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Forgive me if I'm asking the obvious, but, could it be you need a new cutting bit?

It might be, but I only used the lathe two times, and both times they came out rough, so I just gave up. Do they dull out that quickly??

I think they go long time, but did you get it new or secondhand?
Was it cheap or expensive?
If you got a cheap one, the cutting bit maybe trash, or it could have play and stuuer a bit... Just guessing.

this is the one I got, brand new from Tower, maybe a year and a half ago:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLBB7&P=7

doesn't look too bad I guess you need some trackside support to help you out.
The cutting oil sounds like a good idea, but hell, what do I know ?

tecnica2001 wrote:The comm comes out kind of rough, not as smooth as other people I've seen do it. I use the black marker method, then I start nice and slow, when I see that the marker line starts to dissappear a little, I move it across the comm, but it comes out rough, maybe I need some type of oil, which one is recommended for cutting commutators??

sounds like you need a new cutting bit.

is it carbide or diamond tip ?

the diamond tips dont leave any markings at all.

i personally use a carbide tip as they are more forgiving on comms, plus you can pick up really good ones for almost nothing on ebay

Edwin

tecnica2001 wrote:this is the one I got, brand new from Tower, maybe a year and a half ago:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLBB7&P=7

heh, how about that. it IS the same one i have.

one thing i found you do need with the carbide tip is cutting fluid.

Edwin

Cool, they have the cutting bit for about $12 on tower and I might as well pick up some cutting fluid

Thanks for the great info guys.

when remember when you are cutting the comm, to make sure its always wet, so be generous with the fluid and always be smooth with the arm

oh, and oil the wheels as the left to right one (the cutter) can get abit tight.

Edwin

Without seeing how you in action with the comm truer..may I suggest a few tips?


EQUIPMENT

(1) Have something that will power the lathe at about 2500-3000 rpm it will be ideal.....alternatively use a 4.8 volt battery pack.
(2) Check the lathes motor as well (oil the bearings and check the brushes) A badly arching motor will give an inconsistent cut as well
(3) check the cutters height and angles
I would suggest getting a diamond cutter once the carbide one is blunt....you do not need cutting fluid with the diamond cutter and they cut so much better.

METHOD

(1) Mount the rotor unto the lathe, oil the supports (where the rotor is supported but do not get any on the comm itself) turn by hand to ensure everything is free
(2) Ensure the cutter is away from the comm..once everything is clear turn it on
(3) Move the cutter in..choose an area which is on the 'high' side first
(4) take the barest of cut on each pass..the cutter only has to touch the comm ever so slightly. Worst thing is to try to take big cuts on each pass...with a diamond cutter you are probably able to get away with it but still not a good thing to do.
(5) take it easy and cut in a consistent motion (as in don't be jerky during the cut)
(6) The cutter cuts in one direction only....you will see the comm change (colour?) when you draw it back...it is not actually cutting but rubbing against the comm
(7) remove rotor once desired finish is achieved
(8) use a sharp blade to remove any burrs left between the comm slots
(9) Use motor spray to clean the rotor let the motor fluid run away from the freshly cut comm
(10) Voila! install rotor back into the can

Hope this helps...cheers!

uzzi wrote:Without seeing how you in action with the comm truer..may I suggest a few tips?
...
Hope this helps...cheers!

Man, now I feel like wanting to buy one and try this myself!

bleh....

thank god for brushless.

Yeah sounds like alot of work but once you have done a few its pretty easy...until the rest of your friends starts passing rotors for you to do at the race track

uzzi wrote:Yeah sounds like alot of work but once you have done a few its pretty easy...until the rest of your friends starts passing rotors for you to do at the race track

Uhhh, remember non-rebuildable stock motors...? Especially the early Yoke and Epic ones with pinned brush hoods. I've still got the old-school alignment tool, fiddlestick, and Cobra stock lathe. I guess I could be the Mike Reedy of the Vintage Nats and cut everyone's old junk in the can...except everyone's running brushless.

Ahh...yes...the non-rebuildable stock motors. Who said stock racing is cheaper?

Wow!! Cobra comm lathe...vintage stuff!! who can forget the Reedy in a can motor spray!