Jul 11

When Life Gives You Lemons…


“When life gives you lemons? Don’t make lemonade. Make life take the lemons back! Get mad!

I don’t want your damn lemons! What am I supposed to do with these?

Demand to see life’s manager! Make life rue the day it thought it could give Cave Johnson lemons! Do you know who I am? I’m the man who’s going to burn your house down! With the lemons! I’m going to get my engineers to invent a combustible lemon that burns your house down!”

– Cave Johnson’s lemon rant after realizing that it turns out ground up moon rocks are pure poison.

Inspired by the speech and the hot temperatures outside we made combustible lemon props. I even hung one on our lemon tree. For science.

Jun 11

Empire State of Mind

amp I don’t really remember why, but for some reason I decided to create some vector artwork of a stormtrooper last weekend. I grabbed an image of a helmet and then did some tracing and editing to get a pretty good silhouette of a stormtrooper helmet. When it was done I was very happy with the results and needed to figure out what to do with it. It turns out that once you’ve got some simple vector art you can do a lot with it.

Paper Soldier

I started out by cutting a piece of cardstock with the Craft Robo paper cutter to make sure that all the contours were closed, etc. I took the resulting piece of paper and stuck it on a little 15-watt keyboard amp just to butch it up a bit. Since the paper I chose was white it looks best against a black background and the amp fit the bill.

Next I used the vector art to cut a screen-printing mask from adhesive-backed vinyl. That plus some yellow screen printing ink applied with a gentle uneven pressure on the screen gave me a T-Shirt with a distressed looking stormtrooper on the front.


Big Finish

The final project I did was something I’ve been thinking of for a while. It’s actually just the first prototype of a more ambitious project that involves motion and some electronics, but first I wanted to verify if the visual effect was what I had imagined. What I did was take the vector image and cut it into strips using geometrics operations in Corel Draw. These strips were then cut from 3mm thick acrylic on the laser cutter. Finally, I cut a base and frame from birch plywood and clear acrylic. The birch got 6 layers of finish and some final polishing so it took a week to complete the project. You can see a few views of it below.

topright-1 closeup

corner-34 off-axis-1

The individual white acrylic slices can be rearranged in the holes at different depths, but I found that it’s best to have adjacent strips no more than one row distant from each other. Otherwise, perspective effects from the difference in distance distort things too much unless you’re very far away. I finished up with a Galactic Empire logo cut from black vinyl on the base. The display looks fairly abstract from most angles and then snaps into a stormtrooper when you square-off right in front of it.


Feb 11

Birthday Laser

For my birthday last year I decided to get a new toy for my workshop – a laser cutter. I spent a fair amount of time researching various options and eventually decided on a 40 Watt CO2 laser. I purchased an inexpensive Chinese laser cutter from Full Spectrum Engineering. FSE imports them and then sells them from their US offices, which means you get to deal with a local US-based company. For just under $2K at the time you got a 40 Watt CO2 laser with approximately 12″ x 11″ cutting area. The specs have only improved since then. Mine also came with an upgraded controller card that allows the laser to be driven from Mach3 or other CNC control software.

My machine needed a bit of TLC after unpacking. The mirrors and laser lenses needed alignment, which I fixed using thermal imprint paper and a very low power setting to figure out where the laser was pointing at each point along the path. At times the answer was — pointed directly at my hands. Good times. This is pretty typical of these imported machines, but the good news is it’s quite straightforward to get them set up and working well.

Once I was done and got it running, I tried the included software and was horrified by what I saw. The circle I drew to test cut out of paper had jagged edges looking like it was at about 75 dpi resolution, which was much worse than the stated 1000dpi. It turns out the included software (NewlyDraw) is complete junk, and the machine is capable of much better results.

By switching out the controller card with the upgraded Mach3-compatible card and driving it with Mach3 I was able to get it running very accurately and smoothly. But there wasn’t a great solution for creating GCode files from CorelDraw or other vector art, so it was tedious to prepare cutting jobs for the laser.I ended up writing software to make this pretty seamless. My software takes an SVG file and converts it to GCode usable by Mach3. When I used it to test the same circles picture I did before the results were stunning. Everything was smooth and the steppers even sounded happier and less jerky being driven by Mach3. So you can edit directly in CorelDraw and then save as SVG and the LaserCAM software spits out GCode.

The pictures below show the software running and then the final results cut from 3mm white acrylic. The file as I edit it in CorelDraw is upright, but it shows up flipped vertically in the LaserCAM software because of how my Y-Axis is mapped on my laser cutter.



IMG 20110225 233228The software is available on my GitHub athttps://github.com/yergacheffe/lasercamand could be adapted for other brands of laser cutters. It’s still a far cry from the nice printer driver interface that an Epilog laser cutter provides, but at 1/10th the cost this is a pretty good alternative for the hobbyist.