Re: Proxxon Mill CNC Conversion

Graham Stabler wrote:

> http://www.indoor.flyer.co.uk/personal.htm
>
> Covers my conversion, a digitizing probe I made for it and on it and
> a 4th and 5th axis add on I made. Also shows some other things made
> using it such as propeller moulds.
>
> The working area is more like 1.5" by 5" It is a very small mill,
> good if you want to make very small things. If you don't then a
> bigger mill will suit you better.
>
> General comments: Spindle is good, runs to over 20k and is quite
> quiet. Takes tooling upto 1/8" maximum. Construction is pretty
> good, it has gibs and the nuts have VERY little backlash. I
> recently replaced the washers that act as thrust bearings with
> normal 6mm ID bearings and that has reduced backlash to nearly
> nothing. Before if you tightend out the axial play of the screw it
> would produce too much friction.
>
> Graham

As it happens, I am just about to undertake CNC conversion of my MF70,
after having seen Graham's site (as well as that of Tim Goldstein, whom
I believe got there first.). I'll agree it is a quality little machine,
although the extruded aluminium table could benefit from being replaced
with a cast table, and the 1/8" chuck capacity is very limiting. I get
the impression that something like the Sherline, while not a lot bigger,
is much more versatile.

Graham, is the leverage caused by the X axis stepper's weight hanging
off the end of the table a problem? I'm not sure whether to try
supporting the weight of a NEMA 23 motor, as you have, or risk a 45oz-in
NEMA 17 to reduce the bending moment (I'm not even sure if this has
enough oomph, as I estimate it takes up to 12oz-in just to shift the
table if it's been sitting for a while.)

As I'm planning on getting a slightly larger mill in the near future, am
I doing the right thing CNCing the MF70, or should I just save my cash
for the larger machine?

Richard