Bearing exploded, now race stuck in motor

[RC-ichard]

I have a scorpion 2221-6 that was sezing last weekend at the field. After a full inspection, i found the inner bearing has exploded inside the motor and was ground down to dust.

The whole inside track is gone, and the outside race is now stuck in the block. I tried to heat it up with s soldering iron, pulling it out with shafts and other things, even tried to ram a nail in there and pull it out.

Normally, i put a shaft down one side the motor and hit it, but the part that is stuck is smaller then the hole going though the coils so there is no lip for me to put the shaft on and hit it out.... its going to have to be pulled out some how...

Has anyone had any luck with this?? Any suggestions are appreciated!

[Digger1973]

Perhaps a 90deg bent punch or a similar type tool to get under it. I have seen very small ones in sets at Canadian tire

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[wanderer56]

I have a similar problem on a tail blade grip. Of course everyone says use heat, but you don't want to do that on a motor. I've tried to thread taps in metric and standard, and bolts. No go.

I'm thinking of trying to drill it out with a carbide drill bit in a drill press. Not completely through the race, but enough that it would weaken it enough to get it out or break the race free form the grip. Might work on your motor.

What we need for someone to invent is a miniature inside slide hammer bearing puller.

Another idea is to use something like an expandable ball link reamer, if you could find something the correct size.

I guy claims that filling the inside of the bearing with solder, letting it harden, then pressing it out works. Haven't tried that yet. That would be tricky on a motor. You'd have to find a way to keep the solder from running down inside the motor.

[wanderer56]

I had another thought. Install a small circular pirce of cardboard inside the race to prevent the solder from flowing down inside the motor and then fill the race with metal working solder. After it cools, either try pressing it out or tapping it out. If you don't have an arbor press, a c-clamp works fairly well on an application like that.

I think thats what I'm going to try on my blade grip.

[RC-ichard]

I ened up going to harbor freight and finding some micro drill bits, they are on a 1/8" bit taperd down to as small as .25mm I mean this thing looks like a hair with threads!

A set of 20 ranging from .25mm - 1.5mm cost $8 bucks so i figure its worth a shot even if i destroy all of them

If this fails im going to try that solder idea you had, very nice!!

[slamdance]

I've been successful with a bridgeport mill. Use small carbide end mill to blast out the "stuck" outer ring. With high precision, of course. Get a small 1mm end mill and cut straight down and thru. Ofcourse, you'll take out some motor material if you are not dead nuts precise. If you do don't worry it should not affect fit of next bearing.

The fixturing of the stator/motor housing assembly is easy. Just use the actual motor mount as a fixture to be clamped down onto the machine vice, or make a comparable fixture with a flat plate and thru holes. Referencing the face of the motor housing to be perpendicular to the stator bore.

Also, for further improvement I would recommend a modification to install another bearing in that location. (The KBDD motor(the best) has 3x bearings in that location.) Mill deeper to extend the bearing bore so you can fit 2x bearings. I would err on deeper side, because you can always shim back. For higher precision I would recommend doing it on the lathe. Use an expanding collet to fixture. Don't use drills. Use end mills and reamer.. Absolute precision is required to prevent early bearing failures due to unbalance. Good luck.

[wanderer56]

Originally Posted by slamdance

I've been successful with a bridgeport mill. Use small carbide end mill to blast out the "stuck" outer ring. With high precision, of course. Get a small 1mm end mill and cut straight down and thru. Ofcourse, you'll take out some motor material if you are not dead nuts precise. If you do don't worry it should not affect fit of next bearing.

The fixturing of the stator/motor housing assembly is easy. Just use the actual motor mount as a fixture to be clamped down onto the machine vice, or make a comparable fixture with a flat plate and thru holes. Referencing the face of the motor housing to be perpendicular to the stator bore.

Also, for further improvement I would recommend a modification to install another bearing in that location. (The KBDD motor(the best) has 3x bearings in that location.) Mill deeper to extend the bearing bore so you can fit 2x bearings. I would err on deeper side, because you can always shim back. For higher precision I would recommend doing it on the lathe. Use an expanding collet to fixture. Don't use drills. Use end mills and reamer.. Absolute precision is required to prevent early bearing failures due to unbalance. Good luck.

Wish I had a Bridgeport. Sometimes I can do minor milling with my drill press equipped with an x-y vise from harbor freight bolted to it.

Oh but the damage I could do with a real manual mill!

Good idea using the motor mount, or an extra one if you have one laying around, to hold the motor in place in a vise.

[RC-ichard]

Update : I used a dremal and diamond burr file and was able to knock out 1/8 of the stuck outer race, then pried the remainder out!

Thanks for all the suggestions!

[wanderer56]

Yay! Glad you got it out.

[jrod155]

same thing happened to me, but the magnets got chipped from the balls flying out.

while i was trying to dremel the race out, i nicked the stator wires, i gave up and just got a new motor.

at least the rave motors are still cheap.