Re: [CAD_CAM_EDM_DRO] Re: How hard to rotate should preloaded ballnuts be, anyway?

I have been nuts for a lot of years then.

Pay attention and reload the balls without allowing a ball it get past
the return and you will be fine. The final balls are loaded into the
return tube which has been packed in grease and gently placed on the
nuts. You may encounter two sizes of balls in each circuit and a
differnet size large ball in adjacent circuits. Just be careful to
alternate the load balls (big ones) with the idler balls (small ones)
and load with the same number. If the load balls are different diameters
in adjacent circuits make sure that these return from wince they came.

I have reballed, cleaned and adjusted ballscrews from 1/2" to 6 inched
in diameter without a problem. These have included nuts that are solid
and preloaded using detimed circuits, twin nuts preloaded using ground
spacers and spring loaded nuts. A fully preloaded nut will have
resistance to turning by hand BUT it will turn smoothly.

The only way I have found to completely clean and inspect a ball nut is
to disassemble the screw. Usually if a nuts feels "gritty" and there is
no sign of contanination, the load balls are scored and/or the ball nut
surface is rough. If the damage is not severe (means barely noticable)
the ball nut surface may be pitch lapped and smoothed up, then the screw
reloaded with a slightly larger load ball, idlers remain the same. If
the balls show signs of surface damage or the ID of the nut is spaulded
it is most likely time to spend money!

This is based on hands-on not theoretical experience.

gary

Harko Schwartz wrote:

> Anybody that removes the balls is nuts they are placed in a size varying
> order to allow the balls to move and the preload shouldnt be to where you
> can't turn the nut. You can send the screw out and be reballed and checked
> out for a few hundred dollars.
>
> On 4/18/07, Polaraligned <polaraligned@...
> <mailto:polaraligned%40optonline.net>> wrote:
> >
> > The ballnuts should turn freely without any gritty feel.
> > If you can, submerse the whole ballscrew/ballnut assembly in
> > a solvent and run the ball nut back and forth to flush
> > any foriegn particles out. It could be hardened grease
> > combined with metal particles causing the problem.
> > This method is recomended by Bridgeport in their BOSS CNC
> > manual to flush the ballscrews.
> >
> > Scott
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com
> <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>
> <CAD_CAM_EDM_DRO%40yahoogroups.com>,
> > Abby Katt
> > <cncgroupnospam2@...> wrote:
> > >
> > > Howdy Folks,
> > >
> > > I'm recomissioning a neolithic ORAC CNC lathe with modern CNC-controls
> > > (Mach3/new electronics etc) but in cleaning it up have run into a
> > > mechanical conundrum. The ballscrew along the long-axis is really
> stiff
> > > and gritty to turn, I've been cleaning it up with WD40, but so far
> > to no
> > > avail. I'm beginning to come to one of those deadly-fatal conclusions
> > > where I give up and let all the little balls out...
> > >
> > > My question is - how hard is to to rotate by hand preloaded
> ballscrews?
> > > (I assume this thing is preloaded, it has a massive ballnut) It has
> > some
> > > screws on the tubes through which the balls recirculate. Is it easy to
> > > open this and remove/clear/reinstall the balls, or is this just
> > > spherical-based-madness?
> > >
> > > The mounting block is also under tension, and also quite hard to
> turn..
> > > how tight should this really be?
> > >
> > > Oh, I have some pics of it here too:
> > > http://www.silverkatt.co.uk/Lathe/Default.aspx?Page=2
> <http://www.silverkatt.co.uk/Lathe/Default.aspx?Page=2>
> > >
> > > BTW> This machine has been in storage for 10+ years...
> > >
> > > Regards,
> > > Abby
> > >
> >
> >
> >
>
> [Non-text portions of this message have been removed]
>
>

[Non-text portions of this message have been removed]