Re: Ballscrew installation issues

stratton@... wrote:

> preloading some tension on the screw with bearings at both ends,
> compared to the single end support present now. So the only real
> question on loading is what the balls themselves can take. Chances
> are if I'm overloading them, they just won't last as long. But for
> $20 a nut, I can afford to replace them after a year of light use.

Baccscrews themselves can take enormous loads. These screws/nuts are
probably rated around 1000
Lbs!

> McMaster only sells right hand screws/nuts. Anyone know a cheap
> source of the left hand ones? Having a lathe with a backwards
> crossfeed would be somewhat annoying - almost enough that I'm tempted
> to put the handwheel on an encoder rather than on the screw and always
>
> use the motor to move the crosslide even for manual work, probably
> with a simple circuit to generate step/direction when the computer is
> off.

I made a replacement acme screw and nut for my crossslide, and didn't
notice
it should have been left hand. I used it for over a year before
replacing the
lathe with a better one. It really isn't that bad.

> Will I be able to machine the screws with carbide insert tooling?
> Hardened linear shafting machines like a charm this way, and I was
> doing some extremely interrupted cuts on mild steel the other day
> without breaking the inserts, albeit with fine feed. So if I feed
> slowly and carefully, can I turn the ends down or groove them to make
> it easier to clamp on?

Well, I wouldn't say it machines like a charm, but you can machine it.
once you get .025"
or so below the bottom of the threads, it machines VERY well. Up in the
hardened
area, it can be just a bit tough, but the carbide can get through it.
This mostly applies
to my experience machining ground ballscrews, some of the rolled stuff
might be a bit
harder.

Jon