GearHeads Forum

Uh... whut?

Sort of like rounded over peg gears?

I don't understand how 'spherical teeth' would provide an advantage if they're simply fixed teeth on a pair of gears.


They have an undefined (but small) contact surface and engagement angle. Conventional gearsets have a fixed angle relationship. Deviate by even a small amount from that and bad ...

But OTOH, rounded tooth gears would tolerate a variable angle of rotation much better than conventional gears. I'm not sure why you would design a mechanism that needed to, but... there you go.

As in literal points of contact that would be very small percentages of the entire surface area of the teeth. The material would have to be very hard faced and lightly loaded to be of practical use.

Or make the gearsets slightly oversized, put them in a jig, and then run them for a while dry or with a cutting fluid (or even abrasive powders!) to let them "mill themselves". 

Hi Art, thanks for the reply.

To me this is a simple straight cut crown gear:

http://rt-ho.com/3d-crown.jpg

This I guess is also know as a "face gear". But is more practical, and what I am looking to produce:

http://www.centa-uk.co.uk/files/2813/5782/9351/ASS%20AG%20Face%20Gear%20Set.jpg ...

On most I see the "lands" between the teeth get wider but the teeth themselves have the same width all the way. The "hooking" of the pressure angle I think is mostly to reduce thrust on the gears, not so much to fill the gap. At least that is what I dimmly recall.

Are you saying its hard from a ...

Anymore thought on this? 

I need a crown gear and I'd rather not do it the hard way (tooth at a time)....

Thanks,
-james

Hi, I see my thread has run off on its own..

Yes, once you get comfortable with metric it really is easier, both the maths and visualization, than inches. I still have trouble at the macro, meters and decimeters, but for small scale stuff, millimeters and down to microns, metric is the way to go ...