RE: [CAD_CAM_EDM_DRO] Hp 7475 Plotter Servo's, 3D surface modeling for EGG-BOT

Hi Victor,

To bad you're not in the area, I'd love to take a look. I never did find my
plotter manual, so it's in one of the 12 or so shipping boxes in the garage.
;>)

If the blinking error light never goes off, even with power down/up, then
it's an internal problem. The baud rate switches could be dirty, and not
reading correct? Maybe exercise them, or try 1200 baud vs. the 9600 you are
using?

I was hot to build an egg-bot a few years ago, almost made it, but I started
to over-engineer it, and got side tracked after that. It's pretty easy to
drive small steppers (NEMA #17) with nothing more then a ULN2003 for the
unipolar motors, and an H-bridge package (forgot #) for the bipolar ones.
Easy to steal stepper motors and driver parts off old 5" floppy disk drives.

I believe TurboCNC can run 4-phase (unipolar) stepper drivers. I've seen
some little boards with similar drivers to the ones mentioned above for
about $20.

It would be interesting to "project" an image onto the eggs surface. I
think one would have to do a NURBS surface (egg might be a little tougher),
and then project the drawing on it. I know, overkill for an egg-bot! ;>)

Vector CAD/CAM with the 3D surface modeling addition can no doubt do an egg,
although I'm not there yet in my continuing education! Then the drawing
would have to be translated to an 'A' (rotary) axis, I think. The egg-bot
would have an A, X, and either Y or Z axis. I'm guessing that the Z (or Y?)
could be reduced to a pen up/down solenoid. Interesting CAD/CAM/HARDWARE
project!

I'm interested in trying some "organic" shapes; I guess an egg would fit
that! So far, I only machine "regular" shapes (?), like flywheels and steam
engine cylinder blocks. My next goal: buy the "3D surfaces" upgrade, and
learn the surface modeling!

I do need a way to "clamp" the egg. I know they showed some real simple
holding devices on the website, but I found it a little tricky! Their pix
shows an 'A' axis and a 'B' axis (?) that acts like an X axis and
transverses top to bottom of the egg. (MILL axis convention) The pen is
loosely held, manual pen up/down here!

http://www.taomc.com/bits2bots/

And you've probably seen them, but there are some references here:

http://www.taomc.com/bits2bots/reference1.htm

Cheers!

Alan KM6VV