Go Back  R/C Tech Forums > General Forums > Electric On-Road
how to measure a comm >

how to measure a comm

how to measure a comm

Old 08-15-2004, 01:55 AM
Tech Master
Thread Starter
onnetz's Avatar
Join Date: Apr 2004
Posts: 1,727
Default how to measure a comm

how do you measure a comm?
onnetz is offline  
Old 08-15-2004, 02:00 AM
Tech Elite
iTrader: (28)
Join Date: Aug 2003
Location: Henderson, NV
Posts: 4,166
Trader Rating: 28 (100%+)

take it out of the can/endbell and put a dial caliper over the commutator.
Scott Fisher is offline  
Old 08-15-2004, 02:15 AM
Tech Master
Thread Starter
onnetz's Avatar
Join Date: Apr 2004
Posts: 1,727

thanks... I had a feeling it would be somthing else to buy...
onnetz is offline  
Old 08-15-2004, 02:19 AM
Tech Fanatic
iTrader: (30)
MrRolla's Avatar
Join Date: Mar 2004
Location: Sans Souci, Sydney, Australia
Posts: 962
Trader Rating: 30 (100%+)

Just get a cheap pair of plastic vernier's

while we're on the subject at what size would a com be ready for the bin??
MrRolla is offline  
Old 08-15-2004, 02:32 AM
Tech Master
iTrader: (55)
Join Date: Aug 2001
Location: Australia
Posts: 1,015
Trader Rating: 55 (100%+)

tones is offline  
Old 08-15-2004, 02:43 AM
Tech Champion
iTrader: (31)
JDM_DOHC_SiR's Avatar
Join Date: Aug 2002
Location: Chula Vista, CA
Posts: 9,087
Trader Rating: 31 (100%+)

Originally posted by tones
Man thats playing with fire with a comm that small... I usually never go below 7.0mm
JDM_DOHC_SiR is offline  
Old 08-15-2004, 09:45 AM
Registered User
iTrader: (2)
Join Date: Jun 2004
Posts: 2,025
Trader Rating: 2 (100%+)

Man thats playing with fire with a comm that small
What exactly can happen?
Desolas is offline  
Old 08-15-2004, 12:49 PM
Tech Elite
Join Date: Feb 2003
Location: Kansas
Posts: 2,543

the segments will come apart or start chipping off of the comm and it can ruin the end bell and also lock the motor up. let alone cause you a big head ache especially during a race
crazymechmow is offline  
Old 08-15-2004, 03:12 PM
Tech Addict
jeepnyy's Avatar
Join Date: Oct 2003
Location: The Great Smokey Mountains, TN USA
Posts: 553

Originally posted by JDM_DOHC_SiR
Man thats playing with fire with a comm that small... I usually never go below 7.0mm
Corecctamondo !!!!!!...I never go down that low anyways. Always use a digital calipher. Ebay have one for less than 20 bux.

Henry E.
jeepnyy is offline  
Old 08-15-2004, 04:13 PM
Tech Fanatic
SalvadoriRacing's Avatar
Join Date: Dec 2003
Location: Brazil, Sao Paulo
Posts: 928

the min. (safe) size is 6.86mm or .270in
SalvadoriRacing is offline  
Old 08-15-2004, 11:58 PM
Tech Champion
iTrader: (17)
Jon Kerr's Avatar
Join Date: Jul 2002
Location: San Diego
Posts: 9,659
Trader Rating: 17 (100%+)

When you're measuring with the digital calipers, make sure to measure the top and bottom of the comm to make sure your lathe is cutting true.
Jon Kerr is offline  
Old 08-16-2004, 07:27 AM
Tech Master
iTrader: (8)
N4S's Avatar
Join Date: Aug 2003
Location: Clearwater, Florida
Posts: 1,003
Trader Rating: 8 (100%+)
Default Run em' till they explode !!!!

If you have ever run one down to or below .268in. the motor is the best its ever been . usually the last run of a arms life is the best. I have really noticed this with the monster stocks
N4S is offline  
Old 08-16-2004, 01:07 PM
Tech Master
Join Date: May 2003
Location: UK
Posts: 1,244

in engineering terms a micrometer would be best and you should check the dia. at the top middle and bottom and record the difference.
if u had a dyno as well u can check how its effected performance.
trf racer is offline  

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
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 Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2022 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.