Re: MaxNC modifications

Jon Anderson <janders@...>
Subject: New member, something interesting

Hi, I'm new to the list, thought I'd introduce myself.

[Welcome aboard, Jon!]

I presently have
a heavily modified MAXNC and am building a CNC retrofit for my Hardinge
chucker, Omniturn style.
Using Ah-ha software at the moment on the MAX, but I'm going to be
building up a Linux box and giving that a shot.

[What is the advantage to using Aha software on the MaxNC, over using their
supplied software?]

Modifications to my MAXNC include 198 oz/in PacSci motors,

[Were these easy to mount, or did you need to machine new mounting plates?
How much were these motors, and did you get them new or surplus?]

Computmotor
OEM 650 drivers,

[Where did these come from? Are they what Aha recommends?]

motor mount plates with preloaded ball bearings to
handle thrust loads,

[Were these something you purchased or built from scratch? ]

BS&A ActiveCam nuts and 16 pitch screws,

[Are these ball-screws, or is this an anti-backlash modification to
standard screws?]

a Sherline
spindle assy and DC motor.
Somewhere down the road when I get some free time I'm going to post
drawings of all the mods, making them available at no cost.
If anyone has seen the Flashcut CNC Sherline at the Santa Clara Machine
Tool show a couple years ago, I built it.

Something I just ran across that might be of interest to some folks is a
new low cost ball screw from Thomson. They have a design contest going
and are giving out free samples for as long as they last, you can apply
at http://www.thomsoncontest.com
Just got mine today. These sure are no substitute for ground or even
precision rolled screws, but they just might have some potential for the
low end HSM CNC. Screw dia is fixed at .380 with a 16 pitch. Lengths
available are 6", 12, 18, 24, 36, and 48".
Nut has no provisions for mounting and is .75 in dia and .775 long.
There is a single return tube held in place by an injection molded cap.
Backlash specs are between .002 to .007, mine came in at .005. It should
be possible to clamp two nuts in a split block with perhaps a spring
washer to help set a light preload (obviously, before the nuts are
clamped).

[Do you think they would fit a stock zero-backlash nut?]

Mine felt a bit rough, but was dry. A bit of grease helped a lot.
Mounting these on a Sherline would require some significant
modifications, less so for a MAXNC. They might well be a viable option
for a scratch built machine. I saw this in last months Machine Design.
The screw came out of new mfg methods developed for the automotive
industry and mention was made that they could cost as little as $5 ea.
Obviously a qty price, but it ought to give an idea where these might
sit relative to existing ball screws.

Jon

[Do you think the 48" screws would be adequate to run a CNC router, or are
they too skinny? Was there any indication of their price in small
quantities (like six each?) I've been thinking about building a "big cube"
router from scratch, and cheapness is definitely a consideration, but I
thought I'd probably need beefier screws than this, or some other kind of
drive mechanism. Any advice is welcome, including thoughts on the control
system and the advisability of using linear motion bearings versus other
systems, (like skateboard wheels rolling on angle-iron rails).]

Andrew Werby

Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com