Cutting a motor commutator & motor tweaks

[kurtus]

Originally Posted by Charlie-III

When finished, you need it to be segments, each one is connected to a winding/pole. A 3 pole motor has 3 segments, a 5 pole motor has 5 segments.

I knew that was going to be the answer damn it. That is going to make it a little trickier then.

What a dumbass I am lol. If I noticed there was more than the one page to that link I would have got the answer and not asked such a silly question pfff newbs lol

[Jcplante]

I can make the id and od anything you need without a prob. Im a machinist so i can make just about anything and i just happen to have a bunch of scrap copper bars


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[EGRESSor]

Originally Posted by kurtus420

EGRESSor, would I need it to have those segments on the comm or is a solid copper ring ok?

i just precutted the slots
and didn´t turned the comm down to the plastic core
i used copper pipe solder stuff
ROTHENBERGER ROSOL 3 in plastic bottle
ROTHENBERGER Fitting Solder
ROTHENBERGER ROTHERM 2000

years ago a shop solds comm rebuild rings for rc motors ,EddieO may remember

[kurtus]

Originally Posted by EGRESSor

i just precutted the slots
and didn´t turned the comm down to the plastic core
i used copper pipe solder stuff
ROTHENBERGER ROSOL 3 in plastic bottle
ROTHENBERGER Fitting Solder
ROTHENBERGER ROTHERM 2000

years ago a shop solds comm rebuild rings for rc motors ,EddieO may remember

Well buddy just rolled in and upon further inspection I think I'm screwed for fixing this one, I was pretty excited to try my hand at it too

[kurtus]

Made a mistake in thinking these where 767 because I didn't read the fine print before purchasing on ebay. These are actually Reedy 769 serrated cavity style brushes, is this going to cause problems/poor running on a 27t brood or holmes motor??

[EddieO]

769=767 with a hole in it. Ive run them in crawler motors with no issues.


Attempting to fix a comm is more trouble, time and money than its worth. We sometimes would do it back in the day, but thats cause some arms were just super fast....not so much a big deal now.

Fussy brush was the company that made it. While it worked, it was NOT fun. The copper in comms is different than the more common copper in pipes and such, though in a crawler motor I doubt its a huge issue. I have replacement comms straight from sagami.

Later EddieO

[kurtus]

Originally Posted by EddieO

769=767 with a hole in it. Ive run them in crawler motors with no issues.


Attempting to fix a comm is more trouble, time and money than its worth. We sometimes would do it back in the day, but thats cause some arms were just super fast....not so much a big deal now.

Fussy brush was the company that made it. While it worked, it was NOT fun. The copper in comms is different than the more common copper in pipes and such, though in a crawler motor I doubt its a huge issue. I have replacement comms straight from sagami.

Later EddieO

Enough said EddieO and thanks, I'll give it back to him so he can keep the papers from flying around on his desk......moving on lol. Out of curiousity is that winding supposed to be attached in that picture I posted?

As for the cavity brush, what performance does the effect?

[JohnRobHolmes]

Yes, that wind should be connected. Looks like he may have gotten some debris in the motor that knocked and nicked things up. We provide new armatures if he just wants to rebuild it instead of buying a whole new motor. If it is a MOA rig he should get two arms.


Cavity brushes increase pressure on the leading and trailing edges, which in theory can help performance since leading edges have higher amp density. It also leads to faster wear and higher heat. In a crawler, doesn't seem to be very useful vs just adding a few degrees of timing or getting a slightly faster wind instead. Since we aren't limited to a specific motor build we can use other "tricks" that don't impact lifespan as severely.


I have bare comms here for all the motors we make plus extra sizes for customs, but it isn't very feasible to swap a new comm on an old armature. I've tried, and it takes less time and money to just buy/ build a new one.

[6sharky9]

we need silver comms and windings

[kurtus]

Originally Posted by JohnRobHolmes

Yes, that wind should be connected. Looks like he may have gotten some debris in the motor that knocked and nicked things up. We provide new armatures if he just wants to rebuild it instead of buying a whole new motor. If it is a MOA rig he should get two arms.


Cavity brushes increase pressure on the leading and trailing edges, which in theory can help performance since leading edges have higher amp density. It also leads to faster wear and higher heat. In a crawler, doesn't seem to be very useful vs just adding a few degrees of timing or getting a slightly faster wind instead. Since we aren't limited to a specific motor build we can use other "tricks" that don't impact lifespan as severely.


I have bare comms here for all the motors we make plus extra sizes for customs, but it isn't very feasible to swap a new comm on an old armature. I've tried, and it takes less time and money to just buy/ build a new one.

Thanks for the input John, since this arm is so bad I'm just going to scrap the whole idea and get him to buy a new motor. He can always upgrade it in the future but the downside is the higher shipping cost to Canada. We can buy from amain with free shipping but they dont carry the arms unfortunatly, it is what it is.

As for the brushes, are we talking more comm wear or brush wear? I can live with the brushes burning out quicker but I dont want to cut comm life down just to make use of these. Would it be advisable to just use zero degrees to get closer to the 6-9 degrees I would normally run? This is on a 27t brood motor.

Also, I just bought a 27t torquemaster pro that has a 7.5mm comm with standup checkpoint brushes, is it possible to use xipp brush cutter to reshape some 766 laydowns into standup brushes for this, any issues doing this aside from shortening up the brush?

Thx

[JohnRobHolmes]

Originally Posted by 6sharky9

we need silver comms and windings

If you wanna pay big bucks, sure we can do it. for that sort of cash, might as well make it brushless so you aren't literally burning money when it is used

Originally Posted by kurtus420

Thanks for the input John, since this arm is so bad I'm just going to scrap the whole idea and get him to buy a new motor. He can always upgrade it in the future but the downside is the higher shipping cost to Canada. We can buy from amain with free shipping but they dont carry the arms unfortunatly, it is what it is.

As for the brushes, are we talking more comm wear or brush wear? I can live with the brushes burning out quicker but I dont want to cut comm life down just to make use of these. Would it be advisable to just use zero degrees to get closer to the 6-9 degrees I would normally run? This is on a 27t brood motor.

Also, I just bought a 27t torquemaster pro that has a 7.5mm comm with standup checkpoint brushes, is it possible to use xipp brush cutter to reshape some 766 laydowns into standup brushes for this, any issues doing this aside from shortening up the brush?

Thx

I can get people to start carrying replacement arms, its a good idea.

Slotted/ drilled wear out comm and brush faster because of the localized higher current density. Maybe Eddie can comment on the real world rates or if the punchyness is noticeable. I couldn't tell a difference with slotted and drilled stuff. Add a few more degrees of timing if you want a midrange and high range boost. Use silver brushes if you want an all around boost. More power always wears comm and brushes faster, and larger brush surfaces win for longevity.

Reshaping a brush from Ld to standup is fine and handy. The spring groove isn't usable, but unless you are chasing .05% gains it isn't a big worry.

[kurtus]

Originally Posted by JohnRobHolmes

If you wanna pay big bucks, sure we can do it. for that sort of cash, might as well make it brushless so you aren't literally burning money when it is used



I can get people to start carrying replacement arms, its a good idea.

Slotted/ drilled wear out comm and brush faster because of the localized higher current density. Maybe Eddie can comment on the real world rates or if the punchyness is noticeable. I couldn't tell a difference with slotted and drilled stuff. Add a few more degrees of timing if you want a midrange and high range boost. Use silver brushes if you want an all around boost. More power always wears comm and brushes faster, and larger brush surfaces win for longevity.

Reshaping a brush from Ld to standup is fine and handy. The spring groove isn't usable, but unless you are chasing .05% gains it isn't a big worry.

Make sure Amain gets some, I know my buddy would get one and I would probably grab a few to use with some other cans I am getting.

guess I'll use the brushes and just keep a bit closer eye on the comm then, maybe just run them at 1 degree to play it safe. It is kind of nice to have the option of more rpm for my scalers though if needed.

As for the spring groove, could I just file a new one in where your checkpoint ones are and be fine?

[JohnRobHolmes]

Yes, you could file a new groove.

[kurtus]

This just in, not bad for 21 bucks, it looks brand new and smooth as butter.

[kurtus]

Maybe John, EddieO or anyone that knows, can you guys help me identify these arms? The seller included them as practice arms but it would be nice to know what they might be for possible future use. I tried to get pics of whatever part numbers where on them.

This one has no markings other than the jiffy marker on it.


This one says epic27


This has 122021 etched into the side and 17.8 as well


Finally this one that has 7015w stamped on it


Obviously the epic 27t is what is says but the other 3 I'm clueless. Thanks for any insight gents

[Charlie-III]

Kurtus, last 2 pictures are the same!




Some of the bottom arms look like "doubles" where you run 2 strands next to each other when you wind.
They all look quite fast!

PS, all the comms look pretty clean, shouldn't take much to make them nice.

[kurtus]

Originally Posted by Charlie-III

Kurtus, last 2 pictures are the same!




Some of the bottom arms look like "doubles" where you run 2 strands next to each other when you wind.
They all look quite fast!

PS, all the comms look pretty clean, shouldn't take much to make them nice.

See if I wasn't trying to rush so the boss doesnt know what I'm up too I would have got that right

I was really suprised by these arms too, they all look like new practically with low run time. Great specimens

[JohnRobHolmes]

The 17.8 is an 8 turn double. The split stack ones are stock arms, not very usable in a crawler as they tend to overheat. The last pic is probably a 10 turn double.


Good score on the lathe. Keep the rollers clean so your arms don't jump around.

[kurtus]

Originally Posted by JohnRobHolmes

The 17.8 is an 8 turn double. The split stack ones are stock arms, not very usable in a crawler as they tend to overheat. The last pic is probably a 10 turn double.


Good score on the lathe. Keep the rollers clean so your arms don't jump around.

Thanks John, I took the bearings out of it and put the v-blocks in. One of the vblocks was really tight though so I had to use the force to get it in there. Doubt I'll ever get it out now though but I assume shouldn't need to anyways?

[JohnRobHolmes]

Keep them lubed and don't spin the arm too fast, you will be fine for hundreds of cuts at least. 3s or 12 v is good for 55t drive motors, 1s or 3v is good for 35t or 27t motors. I run a 13t crawlmaster sport/ expert on my production comm lathe @3v, it spools up smoother and makes less vibration on the lathe. I feel like a bit of a snob doing it, but never regret it while running the lathe.