GearHeads Corner

General Category => Suggestions for Future => Topic started by: tweakie on January 18, 2020, 03:20:02 AM



Title: Cycloid Reducer.
Post by: tweakie on January 18, 2020, 03:20:02 AM
Something that has fascinate d me for a long time now is the mathemati cal complexit y yet mechanica l simplicit y of the Cycloid Reducer.

Art, if you ever get bored and need a new project a hypocyclo id cam generatio n may be an interesti ng addition to Gearotic (perhaps ?).

https://binged.it/2RxIHqK

Tweakie.


Title: Re: Cycloid Reducer.
Post by: ArtF on January 18, 2020, 10:41:09 AM
Hi Tweaky:

  It was just released in Vexx, I just havent yet made a video on the topic. :)
Youll find a new button on the vex tools that calls up the cycloidic reducer tab.

Art


Title: Re: Cycloid Reducer.
Post by: tweakie on January 19, 2020, 02:11:38 AM
Thanks Art, that is a real co-incidence ( or is it sublimina l )  :)
I will power-up Vexx and give it a whirl.

Thanks again.

Tweakie.


Title: Re: Cycloid Reducer.
Post by: tweakie on January 19, 2020, 03:12:40 AM
Unfortuna tely...

My version of Vexx is 2.24 which does not appear to have the cycloidic reducer tab and Win10 (in it's wisdom) will not allow me to download Current Developme nt 3.xxx (Click) Even disabling Defender Firewall and Smart Screen it still thinks the download contains a virus and deletes it.  :'(

Tweakie.


Title: Re: Cycloid Reducer.
Post by: ArtF on January 19, 2020, 10:08:00 AM
Tweaky:

 Did you try the win10 based .msi loader on the main download page? It usually works without complaint .

Art


Title: Re: Cycloid Reducer.
Post by: Dan Mauch on January 19, 2020, 01:20:40 PM
I too have Vex 2.24 on a win 7 pc and I could not locate the button for the cyclodic function.
Dan Mauch
Unfortuna tely...

My version of Vexx is 2.24 which does not appear to have the cycloidic reducer tab and Win10 (in it's wisdom) will not allow me to download Current Developme nt 3.xxx (Click) Even disabling Defender Firewall and Smart Screen it still thinks the download contains a virus and deletes it.  :'(

Tweakie.


Title: Re: Cycloid Reducer.
Post by: ArtF on January 19, 2020, 05:45:05 PM
Hi Guys:

  Please try redownloa ding either of the .exe setups. I have been working to eliminate the
virus warnings and other errors. New setups are now online. Vexx is version .25 if installed
correctly from last setup.
  Id appreciat e any experienc e reports with how it works ( or doesnt) for you.

Thx
Art


Title: Re: Cycloid Reducer.
Post by: tweakie on January 20, 2020, 01:42:19 AM
Thanks Art, the Current Developme nt 3.xxx (Click) download now works perfectly and is accepted by Win10.

I now have Vexx 2.25 to explore  ;D

Tweakie.


Title: Re: Cycloid Reducer.
Post by: ArtF on January 20, 2020, 07:12:56 AM
Tweaky:

  Thanks, the button you were looking for is beside the clubfoot escapemen t button. :)

Art


Title: Re: Cycloid Reducer.
Post by: Mooselake on January 20, 2020, 02:32:51 PM
Any way to export one as a (series of) stls?

Kirk



Title: Re: Cycloid Reducer.
Post by: ArtF on January 20, 2020, 02:36:41 PM
Kirk:

  Each f the component s, when generated, are grouped as to function. So, if you select just the
rotor for example, you shoudl be able to select "extrude" in the tools and extrude just the rotor
to an stl.

 I havent tested there at all, Im still finalizin g that module... Let me know how it works out. :)

Art


Title: Re: Cycloid Reducer.
Post by: Mooselake on January 20, 2020, 03:08:28 PM
34 minutes, less if it fails, and I'll have at least the sun and planet (forgot the cycloidal reducer part names).  The pins show up in PrusaSlic 3r but not in Repetier-Host so I'll need to look into that one.  Is there only 3 parts?

Kirk


Title: Re: Cycloid Reducer.
Post by: Mooselake on January 20, 2020, 04:24:20 PM
With some random giggling I came up with this (http://edge.rit.edu/edge/P16201/public/P15201%20files/Research%20Papers%20Humanoids/2012%20-%20Design%20of%20a%20Planetary-Cyclo-Drive%20Speed%20Reducer%20Cycloid%20Stage%20%2C%20Geometry%20%2C%20Element%20Analyses%20-%20Borisov%2C%20Panchev.pdf) page which among other things included the attached picture that gives names (at least their names) for the parts.

The pic shows a high speed shaft that looks a lot like a cage gear (although iirc the stl has bad pins), just leaving the low speed shaft and the way it connects to the ring gear.  Do you have any plans to add something like these, or the parts in Tweakie's gif?

The cycloidal disk and ring gear printed OK, although I really should take the time to properly get this new ender 3 pro printer properly set up, particula rly as my regular chair sitting time is slowly increasin g.  Black 6mm pins are printing as I type this, will either post a photo or pretend it never happened depending on the results :)

Kirk


Title: Re: Cycloid Reducer.
Post by: Mooselake on January 20, 2020, 05:33:12 PM
My camera thought it was a face :)

The pins are oversize, 6.2 instead of 6.0mm so it's hard to turn, but turned out pretty decent.

Kirk


Title: Re: Cycloid Reducer.
Post by: ArtF on January 20, 2020, 08:53:54 PM
Kirk:

   If you include the bearing ring, it becomes a different ial reducer, hold the ring and the center disk turns, hold the
centering disk and the ring turns..

  I am designing a clock to use cycloidal s so Im hoping to hold the video until I can show at least one stage
operating . The shaft is usually the hard thing, but Im using small lazy susan bearings that allow you to simply
glue the bearing to the wood offset from center. Makes one easier to make out of wood.

Art




Title: Re: Cycloid Reducer.
Post by: tweakie on January 22, 2020, 06:38:49 AM
Well, I have made a start  ;D

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.


Title: Re: Cycloid Reducer.
Post by: ArtF 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.. :)

Art


Title: Re: Cycloid Reducer.
Post by: Mooselake on January 22, 2020, 08:50:55 AM
How did you make the back plate and eccentric inserts?

Kirk


Title: Re: Cycloid Reducer.
Post by: tweakie 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  ;D

Tweakie.


Title: Re: Cycloid Reducer.
Post by: ArtF 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


Title: Re: Cycloid Reducer.
Post by: tweakie 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.


Title: Re: Cycloid Reducer.
Post by: ArtF 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


Title: Re: Cycloid Reducer.
Post by: tweakie 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  :)


Tweakie.


Title: Re: Cycloid Reducer.
Post by: Hessel Oosten 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


Title: Re: Cycloid Reducer.
Post by: tweakie on January 24, 2020, 10:12:13 AM
Excellent informati on Hessel - that is all going to take some reading.  :)

Tweakie.


Title: Re: Cycloid Reducer.
Post by: Mooselake 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


Title: Re: Cycloid Reducer.
Post by: ArtF 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


Title: Re: Cycloid Reducer.
Post by: ArtF 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


Title: Re: Cycloid Reducer.
Post by: tweakie on January 26, 2020, 08:10:06 AM
A few seconds of poor quality video, just to prove that it works  ;D

https://youtu.be/u3Mh1E4GgHE

Tweakie.


Title: Re: Cycloid Reducer.
Post by: Hessel Oosten 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 .... ;)

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


Title: Re: Cycloid Reducer.
Post by: ArtF on January 26, 2020, 11:14:41 AM
Tweaky:

   Nice work. Nice to know the numbers work out in reality. :)

Art