Source for wormgear system-building rotary stage

[vger]

You might look at an electric window lift motor and gearbox, I think they are worm and wheel. I made my own rotory table with a brass wheel and 1/2" 10 tpi acme as the screw. It's 180:1 ratio so that a 200 step/rev stepper makes 0.01 degree increments. I used 3/8" thick brass plate 5.875" diameter and milled a concave in the edge such that the center of the valley was of 5.785". The diameter was calculated by 180 teeth divided by TPI divided by pi, then added .055" for half the thread depth. Getting the backlash out was a real pain!!! The screw ends had to be turned down dead on concentric with the od of the screw. Then I found there was just the slightest bend in the screw (about .002 offset at the center) so had to straighten it. Anyway, if I had to do it again I would just order one of the sherline tables.

[Kipper]

Originally Posted by Geof Not in a car gearbox to my knowledge.

"Cough" Speedo drive "cough" Although they are way too weak for any torque...If you can find an ancient (1960's maybe) wiper motor you could be in luck as some were made of brass/bronze....Also when cars were "real" they used worm drive for oil pumps and indeed for the distributor drive on some.

[Geof]

Originally Posted by Kipper "Cough" Speedo drive "cough" Although they are way too weak for any torque..

I always thought they were a 'back-driving' worm arrangement almost 1 : 1; somewhat similar to the distributor drive from the camshaft.

[HuFlungDung]

Some older makes of garden tillers had a worm gear drive. These would be quite easy to spot, because they do not use a chaincase reduction. A chaincase is easy to distinguish from the fancy casting used in the worm gear tiller.

Now, they do see severe duty, so you might have to scrounge through a lot of junk tillers to find one in pristine condition. But, it would be pure luck if the ratio was a good one for dividing into 360°

These tiller gears are fairly beefy, maybe 8 or 10 diametral pitch.