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Author Topic: Cycloid Reducer.  (Read 9486 times)
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tweakie
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« Reply #15 on: January 22, 2020, 06:38:49 AM »

Well, I have made a start  Grin

I tried laser cutting but the dimension al accuracy is just not there so resorted to milling. Once I get a few parts machined and assembled I will take a few more pics.

Tweakie.


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ArtF
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« Reply #16 on: January 22, 2020, 08:41:40 AM »

Tweaky:

   Dimension wise I was of the opinion one should enter a pin diameter slightly larger than that they intend
to use. The drawings are done with zero allowance . I expect a backlash is required to allow for at least
some tolerance .  Other than that they should ( math wise anyway ) work out well.

 Love to see your end product.. Smiley

Art
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Mooselake
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« Reply #17 on: January 22, 2020, 08:50:55 AM »

How did you make the back plate and eccentric inserts?

Kirk
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tweakie
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« Reply #18 on: January 22, 2020, 09:35:45 AM »

Hi Kirk,

The stator had the OD added in Vectric with the pin positions from the Vexx DXF.
The cam was produced in Vectric using the offset displayed in Vexx.

Hi Art,

I am not yet sure of the best way to achieve the running clearance s - a system I used from a previous project was to lie about the tool diameter when creating the path but it needs a few practice runs (trial and error) - I think I have plenty of engraving laminate in stock so that is what I am trying  Grin

Tweakie.
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ArtF
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« Reply #19 on: January 22, 2020, 08:12:24 PM »

Hi Tweaky:

  When designing it, say you want to use 5mm outside pins, declare them as 5.25mm pins. Then
cut to profile for the toolpath. You should get a .25 clearance . Though thats basically  the same
as you just defined only from the tool side.
  I use about that much for my laser..

Art
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tweakie
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« Reply #20 on: January 23, 2020, 06:45:20 AM »

Hi Art,

Many thanks for the info.

I have yet to make the drive disc but I am making progress albeit very slowly.

Tweakie.


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ArtF
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« Reply #21 on: January 23, 2020, 07:27:35 AM »

Tweaky:

  Looks pretty good. Ill be intereste d in how you find it works.
I have a few lazy susan bearings that will be used as my
axis drive. They have a large enough hole in the middle to
contain the center bearing and should ease that rotationa l friction
you may hit with the small offset circular parts.

  Keep posting your experienc e.. Ill post my first stage when
its cut.

  You know I have a conjectur e on the number of pins needed to
be used on the outside ring. If, for example, you use 21 outside pins,
you get a 20:1 reduction, but my thought is that you need use
only the number of pins in construct ion as determine d by torque
requireme nt. The number of pins used must be  (n > 2) for any
ratio above 2.

  So a 20:1 reduction could in construct ion use as few as 3 pins
if the torque requireme nt is low. I intend to use 3 pins on each
of 4 stages to reduce a clubfoot to  the hour hand.

  Dunno how that will work out, but simulatio ns seems to show
a min of 3 should do the job.

Art
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tweakie
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« Reply #22 on: January 23, 2020, 08:16:49 AM »

Hi Art,

Itís early days yet (for me) but I had planned for ball bearing the cam (shaft and outer) but (from my model) observati on shows that although the cam will roll on a pin the exact opposite side of the cam slides on a pin and there is quite a lot of friction there especiall y as I plan on dual cams / rotors. Looks like my pins will be ball bearings as well and while I am at it ball bearings for the final drive dogs.
It could turn out to be a neat little reducer but it is going to be heavy  Smiley


Tweakie.
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Hessel Oosten
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« Reply #23 on: January 24, 2020, 09:53:47 AM »

If I'm well, the hypocyclo id reduction was (amongst others ?) invented by the famous clockmake r Aaron Dodd Crane:

https://www.google.nl/search?q=aaron+dodd+crane+clocks&tbm=isch&source=univ&sa=X&ved=2ahUKEwiHs_P2vZznAhWHEVAKHdfvBFYQsAR6BAgKEAE&biw=1920&bih=894

A well known appliance is the "daisy wheel": a small number of pins (e.g. 3 or 4 or ..) on the outside and (flower..) lobes/"teeth" (e.g. 11) on the inside.
A nice clock with the mechanism as 12:1 reductor (here 3 pins and 11 lobes) here:

http://woodenclockspot.blogspot.com/p/grasshopper-regulator.html

Animation here:

https://www.youtube.com/watch?v=RVWd-QedUTY

Hessel
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tweakie
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« Reply #24 on: January 24, 2020, 10:12:13 AM »

Excellent informati on Hessel - that is all going to take some reading.  Smiley

Tweakie.
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Mooselake
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« Reply #25 on: January 24, 2020, 10:14:42 AM »

That's a pretty cool clock!

I've got a stack of russian birch and thin hardwoods (including some nice in the picture quarter saw white oak)  sitting in my Ocooch Hardwoods shopping cart.  Maybe it's time to click the buy button and quit screwing around with goopy plastic stuff.

Ocooch HW is just down the road (if you call 6 hours driving "just") from the Mooselake Manor, but quite a bit further to the snow free winter cottage.  They get good reviews but never bought from before.  Anybody dealt with them?  I have a few bucks left before the flat rate shipping jump, any suggestio ns on a nice clock/ticker hardwood before I pull the trigger?  Who knows, maybe I'll actually complete something this time

Kirk
« Last Edit: January 24, 2020, 06:01:26 PM by Mooselake » Logged
ArtF
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« Reply #26 on: January 24, 2020, 05:02:44 PM »

Kirk:

 Im a fan of almost any african hardwood. Im trying to make it so my rotors are only a few inches across
to preserve wood.

Art
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ArtF
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« Reply #27 on: January 24, 2020, 05:08:55 PM »

Hessel:

 Thx, good informati on. Proves my thought that 3 pins are enough as well.
I like it.

Art
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tweakie
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« Reply #28 on: January 26, 2020, 08:10:06 AM »

A few seconds of poor quality video, just to prove that it works  Grin

https://youtu.be/u3Mh1E4GgHE

Tweakie.
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Hessel Oosten
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« Reply #29 on: January 26, 2020, 08:52:33 AM »

Great Paul/Tweakie !

If I remember well NYC CNC (on YouTube) once made a hypocyclo id reductor of a normal speed electric motor to 1 rotation in 30 years !!!
They did put several reducer layers behind each other, so it's clear now that Paul is --not-- fully ready at this moment .... Wink

https://www.youtube.com/watch?v=Eds48L4cJjM

Some nice explanati ons also here:

http://www.zincland.com/hypocycloid/

and

http://www.meccanotec.com/gearlesshands.htm

Hessel

p.s.

My interest in this subject is caused by the fact that I'm trying to build the Woodward gearless clock
(which has in the John Wilding drawings, also a daisy wheel for the 12:1 reduction for the dials).

https://www.dropbox.com/sh/jjwli7femazj0vz/AADswfFzc4C_xNEGiB7gYszSa?dl=0
« Last Edit: January 26, 2020, 08:57:33 AM by Hessel Oosten » Logged
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