RE: [CAD_CAM_EDM_DRO] Best ball screw prices? (was: Ball screw load ratings)

Jon -

I haven't used them yet, but I ordered Thomson "extra precision" 5/8 x .200
rolled ballscrews direct from Thomson, with .0015" accuracy per foot (vs.
standard .004"/ft), at a 50% premium over McMaster Carr prices. It's still
only $1.50/inch. And ballnuts are only $19/ea, so I'll use 2 to make a
preloaded system. I'll let everyone know how they work, for sure, when I
get there.

Carlos Guillermo
VERVE Engineering & Design

-----Original Message-----
From: Jon Elson [mailto:jmelson@...]
Sent: Thursday, March 08, 2001 1:16 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Best ball screw prices? (was: Ball screw load
ratings)


Doug Harrison wrote:

> ----- Original Message -----
> From: Jon Elson <jmelson@...>
>
> > > Does anyone have a source whose price is significantly (5%+) less
> > > than Thomson's? All I found so far is Reid Tool, and they're a few
> > > cents cheaper.
> >
> > Supposedly, HiWin has the best prices, or at least, very competitive.
>
> I got quotes on Hiwin for ballscrews and linear rails. The rails were

half

> the price of Thomson. The ballscrews were cheaper than Thomson from

Motion

> Industries but still significantly higher than Thomson from McMaster-Carr.
> For some reason, they are dirt cheap from McMaster-Carr if you stay with
> 5/8, 3/4 or 1 inch sizes.

All of this is probably rolled thread low-precision screws for power
transfer,
not for CNC positioning. The nuts are probably single-track, with no
preload. And, the manufacturer probably does not recommend preloaded
nuts on these screws. I've used some of this stuff (Thompson) in a proof
of concept
machine, and while they work, they are VERY loose. I later had to replace
the screw with a BSA screw with plastic anti-backlash nut. That was for
an optical carriage, so there was no force to speak of. But, these
ballscrews
would not work very well for a high-quality CNC machine.

Jon