Slightly embarrassed - never installed a pulley before. Questions...

[67carl]

So I've never installed a pulley on an electric motor. Should be straightforward, but with me, never is. The shaft has the groove and key, pulley has 2 set screw holes.

1. Do I take the key out, slide the pulley on then insert the key?
2. The shaft, other than the key groove, is smooth and round. Will the set screws have enough... purchase... on the shaft to keep it from moving, or do I need to mark where they contact and flatten the spot. Or something?

 

[Old Man Roger]

I usually install the key then the pulley. Usually the set screws will make a little indent on the key that will hold it in place.

 

[B_Bimmer]

No reason to be embarrassed about trying new things, the greatest failure is to never try. It doesn't matter key in first or last, whatever works, but usually first is the easiest. With a snug fit a setscrew is more than enough to hold the pulley in place forever. I usually snug them up and then give the end of the hex key a light bump with a dead blow to lock them in place.

 

[WisJim]

Usually (in my experience) one of the set screws hits the key and can be tightened a lot as it will only mark the key. The other setscrew will help hold the pulley in position but the key is what keeps it from turning on the shaft.

 

[JradM]

Key, then pulley. don't flatten anything.

The set screw only keeps the pulley from pulling off. It's the key that makes the pulley turn with the shaft. A little locktite on the set screw might be useful.

If you did make an indent on the key where the set screw makes contact - that's not going to hurt anything. If it makes you feel more confident, I'd say go for it. Maybe put the pully on, line it up, insert a drill bit through the set screw hole and twist to make a mark. Then take the pulley and key off and drill a little dimple there.

They aren't moving parts (relative to each other), so you could even drill the dimple while the pulley is mounted - though that's obviously a little riskier for those tiny set screw threads.

 

[no704]

Some like to put a second set screw in after the one doing the work to act as a lock.

 

[Leaflessshadetree]

Sometimes it's easier to instally the key sticking off the end of the shaft to get the pulley started. Then tapping the pulley and key on at the same time. The tip of the set screws should bite into the shaft (or key).

 

[lilredex]

From your picture, it looks like the set screw on the left will contact the shaft. It should have a small flat spot on the shaft, there. I like to file a flat spot anywhere a set screw touches a shaft. Any deformation caused by the set screw is on the flat and below the shaft's surface, making it so much easier to slide the pulley off in the future.

Put the key in first.

 

[unslow1]

I'm sure there are plenty of videos on Youtube if you still aren't confident after these replies. Better to ask or watch a video than risk screwing something up. Sometimes I watch videos on something I haven't done in a while just so I don't forget a step.

 

[67carl]

Thanks everyone, appreciate the replies. I need to order the pulley, then will work on the installation. It's going on y bandsaw and I'll need to modify the motor mount a bit as well.

 

[larry_g]

From your picture, it looks like the set screw on the left will contact the shaft. It should have a small flat spot on the shaft, there. I like to file a flat spot anywhere a set screw touches a shaft. Any deformation caused by the set screw is on the flat and below the shaft's surface, making it so much easier to slide the pulley off in the future.

Put the key in first.

X2 on this. A small flat on the shaft will make future life better. Assemble first and align things. Then use the second setscrew to mark the shaft, remove pulley, file a flat and reassemble.

lg
no neat sig line

 

[matt_i]

If you are designing using the step-pulley you need 2 identical ones for the drive to work correctly. Otherwise you will get different pitch "ovals" and need a *lot* of travel in the takeup.

Its a balance between getting enough torque to hold the pulley stationary thru natural vibrations but not so much that you strip out the tapped hole in the diecasting. Great place for a drop of loctite.

If you ever make your own keyed shaft I strongly recommend cutting a closed-end slot with an endmill. The key can be made to fit with a belt sander or file depending on size. Seems like I've been to 50 breakdowns in my life where a key fell out of the open ended slot and the shaft is spinning with no positive drive.

A very bad practice imo is to use abrasive paper to undersize the shaft or file the key and get an easier installation.

 

[Jarhead0408]

“Key, then pulley.”

(Makes a mental note.)

You weren’t the only one who didn’t know. Now I know something too. Thanks for asking it!