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Old 08-07-2004, 01:18 PM   #61
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Well an auto lathe is awesome, but for us low end racers, its not necessary to spend that much. I make minimum wage, and play w/ modifieds, certainly can't afford an arm every week, and skim every run like some of the pros. they can use their batteries for 8 runs and then sell them off second hand here.

So for me, I will just stick to my 3racing lathe, and tell u all about it. I am just wondering will i break my carbide bid, if i try to skim a com that's already cracked that's all.
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Old 08-07-2004, 05:02 PM   #62
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Thats one of the best things about the integy auto lathe is the low cost .....I think it's by far the best product for the money, matter a fact, it's quite a bit better than some of the lathes twice it's price.......you can get one on brand new on ebay for like 139.00.......
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Old 08-07-2004, 07:06 PM   #63
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If you guys are thinking about mod then you will go through more then 1 arm per season. Hard core = 3-4 arms, casual = 2-3 arms. For stock you can get away with 1-2 arms but not mod unless you run 1/12th.

Stock - You can get away with cutting every 10 runs. I cut every 5 or so runs.

Mod(standups) - You should cut every 5 runs or less.

Mod(revolution) - I've heard upwards of people running those things for over 15 runs(enduro brushes) without a cut.

Motor performance does go down with every run. If you want a stock motor to run better in between cuts go with a brush like the reedy 766 which polishes the comm instead of destroying it like others do. In mod there is really no way to seriously cut down on comm wear unless you run a Orion revolution.

rcnewb2004 - What exactely do you mean by a cracked comm? Also I run the integy carbide bits and they work great and last ages.
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Old 08-07-2004, 07:45 PM   #64
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Boy.... I wish I could get 10 races at top performance before needing a cut and re-build on my stock motors .....the competetion at my local track pretty much leaves you in the dust without cutting the comm and putting new brushes (or touching up the serrations on the existing ones) every two or three runs at the most....and nearly "every" run on most low wind mods.....
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Old 08-07-2004, 08:06 PM   #65
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FD,
cracked comm=the copper on the com has already all worn out.
I am just wondering if i practice lathing an armature that has a worn out comm, would it damage the carbide bit

Joe B,
cutting the comm every race? that's gotta be some crazy competition over there.

Btw, what exactly do serrations do? is it the same thing as the "trench" that I see on some brushes? I though serrations was to only help you break in the motor a little easier so the rough unbroken in edges on new brushes don't scratch up the comm??
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Old 08-07-2004, 10:56 PM   #66
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Your exactly right ,When they first started with serrated brushes it was designed to give a faster break in, but it was quickly noticed that the more edges you have on the surface of the brushes against the comm....the more electricity that they're able to flow or conduct, which gives you slightly more power.....the trench or "slot" that you mentioned is based on the same thing.....practicing on an old arm with your carbide bit wont hurt anything....you can almost hit the tabs of the arm your cutting with out hurting a carbide bit too much.... thats the great thing about carbide.....you can always easily sharpen them or get a bran new one for like 2 bucks Joe
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Old 08-07-2004, 11:09 PM   #67
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Joe B - You've got to remember that a perfect motor for them really isn't going to make much difference for a while untill they are able to weild it. At my local track in mod and 19t the fast guys also cut every run.

rcnewb2004 - Generally people stop cutting an arm if the copper on the comm is below .270 for standard sized arms or .300 for 9mm arms. It could blunt the bit, I'm not sure.
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Old 08-08-2004, 12:03 AM   #68
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I agree.....but I don't think it hurts for anyone interested in racing to have an understanding of the way to get the most power out of their motors, so that as they progress in skill ,they know how to step things up a notch when needed....instead of having a motor with 15 runs on it and not thinking that it could be the reason their not keeping up.....
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Old 08-08-2004, 02:33 AM   #69
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JoeB:
Icic,
but how come a flat faced brush offers less surface area than a serrated brush?

FD: I just mean i want ot use an old arm to practice lathing on, because i never lathed before in my life.

JoeB:
Will lathing every run actually wear your motor out faster or slower than when u lathe it 15 times, given that you race the amount ?
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Old 08-08-2004, 04:28 AM   #70
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....It's not the overall surface area (like having a bigger brush)that makes the extra power, its having the curves and edges of the serrations "against the comm" itself that flowes and transfers more energy that gives the power increase....remember it's only the serrations that touch the comm ,so it's considerably less contact on the comm than a full face brush will give....for your other question....to give you a simple answer to a question with a million variables I would say that the lifes of the two differently treated motors would be pretty similar except for the fact that the one you completely rebuilt and cut every run or two....would always (through it's life) run at it's peak..where as the other would have a hourglass shaped comm after several runs that would progressively get worse and cause brush bounce....excessive arcing....possibly glitching...way less rpm....not to mention that your brush spring tention is less with every run because of the brushes getting shorter..(you could constantly compansate for the changing spring tention ,but talk about work)..so after 15 runs you'd be way off from what it was, and when you did cut it , it would take a pretty big cut to get it true instead of just a skim....I could list about 50 other reasons but you get the idea
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Old 08-08-2004, 01:55 PM   #71
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JoeB,

I don't mean to argue with ya JoeB, but I just think... just "maybe", your concept of energy transfer could be incorrect.

Did some thinking last night, what I am came up with is:

Less surface area between comm and brush does not equal more flow of energy from the brush to the comm. Infact the flow could even be less.

Less surface probably equal Less friction between the brush and comm causing the armature to spin more freely and results in a performance improvement.

Less surface area between comm and brush causes greater comm wear, due to higher pressure on the comm and therefore requiring more maintanance.

So JoeB, I think basically, all the guys at your track is just killing their comms to keep up with one another, it works, but its comes at the price of a new arm really quickly.

And yes, I think you are right, skimming will make the motor not just more efficent but even have a longer life.

However, with a revolution motor, I am still thinking about cutting the com every 10 runs if I use enduro brushes. (and will maybe cut every 15 runs, if the com proves to be very round and clean still).
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Old 08-08-2004, 06:29 PM   #72
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I'm not sure if we have the reasoning correct, but all I know is that serrations work. Could it be more overall pressure for the given brush area?

One thing that I've noticed with one of my v2's is that it's easy to burn the brushes before the comm needs to be cut. I overgeared an orion 9x2, and the comm was perfectly fine even though the brushes were gone. Anyone have similar experiences?

rcnewb: I don't think you'll have any problems cutting comms. Just remember that taking off a little bit of material at a time is better than cranking it and trying to smooth the comm in one shot.
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Old 08-08-2004, 07:57 PM   #73
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So when u overgear the v2 (a little), the brushes take a beating rather than the comm?
That's interesting.



(just a few guys at my track keep scaring me that if u don't know how to lathe, u can damage the arm... and that's the last thing i want to do to a brand new v2 motor)
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Old 08-09-2004, 04:11 AM   #74
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Ok, I checked with 3racing about their motor lathe.

The HKU-1002 is using the HKU-1101 cutter.
The spare V Block is US$6.41/pair
Smallest increment is 0.05mm

The smallest increment is the reason why the lathe is cheap i think.

The 79.99 lathe from integy is 0.01mm smallest increment.

(But is 0.05mm off a comm at a time a VERY big number????)
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Old 08-09-2004, 08:31 AM   #75
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Even when the brushes discolor on a V2 the performance doesnt drop off as half as much as with the old style motors.
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