Cutting a motor commutator & motor tweaks

[JohnRobHolmes]

Looks fine to me. Curlies are ok as long as the bit isn't chattering. You could reduce the feed or depth a bit to avoid them, but copper naturally strings when cut properly.

[Jcplante]

I don't have any experience with cutting com's, but I have lots of experience turning copper. If the speed and feed is correct then a curl chip is what comes off. If it wasn't for the interrupted cut it would come off all in one long chip. If you are not getting a curl then chances are it is chattering and won't be a uniform cut.

[cherokee95]

Thought it may be dull, just ordered new cutters from McMaster last night. The bunching of the shavings is from me trying a little bit of cutting oil on the last cut causing the shavings to stick together, otherwise it was more of a copper dust. I won't be doing that again. I only advanced the bit one mark on the wheel at a time. Should I drop down to half?

[cherokee95]

No chatter at all, I would say taking at least 30 or so seconds per pass.

[Cordwood]

My integy, cobra, Hudy or Fantom have ever made a copper pube.

Just dust

[EddieO]

I am guessing the bit is dull. You sure its at the right height? Most Hudy lathes need to be ran at 5 volts or so, as they use really high turn motors. Curls only really happen on really deep cuts. They should not happen very much on shallow cuts, as the comm is 3 pieces, so they don't get a chance to form very much before you skip to the next piece. I put some old arms in your box so you can practice on them.

If you just wanna take bearings out, I have a simple tool fussybrush used to make for that. To install though, the can is the tricky one. A piece of wood dowel and bang it in works, but I have been using the LRP tool...Works and doesn't ruin anything.

Later EddieO

[cherokee95]

Bit is just above the centerline, I'll be waiting for my new bits before I do anymore cuts. I had it at 4.8 volts per the manual I downloaded.

Thanks for the old practice arms Eddie, they will be put to good use.

I just found and ordered the LRP puller from my LHS tonight, glad to hear it works well.

[anuthabubba]

Got a Cobra Pro lathe with diamond cutter a while back but haven't used it yet. Only running brushed on the Micro crawlers and brushless on the LCCs. Do have some brushed 540s waiting to be used in a couple of 'back burner' builds though. Guess I should find some old motors to learn how to use the lathe. Also have one of the Cobras with the BIG motor clamp. Couldn't I order the V blocks and convert this one?

Where do I get a brush cutter/shaper?

Used to rewind and balance slot car motors, build soldered piano wire low cg chassis (under the tutelage of a couple of adult enthusiasts) and paint bodies back in the mid '60s when I was in Jr High. Mrs. Wendt, the owner, let me turn marshall race nights, help maintain/assemble tracks, sweep up, etc. to get my cars/parts out of 'layaway'. Great lady.

[EddieO]

Integy was blowing out the shapers/cutters last I saw....might check their site.

Your lathe sounds like one of the old stock motor lathes. Those had a sealed can, so to cut the comm you removed the brush hoods and the bit went into the endbell to cut the comm. They were not fun to use and I think more comms were screwed up than actually cut. You can't convert them that I know, besides you can buy complete working lathes with diamond bits for $50 or less on ebay, racing forums, etc...

Later EddieO

Originally Posted by anuthabubba

Got a Cobra Pro lathe with diamond cutter a while back but haven't used it yet. Only running brushed on the Micro crawlers and brushless on the LCCs. Do have some brushed 540s waiting to be used in a couple of 'back burner' builds though. Guess I should find some old motors to learn how to use the lathe. Also have one of the Cobras with the BIG motor clamp. Couldn't I order the V blocks and convert this one?

Where do I get a brush cutter/shaper?

Used to rewind and balance slot car motors, build soldered piano wire low cg chassis (under the tutelage of a couple of adult enthusiasts) and paint bodies back in the mid '60s when I was in Jr High. Mrs. Wendt, the owner, let me turn marshall race nights, help maintain/assemble tracks, sweep up, etc. to get my cars/parts out of 'layaway'. Great lady.

[anuthabubba]

Thanks. Got their Master brush cutter for $14.

[cherokee95]

Oh it's on now! Thanks Eddie.

Got my new bits today too....time to break some stuff

[cherokee95]

Looks better to me. Like I have seen said in this thread a few times, looks like the bottom of a CD to me.

[Master Basher]

can someone tell me why not just clean up the copper com with some sandpaper? Seems like it would take less off and achieve a decent result. (complete newb question to this topic).

[EddieO]

Because you want the comm to be as perfectly round as possible. Sandpaper will ALWAYS lead to high and low spots....

God kills a kitten every time someone uses sandpaper on a comm...

Later EddieO

[cherokee95]

This lot of motors worth $68? Would like to put crawler arms in the good ones.

[Cordwood]

Id say no. I passed it up for 70.

[cherokee95]

Picked up a motor lot for $20 the other day. Team Brood Intensity machine wound, Epic 6x1 and 10x1. Any help picking out what motors would be good for crawler rebuilds would be much appreciated. I can get more pictures later.

[JohnRobHolmes]

All the mod housings will be great to throw crawler arms into. Most will take 7.5mm comm, but you could change thee hoods to fit 10mm. Overall, great score!

[mrG]

Matched pair question, what exactly is matched? RPM or amps? For crawling I would think amps, as amps equal torque not rpm.

[JohnRobHolmes]

amps make torque, but torque per amp depends on motor speed and efficiency. I have found it best to speed match or make the front motor slightly faster, it offers the most balanced drive and least difficult method.