Electric motor com

Discussion in 'RC General & Getting Started' started by mastmec, Jan 31, 2004.

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  1. mastmec

    mastmec Member

    Does anyone know the minimum diameter of the com. on standard epic motors, not the P94 motors, that can be cut to? I've searched for these specs but can't seem to find them. Thanks
  2. timrock

    timrock Active Member

    now why in the world,would you want to know that?
  3. timrock

    timrock Active Member

    this is boring.
  4. Steve M

    Steve M Member

    This is a good question and one that is far from boring.

    The minimum you want to cut your comm to is .270 inches. Most new motors come with a comm that measures .290 or larger, and will give a long life at its best performance if you cut the comm occasionally.
  5. mastmec

    mastmec Member

    Thanks Steve. Is this for both laydown and standup motors? Is this where the copper gets too thin or the coging effect becomes too great? Seams like you could go a little smaller on standups. Like the P94s the more you cut the com. the better it runs. Thanks for the info.
  6. timrock

    timrock Active Member

    mastec:it says you edited this.why does it say that?

    also i think it is a waste of time and money to get a lathe and cut coms.motors are cheap enough.
  7. mastmec

    mastmec Member

    Because I said thanks, and then remembered another question. And as far as the lathe, I have motors that Ive had for years, that still work as though they were new, and some alot better. And if I burn a comm. I can cut it and be back on the track. The lathe has paid for its self many times over.
  8. timrock

    timrock Active Member

    i still dont understand why it says `Edited by mastmec`
    you dont cut a com in between heats at the track.no one does that because ususaly there isnt enough time.

    also if you have motors that lasted you for years,maybe they werent ran much and if you have been cutting coms for years then you wouldnt ask in a forum what the min. diameter you can cut down to.
  9. mastmec

    mastmec Member

    Because I edited it after I posted it. And yes, people do cut them in between races, I don't though. And I have cut comms for years, just never knew the exact minimum thickness, just cut them till they burnt the brushes then just got a new arm. And why not ask, is it better to just be ignorant of the specs and just doit by eyeballing it?
  10. Steve M

    Steve M Member

    1) It says "Edited by mastec" because the original poster edited his own comments. That is perfectly acceptable.

    2) Almost every A-main racer in my club cuts their comm between qualifiers and at the very least before the Mains. A freshly cut comm makes better power than a used one. Is that simple.

    3) Motors are NOT cheap and cutting your comm will ensure your motor puts of the best power possible. Once you get to .270 inches on the comm rather than buy a new motor all you need is a new armature. Much less expensive this way.

    4) Let's try to be positive with our posts please. :)
  11. Steve M

    Steve M Member

    The copper gets a bit too thin around .270 and a mod motor might just get it too hot and you could end up with a comm failure. I've seen it happen.
  12. mastmec

    mastmec Member

  13. timrock

    timrock Active Member

    ok Steve.how do you edit what you post?
    also,cutting the com takes more than a few minutes.a lond time ago when i raced.there wasnt enough time to be able to go through all that.but that was just another orginization.so if you guys have the time to do that stuff in between heats,then thats cool,what ever works for ya under the conditions.

    also,maybe you are right with your opinion about motors not being cheap as i said they are but you can replace a machined wound 27 turn arm for less then 10 bucks.but you would need a rebuildable motor assembly
  14. Steve M

    Steve M Member

    Click on the small icon of the notepad with the pencil in one of your posts and make your changes. You can only edit your own posts.
  15. timrock

    timrock Active Member

    you mean you can edit one of your posts after you posted it?
  16. timrock

    timrock Active Member

    Steve,if u guys cut coms al that often.it might be a good idea to pick up a bunch of arms and have them ready when racing instead of bringng the lathe and cutting the coms on the track you can cut them at home.
  17. Steve M

    Steve M Member

    With the price we pay for motors here in Canada I'm lucky to have anything. A Fantom 19 turn motor retails here for $80 before taxes and the armature alone isn't that much cheaper. The really fast guys (meaning sponsored) cut their comms between every qualifier and main, but I cut mine before the day's racing and not again until the next race day.
  18. timrock

    timrock Active Member

    yeah them sponsered guys get anything they want.

    so you race 19t.i think you can mail order 19t arms for alot less than the cost of the whole motor but they would be machined wound not hand wound.i bet you wont run an arm that is machined wound.im sure the sponsered guys don`t.

    what if the sponsered guys run out of copper on thier coms when they go to cut them?dont they swap the armature to a new one?
  19. Steve M

    Steve M Member

    The top guys have several armatures all set to go and just swap them out between qualifiers.
  20. timrock

    timrock Active Member

    why dont they just swap them instead of cutting them?do they experince better performance from a com that is used and cut rather than just replacing the arm with a new one?
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