misaligned floating sheave on motor shaft

[peterag]

Update: last night I removed/disassembled the sheave assembly from the motor shaft, and found that there certainly were issues.

Of course, there was dirt (rubber from the belt); but more to the point, when I took the floating sheave off, the key came with it. Maybe my recent oiling had set it free... Be that as it may, it seems that the key had been sliding with the floating sheave, and presumably it sometimes blocked against 'something' - I would guess against the fan sheave. Next, not only was there no set screw in the fan sheave, but there was no spacer holding it away from the motor. Now, when I had changed the belt, I had noticed that the bottom sheaves were not aligned with the top sheaves. I had thought that odd, but had decided that was how the gods of Shopsmith had made designed it. Apparently not. My father-in-law (ex-owner) says that while he himself had never done surgery on the unit, he had had service done (I assume in Montreal) at one point. Hmn!

Finally, I assume that, as per my comment above, the running of the new belt 1/8-1/4" below the rim on the top sheaves at highest speed, even when the bottom sheaves came together completely, was caused by the misalignment, and that it didn't happen (I think!) with the older belt was because the latter had stretched. Maybe.

In any event, the key has burrs, not only on the face where the set key would have held it, but also on side face(s?). I probably could have filed off the damage, but just ordered the replacement pieces.

Again, thanks, all, for the help.

Peter

[JPG]

For reference when you reassemble it.

The key is retained by the setscrew in the fan sheave.

Tightening that set screw is one of the few instances where a gorilla becomes desirable.

Since one sheave on opposite sides of the two pulleys move in opposite directions, that cannot line up directly.

At the two extremes of movement, the movable sheave on one pulley will align with the fixed sheave on the other. In between it varies.

[peterag]

Hi All,

A) My last post was inaccurate: contrary to my assertion, there was a spacer on the motor shaft, but I had not known what I was looking at. And sadly, my problem is now with that spacer... I wanted to replace it with a new one, but I can't take it off - sigh.

[With sheaves, key etc. removed from the shaft:] When the (original) spacer is pushed in as far in it goes (as had been the case when I removed the fan sheave), about 8/64" of the spacer extends past the motor plate. It turns freely on the shaft (even before I used a bit of WD-40), and I can pull it out so that I see about 12/64" of the spacer, but no further, upon which it catches.

Is it possible/normal for the spacer to be caught/hooked onto something inside the motor casing, other than some shaft irregularity? Does "something" = "bushing"?

Any recommendations?

I am worried about trying to force the spacer open by forcing something into the slit, in case the spacer is indeed caught on "something." Is it worth opening up the motor? Is that unwise?


I am also a little worried about NOT replacing the spacer as I think there is some wear on it - namely when I turn the spacer, there seems to be a wave to the outside edge that faces the sheave.


B) While I am asking about motors... On the shaft/sheave side of the motor case, there are two screw holes about 24/32" away from the shaft (the holes and shaft are co-linear, with the shaft in the center). However, only one hole is being used ( a nut is screwed from the outside of the case onto a protruding small bolt, which was presumably screwed on from the inside ); the other hole is unused.

Is the use of only one hole normal?

Thanks again!
Peter

P.S. the motor is an 1 1/8 hp Emerson.

[wa2crk]

The holes that you refer to hold some "L" shaped retainers for the bearing to prevent the bearing from falling out when reassembling the motor. There should be 2 but one should be OK as long as the motor is not opened up.
At this point I would leave the spacer alone. When you put the sheaves back on make sure that the fan sheave clears the motor housing by at least 1/16 inch all the way around it's circumference. The fingers on the fan sheave and the floating sheave should interlace when the assembly is correct. Your mis-alignment may have been caused by the key way problem and the missing set screw. Replace the set screw and make sure that the key is long enough to do the correct job. Someone may have substituted the wrong key. As JPG has said that set screw has to be tightened very firmly. A drop of blue Loctite may be advisable. A new piece of key stock should be used and the groove on the motor shaft should be filed gently to remove any burrs that could impede movement of the floating sheave.
Any more questions come back and there is someone who can give you the info you need
Bill V

[peterag]

Thanks -

You're right in that the old key was too short. In a video of Nick Engler repairing a Mark 500, if I remember and saw correctly, there was a model of the 500 with a shorter key slot on the shaft than in the one I have; I assume the key that had been in my unit was really for the other model.

[JPG]

Thanks -

You're right in that the old key was too short. In a video of Nick Engler repairing a Mark 500, if I remember and saw correctly, there was a model of the 500 with a shorter key slot on the shaft than in the one I have; I assume the key that had been in my unit was really for the other model.

I am not aware of a 'different' key on the motor shaft. Are you possibly thinking of the key on the idler shaft? As long as it does not extend beyond the end(less room for the retaining clip etc.) of the motor shaft it s/b ok.

The sleeve abuts against the inner race of the bearing. It spaces the fan sheave on the shaft(and thus provides clearance for the fan sheave). As for removing it, unless it has somehow gotten mashed, there should not be anything inside to prevent it's removal. That said, if it is 'wavy' perhaps the 'wave' is causing an interference. Can it be rotated on the shaft when it is pulled out?

FWIW, there is a history of the spacer getting embedded into the fan sheave thus reducing the sheave to motor clearance. A new sleeve will not fix that. A 5/8" retaining clip will.

[peterag]

The key size video: I was thinking of 1:05 ++ in https://www.youtube.com/watch?v=1HoUwYug-6k

(So Jacob Anderson, not Nick Engler, as I had remembered.)

In the video the key slot ends somewhat below the end of the shaft - do you agree? I think the key I have would fit in that slot.
The slot on my unit runs to the very end of the shaft. In any case, my old key is about 3 1/2", whereas the replacement is about 4 1/4".

The spacer rotates freely on the shaft, whether pushed inward, or pulled forward as far as it can go.
The slight 'wave' that I am noticing is parallel to the surface of the shaft, and not radial, and I don't believe that it is the outward (fan sheave) side that is catching on the shaft - but of course I might be wrong about that.

Do you agree with Bill V's suggestion that I leave well enough alone and not try very hard to remove the spacer? As I said, I could try opening it by prying it apart along the slit on the spacer...

thanks again - Peter

[wa2crk]

As JPG said the spacer is exactly that, a spacer, to hold the fan sheave the proper distance from the motor housing.If you can set the fan sheave 1/16 inch away from the motor housing and put some Loctite on the set screw threads and crank down good and hard on the set screw it should be OK. I have tapped a small screwdriver into the slot on the spacer to open it up slightly and it came off the motor shaft easier
Bill V

[peterag]

Thanks again!

I gave the spacer a good-bye yank with pliers, and this time it came off. The interior is a bit rough, but the shaft seems fine.

In any case, I will use the new spacer.

Peter