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I usually check a motors timing marks before I go into them, buuuut, this time I forgot somehow. The only technical thing Im familiar with about motors, is cutting the Comms. Which is how this got started in the first place.
The motor Im having trouble with now is a Reedy Flash Point. When I started putting it bcak together, I noticed the End Bell has Timing Marks on BOTH sides. I believe most motors Ive seen have only had marks by ONE End Bell Screw, making it pretty obvious where to "Start". The Can Mark is plain to see. So, which screw do I start at the Can Mark?

Whats a good "all around" setting (meaning even amounts of torque and speed)?

Thanks

The endbell should be rotated in the opposite direction that the armature spins by more than 2 and less than 15 degrees (might be some debate here) past zero for most motors.
There is no magic spot, really, and opinions vary.
If I ever lose the factory setting, I just turn the endbell enough to be sure it is advanced (retarded timing is evil) and call it good. Like 5 degrees or something.

If you can't find zero mechanically, you can do it pretty easily electrically. Just hook one of the motor wires in series with an amp meter (be sure to get one that can do more than a few amps) and rotate the endbell back and forth until you find the lowest amp draw. That is zero, or very close.

So, if I set it with one of the screws and it turns backward, it should be set with the other screw?

I believe Ive heard that 12* is a pretty good starting point. Correct.... or "close enough"?

On another note: How short is TOO short for brushes. The arent discolored, but one is a bit (maybe 1/8) shorter than the other. Longest being only slightly shorter than 3/8.


Sorry if I seem like a dufus. hehe

I'm confused on the screws portion of your posts...

Can you elaborate?

There are 2 screws holding the End Bell in place. On this motor they both have Timing Marks under them on the End Bell. Which one should be "lined up" with the Timing Mark on the Can? Does it matter (i assume it does)? I figured since they are 180*s from each other, they would cause the motor to spin in opposite directions.

Again, I apologize for my "ignorance". Your patience is much appreciated.

The orientation of the endbell makes no difference. If it has polarity markings, hook up your ESC to it correctly, and then rotate the endbell if it spins the wrong way. Just remember, regardless of how you end up with things, advancing the timing (what you want to do) requires you turn the endbell the opposite way the armature is turning.

For what it's worth, I normally put all my capacitors on one side, normally opposite of the label. On the label side, I scratch a mark on the can, so I can go back to the original manufacturers timing mark.

Sometimes I forget and line the wrong mark up, but as I always test my motors first on a 4-cell battery, it's a simple matter to turn the end bell 180 if I need to.

For the rest of the comm cutters out there, how do you measure the comm before you cut?

Why measure?

Ron Jeremy wrote:Why measure?

There's a limit on how far you can cut them down. At the moment I don't remember what that limit is. I have a Cobra lathe, and the destructions give you that magic number, and I've found it to be true.

For measuring, I use a dial caliper to measure the uncut comm, to find out if I can cut it. And then I use a micrometer to measure it after I cut it so I know roughly how many cuts I have left. I also write all that info down in a book with details for each motor.

If I'm doing a motor for somebody else, measuring lets me tell them if I can cut it, or if they should just go buy a new one.

OK, right.
But you don't measure if the comm is relatively new, do you?

In case anyone is curious, this is what happens when you cut a comm that is too thin.
This was my origninal Trinity Pure Gold that I ran on my ultima and JRX-2 way back when. A couple years ago I bought a comm lathe. I thought I would try to get that old motor going, and this is the result. I haven't had this happen on any newer motors.
-Anthony

I believe that magic number is around .265-.267. A New Comm being around .300. Correct?

yes, new coms are usualy about .300 i wont turn any below .275 cause usualy the copper flies off.

.270 is the safe minimum, but I have heard of rocket ship motors as low as .265". They DO get faster as they get smaller, but once you get below .270", you start taking chances with them blowing apart. If you aren't racing, that's not really a big deal.

On a big comm motor, which start at about .350" (like Reedy Quads), you can go down to .315" fairly easy.






ALWAYS mic a motor comm before and after you cut. You don't need to take a lot off to clean the surface, and if you do it often enough, you will prolong the life of the motor even longer. Just dust the surface and only take off as much material as you need to true it up. It's those massive turns on a lathe that will really kill the life of the motor...

apexspeed wrote:On a big comm motor, which start at about .350" (like Reedy Quads), you can go down to .315" fairly easy.

Hey, wait a minute. The Reedy Flash Point IS a Quad Magnet Motor. Dont remember what it was when I measured it (before cut), but I know it was below .315, because I remember thinking it was fairly new.

Is it gonna blow on me now?

I decided to give it a Cut because it was pretty slow. Plenty of "Take Off", but then you could see it stop accelerating around 15-20 ft. The Comm was pretty bad. It was Traingle Shaped. Took several Cuts to get it round again. Im sure its around .280 now, at least.

Should I see a difference if it doesnt blow (or until, hehe)?