How did this happen? Motor brush melted

[gbrlbll]

Came out to the wonderful smell of melted plastic and electricity to find a partially finished carved :(

Upon investigation I determined the cut motor was seized up. Expecting to find bad bearings I pulled everything apart. Unexpectedly I found one brush side had completely melted. The brush welded into the plastic mount and the mount completely deformed from heat. Not a cheap repair, but before I do I am wondering what the underlying cause could be? I dont wanna spend $200 only to melt the next one. LHR service guide doesnt even spec brush replacement until 250hrs, only had 197 hrs on this one. Pics show the one side being good with about 50% brush life remaining. The other side completely seized and melted.

[Dale]

I do not know what caused the meltdown, but I had the same problem. I had about 25 hours on a new set of brushes when it happened. The motor did start making a slightly different sound. I stopped the carve and checked things over but found nothing wrong so continued until I also had the smell of melting plastic.. Next time the motor starts to sound different I will check the brushes.

[Digitalwoodshop]

My first thought for both....

Do you have a dust collection system?

Do you do any Acrylic?

Do you have anything connected to the Cut Motor Muffler?

Since the cooling fan sucks air through the fins near the brushes then through the motor as seen be the dust in my covers over the years... It is possible for dust contamination to get between the moving copper and the carbon brush leading to a LARGER ARC. This larger arc would lead to more heat destroying the brush holder.

Would love to have seen a picture of what the inside of the Motor Case looked like when you first opened it.... full of dust?

AL

[bergerud]

The main cause of such heat could, of course, be resistance. A poor connection. For example, the connecting clip or the brush wire. I would be hard to say what actually started the heat up as everything ends up oxidized. If the motor was cooling properly, I would think that the problem is internal to the motor and that a new motor would get you up and running again.

[Dale]

I my case: Yes I have a dust collector
No I had not done any Acrylic
No Nothing attached to the the cut motor muffler.
When I took the motor apart, it had very little dust in it, just a big glob of plastic around one of the brushes.

[Digitalwoodshop]

I my case: Yes I have a dust collector
No I had not done any Acrylic
No Nothing attached to the the cut motor muffler.
When I took the motor apart, it had very little dust in it, just a big glob of plastic around one of the brushes.

Thanks !!!! for your answers... to better understand.

AL

[gbrlbll]

Thanks !!!! for your answers... to better understand.

AL


Same for me

Yes DC

Tried cutting acrylic once a long time ago(maybe hour 30-40), didnt end well so I never tried again.

Nothing attached to muffler

Only a little dust pack in the center nook of the housing, nothing near the armature or brushes.

[gbrlbll]

Same for me

Yes DC

Tried cutting acrylic once a long time ago(maybe hour 30-40), didnt end well so I never tried again.

Nothing attached to muffler

Only a little dust pack in the center nook of the housing, nothing near the armature or brushes.

Also as a side thought....

My CW is ridden hard and put away wet, runs long n dirty and has never given me too much fuss. So I am not that disgruntled about it, it really doesnt owe me a darn thing. Although it could decide to die during a much more profitable project! I just wanna be sure Im not missing some underlying cause that will burn up a new one or this one again if I rebuild it.

[lynnfrwd]

You do need to replace the cut motor.