use metric gears with inch gears ?

[AlbertH22]

Anyone have experience driving metric #1 module spur gear with a 24DP gear. I can adjust the center distance between the gears.
FYI:
Circular pitch of #1 mod gear is pi mm....(.12368")
Circular pitch of 24dp spur gear is... (.1309)

Thanks for any info.

 

[TheTick]

Interesting question. I suppose it could work if the pitches are not too different, and the gear tooth profiles are compatible.

In theory, an involute is an involute, and differences in center distance result in a difference in pressure angle. However, if the pitches aren't the same, you don't get continuous contact between sequential sets of teeth. One set of contacting teeth will grab a little too soon or a little too late. This will result in chattering and unusual wear.

That said, I would say don't do it.

 

[drawoh]

AlbertH22,

The tooth pitches are close. If you back them off, both gears are no where near their line of action. It should not be any worse than a wheel of toothed pegs. If you don't mind slop, and low efficiency...

--
JHG

 

[dhengr]

Sounds like a good way to use up all those misc. extra gears laying on shelves around the world. And, you’ll use them up quick. Maybe check the secondary market for bulk metal fillings, as a waste product. Try to match the tooth hardness so they wear evenly.

 

[BrianPetersen]

What force and speed ... ? ? ?

Occasional / intermittent / light load low speed / gears substantially overdesigned, perhaps you can get away with it.

I know there is a retrofit kit for a motorcycle that I own, to get a lower 1st gear ratio, and they are only changing the driven gear on the output shaft (for one having one tooth more), so there must be some sort of mismatch - and I've heard that the gearbox howls a fair bit in 1st gear when this is done, which is indicative of mismatched tooth profiles. But 1st gear is only used for a brief moment when starting off, and after that, it's just spinning with no appreciable load on it. I have no doubt that if you tried this stunt for top gear, it would not live long.

 

[fegenbush]

BrianPetersen,

If you're talking about "adding a tooth" or "dropping a tooth" on a motorcycle, that refers to the output sprocket that connects to the drive chain. I did it on my motorcycle years ago, and the difference in chain length is near negligible.