Re: Mill/Drill CNC Conversion

Hello,

There is another way. If you use the square single nuts, a flat or
angle glued or screwed to one will keep the second from turning. Now
usually the preload is place between the two, but if you bend one end
of this flat up and drilla hole through it for the screw to pass
through it can be the pressure point fo rwhatever means of preload
you desire to employ (urethane/ belleville washers/spring/ etc.
one simple technique is to use spring steel for the flat piece and
make the upturned end a more than 90° bend. then it alone can provide
the pre-load.

If the flat is screwed to the first nut through slots, the preload
can be adjusted with a big pair of channel-locks and a screwdriver.
Be sure the holes for the plate mount do not go through to the
ball "runs" in the nut!!!

Having said all this, don't forget the even easier route employed by
Dan M (and posted a few times already on this list); which is to re-
load the ballnut with slightly larger balls, thus making the single
nut a pre-loaded type! (but do the calcs to be sure the single nut
chosen can handle your loads; no problem for a mill drill, but
essential for a larger tool)

Hope this helps.

Ballendo

--- In CAD_CAM_EDM_DRO@y..., "jeffswayze" <jswayze@o...> wrote:
> --- In CAD_CAM_EDM_DRO@y..., ccs@m... wrote:
> >
> > > I figure I'd start with non-preloaded nuts as they are
> significantly
> > > less expensive than the preloaded ones ($20 vs. $160.) In
> my initial
> > > test of my table I found no perceivable backlash, but that of
> course
> > > will change once loads are applied. I guess I'll cross the
> backlash
> > > bridge when I come to it.
> >
> > The preloaded nut I bought is really an assembly of two nuts.
> If I
> > had to do it again, I'd just buy two plain nuts. Dump the balls
> out,
> > grind two grooves in the end opposite the mounting threads of
> each, on
> > two opposite corners on each nut. Clean the nuts thorougly
> and repack
> > the balls. Then make up a short OD threaded tube to go
> between them
> > with male tabs to fit in the notches. Put some rings with set
> screw
> > lock on the threaded piece, and a stiff wavy washer type spring.
> Use
> > this to adjust the preload force...
> >
> > Chris Stratton
>
> Good info Chris. Looking at the pictures, it did appear that they
> were just two $23 nuts connected together with a magical $120
> interface. However I wasn't sure how they kept the to from
> rotating relative to each other under load.
>
> Could you post or e-mail a drawing of what you are proposing?
> I'm having trouble picturing the "short OD threaded tube" and
> how it's used.
>
> Great info, though. Thanks!