Re: Modifying an X-Y table

I have a vice like this. The original backlash was about 3/4"! The Acme
threaded rod seemed rough, too.

I replaced the Acme rods with 7/16-20 threaded rod. On one casting I
drilled out the threads and inserted a metal tube which I had tapped
at 7/16-20.

The other Acme went through a threaded steel insert which was just a
press fit into a hole in the casting. I destroyed the thing getting it
off, so I turned a replacement out of aluminum. I added thrust
bearings to both axes. One axis works well, but so far mounting the
other stepper is an unsolved challenge.

I understand that nuts made of delrin have low backlash. Acme taps are
very pricey, about 2 1/2 times the cost of your vice. You can make
your own tap with a piece of threaded Acme rod, though.

If you can drill out the present threads and replace them with a
delrin rod with Acme threads cut into it you might have a better vise.
As I think about it, an easier option would be adding delrin nuts at
one end of the casting threads. Fixing the nuts stationary would
probably be an easier challenge than aligning the previous setup
mentioned. I understand from John Kleinbauer that a delrin nut with a
length twice the diameter of the rod minimizes backlash. If you are
interested in low cost CNC you might look at his website.

http://www.crankorgan.com/

Good luck and have fun.

Grant

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Chuck Knight
<chuckknight@h...> wrote:

> Well, today there was one of those neat tool sales they hold out in
> rural area.
> While I was there, I found a fun little toy. Its castings are a

bit

> rough, but it's a cross-slide drill press vise, essentially a 4x6
> inch X-Y table with a vise on top.
> [snip]
> -- Chuck Knight