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Old 19th June 2008, 11:52 PM   #1
martyh is offline martyh  United States
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Default Belt drive motor pulley wobble

Im just putting the finishing touches on my belt drive project and I noticed a slight wobble in the pulley. I measured it with a dial indicator at .009. I was able to make an adjustment and have it down to .003. Im using a VPI hw-19 motor, pulley and belt so Im wondering if the elastic belt will take up some of the slack. What say you, should I order a new set or will this one be okay?

Thanks in advance,
Marty
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Old 20th June 2008, 02:54 PM   #2
EC8010 is offline EC8010  United Kingdom
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Eccentricity on a motor pulley will cause wow and flutter - changing the belt won't help.
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Old 20th June 2008, 09:29 PM   #3
YNWOAN is offline YNWOAN  United Kingdom
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'order a new set' of what exactly? As stated above, changing the belts will not make any difference.
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Old 21st June 2008, 12:12 AM   #4
martyh is offline martyh  United States
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Thank you for the replies. Im sorry if the original post was confusing. I meant to ask if I should order a new motor and pulley set. My hope was that the elastic nature of the belt would mitigate some of the variation.

Thinking about it further, I see that the wobble is effectively changing the radius of the drive pulley by .003 20 times a second. As I see it now, the elasticity may lower the peak speed variation but never eliminate it.
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Old 21st June 2008, 08:49 AM   #5
EC8010 is offline EC8010  United Kingdom
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Quote:
Originally posted by martyh
Thinking about it further, I see that the wobble is effectively changing the radius of the drive pulley by .003 20 times a second. As I see it now, the elasticity may lower the peak speed variation but never eliminate it.
You have it exactly. My commiserations. Some members have said that they have been able to true pulleys by running them with a clamped Dremel (or similar) carrying a grindstone brushing lightly against them as they run. If you have a Dremel and you're going to buy a new motor and pulley anyway, you've nothing to lose.
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Old 21st June 2008, 06:59 PM   #6
AVWERK is offline AVWERK  United States
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Yeah, you would want to lock the body of the motor and the same with the Dremel in some way.

Think in terms of a lathe principle so the runout error is focused and ground down only.

Regards
David
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Old 21st June 2008, 10:39 PM   #7
martyh is offline martyh  United States
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Great idea, thanks. In the mean time Ive pulled another set from my hw-19 to use.
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