My egg-bot (frame and design by Bruce Shapiro) is working! After a couple of on-again-off-again sessions, I managed to get proper power to all the needed places, got QBASIC installed to drive the parallel port, and connected the parallel port to the appropriate pins. The last step was to give up on mating the 25 pin connector directly to pins on the breadboard, and instead run wires from the pins I needed straight into the connector.
Now that I finally have the thing working, it’s opening up all sorts of creative parts of my brain. First off, any thing approximately the size and shape of an egg, can be plotted. To my mind, this includes wine glasses, coffee mugs, and a wide variety of other stuff.
Here are the current issues, as I understand them:
1) Moving vertically too fast (particularly in the middle part of the object) results in a nasty wiggle.
– Move slower
– Shorter pens
– Damping / tighter grip on the pen
2) Pen skips off the medium from time to time
– spring to hold it on?
3) It’s a pain to get the medium properly centered
– Dunno. Centering program with a stylus that can move the object? Seems like a good way to break stuff.
4) Rotor shaft unscrews if we go for too long in one direction
– Balance rotation with software.
Possible improvement: I think that Bruce’s production version has a “pen up / pen down” motor.