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Author Topic: Cam lobe generator ?  (Read 3058 times)

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Cam lobe generator ?
« on: October 22, 2019, 11:03:06 AM »
 :) Hi folks.
I've got a project that requires a cam lobe of specified duration running in a yoke/fork with minimal clearance through complete revolutions.
 Say the yoke/fork had a 2" opening. A 2" diameter cam follower offset .1" from its shaft centerline would oscillate the yoke .2 per revolution.
But ......
I want an egg shaped cam lobe that will have a duration of lift as much as possible per revolution but always measure 2" diameter at any point as to keep the yoke/fork free of backlash. I assume it would be shaped sort of like a guitar pick.  ::)
Is there a formula, or generator for this sort of thing ?
I can make a crude sketch if necessary.
Thanks.
Re: Cam lobe generator ?
« Reply #1 on: October 22, 2019, 11:18:01 AM »
In the attached, can I assume that as long as the red and blue are exact mirror images of one another that the OD would be the same anywhere around the periphery ?
Re: Cam lobe generator ?
« Reply #2 on: October 22, 2019, 11:22:47 AM »
uh .... nope. I see that wont work ...... standing by  :)

Offline Chaoticone

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Re: Cam lobe generator ?
« Reply #3 on: October 22, 2019, 11:42:33 AM »
Arts Gearotic might help?

http://gearotic.com/
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Cam lobe generator ?
« Reply #4 on: October 22, 2019, 11:49:13 AM »
That did cross my mind. I have it on a different pc, will check it out, thanks.
Re: Cam lobe generator ?
« Reply #5 on: October 22, 2019, 12:47:11 PM »
Didn't see anything related in the SW, might ask on their forum.
Here is an example of a triangular cam and yoke I found.
The radius's of the cam are ever changing but the ramp up and down at the duration segment are relatively gradual, not a pure motionless dwell but blended closely enough for practical purposes.
This is giving me a worse headache than the Wankel engine  :P  :o
Cheers  :D
« Last Edit: October 22, 2019, 12:52:17 PM by Overloaded »
Re: Cam lobe generator ?
« Reply #6 on: October 22, 2019, 02:36:48 PM »
Found a link to exactly what I need, just need to figure how to draw it so I can cut it out with my nc mill.
https://www.youtube.com/watch?v=bSVPOGibdHA
I can get it pretty close with cad but wondering if there is a "dead nuts" way/formula/generator out there.
Thanks,
Russ

Offline Chaoticone

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;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Cam lobe generator ?
« Reply #8 on: October 22, 2019, 04:14:43 PM »
Thank you Brett, Graham and especially Mr. Reuleaux  ;)
All is good now.
 :)
« Last Edit: October 22, 2019, 04:19:11 PM by Overloaded »

Offline Chaoticone

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Re: Cam lobe generator ?
« Reply #9 on: October 22, 2019, 04:49:04 PM »
Graham knows all them fancy words! Reuleaux, who would have thunk?
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!