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Old 06-17-2007, 02:11 AM   #1
JL
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Default brushes: cutting trailing edge

Has anyone found an easy way to cut the trailing edge off brushes?

So far I've been filing away and it's starting to become a real pain as it tkaes ages and it's had to get ana ccurate cut.
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Old 06-17-2007, 06:29 AM   #2
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Something like this would do the trick easily:
http://www.kose-rc.com/new/new2004[1].htm

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Old 06-17-2007, 04:52 PM   #3
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Wouldn’t that make the brush offset to one-side?
Yes, you get a very short trailing edge but the inner diameter is all wrong. You will probably end up having to realign the brush hood otherwise it will take quite a long while before the brush sits completely on the armature..
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Old 06-17-2007, 05:13 PM   #4
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Something like this would do the trick easily:
http://www.kose-rc.com/new/new2004[1].htm

I've actually got this piece of kit (which I use to reserate brushes) But how does it remove just the trailing edge?
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Old 06-17-2007, 09:40 PM   #5
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Have you tried a dremel?
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Old 06-17-2007, 09:57 PM   #6
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The best setup I've found is an old item from S&K -- they are out of business, but many hobby shops, etc still have their stuff in stock. it was a simple rig that mounted an old stock motor to the base, then added an extension onto the shaft that allowed you to mount a fiber cutoff wheel (dremel style) onto the shaft. Also attached to the base was a vertical molded plastic piece that helped you hold the brush as you slid it up to the cutoff wheel. By adjusting the disk up/down, you could slot brushes or shave the trailing edge...
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Old 06-17-2007, 10:32 PM   #7
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Quote:
Originally Posted by wyl03 View Post
Wouldn’t that make the brush offset to one-side?
Yes, you get a very short trailing edge but the inner diameter is all wrong. You will probably end up having to realign the brush hood otherwise it will take quite a long while before the brush sits completely on the armature..
I wouldn't see why it would take long to realign the brush hood. As long as it was aligned before you cut the trailing edge off, the rest of the brush should completely sit on the comm. Cutting the trailing edge is almost like increasing the timing on the motor.
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Old 06-18-2007, 07:42 PM   #8
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Tek Nickal - i was referring to the shape of the brush after cutting it on the brush cutter.

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Old 06-18-2007, 08:52 PM   #9
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Oh I see what you mean, but when you cut the trailing edge off you usually reduce the brush surface by about half. In your last illustration where you said to remove the colored area is exactly right, except you would probably remove more than just that. This is my interpretation of it.
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Old 06-18-2007, 09:19 PM   #10
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Good, we’re on the same page.
I’m doing that as well …

But always wonder… is that the right thing to do?
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Old 06-18-2007, 10:23 PM   #11
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The best way I've seen it done is to take a small file and shoe goo it to pretty much anything flat. A file that's about .060 thick works pretty well. Then simply lay the brush on the flat surface and slide it against the side of the file. Comes out perfect.
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Old 06-18-2007, 10:48 PM   #12
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Filing is really pretty easy, even by hand.
For best performance, cut the brush width to one half of the comm diameter.

It sounds really simple. What it does is allow the MOST brush wrap while NOT allowing any shorting accross any comm segment.

i have played with this a bit and found mixed results. But it seemed to add a little torque in high RPM motors, but overall power was a bit decreased. But still a tuning option.

Comms last longer though
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Old 06-18-2007, 11:49 PM   #13
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also remember that taking off too much will have an effect on timing .. as do timed brushes ... butt if its just the trailing edge I usually use a Xacto blade and take off what i feel will work .. never had any problems doing this ... my motors run very good and dont loose any performance ..
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Old 06-19-2007, 04:08 AM   #14
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Quote:
Originally Posted by gubbs3 View Post
The best way I've seen it done is to take a small file and shoe goo it to pretty much anything flat. A file that's about .060 thick works pretty well. Then simply lay the brush on the flat surface and slide it against the side of the file. Comes out perfect.

Gubbs3 this is exactly what I wanted and what I'll do with my brushes. Thanks

Thanks for everyone else that replied too.
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Old 06-21-2007, 03:17 PM   #15
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Quote:
Originally Posted by JL View Post
Gubbs3 this is exactly what I wanted and what I'll do with my brushes. Thanks

Thanks for everyone else that replied too.

JL can I ask are you wanting to time your brushes, increase effeciancy, or reduce arching?
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