Help! Where to find a replacement pulley for my drill press

[Roger Feeley]

I replaced my drill press motor with a new motor and VFD. But the new shaft had a keyway instead of a flat. So, thinking that I was a good little soldier, I took the step pulley from the motor to a local machine shop to have a keyway cut into it. The first time they pressed the broach, the pulley cracked.

So now I'm on the hunt for a new motor pulley.

There are two complications:

1. I don't need a step pulley but I do need a boss that offsets the pulley about 1.5" above the shaft which is what the old pulley did. At least I think I need the offset.
2. The existing belts on my drill press say m-19 and m-21. I don't know what the replacement for m-profile belts is. They are 35 years old but appear to be in decent shape. They are about 3/8" wide at the widest and about 1/4" thick.

The first thing I need to know is the answer to #2 above. Then I can go off and hunt for that belt profile on the all knowing internet. I sort of looked on McMaster Carr and MSC but I didn't exactly know what I was looking for.

The shaft is 5/8" with a 3/16" key.

[Roger Feeley]

I've been researching this on my own.
http://www.lkh.com.sg/products_conventional_vbelts.html
This page tells me that all the angles on belts are the same at forty degrees. It appears that to get a good fit, I need to compare the bottom width on my belt to another belt and also insure that the top width will fit in the new pulley.

I'm thinking that I can use an 'A' profile pulley with a 'm' belt and get away with it.

Is there any harm in trying?

[Wayne Lomman]

Yes the angles are the same but you have to make sure that the belt does not touch the bottom of the pulley. If it does, you won't get correct power transmission. But before you buy on the net, go in person to a bearing supplier - they carry this sort of stuff - put the pulley on the counter and ask for one the same. You are stepping into an area where the net does not in any way give you a good idea of what is available. Face to face is the only way. By the way, if one of my guys cracked your pulley, there would be an apology and a replacement in front of you, no questions. Cheers

[Roger Feeley]

Yes the angles are the same but you have to make sure that the belt does not touch the bottom of the pulley. If it does, you won't get correct power transmission. But before you buy on the net, go in person to a bearing supplier - they carry this sort of stuff - put the pulley on the counter and ask for one the same. You are stepping into an area where the net does not in any way give you a good idea of what is available. Face to face is the only way. By the way, if one of my guys cracked your pulley, there would be an apology and a replacement in front of you, no questions. Cheers

That bit about the belt not touching is a great piece of information.

The guy was sick about it but I declined a replacement. The pulley is 35 years old and probably not replaceable.

The quill pulley is one I'm definately not going to touch. That is an 'M' profile and I don't know if those even exist anymore. It looked to me like an 'A' belt is about the same. I'm going to have a closer look now that I know a bit more. It kind of depends on how deep the pulley is. I'm guessing that having the belt stick out of the pulley is a bad thing.

[Larry Edgerton]

I use Brownings, have solved vibration problems with their sheives. What about replacing both new. No belt worries that way. Grainger has about every Browning I have ever asked for.

[Rollie Kelly]

When I replaced the old M belt on my old Enco drill press, I got a 3/8" belt at Motion Industries. It is the motor (2 hp) to idler belt and the driving pulley is only 2.2" in dia. So far no slippage, YMMV

[Jerry Bruette]

Near as I can figure an A section belt would fit your pulley, but why not do as Larry said.

I'd replace the pulleys, you have to buy one anyway, and use QD bushings to mount them. Easier to align or realign and no boogering your shaft with set screws.

You could measure the O.D. of your present pulleys with a tape measure and you'd be close enough for replacements.

A section belts would work just fine and if you have small diameter pulleys you could get what is referred to as notched belts, would be designated AX, and they would give you a better wrap on the pulley.

[Roger Feeley]

I took a field trip to Graingers (turns out there's one nearby) and took the pulley and belt. The guy took me in back and we tried some belts. 'A' was too big. It was between 2L and 3L. I opted for the slightly larger 3L based on Waynes advice about the belt not bottoming out (thanks Wayne!).

I got a 3L pulley and hit the belt size on the first try. Now my question is about whether I should keep this pulley or get a bigger one. I'm matching the size on the quill pulley and the one I got is up a bit high which puts the pulley out at the end of the shaft. If I match a different pulley on the quill, I can be about an inch lower on the shaft and closer to the motor. My gut tells me that it's better to put the force closer to the motor. So it's back to Graingers to do an exchange tomorrow.

[Dan Friedrichs]

There are bearings on both ends of the motor shaft, and the load you're putting on with the belt tension is virtually nothing. Don't worry about it - use the one you have. An extra inch of lever won't hurt anything.

[Roger Feeley]

There are bearings on both ends of the motor shaft, and the load you're putting on with the belt tension is virtually nothing. Don't worry about it - use the one you have. An extra inch of lever won't hurt anything.


Thanks Dan,
Based on your post, I cancelled the order for the other pulley and belt and will go with what I have. still need to put loctite on the set screw but other than that, I'm good to go.

I haven't really played with this VFD motor to see what the torque is like at low speeds because I haven't unpacked my circle cutter yet. Honestly, I don't know where it is but it will turn up. FYI: I moved into a new house/shop after having my stuff in storage for a year. I'm still reacquainting myself with my 'old friends'.

[Don Jarvie]

Surplus center.com has belts to the inch so check them out. Much more reasonable than Grainger.