View Full Version : Cutting belt pulley

10-10-2008, 11:45 PM
I need to cut a pulley for a 3/8 inch belt, I guess I need to find a cutter, any suggestions on where I can find one.



doctor demo
10-11-2008, 12:13 AM
I need to cut a pulley for a 3/8 inch belt, I guess I need to find a cutter, any suggestions on where I can find one.


Steve , Hog out the bulk of the material with any tool You have. Then set the compound at the proper angle to cut one side of the pulley and use a parting tool ground with a radiused nose to finish. Turn compound for other side and repeat. Not the fastest way to do things but I have done it that way and it worked for me.


10-11-2008, 12:35 AM
If its a V belt there is a specific angle for the groove based on the diameter of the pulley. It should be in your copy of Machinery's Handbook.

Otherwise just make a cutter and set the compound and cut it.

10-11-2008, 04:15 PM
I've just used the compound; unless your machine is quite rigid a form tool for a 3/8" v-belt can chatter. The critical dimension is the angle; the groove should be deeper than the belt will drop into since the belt grabs on the side, not on the bottom.

10-11-2008, 06:11 PM
Its needs to be a toothed pulley, timing belt type for fuel pump drives.

Thanks again.


10-12-2008, 01:06 AM
grind a cutter to the profile of the tooth you need to cut (well, the groove between the teeth).
put cutter in shaper and have at it. :)

andy b.

10-12-2008, 02:09 AM
Find the pitch form and order one from someone like http://www.sdp-si.com A whole lot cheaper than even the endmill.

Forrest Addy
10-12-2008, 03:30 AM
Its needs to be a toothed pulley, timing belt type for fuel pump drives.


These little details. V-belt or Gilmer style pulley? There's a only a difference in spelling between circumcision and castration but the results are far different.

Buy a toothed pulley from MSC or someplace and forget about making one. Save you all that indexing sweat and they[re only $30 to $45 depending on size and material.

Mike Burdick
10-12-2008, 11:56 AM

I know you didn't ask, but this is how I make geared pulleys on a lathe... it's really not that difficult. I've made them from materials such as steel, brass, or aluminum using the following method...

I grind a HSS lathe tool bit to the required shape - this is not complicated and can be accomplished fairly easily with an ordinary bench grinder. One can find the proper dimensions via the internet from companies that manufacture them.

First determine the the number of "notches" needed and then determine the proper diameter for the pulley required. Machine this on the lathe and be as accurate as possible - measure using a micrometer as this will effect the spacing and is critical since any error makes it difficult to keep the belt on, especially at higher speeds. Do not remove this blank from the lathe!

Now, how to cut the "slots"....

For this I made a table that fits on the outboard side of the lathe. It is made such that I can attach a dividing head directly to the end of the spindle. Be sure and take the lathe out of gear and/or remove the electrical cord while this is attached!

Place the shaped bit into the tool holder on the lathe and set the bit's midpoint exactly on center line of the spindle. Now, using the carriage like a shaper, cut the slot to required depth, index, and continue until all the slots are cut!

Finish with keyway, set screw, etc.

You're done!

I know sometimes people recommend that it is much less aggravating to buy something already made, and to some extent, that is very true. But...why did we spend all this money on equipment if we are going to buy what we need? Now if one is doing this on a commercial basis, then of course, that's a very different scenario...

I now have a collection of bits for geared belts and I can usually make the exact pulley I need in less time than I can order one - especially the smaller ones! So far, they have stood up for my applications very well.

One other thing to note...

Making a "table" to attach a dividing head on the out board side of the lathe comes in handy for many different operations and is one simple "tool" that everyone should have!



10-12-2008, 01:35 PM
I have looked at purchasing some pulley stock, that is what I did last time I needed some, but I am hoping to save some cash by cutting my own, I have been making fuel pump drives using a 16/32 combination. I do go through a fair amount of the stuff.

I want to set it up in the mill and use my dividing head, I did a test cut yesterday on a peice of aluminum, it worked out pretty good. Only problem again is to get a cutter with the right profile.

I tried grinding a single bit and putting in a boring attachment, but it was too violent. So I finished the test with a saw blade, it turned out good.

I dont have much luck grinding tools.


Mike Burdick
10-12-2008, 03:12 PM

Okay, I see what you need from your website.

Since you are doing this commercially I will assume that you have a fairly heavy lathe...

I'd make a slotting attachment that can be put on your lathe's carriage instead of the compound or find a turret attachment that fits your lathe. I bet if you cut them like my previous post suggested you could cut them in very little time - perhaps two strokes per slot - one for the majority of the material and one for final dimension... then index. The dividing head on the outboard side should be made to back off the spindle very quickly for the next one to be turned.

This way you can have the mill setup for all the vertical milling and the lathe setup for all the turning and slotting.

Okay... only you know best what you need so I'll not comment any further. I was assuming you were doing this with conventional hand operated equipment and not CNC.

10-12-2008, 05:31 PM
Its all by hand, all if have is 9x42 knock off and a 10x24 logan lathe (825 I think).

So the lathe really isnt big enough for anything to big.

I do have a turret attachment for the lathe though.

Thanks for your input.