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

Actually there is no change to the power head frame using my method inside the machine. I leave the pinion shaft bushing bores alone. I simply made replacement excentric bushing to replace them. I bought a replacement pinion shaft from enco for $25 and machined the diameter down on the fine feed side to accomodate the right hand side excenetric bushing. I had to elongate the holes in the fine feed worm wheel housing to take the slack out of the worm to worm wheel.
I then replaced the fine feed handwheel with a pulley.
Here's a link to a video of my mill drill running at 264 IPM .
http://video.google.com/videoplay?docid=7735093752200071391&q=mill+drill+servo&hl=en
the eccentric bushing can be seen on the left side of the quill and my pulley attached to the fine feed shaft is also visible.
Dan Mauch
economical 3D scanner software and kits
low cost stepper and servo motors.
cases for Gecko drives
kits and assembled 3-4 axis drives
www.camtronics-cnc.com
www.seanet.com/~dmauch

----- Original Message -----
From: arquibaldo2001
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Saturday, April 28, 2007 11:36 AM
Subject: [CAD_CAM_EDM_DRO] 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





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