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Author Topic: Hypocycloid Gear  (Read 34596 times)
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Dan
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« on: October 28, 2011, 10:54:29 AM »

Hi Art,

Can you consider adding these? Appears to be lots of informati on on these and even the math involved. See this link:

http://www.zincland.com/hypocycloid

Dan
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ArtF
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« Reply #1 on: October 28, 2011, 11:16:19 AM »

Dan:

 I think thats pretty muc a internal cage gear as shown here..

Art


* ringhypo.png (12 KB, 487x431 - viewed 1008 times.)
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Dan
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« Reply #2 on: October 28, 2011, 11:58:07 AM »

Ah.. interesti ng, Art, I haven't thought about this. It's pretty close. But the transitio n between the valley and lobe is not smooth and increasin g the pins diameter makes things worse and at some point Gearotic can't handle it.

Dan
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ArtF
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« Reply #3 on: October 28, 2011, 12:10:25 PM »

Dan:

  Actually, it should be identical .. I think this is a bug and it has been added to my bug list. That pin hole
should translate smoothly to the outside hypocycli c curve. Early code, so I hadnt noticed the error. I think when fix it would do as you describe in that thread..

Art
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Dan
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« Reply #4 on: October 28, 2011, 12:20:42 PM »

Art,

Thanks for that. Would be interesti ng playing with it. Please let know when it's fixed.

Dan
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BobL
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« Reply #5 on: October 28, 2011, 05:16:08 PM »

Dan;

 That particula r gear reduction method would make an awesome reduction mechanism for a clock !!!!

Thanks for posting

Cheers
Bob Wink
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Bob
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« Reply #6 on: October 29, 2011, 12:55:56 AM »

I was thinking that, too.  How much drag would it have?

Kirk
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Dan
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« Reply #7 on: October 29, 2011, 01:00:50 AM »

Yes, Bob, it would. They are very compact and theoretic ally you don't have a limit on a single stage transmiss ion ratio.

Kirk, these drives are very efficient . Single stage efficienc y in access of 90%.

Dan
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Mooselake
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« Reply #8 on: October 29, 2011, 09:48:43 PM »

Way back when I cut a lantern and pinion gearset, with 1/8" pins, that ended up with very pointy teeth that had problems with binding even after a lot of fine sanding.  At the time I assumed it was a problem on my part, but never got back to it.  I'll try to make it again after the changes.

Art, would it be hard to be able to vary the cage size while you're in there?  The pin holes left gaps in the outside edge where the pins were flush with the edge.  With the little dowels I had to remake it several times because it kept breaking when inserting the pins, probably my hand-eye coordinat ion problem.  IIRC correctly I finally had to soak the pieces in superglue to strengthe n them.  It would be pretty handy to be able to add a little extra beef on the outside of the pin holes for those of us approachi ng mature citizen status.

Did I read the reference d article right?  A 60 tooth pinion and a 59 tooth lantern would give 60:1 in one shot?  My 56 tooth 1/8" pin pinion is just a bit over 3" across, so 60 would be pretty easy with my mini router.  The result would certainly make an unusual clock.

Kirk
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Dan
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« Reply #9 on: October 30, 2011, 12:30:53 AM »

Hi Kirk,

Hope a fix will come soon.

Did I read the reference d article right?  A 60 tooth pinion and a 59 tooth lantern would give 60:1 in one shot?  My 56 tooth 1/8" pin pinion is just a bit over 3" across, so 60 would be pretty easy with my mini router.  The result would certainly make an unusual clock.

Yes, that's true! 60:1 in one stage!

Dan
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Mooselake
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« Reply #10 on: October 30, 2011, 10:37:10 AM »

Me, too.  More amazing things from GM!

Seems like just yesterday CNC took multi-million dollar mainframe s, APT post-processors, and big buck milling machines (had a summer job around 1970 where a couple coworkers worked on those post processor s while I wrote a large fortran program that cranked out giant (non-cnc) cobol programs); now I have one in the basement.

Art, how did you make that picture?  Every combinati on of DP and pin size I tried still ended up with pointy gears.

Kirk
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ArtF
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« Reply #11 on: October 30, 2011, 12:11:13 PM »

Kirk:

  Latest version fixes the errors in it, but that photo was from the last version. You get those rounded teeth, ( which are epicycloi ds mixed with hypocyclo idals )
by selecting the cage gear as an planetary gear..jus t make the cage have more pins than the spur and the internal selection will light up for selection .

Art
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ArtF
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« Reply #12 on: October 30, 2011, 12:15:11 PM »

Hi Guys:

  Just a note.. unless Im missing something, I think the ratio you were seeing was more like 60:59 , not 60:1..
Harmonic drives, ( which I think that is..), reduce very little, very efficient, but very small reduction unless the
pin number is 60 times the spur gear tooth count. When you see the two gears beign similar size, thats a very
low reduction of about 60:59 ( assuming there is 60 tooth pin, and 59 tooth spur)..

   Hmm, I wonder how a successsi on of gears inside one another each reducing a few % woudl look.. Smiley )

Art
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ArtF
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« Reply #13 on: October 30, 2011, 12:17:52 PM »

Ahh, I take that back..dri ll test makes it pretty clear.. The eccentric shaft fooled me a bit.. Does look like a pretty good method o
reduction, very smooth too.. make a great clock Id think..

ARt
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Dan
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« Reply #14 on: October 30, 2011, 12:31:53 PM »

Hi Art,

Yes, a very neat drive system. I wonder who invented it. Pretty clever.

I downloade d the latest version it looks better now and I can't see nay interfere nce any more, but the transitio ns are still too distinct I think. Especiall y when the pin diameter is bigger than the module.

The attached screen shot is of module 3 and 5mm pin diameter. I don't know if the sharp transitio n is bad or no (simulatio n look good) but common sense tells me that smoother is better.

Dan


* Hypocycloid1.jpg (63.6 KB, 482x466 - viewed 899 times.)
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