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Comm Cutting . . .

Comm Cutting . . .

Old 07-13-2004, 04:17 PM
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Default Comm Cutting . . .

hey guys,

took apart and cut my first comm today

couple questions???

i think i may have taken a little too much off the comm on the first cut

i put it on the lathe, put a sharpie marker on the comm and made one pass, it seemed like a lot of debris came off on my first pass

not sure if the debris was normal or too much, made a second pass and that seemed to go much better

when i put the motor back together the 1st time it was binding and did not want to spin took it apart and back together and it worked fine

1. any tips or trick to measure how much you take off the comm? i am using a integy zipp lathe

2. what could i have done wrong the first time i put the motor together to make it bind up???

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Old 07-13-2004, 04:27 PM
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You need to get a set of calipers. There is a digital set on Harbor Freight that is around $20, a lot of people have given them good reviews.

I can't remember what is the minimum diameter, so I'm sure that someone will chime in.

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Old 07-13-2004, 05:08 PM
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Its .275" From what I've heard.
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Old 07-13-2004, 05:19 PM
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Comm Cutting isn't an exact science.

every comm is a diffrent diameter..typically you want to do once you get your comm cutter is to practice on some old comms first before to shred a good one.

You want to get a caliper to measure the com dia along the end and the closest in.

make sure they are the same.

Make your first cut just barely skimming the comm you won't remove all the marks yet. you don't want to see comm chips flying ok this is not a wood lathe nor a saw mill.

The measure to make sure your cutter is aligned correctly.

Proceed with a minimum cut each time until it is clean (no scorch marks)

then use a ball point pen to knock down the edges along the groves to elimnate any ridges that the brushes can hop on.

get a diamond bit if you can the carbon ones onlylast a feqw cuts and then do more damage then good.
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Old 07-13-2004, 05:24 PM
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The trick is very lite passes.....After you sharpie the comm...practice until you have to make two or more passes until the sharpie is gone.....and only cut the comm in one direction..if you back cut the comm, it will sometimes push some copper out of round and it's nearly impossible to detect with the naked eye...this next thing is not nesessary but, you could also find out what the ratio is on your feed wheel on "that" particular lathe...for example: for every notch you turn on the wheel = 5thou worth of material removed on the comm......most stock motors like the Monster... the p2k2...and MVP...... can be cut to around 265 thousanths before the copper is ready to lift......
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