At 08:14 PM 13/05/2013, you wrote:
>On 2013-05-13 8:47 PM, Gordon Williams wrote:
> > Casting your own gear without making it oversize and machining it down =
to
> > size is unlikely to work very well or for very long.
>
>It's not a high speed or precision part. The rollers turn at less than 4
>RPM and there is enough play to allow for quite a bit of error in gear
>size with respect to the quality of the mold.
>
>Plaster is an excellent mold material. I think this should turn out
>better than expected.

For fine detail you need some pressure.. for gravity casting, the mold
would likely be made deep with risers (not vents). I don't think this is
going to work for you, but I'd like to see the results regardless.
You might get better results with pot metal (zinc alloy). A lot of
stuff is made from this, such as V-belt pulleys and car parts. Melts at
a lower temperature and should flow better- often used in die casting.

Spur gears in brass or aluminum are relatively easy* to cut one tooth
at a time if you have patience and some basic machine shop equipment..
see the many online guides.

OTOH, you may be able to just buy the gears in brass or whatever..
try Stock Drive products.

--sp

* well, compared to worm gears and helical gears.=20

--=20
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