This is a Really Bad Idea. A lap works by having the abrasive embedded
in it, and it's the harder material that will be worn down. Further,
carborundum abrasive will be virtually impossible to remove once
embedded in the softer worm gear and it will continue to grind away. A
method of making laps involves rolling a copper cylinder over diamond
dust on a hard steel plate, the diamond gets embedded in the copper
(just to illustrate).

I *have* tried 'lapping' the precision worm gears I made myself, but
this was using metal polish which was subsequently removed with solvent.
The 'lapping' effect is very modest indeed, and it probably does no more
than put a surface polish on the the teeth, it was not intended to
correct any tooth irregularities. If you could mount the worm gear and
worm in a hobbing machine you could use pressure to 'cold-form' the
teeth - unlikely the average amateur will have the equipment though.

For an overview on making precision worm gears in a home workshop I have
written an article which is listed below:
http://easyweb.easynet.co.uk/~chrish/worms.htm
I have so far been unable to test these gears (my home-made GEM is as
yet inconplete) but I will be disappointed if they are anything less
than very accurate. If successful, I will make replacement RA gears for
my LX200.

Chris Heapy


Vince Gardiner wrote:
>
> There has been a lot of discussion lately about PEC training and the
> suggestion that the
> worm wheel may not be sufficiently uniform over its whole circumference
> for PEC to be of much use outside the original training area.
> I recall some time ago some-one (I forget who) mentioned he used a
> lapping paste on his worm and wheel, but I don't recall any discussion
> as to whether it improved anything.
> It would appear at first sight to be the way to go. The worm being
> stainless steel and hard, it should be able to smooth out the softer
> worm wheel with the lapping paste.
> Does any-one know the result of that method, or have any ideas as to its
> possibility?
>
> Regards

--
*Model Engineer Support Page*
Engineering: http://easyweb.easynet.co.uk/~chrish/homepage.htm
Astro Stuff: http://easyweb.easynet.co.uk/~chrish/lx200.htm

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