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Planetary gear challenge

7 REPLIES 7
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Message 1 of 8
egoaudio
2013 Views, 7 Replies

Planetary gear challenge

Hello Everyone,

 

thanks for helping, in advance. I am wondering why my gears are not lining up. I followed directions from this link but with different size gears and it seems like they won't end up working as they are designed as the teeth collide, likely. 

 

https://www.youtube.com/watch?v=xlho1DjwCbc

 

The sun gear is 60 teeth, planet gears are 10/each, and the internal ring gear is 2x planet plus sun (80). Is there a rule I'm not aware of for planetary gears? I tried looking around but have obviously not found a resolution yet.

 

Any assistance will be very much appreciated!

 

Thanks,

 

Erik

7 REPLIES 7
Message 2 of 8
egoaudio
in reply to: egoaudio

I think i figured it out..... if the planet gears are to be evenly spaced then the Sun and Ring gears need to be evenly divisible by the number of Planets. 

 

https://woodgears.ca/gear/planetary.html

 

"Constraints on number of teeth and planets" section of page.

 

Pretty sure this is the reason mine looks goofy. I will adjust teeth on Ring to 78 and planets to 9 and see how it goes!

Message 3 of 8
egoaudio
in reply to: egoaudio

this fixed my issue! now I'm just curious about tolerances..... things look awful tight in the model. Any suggestions?

Message 4 of 8
egoaudio
in reply to: egoaudio

May very well have resolved my second issue (Slightly larger module might work, see attachment). Would still like input from those knowledgeable 🙂

Message 5 of 8
etfrench
in reply to: egoaudio

Changing the module # for only one gear in a set will not give you a very good set of working gears.  You can adjust the backlash setting in the spur gear script to get the proper clearances.  The diametrical pitches of the gears must be tangent.

ETFrench

EESignature

Message 6 of 8
egoaudio
in reply to: etfrench

Thank you ET! this is what I was looking for..... right in front of my eyes!

 

Any general rule for how much backlash is good? as a percentage?

Message 7 of 8
etfrench
in reply to: egoaudio

That would depend on how you're manufacturing the gears.  This book may help.

ETFrench

EESignature

Message 8 of 8
egoaudio
in reply to: etfrench

Thank you again for chiming in ET, even for my beginner questions. very very helpful. 🙂

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