Frickin' lasers

I suspect many people who use a laser cutter go through these phases:

1. Hmm, a laser cutter could be useful for this project. I should learn how to use one.
2. Wow! I can make all kinds of stuff! This is so much fun!
3. I AM TOTALLY BUILDING MY ENTIRE HOUSE OUT OF QUARTER INCH ACRYLIC
4. Crappity crap crap, nothing works, my stuff won't separate, everything is charred, grr

Presumably there's some phase afterwards that involves a mature understanding and respect for the strengths and limitations of this tool as well as an expanding repertoire of tricks and techniques. I wouldn't know, I'm not there yet. The world of matter continues to disappoint.


Actually, today wasn't so bad. I learned the following things:

1. 1/4" acrylic is actually pushing it on the 45W laser. You have to go really slow.
2. The laser has a nontrivial kerf, which is bigger for thicker substances (due to defocusing).
3. Cutting depth varies (nonflat bed?), so use a little more power than you think you need.
4. Small holes in thick materials don't work very well. The center melts and sticks.
5. Acrylic is kind of brittle, and tends to crack at the thinnest load bearing point.
   
6. Hardwood tends to get smoky and sticky, and doesn't etch very well.
7. Acrylic etches perfectly well, but the result is somewhat subtle and not clearly visible.

Nonetheless, I have a second revision (I'm sure not the last) of the base airframe.



(You can see remnants of previous versions in the background of the second photo.) Notable features include a plethora of slots for zip-tie tie-downs, a newly beefed up "undercarriage" (the old one kept breaking), and an expanded "deck". I haven't taken the protective film off the acrylic yet, is why it's blue. And yes, the leads to the ESC are way too long, I'll shorten them eventually so the ESC is tied to the strut leading to the motor.

At Fry's today, I discovered these:
These are part of the "schmart board" system, which is designed to make it easy to prototype with surface mount parts, which I don't care about -- but ooh, a bundle of 100 wires attached to single-pin slide-on header connectors? This solves a whole bunch of connectivity issues all at once! I just have to make sure everything is exposed as some kind of pin header, and then I can wire them all up individually. I'm sure this will all end in tears somehow like all my hare-brained schemes for avoiding PCB manufacture do, but for now I'm looking forward to a new era of zip-tie-and-plugboard construction.

In other news, I got the XBee radio modules going using the Adafruit adapter board, connected to a laptop. The next step there will be to connect it to the Propeller (using those exciting new jumper cables!) and see if I can drive it from there. Because then in theory I can start talking to the Propeller over the air (look, ma, no USB) and telling it to do things like run the motors at different speeds (which I also got working in the last couple days -- turns out Parallax has a lovely servo control object in the standard library, and ESCs take servo inputs).