Boxstock motors

[GaryH]

Monty, I got 2 boxstock motors from you in April...Kelly can, blue dots, p/s endbell, 45 degree arms.... One has been great in all respects, but the other has had an overheating problem. So much so that I rarely run it. I took it apart last week, cleaned it and reassembled it using the same brushes (still nearly new) and it still overheats. I've tried 8 and 9 tooth pinions with 37-39 spurs. Any other suggestions for solving this?

GaryH

[Bent rim]

Gary try a new set of brushes, it is possible to get a bad brush.
Sorry Monty, didn't mean to step on your toes, just trying to help.;)

[Monty @ B.O.W.]

Bent,

Not a problem, as long as I agree with you! In this case, I do. I'll go as far as answering the next question nobody asked yet but related to this subject:

Yes, once verified as a good set of brushes (because they come from a motor that ran well) you can re-use them until they no longer have a practical length.

[Bobhardt]

Monty,
When re using a set of good brushes in the same can and endbell that they came out of but this time using a different arm, would you do anything to prepare the brushes? I've seen guys scrape the surface with a razor blade. They say this removes any glaze that is on them. Any truth to this? I usually just put the brushes in and give them a slight break in.
Thanks.....

[Monty @ B.O.W.]

Bob,

Yes, I use my radius tool and clear the shiny surface off. This may be actually unneccessary, but its one of those builder's lore legends that can't hurt, unlike, say... beveling com slots with a pen.

[GaryH_at_work]

There are sorta dark spots in the center of each brush. Kinda looks like a hard spot or something. Would you suggest Bigfoot or Gold Dust?

This is a really fast motor I don't want to screw it up.

GaryH (at work darn it)

[Monty @ B.O.W.]

Gary,

I use Golddust brushes, but Bigfoot brushes are OK too. Don't worry, changing brushes may or may not solve the problem, but you won't hurt anything beyond repair unless you continue to run the motor AFTER it overheats.

[Mark Woday]

Monty, can you clarify what you mean about beveling the com slot. Thanks, Mark

[Goat_Boy]

What Monty is refering to is the act of taking a ball point pen and running it down the com slots. Some people do this after turning an arm to take off the burr. I personally have not seen to many people do it on a slot car arm but in RC racing its pretty common. Hope this explains it good enough :D

Ian

[Monty @ B.O.W.]

Guys,

I referred to the use of a ballpoint pen in this fashion as a harmful legend! Now that you know, don't do it!

By way of explanation: The bevel thus created is a narrow flat spot created by deformation of the metal, not removal of the metal. Any burrs that were there are now deeper in the slot (where you certainly don't need them!) and there is a tiny raised ridge of material extending above the cylindrical surface of the comm. Even assuming that this ridge wears away quickly during breakin, and the burrs don't short you out, you now have an artificially wider slot, meaning less area on the surface. You might just as well have arced this material away - just what we try to avoid when doing the easy breakin, with or without water (I prefer the water method).

The proper method to deburr the slot is to use a knife edge - being careful, of course - drawn along the slot perpendicular to the shaft. The back edge of a #11 blade works well for this, after you grind away the first .010 of the point so you don't waste a lot of effort making the slot deeper.

[Bent rim]

Monty, what am I supposed to do with all these ball point pens.:D

[multiracer]

Write more orders...... of course!!