Rotational accuracy required for gear cutting?

The higher the worm ratio, the finer the resolution.

AFAIK the accuracy required rises with the speed and power they transfer, the speed due to rotational inertia. For a model you can cut the tooth gaps oversized.

I had a big problem with uneven residual play in the worm wheel and had to manually preload and lock the spindle for each cut. jsw

It is a gear for a cheap telescope drive, must be a bastard size. That is why I am making it, no one seems to sell it.

The old nylon gear is totally smeared, took me all day to identify it by measuring the mating gears & mocking up the gear pitch diameters & shaft spacing dimensions in Autocad as a double-check. (Good thing there are free gear profile DXF generators!)

I expect the cheaper rotary tables to be sloppy, but like you did, that can be worked around.

I will probably have to cut a couple of them before I get it right, but it will be nice to have the capability to be able to make gears for other future repairs too.

MikeB

What is the a minimum ratio that would be acceptable based on 2000 steps/rev?

The table I am considering has as 36:1 ratio.

MikeB

You might be able to properly identify the last parameter, the pressure angle, from an unsmeared gear.

Isn't there anything from Boston Gear that would work?

Depends on the gear accuracy class you trying to achieve.

If you use a 36:1 dividing head each step is 36/43 of an input shaft turn, or 1674.4186 steps. You should distribute the over and under steps evenly so the last tooth space isn't too near or far from the first. A non-cumulative error of about one part in 3000 should be well below your machining tolerance on a gear 0.886" in diameter.

If you enter the data into a spreadsheet you can manually modify the step allocation to see how it comes out at the end. jsw

Good, thanks!

I'll get that table then.

I was reading up on my stepper drive & it claims it can mico-step to

MikeB