Thread: Pulley bore enlargment

I'm installing a VFD on a WW lathe and using a 3P motor with a 24mm diam shaft.

The current V-rib Al stepped pulley has a 19 mm bore and a keyway and a slightly tapered outer hub - see below

If I drill out the bore from 19 to 24 then add a keyway there will be very little left of the pulley hub for the motor shaft to hang onto so I was thinking of turning a steel collar to go over the top of the tapered hub.

Like this.
I have exaggerated the taper of the hub.

Pulley.jpg
The current pulley hub has a grub screw through the hub onto the key way, accessed thru a hole in the outer step.
I was thinking of doing the same but having the grub screw run through the collar as well.
Maybe adding another grub screw on the other side.
I will need to completely remove the smallest step to allow me to run a keyway broach all the way through the bore.

Can anyone see any issues with this?

Hi Bob,
If you have enough clearance on the length of the pulley when in the installed position you could make up a round disc out of say 3mm plate the diameter of the large end of the pulley and weld that to your steel collar and either weld it or bolt it to the outside diameter flange on the pulley. Hope this makes sense.
Bob

Originally Posted by krisfarm

Hi Bob,
If you have enough clearance on the length of the pulley when in the installed position you could make up a round disc out of say 3mm plate the diameter of the large end of the pulley and weld that to your steel collar and either weld it or bolt it to the outside diameter flange on the pulley. Hope this makes sense.
Bob

Do you mean like this?
PPplan1.jpg


As you can see there is plenty of clearance.
IMG_6727.jpg

The rim is wide enough so I can probably use M6 CS screws?
IMG_6728.jpg

Would you be able to bore the taper in your steel collar then shrink it onto the hub and then bore your hub?

What about turning down the motor shaft to 19mm? Keep the pulley as is.

Originally Posted by RayG

What about turning down the motor shaft to 19mm? Keep the pulley as is.

I've thought of this but my ability and gear access to cut a keyway in the shaft is not as good as cutting it in the bore the pulley.

Originally Posted by BobL

I've thought of this but my ability and gear access to cut a keyway in the shaft is not as good as cutting it in the bore the pulley.

Looks like the previous setup didn't use the keyway anyway, it looks like it previously was just a grub screw through into the keyway, all you would need is a flat for the grub screw if you wanted.

Maybe someone over in WA could cut the outside keyway for you, it's a 5 minute job on a mill.

Originally Posted by RayG

Looks like the previous setup didn't use the keyway anyway, it looks like it previously was just a grub screw through into the keyway, all you would need is a flat for the grub screw if you wanted.

Maybe someone over in WA could cut the outside keyway for you, it's a 5 minute job on a mill.

I could take it into the former workplace and do it there. It's a question of whether that plus time to breakdown the motor is worth the time trouble,

Hi Bob,
Yes like you have drawn it, now that I can see the hub you could turn the outside diameter of the hub parrallel and make your bush a light press fit with the large diameter disc added on for extra security. You would not need very big bolts say 4 or 5mm to hold it in place.
Bob

Originally Posted by BobL

I could take it into the former workplace and do it there. It's a question of whether that plus time to breakdown the motor is worth the time trouble,

Must be getting close to time to buy a mill?

With all the other projects you do, I think you'd get a lot of value from a small to medium mill.

Ray

Originally Posted by RayG

Must be getting close to time to buy a mill?

With all the other projects you do, I think you'd get a lot of value from a small to medium mill.

Ray

I agree, should have go one years ago. Its my number one look out. But it has to be a very very small one )

Originally Posted by RayG

Looks like the previous setup didn't use the keyway anyway, it looks like it previously was just a grub screw through into the keyway, all you would need is a flat for the grub screw if you wanted.

I bored it out to 24mm and it's a nice tight fit so we decide to try it with just the 8mm grub screw into the keyway and it works a treat.

The original flange mounted motor has been replaced with a foot mount as follows.
IMG_7054.jpg
IMG_7056.jpg
IMG_7057.jpg