Crown Gear

[JamesTSG]

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".  ;)

[ArtF]

:)

  That IS one way. Id be interested in peoples experiences having done that. The STL's
and models GM puts out could be used in Vectric and such to generate a path for engraving
type cutting.. I may try that method to see what I get in the new year. Ive designed Auggie
to be able to shut down anytime and resume the next day, so I wont mind so much those
multi hour engraving paths..

Art

[Nate]

The approach I'd been originally thinking of seems to involve undesirable undercuts.

How about using "improved peg gears" as crown gears?

[ArtF]

:)

Think Id prefer two disks, a length of brass rod and just make them from pins..

Even those teeth look like they need to narrow toward center... :)

Art

[Nate]

More fiddling...  I guess they don't need to be peg gears to work as 'straight sided bevels'.

[ArtF]

Nete:

Much better, I think they have the benefit of running on a single line of contact.. and really at any
angle of bevel..

Art

[Nate]

Much better, I think they have the benefit of running on a single line of contact.. and really at any
angle of bevel..

The contact properties really aren't ideal, but I guess that's expected.  They are straight-sided though, so it should be possible to make a set on a CNC set up with an untapered end mill.

[ArtF]

Nate:

Has me wondering if the perfect bevel isnt spherical teeth, any angle woudl have a single contact point... :)

Art

[Nate]

Has me wondering if the perfect bevel isnt spherical teeth, any angle would have a single contact point... :)

I'm not sure what you mean by "perfect bevel".  If you can mill profiles, proper involute bevels will be better for fixed angles because they have contact along a line.  If you want to 'act through a hinge' these pseudo-involutes should have a single contact point at any angle already.

[ArtF]

I guess I should have said universal, if the teeth where spheres I figured they'd work at any angle or an angle thats varying, as you say..like a hinge.. But true, these shapes would also have a single contact point.

Art

[JamesTSG]

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.

[ArtF]

True, for some reason ball bearings came to mind.. but then everything I do tends to be very lightly loaded decorative type things. :)

Art

[Nate]

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.

Yeah, it's optimized for easy manfacture (laser cutter or straight mill) rather than good mechanical properties.

[JamesTSG]

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.

[ArtF]

Yeah, thats what I meant by hinge effect.

Art