkscape.

If the Hershey Text extension is installed correctly, it will show up in the "Render" submenu of the Extensions menu in Inkscape.
Using the extension: Rendering text
To create a line of text, type your text into the box. Make sure that "Typeset that text" is selected as the "action," select your font face, and click "apply."

If all goes well, the line of text that you've entered will appear on your drawing. The line of text shows up as a group of path objects. The text is rendered as a drawing, not as editable text. You can resize and move the text object as you see fit. You can also use all of the usual path manipulation tools to edit the shapes within Inkscape.
Using the extension: Glyph tables
The fonts included with the extension are a classic set of Hershey fonts, spanning normal keyboard characters. While many of the characters are straightforward to locate, others- particularly obscure symbols - don't have a clear keyboard mapping. The extension has a mode to create a glyph chart, to help you locate and type interesting symbols.

To use the glyph table, make sure that "Write glyph table" is selected as the "action," select your font face, and click "apply."

Here's a typical result. The table contains a pair of characters for each symbol in the font face. The left symbol is the "standard" keyboard character- as rendered in the single-stroke sans font - and the right symbol is the corresponding glyph from the selected font face.
Using the extension: Fonts and name conventions
The extension contains a selection of more than 20 font faces.

We have modernized several of the font names, to reflect conventions developed in recent years, and strictly for reasons of clarity. Instead of "Roman Simplex" and "Roman Complex", we've used terms like "Sans," and "Serif." Likewise, rather than "Simplex," "Duplex," and "Triplex," we've used the terms "1-stroke," "medium," and "bold" - reflecting one, two, or three-stroke wide characters.

Single-stroke fonts have but a single pass through each major section of each character. The wider fonts fill in as needed to create the correct medium or bold appearance.

Three of the font faces are true single-stroke fonts that are extremely efficient for machining operations:

Those are, "Sans 1-stroke," "Script 1-stroke," and "Greek 1-stroke."
Smoothing the characters
You may notice that the drawing above seems a bit "jerky." that's because these fonts are made of straight line segments. And, this is actually the full resolution of the original font design.
You may find it convenient to simplify the paths to create a smother shape.

To do so, select the Hershey Text object that you wish to smooth, and select Path>Simplify from the menu.

Having done so, here is the result: Smoother text.
About Hershey and his fonts
The engraving typefaces built into our Inkscape extension have been around for quite some time. They are a subset of those designed by Dr. A. V. Hershey while working for the US government in the 1960's, and then widely disseminated by the US National Bureau of Standards in the 1970's, in "Tables of Coordinates for Hershey's Repertory of Occidental Type Fonts and Graphic Symbols."

They are now generally considered to be in the public domain.

The complete Hershey library contains thousands of characters in many languages. Each symbol is composed solely of straight lines, and is defined individually through a "moveto/lineto" kind of script.
You can read more about the Hershey fonts here and here.

Special thanks to Marty McGuire for motivating this with his SVG Hershey Font collection and to Dan Newman for additional test and symbol verification.

Update January 31, 2015: As of version 0.91.0, the Hershey Text extension is included with Inkscape.

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Hershey Text: An Inkscape extension for engraving fonts

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Hershey Text is an Inkscape extension that can render a line of text in one of several stroke-based "engraving" fonts. This extension solves a persistent problem, and one which we have come across in many different contexts: How to easily create simple and readable vector representations of text.

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To calibrate the machine for your material and job, you must set the home position on the machine.

To do so, you must turn on the red laser pointer using the control panel.

To do this, press the “Pointer” button on the control panel. This will turn on a red laser pointer, indicating where the laser beam is pointing.

The dot will appear on your material, and will be your guide when moving the X and Y axis.

Next, you must disable the X/Y stepper motors so that you can correctly position home. Do this by pressing the “X/Y” button on the control panel, this will bring up a message on the screen saying, “X/Y Off? GO/STOP”.

After seeing this screen, press the green “GO” button and the stepper motors will disable and you will be able to move the laser I-beam.

You will a screen that says, “X/Y Disabled” for confirmation.

You’ll want to get the red dot as close to the left corner of your material as possible.

This will ensure that you job won’t bleed off the edges of your material.

Once you’ve got the red dot as close as you can get it, set the home by pressing the “Set Home” button on the control panel and the setting will be stored for as long as the machine is running or until you set a new home position.

Once you press the “Set Home” button, you will see a screen on the display that says “Set Home/Center”, this indicates that home position has been set.

You can now press the “Reset” button to get out of that screen.

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It is best to manually focus the laser cutter on your material rather than using the autofocus feature, this will provide the best results.

The cutting bed needs to be raised up or down to be in focus on your material, you will have to use the control panel to make this adjustment.

First, take the manual focus tool (metal triangle) and position it on the cutting head so that it’s pointing down towards the material.

Next, put the machine into focus mode by pressing the “Focus” button on the control panel. This will display “Focus Mode” on the display screen and now the up and down arrow controls will control the height of the bed, adjust them so that the tip of the manual focus tool is touching the material that you are focusing on. It should look similar to the photo above.

Once you have focused the machine, press “Reset” on the control panel you will go back to the default screen on the control panel. You are now ready to send a job from the computer to the laser cutter.