Pen tests for drawing machines

Jenslabs has published a thoughtful and thorough evaluation of a number of currently available rollerball and gel pens. He tested them using his Circlon machine.

One thing that anyone who as ever built a drawing machine realizes, is that to get quality results you need a quality pen. There are millions of pens out there, but after a little trial and error I realized that rollerball pens or pens with gel ink are the best pen types for my machine. Both rollerball and gel ink pens use a water based ink that is less viscous then the oil based ink used in ballpoint pens. The Circlon machine sometimes move very fast, so the pen has to be able to release enough ink to make solid lines even at high speed.

This is an excellent resource for folks with other drawing machines, such as Egg-Bots and WaterColorBots. We’ve linked to it from our page about choosing pens for the Egg-Bot as well.

Electro-Kistka: Alternate In-Place Egg Dyeing Technique

After seeing our recent post on dyeing in eggs in place with the Eggbot, Ragnar posted instructions in the forums for an alternative egg dyeing technique.

It involves pre-installing a plastic dyeing bag at the time of positioning the egg in the Eggbot. Full instructions (with more photos) are in the forum post. Thank you for demonstrating this technique, Ragnar!

Electro-Kistka: Dyeing an Egg in Place?

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In our annoucement article about the EggBot Electro-Kistka — the hot wax dispenser for the EggBot — we noted that it can be challenging to reposition an egg after taking it out to dye the egg between wax layers.

As an alternative suggestion, reader Dan commented:

Could you leave the egg in the EggBot and paint on the first layer(s) of dye with a brush? Then dip the egg for the last layer to get the ends covered.

Well, let’s try and see how it turns out!

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The Incredible Computer-Controlled … Computer!

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A guest post by Daniel Gentleman 

About a year ago, I started working on a project that used robotics to control a Surface Pro tablet. Not long after I started, I got my first glimpse at the the WaterColorBot on display at Maker Faire Bay Area 2013. The WaterColorBot is designed to carry a paintbrush over a piece of paper, raising and lowering it as needed to paint a picture. The movement and software control is similar to CNC router with special design modifications to make it lighter, cheaper and easier to control. A CNC router has to move heavyweight cutting bit with friction so needs expensive motors, rails, and belts. The WaterColorBot, on the other hand, needs only to move a paintbrush in a low friction environment.

I was instantly sold on the idea of using a WaterColorBot to control the Surface. I backed the Kickstarter, waited for my bot to arrive, and started working on software. When the WaterColorBot arrived, I was not disappointed. The assembly was quick and I was robotically painting in no time.

With the big mechanical and electronic solutions solved, my attention turned to the tablet. The Surface Pro is rare among tablets in that it uses a digitizer that allows extremely precise tracking with a stylus along with “hover” and “right-click” functionality. It does not need to be electrically grounded like a stylus for a screen that only supports capacitive touch. I was certain that the Surface Pro was the way to go, but not quite how it was going to be held together. The project was about to take a another serendipitous turn.


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The custom-cut spoilboard

At this point, I shared my enthusiasm with Windell and Lenore of Evil Mad Scientist and they gave me a unique offer: Stop by the Evil Mad Scientist shop and together we would make a custom cut spoilboard (lower deck) fitted to mount the Surface Pro 2. Wielding digital calipers and other measurement and software tools, Windell came up with a design that held the tablet firmly and had extra space cut out for the charger, power button, and USB cable.

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The area beneath the tablet has a lip and a lower recessed area. This design reduces wobble and makes it look even better. On the topic of machining – I got a few lessons in how larger CNC machines work. Windell showed me some design considerations in software and gave me a safety briefing about the CNC router itself. This thing can cut fast.

After a little sanding, we fitted the tablet, spoilboard, and WaterColorBot together. Having the co-creators of the WaterColorBot with me on this journey was priceless, as we can see from the final assembly. The first spoilboard we cut matched perfectly and the tablet is held firmly in place.

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With enthusiasm fueled by seeing it all fit together, we decided to tell the WaterColorBot to do some painting. Windell loaded up an example sketch in Inkscape and, with only a minute to calibrate the stylus height, we were drawing!

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The software running on the Surface Pro is called FreshPaint and we chose a simple marker tool. In the video, you’ll hear a laughter break where the Surface picked up the floating toolbar in the app and dragged it around the screen.

Given a little time, we could have taught the WaterColorBot to change brushes and colors in FreshPaint, but our goals for the day were met. The light weight and low friction of the Surface stylus is perfectly matched for use on the WaterColorBot. A custom fitted spoilboard means the Surface will always be at the exact same place on the X/Y plane, greatly simplifying future software development. Next project: Teaching the robot how to see!

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(Full disclosure: My day job is Systems Operations with Yammer, a Microsoft company. This project and use of the Surface Pro 2 is not affiliated with Microsoft in any way nor did they influence the project with sponsorship or exercise any editorial control. If they had, I’d try to talk them into contributing a Surface Pro 3! “Surface” is a trademark of Microsoft Corporation.)

Hershey Text JS

Hershey Text JS

James “techninja” Todd has just released Hershey Text JS, a port of the Hershey fonts to JSON, capable of being rendered quickly via JavaScript & SVG.

The Hershey fonts a classic set of “engraving” or “stroke based” (as opposed to outline based) fonts that are excellent for use with all kinds of physical cutting, drawing, and painting machines. Several years ago we introduced the Hershey Text extension for Inkscape, and you can find a more in depth introduction to the Hershey fonts in that article.  Hershey Text JS is adapted from our Inkscape extension, and provides easy access to the font data for programmers who prefer to work in javascript.

BAMF 2014: Taktia

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Part of our continuing coverage of highlights from the 2014 Bay Area Maker Faire.

One of the most exciting new technologies that we saw at Maker Faire was from Taktia, a startup making augmented-reality power tools. They were showing off their semi-automated handheld wood router.

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The router sits in a robotic cradle with a computer vision system and a screen. The human guides the router by hand, keeping its center within a 1 inch diameter circle shown on the LCD screen. As the human moves the router, the cradle makes fine corrections to put the router bit exactly where it needs to be, allowing a non-expert to cut precise, complex shapes, while only moving the router along a coarse path.

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In the photo above you can see some wooden shapes that visitors were cutting out, by only moving the router freehand, while letting the robotic cradle do the hard work. We can certainly imagine other tools getting the same “robotic upgrade” — this startup will be worth watching.



BAMF2014: Makesmith CNC

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Part of our continuing coverage of highlights from the 2014 Bay Area Maker Faire

Let’s file this under “intro machines.” The Makesmith CNC, currently available on Kickstarter for just $195 including everything but the Dremel tool. It makes very clever use of appropriate technology: Three tiny hobby servo motors, modified for continuous rotation, turn gears that turn the lead screws (well, all-thread) to drive the XYZ stage. An magnetic encoder monitors the rotation, making a high-resolution, closed-loop control system.  No bushings, melamine-coated MDF parts, Arduino control.  Planned for future open source hardware+software release, too.

Perfect?  Nope, but the creators of the project seem to be keenly aware of its abilities and limitations (many discussed here), and oh does it have affordability on its side.

A WaterColorBot Water Clock


We built a evaporating-hand water clock using a WaterColorBot fitted with a Buddha Board. The Buddha Board is a black board with a gray ceramic coating that becomes transparent when wet, so you can paint on it with plain water to make black marks that disappear as the water evaporates.  (And, it fits nicely in a WaterColorBot with the appropriate jig.)


As a clock, once a minute it draws the minute hand, then the hour hand, and finally the outline of the clock face.


As the water evaporates over the course of a few minutes, the old minute hands fade away. It’s a neat effect.

And of course, video:

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