Re: [CAD_CAM_EDM_DRO] ball screw / endblock machining (was Rochester, NY, search...)

Yes Jon I used to do the same thing before I got the grinders.
Good point. I am glad you mentioned it.
I still do it sometimes because I have to give the lathes a time
consuming cleaning after using the tool post grinders... it gets grit
everywhere even if you cover the ways. I only use it if I have several to
do.

I machined .001 over usually.

Carlos, for the typical ballscrew sizes we use the bearing bore should be a
press fit and the housing a push fit. My tables show a mean fit of about
.0004 tight for ABEC-1. If the bearings are a duplexed pair held with a lock
washer you can go looser.. down to about .0001 tight. It should never be
loose enough to just slide on by hand. Get yourself a good bearing catalog
from a distributor and it will have tables for shaft fits.

The threads to be machined on the ballscrew end are usually
32tpi- kinda fine. It is easy to overcut them and then you will find
yourself making a custom locknut like I had to once. Clean
off any burrs before measuring or fitting.

A push fit for the housing is about .0001 tight to as much as
.0005 loose or so. These can be honed to size as well. I use
120 grit sandpaper just like Starrett does to tune their machinists
squares.Undercut the inside corners.You need a dial bore gage. You can use
telescoping gages if great care is taken.

Oh one other thing- watch the temperatures when dealing with
these tolerances. A 45c rise will make a 1" shaft grow .0005". Thats enough
to spoil a fit if you measure it while
it is hot and it later shrinks. This same phenomenon makes
for easy bearing mounting if you warm it before putting it on
however.

I will send you a dxf of the block by private email.

Oh and I use bearing headquarters in chicago.
(847) 966-7575

I used to use motion industries but I have been very unhappy with their
service and prices as of late.

Ok back to attempted linux install for me!

Leslie Watts
L M Watts Furniture
Tiger, Georgia USA
http://www.rabun.net/~leswatts/wattsfurniturewp.html

----- Original Message -----
From: "Jon Anderson" <janders@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Tuesday, January 23, 2001 10:24 AM
Subject: Re: [CAD_CAM_EDM_DRO] ball screw / endblock machining (was
Rochester, NY, search...)


> Carlos Guillermo wrote:
>
> > I don't have a toolpost grinder, so I'm hoping I can get close enough
> > on my lathe, taking very light cuts.
>
> Carlos,
>
> It's the part of the shaft that passes through the bearing's inner race
> that really ought to be ground. Not everyone has a toolpost grinder, but
> there is an alternative. I've lapped the last half thou off with
> Aluminum oxide hand stones