Go Back   RCCrawler Forums > RCCrawler General Tech > Electronics
Loading

Notices

Like Tree7Likes

Thread: Where can I find *hard* brushes?

Reply
 
LinkBack Thread Tools Display Modes
Old 05-23-2017, 02:14 PM   #1
RCC Addict
 
Join Date: Aug 2014
Location: Maryland, Near DC, USA
Posts: 1,126
Default Where can I find *hard* brushes?

I've got some low-turn motors in my RC fleet (11t and 12t), and since I'm not racing and don't need ultimate maximum performance, I'd like to use hard brushes in those motors so the brushes will hold-up to running with LiPo batteries for a reasonable amount of time. I've been using Reedy Plutonium silver-compound brushes, but as I've learned, silver is more abrasive than copper and the result is the Plutonium brushes are wearing-down my commutators faster than I'd like. My commutators start to go out-of-round at the edges of the pads within a few runs, and it's not long after that before they need to be lathed to restore their performance.

Does anyone know where I can get hard-compound brushes that are made from a normal copper/carbon compound, instead of silver? Standup brushes are fine, I'm probably going to convert my laydown motors to use standup brushes in the near future anyway, to reduce the number of different spare brushes I have to keep on-hand.

Last edited by fyrstormer; 05-23-2017 at 02:16 PM.
fyrstormer is offline   Reply With Quote
Sponsored Links
Old 05-23-2017, 02:22 PM   #2
I wanna be Dave
 
Join Date: Sep 2008
Location: PA
Posts: 4,598
Default Re: Where can I find *hard* brushes?

Did you check out Team Brood?

Team Brood Racing :: Brushed Motor Parts :: Brushes

An industrial supply house like McMaster-Carr is another place to check, but I'm not sure if they'll have the correct size. https://www.mcmaster.com/#motor-brushes/=17r6qwe
Teng likes this.
JatoTheRipper is online now   Reply With Quote
Old 05-23-2017, 09:43 PM   #3
RCC Addict
 
Join Date: Aug 2014
Location: Maryland, Near DC, USA
Posts: 1,126
Default Re: Where can I find *hard* brushes?

Hmm. Team Brood does appear to have several options, but unfortunately they don't specify any information about the brush compounds in their product listings.
fyrstormer is offline   Reply With Quote
Old 05-23-2017, 11:10 PM   #4
Owner Team Brood Racing
 
EddieO's Avatar
 
Join Date: Apr 2007
Location: Arlington, Washington
Posts: 2,319
Default Re: Where can I find *hard* brushes?

Thats because most companies never released much info whats in a brush, let alone any customers really caring.

Silver is similar in hardness to copper...its the other crap in the brush that causes the extra wear.

All of the harder long wearing brushes had silver put in them, because if they were copper, they were simply a dog in the motor...the Plutonium brushes along with the XXX from trinity, the CS, etc....all lasted long as a brush, but they ALL ate comms for lunch, even on 4 cell NIMH...

If the truck is not seeing much water, a long wearing softer brush is what you want to prolong comm life....a 729 or an Enduro would be the choice. Both hold up fine to lipo....brushes are like many things....you can't have the best of both worlds. You have to either choose brush life or comm life....you won't find a brush that does both.

Later EddieO
EddieO is offline   Reply With Quote
Old 05-24-2017, 02:01 AM   #5
RCC Addict
 
Join Date: Aug 2014
Location: Maryland, Near DC, USA
Posts: 1,126
Default Re: Where can I find *hard* brushes?

What is the "other crap" put into silver-compound brushes that makes them so much more abrasive than copper brushes? I know that copper is a self-lubricating metal, hence its use to make bronze bushings, but silver apparently isn't; I was under the impression after talking to various motor experts that this was the main reason silver brushes cause so much more wear.

The brushes in disposable motors seem to strike a good balance between brush hardness and comm longevity. That's what I'd like to get in my rebuildable motors. When I look at the surfaces of disposable-motor brushes, they're always dark grey and glossy, which tells me they have a lot of graphite in them. Does anyone make graphite brushes in the standard size used by RC motors? I know Holmes has some for their Puller motors, but those are a non-standard size as far as I can tell.

The motors I want to change the brushes in don't see water very often (or at all, in the case of my touring cars and rally cars), but they do see high amperage, due to the application. I know high amperage contributes to comm wear from arcing, so I'd like to mitigate that as much as possible without switching to brushes that have to be replaced every time I turn around.

Last edited by fyrstormer; 05-24-2017 at 02:11 AM.
fyrstormer is offline   Reply With Quote
Old 05-24-2017, 04:31 AM   #6
Quarry Creeper
 
Join Date: Aug 2014
Location: home
Posts: 280
Default Re: Where can I find *hard* brushes?

Subbed

Sent from my LGAS375 using Tapatalk
kongluc is offline   Reply With Quote
Old 05-24-2017, 06:05 AM   #7
owner, Holmes Hobbies LLC
 
JohnRobHolmes's Avatar
 
Join Date: Nov 2004
Location: Volt up! Gear down!
Posts: 19,427
Default Re: Where can I find *hard* brushes?

Silver is more abrasive to copper than copper is. Our silver brushes are the same density and graphite content as the standard soft copper brush, but with some copper replaced by silver. If silver content is more than 1/20 of copper content, the hardness starts to drastically change. As Eddie stated, it will always be a trade off to tweak compound or hardness. Brush life or comm life, can't have both with a high conductivity brush.


The origional Puller brushes wore so long because of a teeny tiny doping of molybdenum. It affects conductivity too, makes them less conductive which also suppresses arcing. The larger size offset conductivity losses.
JohnRobHolmes is offline   Reply With Quote
Old 05-24-2017, 08:30 AM   #8
Owner Team Brood Racing
 
EddieO's Avatar
 
Join Date: Apr 2007
Location: Arlington, Washington
Posts: 2,319
Default Re: Where can I find *hard* brushes?

I will be honest, I am not a chemical engineer.....my info comes from the guys at Keystone, who made many of the brushes we saw in rc racing. Silver needs different bonding agents from my understanding. As a metal its typically softer than copper. Abrasiveness is basically measured in the hardness of the material. As John stated though, rubbing copper on copper is less abrasive than silver on copper, which is actually the same thing the keystone guy said to me when I was looking into getting a brush made. The Keystone guy explained this as a reaction between the two metals along with increased conductivity that accelerated the comm wear.

As to the other crap, your guess is as good as mine....They would put all types of different stuff in them in search of the holy grail brush. Besides the standard copper, graphite, silver, etc...they would use materials like John mentioned to dope the brush, along with bonding agents depending on the materials used to make up the brush. Brush compounds were closely guarded secrets....on top of that they varied from batch to batch.


Copper is not self lubricating on its own, some of its alloys, such as Bronze are....I would guess Silver isn't used for bearings due to cost along with it not alloying with other materials as well like copper does for brass or bronze.

You won't find a standup or laydown brush like what comes in the mabuchi or johnson style motors very easy. Maybe some old stock from the 90s or older. Companies stopped producing them long ago, simply because nobody wanted them. They made them when I was a kid. I ended up with a pair once, put them in my new motor at a big race, car was slower than can be. Installed new brushes after, was fast again. You could dry to source some graphite brushes and cut them down....be prepared for a mess though

Later EddieO
EddieO is offline   Reply With Quote
Old 05-24-2017, 10:33 AM   #9
owner, Holmes Hobbies LLC
 
JohnRobHolmes's Avatar
 
Join Date: Nov 2004
Location: Volt up! Gear down!
Posts: 19,427
Default Re: Where can I find *hard* brushes?

Certainly, part of (or most of) the increased comm wear of silver brushes is increased conductivity allowing higher current inrush. It also prevents the comm from developing the same "patina" that graphite or copper/graphite promotes. The interstitial patina is a critical part of a long service life, as it has higher conductivity and lower friction than copper oxide that would otherwise form. Water wears brushes by removing the interstitial layer, and the brush wears more while trying to redeposit it. This is also why pure metal brushes use a non conductive lubricant. It serves as an interstitial layer but more importantly seals surfaces to prevent abrasive copper or silver oxide from forming.

Lots of fantastic scientific information on NASAs jet propulsion lab website, buried within white papers and technical documentation. They have gone to great lengths to understand commutating surfaces, and it seems that a jewel of information always comes from seemingly unrelated situations.
JohnRobHolmes is offline   Reply With Quote
Old 05-24-2017, 04:11 PM   #10
RCC Addict
 
Join Date: Aug 2014
Location: Maryland, Near DC, USA
Posts: 1,126
Default Re: Where can I find *hard* brushes?

I didn't realize only 5% silver was necessary to significantly increase the hardness of the brush. This changes my opinion about "silver-containing" brushes that are obviously copper-colored. So for my application, where I have low-turn high-wattage motors that don't get wet often (or ever), and I'm willing to trade *some* increased comm wear for slower brush wear, would you recommend something like a 5% silver brush instead of a plain copper brush? If so, can you recommend one? I only see soft copper brushes and full-silver(?) brushes on the Holmes website, Team Associated seems to be sold out of most of their brushes, and I can't tell if Team Trinity even makes brushes anymore. It would be nice if the brushes had no eyelets on the ends, because I prefer to solder the shunts directly to the tabs, and cutting off the ends of the shunts to remove the eyelets makes it a little harder for the shunts to reach the tabs.

Last edited by fyrstormer; 05-24-2017 at 04:29 PM.
fyrstormer is offline   Reply With Quote
Old 05-24-2017, 04:22 PM   #11
MODERATOR™
 
EeePee's Avatar
 
Join Date: Jul 2004
Location: Ohio
Posts: 18,827
Default Re: Where can I find *hard* brushes?

Stormer always had a stash.

https://shop.stormerhobbies.com/cate...ce=&maxprice=3

https://shop.stormerhobbies.com/cate...show=10&page=1
EeePee is offline   Reply With Quote
Old 05-24-2017, 05:44 PM   #12
owner, Holmes Hobbies LLC
 
JohnRobHolmes's Avatar
 
Join Date: Nov 2004
Location: Volt up! Gear down!
Posts: 19,427
Default Re: Where can I find *hard* brushes?

Abrasiveness would be more accurate than hardness to describe higher silver content I suppose. If I recall correctly, my silver brush is 5% silver. I'll have to find my notes, but it is a low amount. They look more silver because of the process. Size of the powder and order of mixing influences color. I sent off many brushes to a mass spectrometry lab and found that color doesn't always reveal the full story.

I would choose Putnam brushes for what you want, any type. I have a stash that I don't really want to sell, maybe there are some left online somewhere?
JohnRobHolmes is offline   Reply With Quote
Old 05-24-2017, 05:45 PM   #13
RCC Addict
 
Join Date: Aug 2014
Location: Maryland, Near DC, USA
Posts: 1,126
Default Re: Where can I find *hard* brushes?

Dear god there are a lot of different brushes with modified faces. Simple serrated brushes are fine, I don't need holes or slots drilled into them.

Quote:
Originally Posted by JohnRobHolmes View Post
Abrasiveness would be more accurate than hardness to describe higher silver content I suppose.
So silver content *only* improves conductivity, and has no meaningful effect on brush longevity? Hmm.

Quote:
Originally Posted by JohnRobHolmes View Post
If I recall correctly, my silver brush is 5% silver. I'll have to find my notes, but it is a low amount. They look more silver because of the process. Size of the powder and order of mixing influences color. I sent off many brushes to a mass spectrometry lab and found that color doesn't always reveal the full story.
I love how seriously you take your work.

Quote:
Originally Posted by JohnRobHolmes View Post
I would choose Putnam brushes for what you want, any type. I have a stash that I don't really want to sell, maybe there are some left online somewhere?
It looks like Team Brood has some Putnam laydown brushes, but I can't find Putnam standup brushes anywhere. *sigh* Time to add another saved-search to my eBay account.

Last edited by fyrstormer; 05-24-2017 at 05:50 PM.
fyrstormer is offline   Reply With Quote
Old 05-24-2017, 06:21 PM   #14
Owner Team Brood Racing
 
EddieO's Avatar
 
Join Date: Apr 2007
Location: Arlington, Washington
Posts: 2,319
Default Re: Where can I find *hard* brushes?

The putnam standups were just a relabeled brush that other companies sold. I did not stock them, as they were junk in the race motors. His laydowns were very abrasive on the comm, especially the green, blue not as much...red was pretty tame, they were fast though. The last few batches of putnam laydowns were not even the same brushes, he could not get more from them, so he bought other company brushes and dipped the shunts in dye...I threw away the last batch I got from him, as they were clearly not the same brush....

Stormer appears to have some good deals on the Orion brushes....Try the Enduro units, even the sprints are fairly tame...they sold them with lots of different faces (hole, cut, slot, checkered).

Later EddieO
EddieO is offline   Reply With Quote
Old 05-24-2017, 07:31 PM   #15
RCC Addict
 
Join Date: Aug 2014
Location: Maryland, Near DC, USA
Posts: 1,126
Default Re: Where can I find *hard* brushes?

Thanks. I'm using Enduro brushes in an Orion Revolution motor and they've been working pretty well; I didn't realize they were available in a normal rectangular shape too. I'll have to take another look.
fyrstormer is offline   Reply With Quote
Old 06-13-2017, 09:54 PM   #16
RCC Addict
 
Join Date: Aug 2014
Location: Maryland, Near DC, USA
Posts: 1,126
Default Re: Where can I find *hard* brushes?

After trying to hunt down reliable suppliers for various different brushes, I decided to try some 20% silver brushes from Team Trinity. Hopefully they will be able to strike a balance between reducing comm wear without accelerating brush wear too much. I ran-in the brushes with the throttle trim turned up for a couple minutes, then took the car outside for a couple top-speed runs. My multimeter says the 20% silver brushes rate at 0.2 ohms from the face of the brush to the end of the shunt, whereas the Reedy Plutonium brushes rate at 0.05 ohms, but that slightly increased resistance wasn't enough to slow down the car I installed them in for initial testing. After 3 top-speed runs, the serrations haven't worn-down completely, so hopefully the brushes will have a decent lifespan. We'll see how my Traxxas Slash responds tomorrow; that truck has a Holmes TorqueMaster Pro 550 11t motor in it, and it's a brush-devouring monster; slightly higher resistance might actually be a good thing in that respect.

Last edited by fyrstormer; 06-13-2017 at 09:57 PM.
fyrstormer is offline   Reply With Quote
Old 06-13-2017, 11:07 PM   #17
Owner Team Brood Racing
 
EddieO's Avatar
 
Join Date: Apr 2007
Location: Arlington, Washington
Posts: 2,319
Default Re: Where can I find *hard* brushes?

If they are the XXX Brushes, they will last a while like the Reedy Plutonium....but expect extra comm wear. We didn't use them a ton in the racing days, because of price and they ate the comm pretty bad in some cases....lots of fade at the end of the run from them in 19t and stock motors, though we did use them in the ultrabird 19t at snowbirds with adjustable timing at 50 degrees....They worked ok in mod if you had everything right...(timing, spring tension, etc)..

Later EddieO
EddieO is offline   Reply With Quote
Old 06-13-2017, 11:39 PM   #18
RCC Addict
 
Join Date: Aug 2014
Location: Maryland, Near DC, USA
Posts: 1,126
Default Re: Where can I find *hard* brushes?

These aren't XXX brushes, though I've used those in other motors in the past. XXX's are 100% silver or close to it; these have the product code 4403NT and have a noticeable brownish color, though not as obvious as a 100% copper brush.
fyrstormer is offline   Reply With Quote
Old 06-14-2017, 12:08 AM   #19
Owner Team Brood Racing
 
EddieO's Avatar
 
Join Date: Apr 2007
Location: Arlington, Washington
Posts: 2,319
Default Re: Where can I find *hard* brushes?

Ah, 4403...used those occasionally back in the racing days, they were kinda the in between a 4380 and 4383 in performance.

The XXX brushes don't have 100% silver content....I think Jim told me it was still less than 50% or so...there is another element in it that magnified the silver look to them that they added on purpose for the look. Someone had them analyzed way back and the CS Brush had the most...CP INfinity had more than the XXX, so did the Reedy V1, they changed in the second batch, so not sure what it was then.

Later EddieO
EddieO is offline   Reply With Quote
Old 06-14-2017, 11:16 PM   #20
RCC Addict
 
Join Date: Aug 2014
Location: Maryland, Near DC, USA
Posts: 1,126
Default Re: Where can I find *hard* brushes?

I've installed the 4403s in two motors thus far, one high-speed and lightly-loaded and the other high-speed and heavily-loaded, and both motors run at the same speed they used to. So that's good. I haven't installed them in any low-speed motors yet, but that's coming next. The lifespan of the brushes and the wear on the commutator can only be determined through long-term use, though.

I'm not racing, so I don't demand super-high performance, I just want my brushed motors to run a long time between teardowns and without becoming dog-slow. Yes, yes, I know, volt-up and gear-down, but I'm stubborn and I'd rather address it through mechanical changes instead of electrical changes.
fyrstormer is offline   Reply With Quote
Reply



Where can I find *hard* brushes? - Similar Threads
Thread Thread Starter Forum Replies Last Post
Elliptic motor brushes hard to find? MadForce Electronics 10 05-26-2010 10:54 AM
Can't find brushes Jus Electronics 0 02-06-2010 03:42 PM
Hard to find rottenbelly Paint and Body 6 11-30-2008 05:16 PM
why is it hard to find... muddeprived Chit Chat 2 12-23-2007 06:26 PM
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 09:52 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO ©2011, Crawlability, Inc.
Copyright 2004-2014 RCCrawler.com