Re: Z-axis CNC conversion on a mill-drill: a challenge (long)

Thank you for your contributions, R Wink & Dan Mauch. By the
way, I am aware of Dan Mauch's brilliant eccentric-bushing-
modification,
but I think only an experienced machinist should try to implement it.

Let me explain a little: The reason I decided against working on
the rack/pinion backlash itself is twofold:

First, it involves changes deep inside the machine, and if I
screw-up bad enough (I am inexperienced) I end up with nothing,
while WT's modification is external; if things go wrong, I still
have my old machine and can try again...

Second, even if I managed to reduce the rack/pinion backlash, one
problem still remains: where to power the Z axis: if directly on
the pinion, some other reduction would have to be implemented since
the pinion movement is too coarse (80mm per turn instead of 2.5mm
per turn for the X & Y); if on the worm shaft (part 347 in Grizzly's
model G1006/G1007 parts list) we have another link to worry about
(worm shaft-to-pinion) and this one involves friction and the risk
of slippage (although I don't really understand how this link works..
.)

Please refer to the two photos in message #90489 to see WT's design:
http://i14.tinypic.com/344unnm.jpg
http://i14.tinypic.com/2m5ge90.jpg

With respect to Jeff Davis's plans, I followed the link but couldn't
find any details about his Z axis design. If anyone knows the design
and can confirm that it is similar to WT's one, I will gladly part
with the $40 to find out how to implemet a rotating ballnut.

Nelson