Re: Re: Engraving and engine turning

Hi Ian,
It is me again!

On a machine I built a long time ago, I used regular threads also as you describe.

My nut was slightly different in design. I made a very long nut, about 4 times the thread diameter long and machined groves
around it near each end. Then I cut it in half length vise. One half was attached to the carriage via a sideways flexible
mount to avoid jamming and misalignment. The other half of the nut was continuously providing a pre load by O-rings in the end
grooves which forced the nut halves together.

After assembly, I put grinding paste on the screw and run it back and forth until it was well ground and running smoothly
together. Of course, then I disassembled all and cleaned and greased it and it worked well. No backlash and no adjustments
needed for wear, the O-rings take care of it.

Bertho Boman
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> From: "Ian W. Wright" <Ian@...>

> As mine is such a small machine, I was considering a simpler method of

> backlash adjustment. The feedscrews are only basically normal threads

> (not ballscrews) and are 1mm pitch. The nuts are made of bronze and are

> cut across for 3/4 their width part way down the thread and a screw is
> installed to nip the two parts together - the same effect as having two
> nuts sprung apart on the thread. This way I can have a relatively long
> nut to equalise any minor irregularities in the screw pitch whilst
> keeping the main part of the nut always pressed up against one side of
> the thread by just the right amount. This is a more effective method
> than having two half nuts clasped around a thread.