View Full Version : Home 'built' comm lathe

2009.12.07, 12:54 PM
I was having problems with my Atomic Standard BB (thread here (http://mini-zracer.com/forums/showthread.php?t=33249)), and concluded that I had to lathe the comm. Of course I don't have a comm lathe, so I decided to do the next best thing; use a wooden spoon and wire ties.

The motor on the left was driven by two AAA's and the right is the motor that needed lathing.

This worked surprisingly well, but I wouldn't recommend doing it with pinions that you care about. The vibration causes the gear mesh to vary and the teeth did start to squeal a couple times.. I used a broken bit of a dremel disk to refinish the comm.

2009.12.07, 02:04 PM
any pics of the comm?

2009.12.07, 02:13 PM
any pics of the comm?

Here you go. I didn't think to take pictures of the before, but it was a darker copper; similar to left of where it was cut. I also cut a little too far to the right. This method was not very precise, if you hadn't guessed. Although it did work.


2009.12.07, 04:23 PM
You can also use a dremel with variable speed and set it to lowest rpm and then polish the comm. Yeah, polishing only not cutting... I use my $20 cordless dremel.

2009.12.07, 04:50 PM
You can also use a dremel with variable speed and set it to lowest rpm and then polish the comm. Yeah, polishing only not cutting... I use my $20 cordless dremel.

I have a variable speed dremel and am going to try polishing it :)

2009.12.08, 05:07 AM
what will you use to polish the comm?

2009.12.08, 05:26 AM
the condition of the comm surface will tell you how much you must remove.
if the surface has shallow marks than you only need a light polish.
You can use a very fine pc of emory paper or some rouge(1000 or more grit). The easiest polishing compound to use is toothpaste. (small amount on a pc of cloth)
Just remember the idea is to get the comm smooth again. You will be removing like .001". More or less.....

2009.12.08, 09:59 AM
Thanks for the ideas berm.. The only polish I have right now is chrome metal polish; which is a very unabrasive polish. I have 2000 grit sandpaper and I can steal one of those nail buffers from my GF :)

I'll try the polish first because I suppose.

2009.12.08, 11:34 AM
After a light polish using the chrome polish.



2009.12.09, 12:24 AM
Put new brushes on this motor and ran it tonight. It is fast. :)

2010.01.26, 03:46 PM
Ouch! Please don't do that to a motor!

Hudy do a range of comme lathes. Think the best option for mini-z is the slot-car version, as the standard scalextric motors, are the same shape and size as mini-z motors. They're not cheap, but Hudy are a quality name.

Here's the link to the slot-car version

I've got the "fully-auto" big version, but dunno if that would work for mini-z type motors.

2010.01.26, 09:30 PM
for polishing my comm i use MOTHERS MAG& ALUMINUM POLISH.its not to abrasive .and my wal mart dremel