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how to measure a comm

how to measure a comm

Old 08-15-2004, 12:55 AM
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Default how to measure a comm

how do you measure a comm?
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Old 08-15-2004, 01:00 AM
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take it out of the can/endbell and put a dial caliper over the commutator.
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Old 08-15-2004, 01:15 AM
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thanks... I had a feeling it would be somthing else to buy...
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Old 08-15-2004, 01:19 AM
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Just get a cheap pair of plastic vernier's

while we're on the subject at what size would a com be ready for the bin??
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Old 08-15-2004, 01:32 AM
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6.83mm
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Old 08-15-2004, 01:43 AM
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Originally posted by tones
6.83mm
Man thats playing with fire with a comm that small... I usually never go below 7.0mm
-Dave
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Old 08-15-2004, 08:45 AM
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Man thats playing with fire with a comm that small
What exactly can happen?
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Old 08-15-2004, 11:49 AM
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the segments will come apart or start chipping off of the comm and it can ruin the end bell and also lock the motor up. let alone cause you a big head ache especially during a race
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Old 08-15-2004, 02:12 PM
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Originally posted by JDM_DOHC_SiR
Man thats playing with fire with a comm that small... I usually never go below 7.0mm
-Dave
Corecctamondo !!!!!!...I never go down that low anyways. Always use a digital calipher. Ebay have one for less than 20 bux.

Henry E.
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Old 08-15-2004, 03:13 PM
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the min. (safe) size is 6.86mm or .270in
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Old 08-15-2004, 10:58 PM
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When you're measuring with the digital calipers, make sure to measure the top and bottom of the comm to make sure your lathe is cutting true.
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Old 08-16-2004, 06:27 AM
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Default Run em' till they explode !!!!

If you have ever run one down to or below .268in. the motor is the best its ever been . usually the last run of a arms life is the best. I have really noticed this with the monster stocks
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Old 08-16-2004, 12:07 PM
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in engineering terms a micrometer would be best and you should check the dia. at the top middle and bottom and record the difference.
if u had a dyno as well u can check how its effected performance.
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