Fran

iTrader: (213)

I was at my LHS last evening, and someone came in with a 18th scale Mamba where, with the pinion on, you had a hard time turning the armiture by hand. It had rough spots while rotating it. Can you fry a brushless motor? I have never seen this, but I don't own any brushless equiptment, but am thinking of getting one for my M18 and/ or BRp rides. Thanks for your help

Mini RC Talk

I am not sure but it sounds like possibly the wires could be rubbing the comm (magnet). On brushless motors the wires are wound around the inside of the can rather than around the comm like on a brushed motor.. (I know sounds funny huh? Now I suppose its possible that if he had it over geared it could have gotten so hot the epoxy that holds the wire in place could have melted or burnt causing such issues....

But I could be wrong.

duneland

Just a couple of minor corrections; The comm is the segmented copper section on the armature of a brushed motor. The windings are on the 'stacks' of the armature. The comm is what the brushes ride on.
No comm exists on a brushless motor. Armature consists of a shaft with magnets attached. The motor in question, could have a broken magnet or (as mini suggested) a loose winding. Either way, it is rare, but does happen.
I imagine Castle would take care of it if it were sent in.

MrBoyd

A couple of other posibilities exist as well...

You are feeling the magnetic field of the motor, or the bearings could be bad.

Mini RC Talk

thank you for pointing out my mistake duneland... I knew that was the wrong term but I couldn't remember the word armature to save my... Thanks again.

MrBoyd

Well, actually a brushless motor has a rotor, not an armature.

Fran

iTrader: (213)

Thanks to all for your posts. I wish I knew the person who came in with it, so I could see if he gets satisfaction from Castle. It definately wasn't the "thump" of the rotor/ magnetic field. We took a new one out of the box to compare. My guess would be a wasted bearing. My friend behind the counter asked the customer what he had it geared at, and he said what ever the kit came with. With that said... what do people usually gear brushless compared to stock? Thanks again!!

ProudSavageOwnr

i have actually had a look inside a mini brushless motor....the copper wiring is "pressed" into the sides - no epoxy visible

i also had a sorta cliclking thing and it was dirty bearings....my front endbell was loose so i took it off and cleaned out the bearing..the rear bearing i cleaned from the inside with an air compressor...after this the shaft felt fine - no binding

also the magnet on the armature is totally round....does not have any grooves that the wire can catch onto

duneland

The best aproach is to start with the smallest pinion you can mesh. If it tops out to early for the straight, go up one tooth at a time, until it pulls the whole straight (or most of it). Some general guidelines; more kv = smaller pinion. More voltage = smaller pinion.
I run a M18 geared 13/42 with mamba esc/2cell LiPo/8k Mamba motor (now have a C4 9200).