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

Hi Nelson,

The Z axis quill idea is not my own. I learned bits and pieces here and there thru my surfing in the net.

I happened to got hold of a second hand ball screw/nut with exactly the setup wherein the ball nut with the timing pulley is the one rotating driven by the stepper motor and the ball screw will travel linearly.

You are correct that you will need a pair of angular contact bearings to hold the ball nut.

Send me the $40 instead :) . Just kidding!

I am in the process of redoing my Z axis as I need to do the pulley reduction. I will take some pictures of the Z axis assembly and the exploded view as well.

Contact me directly and I can send you the pictures once ready or I may add it to my flickr photos.

WT

----- Original Message -----
From: arquibaldo2001
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Sunday, April 29, 2007 2:36 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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