Wednesday, 16 September 2009

My first drawing is complete

In an act of utter self-glorification, I made the first thing to be written by the 2D repstrap be the first letter of my name (also, it was only orthogonal lines). After some as just unexplained problems with the Y stage refusing to start, and a slightly wobbly fastening of the Sharpie, it indeed made a letter L (in Blocky Outline 83 point or so). I have now successfully programmed and output something with my RepStrap! Woohoo!

The next thing should be a fractal. Just because.

Sunday, 13 September 2009

It moves! It lives!

Having mostly dealt with the problems from last post (Flimsy wiring? Get the right jacks. Overheating driver? attach driver directly to frame. Loose coupling? Tie down coupling with hose tightener (which required dremelling a hole for the screw to rotate through), I have been able to make both X and Y stages move! The whole setup also looks much tidier now.

The stages can move for a seemingly arbitrarily long time, but they still overheat if standing still for about 30 seconds. Have to find a solution for that. I don't know if thermal paste will change much when I've already bolted them tightly together.

Major problem: Both stages have a tendency to switch between running smoothly and getting stuck, depending on exactly how the rod is aligned. I'm guessing the guiding bolt is a little loose, and can change between perfectly aligned with the rod and not quite perfectly aligned.

After cutting off superfluous edges and cutting a notch on the Y stage for the tube tightener screws, I have about 11x16 cm of writeable area. Not a lot, but enough for tests and for a RepRap, should I go that way (requires a plastic extruder, though. First some 2D tests!)

Softwarily, I have refactored the little test program to where I have two functions: move(dir, axis, len) and pauseSeconds(seconds). The move() functions is almost calibrated to move in cm.

For playing around, I am tempted to hook up three three-way switches so each axis can be controlled independently. Or maybe get a mini joystick controller:)

Thursday, 10 September 2009

It's alive!

My mad genius neurons are all a-twitter with excitement! My creation moves! It's alive! (For very small values of alive.)

I've hooked up the new power supply and both of the mounted motors to the stepper drivers, and the Arduino to a solar powered (!) USB power supply. Pins 4 and 5 drive one stepper and 6 and 7 drive another, with the standard test program that merely moves back and forth. And the Y stage moves! Happily, happily back and forth. The X stage, not so lucky, the tubing is not tight enough to move the weight that's on there, so I'm currently glueing it on. Should be ready to run tomorrow evening.

Issue 1: The wiring is flimsy at best. I need some jacks that fit the Arduino, and maybe a little board that I can mount the various things on so they're less random. Just mounting the drivers next to the motors would help.

Issue 2: After 10-30 seconds of power, the stepper drivers start to stutter audibly, whether actually moving anything or not. I suspect the power transistor is getting too hot and starting to flake out. It certainly gets hot. I thought my heat sinks would be enough, but maybe not. Must go to Aarhus Radio Lager and get better.

Issue 3: As I mentioned, the X stage coupling is not tight enough. Not sure what the best way to make it be tight and stay tight is. Maybe just tie a lot of string really tightly. Or tie some string that will shrink when wet.

Wednesday, 2 September 2009

Working power supply

Briefly tested the new power supply, and it works with a big resistor on 5V. Lights up the stepper motor driver bicolor led somewhat prettily. Tomorrow: Rewire the stepper motors according to some hint I got from another Sanyo user.

Tuesday, 1 September 2009

New power supply coming up

Thanks to my brother's people-wrangling abilities (surprisingly good for someone who's pretty Aspy), I have a new old power supply on the way. The two big ones didn't work out. One of them spins up, but doesn't deliver power no matter what I try to put on for load and shorts, the other one doesn't even make a sound.