On Thu, 25 Jan 2018 18:05:06 -0700, Bob La Londe
wrote:

I am sure somebody can tell me why this is a stupid idea, but I needed
to get this ball nut off the ball screw without dumping the balls all
over the floor. I don't know if the screw is salvageable or not. Its got
a bend in it somewhere. If its just in the machining in the end I might
be able to turn it down and machine some bushings. If the screw is bent
in the main span its done. I might be able to straighten that, but it
wouldn't be very accurate anymore. Normally guys screw the nut off onto
a piece of cardboard tube, but I have bad luck with that. This hand made
stub of aluminum "ballscrew" mates up with the end of the ballscrew I
need to check, and I was able to just screw the nut off onto the stub. I
had to hand grind a radius tool out of HSS in order to thread the
holder. It took me a couple hours, but it worked out perfectly. Of
course that time is wasted except for the learning experience if I can't
save the screw.

Anyway, now I can roll the screw on my granite surface plate and
determine where its bent.

http://tacklemaker.info/gallery/1_25_01_18_6_00_57.jpeg
Greetings Bob,
If the screw is indeed bent but the bend is a large radius I think the
screw might still be OK after being straightened. I used to straighten
shafts used in piston to turbine engine conversions for small planes.
The shafts would need to be straight within a couple thou over about
40 inches. After straightening I had to check the shafts pretty much
completely along the length of the shaft. And I never saw localized
small radius distortions, they were always over long distances. So
maybe the same thing would hold true for your screw. As I see it a
sharp bend would cause the ball groove(s) in the screw to be
compressed in one spot and expanded in another, opposite spot. A large
radius bend would cause the same effect but it would be much less. If
the shaft is then straightened I think the distortions in the ball
groove(s) would be lessened to the point that it wouldn't matter.
Eric