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Author Topic: Crown Gear  (Read 13388 times)
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JamesTSG
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« Reply #15 on: December 17, 2015, 10:57:04 PM »

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 themselve s".   Wink
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ArtF
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« Reply #16 on: December 18, 2015, 08:12:08 AM »

Smiley

  That IS one way. Id be intereste d in peoples experienc es 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
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Nate
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« Reply #17 on: December 21, 2015, 07:54:09 PM »

The approach I'd been originall y thinking of seems to involve undesirab le undercuts .

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


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ArtF
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« Reply #18 on: December 21, 2015, 08:26:19 PM »

Smiley

 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... Smiley

Art
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Nate
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« Reply #19 on: December 22, 2015, 01:50:49 AM »

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


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ArtF
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« Reply #20 on: December 22, 2015, 07:21:19 AM »

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
 
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Nate
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« Reply #21 on: December 22, 2015, 10:20:59 AM »

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 propertie s 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.
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ArtF
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« Reply #22 on: December 22, 2015, 10:28:54 AM »

Nate:

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

Art
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Nate
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« Reply #23 on: December 22, 2015, 04:07:41 PM »

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

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.
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ArtF
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« Reply #24 on: December 22, 2015, 04:13:41 PM »

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
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JamesTSG
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« Reply #25 on: December 23, 2015, 11:41:07 PM »

As in literal points of contact that would be very small percentag es 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.
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ArtF
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« Reply #26 on: December 24, 2015, 01:50:53 PM »

True, for some reason ball bearings came to mind.. but then everythin g I do tends to be very lightly loaded decorativ e type things. Smiley

Art
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Nate
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« Reply #27 on: December 24, 2015, 06:16:01 PM »

As in literal points of contact that would be very small percentag es 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 manfactur e (laser cutter or straight mill) rather than good mechanica l propertie s.
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JamesTSG
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« Reply #28 on: December 25, 2015, 06:41:05 PM »

But OTOH, rounded tooth gears would tolerate a variable angle of rotation much better than conventio nal gears. I'm not sure why you would design a mechanism that needed to, but... there you go.
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ArtF
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« Reply #29 on: December 25, 2015, 08:17:57 PM »

Yeah, thats what I meant by hinge effect.

Art
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