How strong are 1/4" , 1/2", & 3/4" shafts for torque apps?

I have a couple dozen 1/4" stainless shafts, and would like to perform gear reduction with them.

How much torque is the max recommended for these sizes?

1/4", 1/2", 3/4"

I've looked for hours, in Mitsumi and Enco catalogs, google, etc. No luck so far.

Thanks in advance.

Without material spec there are no answers. When you say "stainless", do you mean 303 or 17-4 PH H1150?

John

Lots of variables. I don't have the actual numbers but I can certainly tell you that it will vary on how far the supports are to the gear. If you have a 1/4" shaft sticking 2" out of a bearing, with a gear on the end. It won't take much force for that shaft to deflect. While if you have only .020" between the gear and bearing, you can get much more done. I know I'm just stating the obvious, but it has to be part of your equation, somewhere.

John is right, first you need to know what material you have, then you need to know the design so torsional, bending, and shear stresses can be calculated. Ballpark? Look at torque values for similar size bolts.

Yup. You need to lock in all the variables and conduct an analysis specific for the design. Don't be surprized if the different "stainless" alloys vary up to 3X in strength and fagitue resistance.

Garden variety austinetic stainless is not the best material for high strength safting. Neither is it particularly fatigue resistant. And design has a big influence.

Sorry, your question is plain too big.

There are cookbook stress analysis formulae in the standard tests, Mark's Handbook for Engineers, Machinery's Handbook, etc.

Another thing though, is almost any steel, stainless or otherwise will bend the same amount. Once.
So, as long as you are not bending it permanently, all steel will bend the same(!) amount.

Secondly, the torsional stiffness will go up with the 4'th power of the diameter. IOW, a 1/2" shaft will have 16 times more torsional stiffness as a 1/4" shaft. A 3/4" shaft will have 81 times the torsional stiffness as a 1/4" shaft.

As far as Bending.... Someones else can give some good guidelines, or rules of thumb.
I don't think you are designing aircraft parts today. Are you? So, just some general rules of thumb will go a long to getting a TLAR design. (That Looks About Right)
I'm guessing that that is what you are up to today.