Shopsmith Forums

I'm putting new bearings in an A.O. Smith 1 1/8hp motor and I'm experiencing something that seems impossible to be occurring.
I've done this on probably a dozen motors, a couple of 10er's and the rest from MK5's and never had this happen.
When I took off the motor shieves, I removed the lock ring & spring and slid the outer 1/2 shieve, which moved freely, until it reached the end of the motor shaft & then had to pound it off the end. Same with the inner one. It's as if the end of the motor shaft is bigger in diameter at the point where the retainer ring sits. (the machine has not been apart, and there's no evidence of the end being peened over from someone hammering on it)

Now I'm re-assembling it and the shieves simply won't go on. I've tried a rubber mallet, and I'm actually starting to peel away aluminum enlarging the hole trying to drive it onto the motor shaft. There's no way it will go, and even if I did drive it past the end, the enlarged hole would cause the shieve to wobble, as it moved freely on the rest of the shaft before.

How can this be? How could they have been there in the first place??? What am I missing??? I'm supposed to have this unit rebuilt for a friend by tomorrow, and I'm clueless.

Think burr.

Feel for it. File it down.

Sandpaper on the end of the shaft (gently) should help. Also, try heating the sheaves in an oven to about 250 or so, then they should slide on. Good luck!

JPG wrote:Think burr.

Feel for it. File it down.

No burs, also reluctant to file. I want to be sure the retainer clip will hold the big spring.
Will try heating, still wondering how this can happen.

It may be a burr inside the sheave bore that got caught. Try moving it back and forth to see if the burr can be dislodged. Also check the key way and the key for any burrs or a bent key. Did you use a gear puller to remove the sheave? The end of the shaft may have been ballooned by another owner.
Bill V

wa2crk wrote:It may be a burr inside the sheave bore that got caught. Try moving it back and forth to see if the burr can be dislodged. Also check the key way and the key for any burrs or a bent key. Did you use a gear puller to remove the sheave? The end of the shaft may have been ballooned by another owner.
Bill V

No evidence of abuse by previous owner. The machine was never opened before I did. No burrs. I'll try the heat & see if it works. It's makin' me nuts.

Do sand or file the last bit of the motor shaft first, then a little oil....you want the motor shaft to look polished.

have you put a caliper on the shaft? Do you KNOW that it is not mushroomed, it doesn't take much ....

When I said file, I did not mean to decrease the shaft diameter to less than to its original od. I think you have a very small burr on the shaft that has been made worse by forcing the sheaves off. The thing about a flat file is that it can ride the 'normal' part of the shaft and only remove that which sticks out(burr).

Good rule of thumb - never use a hammer to disassemble/reassemble anything that should not require it. If it will not 'go', determine why and correct.

Easier said than done.

I always use a digital caliper to measure the motor rotor shaft and bearing ID. Many times, I find the bearing I believed would fit is either too tight or too large for the rotor shaft. They have 4 different bearing IDs for the same bearing number plus the bearing OD can be different. You can hammer or press a smaller ID bearing onto the larger rotor shaft but the bearing will not turn freely.