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Old 11-06-2001, 06:16 AM   #1
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Default Trinity Motor Question

Quick question for you guys.

How often should I cut the comm on my Trinity D4 10x2? I was told be a guy at my local track (SoCal) to cut the thing every three runs, and replace the brushes as well.

Thats fine and dandy and all, but that would get expensive really fast!

Is he right? Should I really cut it that often? And what kind of brushes should I use in it?

I'm running it in a Losi XXCR.
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Old 11-06-2001, 06:35 AM   #2
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An easy answer to this is that you should be making no more than 2 cuts to clean up the comm. If it cleans up after one skim then run a few more packs until next time to cut etc.

There are too many combinations of brush compounds, gearing, spring tensions, driving style to give you a definative answer!

3 runs seems pretty low.... because my brushes don't really seat properly until the 3rd run!!!
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Old 11-06-2001, 06:49 AM   #3
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Maybe I should email / call Trinity and see what they say?
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Old 11-06-2001, 07:12 AM   #4
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You can try... but they will probably give you a 'conservative' answer like 6 packs..... which really doesn't mean anything!
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Old 11-06-2001, 07:17 AM   #5
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the time when you need a com cut is really depending on what kind of brushes you are running but in general.

you need com cut more frequent with softer/high silver brushes

less frequent com cut with harder/more copper brushes.

some racing brushes require com cut every run.
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Old 11-06-2001, 10:21 AM   #6
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The purpose of cutting the comm is to get it round again. Take the motor out and run it on a four cell pack. Put a jewels screwdriver on one the back of the brush where the shunt comes out. If you can see the end of the handle jumoing and vibrating badly, it is time to cut. You dont need new brushes every time you cut the comm if they are not discolored. Breaking in new brushes is very hard on the comm. I recut my comm after breaking in brand new brushes. For me running a TC3, I cut my comms about every 5 runs or so and replace brushes about every 15 to 20.
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Old 11-06-2001, 10:24 AM   #7
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It also will dpend on the wind. My 13 and 14 turn motors could go a whole race day (3 qualifiers and a main) on a cut and clean up with one or two light swipes.

My 9 double needs to be cut every two runs or it takes a heck of a deep cut to clean up again.

I don't replace brushes unless they're discolored or getting too short.

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Old 11-06-2001, 11:25 AM   #8
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Guys, a quick question here regarding brushes
After you cut the comm, do you reuse the brushes? I mean used brushes that are otherwise fine (no discoloration etc), juz a couple of mm shorter and no more serrations.
Do I need to re-serrate the used brushes before popping them back in? With regards to motor break in, I am using an old 540 as a slave running in reverse, connected with a rubber fuel line to the motor I am running in. The slave is running off a 4 cell pack. Is my method ok? Is the old "dunk the motor in water" trick still relevant to the motors today? Thankx in advance : )
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Old 11-06-2001, 02:53 PM   #9
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It really soesnt save much wear & tear by using a slave motor to break in brushes. The good motor will act like an alternator and the brushes will arc because of the current being built up inside the motor. The arcing is what causes the comm to go out of round. Water dipping is still used for quick brush break-in. Im not sure of the side effects. The worst thing you could do to a motor is apply full load to it with out the brushes broken in. It causes bad arcing which warps the comm. I put a motor with fresh brushes and cut comm on a four cell into the freezer. The motor will come out colder than when it went in. Once the brushes are broken in, I take one light pass on the comm, clean the brushes, and put it back together. This is the ideal combination for power. Fully broken in brushes on a brand new comm.
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Old 11-06-2001, 08:22 PM   #10
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i re-serrate my brushes if theyre still long enough. even after cutting a comm, i often reuse the old brushes after reserrating them. about the water dip method, i only use this for sealed endbell motors.
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