Re: [CAD_CAM_EDM_DRO] re:Ball Screw Disassembly

> So, let me re-assure you that re-loading the balls in a plain ballnut
> is no big deal. The trick is holding the screw CENTERED in the nut
> when you start putting the balls in. Once you have a full 360 degrees
> of balls inserted, it gets easier. You will have to shift the screw
> back and forth at first to get things "on track". And filling the
> ball return tubes can be helped by having a third(or fourth!) hand.
> Be sure to use ALL the balls(don't lose any on disassembly, you'll
> regret it!!!).

I'm sure there are many ways to put the balls back in. I found
putting the filled return channels on a pain, so I start with the
completely assembled but empty nut and one of the cardboard shipping
mandrels that are sued to retain the balls before the nut is put on a
screw. I hold the nut vertically with the cardboard mandrel sticking
up through it, then place balls around the mandrel a few at a time.
By gingerly pulling the mandrel partway out from the bottom end, one
can reach a point where the balls will slip into the races just beyond
the guide spur of the return tube. Just keep putting in balls... turn
the cardboard tube to cycle them down through the nut and up into the
return tube. Doing it this way it shouldn't take very long to reload
the whole nut. Once you have it loaded around the cardboard, simply
turn the screw into the nut, forcing the cardboard out against drag
you apply to it with your fingers to keep a gap from developing
between the two.

Of course you can make your own mandrel if you don't have the
cardboard tubes... but consider making it of wood, or covering it with
paper or something to get the rolling friction the cardboard tube
provides, which is very usefull.

I think the safest place to work on a ballnut assembly is sitting on
a thick blanket in the middle of a clean floor (ie, living room, not
shop). If you drop a ball, simply stand up slowly and look for it on
the blanket - it won't go far, like it would if it hit a concrete
floor and bounced behind your scrap pile.

Chris

--
Christopher C. Stratton, stratton@...
Instrument Maker, Horn Player & Engineer
22 Adrian Street, Somerville, MA 02143
http://www.mdc.net/~stratton
(617) 629-9830 home (temporary), 253-2606 MIT