Re: [CAD_CAM_EDM_DRO] ball screws

In a message dated 06/19/2000 6:13:02 AM Hawaiian Standard Time,
jj@... writes:

<< They
are Thompson Saganaw units with a .625 ball circle and .2" pitch. I'd like
to talk with anyone that has used these to retro-fit one of those Taiwanese
mill/drills. They don't give the max load specs and I'm wondering if they
would be rigid enough.

Joel >>

Joel,
I use them in an EMCO MAIER FB-2. They are OK for this machine but I doubt
I'd use them in anything larger. If you keep the rapid rate low to control
RPM, they would be OK even if fairly long (~14"). Anything longer or for a
fast machine should be larger in diameter (3/4" +). Support the screws at
both ends whenever possible. The Thompson screws have a rough finish that
makes them feel gritty. They wear in after a while since the balls are much
harder than the screws but the gentleman who mentioned polishing the screws
first with diamond powder had a good idea. It really depends on what you are
making but if I had my choice for a mill drill, I'd go precision rolled 3/4"
or 7/8" from Nook or Hiwin. These all should be pre-loaded for best results.

Peter
THRD, Inc.