how far can you turn the comm down before it needs to be replaced?

about 2.62 if it a good com.

do you mean .262? i have one i screwed up tring to use a stock motor lathe with a steel bit and it was all grooved up, so i bought a mod motor lathe with a diamond bit and cut the comm down to .280 to clean it up. i didnt know if that was to far from the sweet spot.

whatever you're using to measure it is wrong or you're reading it incorrectly.

a brand new comm measures .295 or so. i've taken them down to .265 and they still worked. however, i have heard of people flaking the comm segments at .270. maybe it's just another good ole spec thing like the spec packs, maybe he cut it wrong, i don't know. hope that helps.

Cory

my bad, it measures .280. so is there a sweet spot?

.280 is a good place to start

my bad .262 if it is a good com. did not say it would last long.

you can keep cutting it til it flakes,and usually the smaller the better, but work your way into it,dont just cut it all at once,and wast your motor,if you run it you'll get it small soon enough. Besides.......you cant catch the BIG man on motor alone...he he he...just let me take them home and I'll fix them for you ...wink.

You'll get more amp draw at the smaller sizes[more brush wrap],so keep that in mind if you are running a large track and have runtime issues.

DK, happy new year, how's life going for you!!!!

Do you trim/cut brush's any after truing com,or just break them in again. Having trouble getting good #s after 1st cut. Need some advice on building good spec motor??? Thanks.

new brushes every time!

whats a good spec motor run at for amps ?

I found that 2.20's are decent enuf....I have had one as high as 4 amp draw...unfortunately....it messed with my run time a little. You can have an amp draw of as little as 1.60's and still have a fast motor out of it.

Eric L


Gotta warn ya though....everyone's opinion's different. All I can say is
Practice, Practice, Practice different motor set ups to find this out.

As far as a sweet spot...every armetur varies. Once I had one that .272 was at its best. Then lost it at around .267. never quite had the punch it had b4. However, there was still plenty of copper left.

Brushes will be a factor too!!!