Looking for a keyed sprocket

So, I’m looking for a specific part, but I haven’t had any luck finding it. What I need is a #35, 10 tooth sprocket, with a 3/8" bore and a keyway. I don’t have a broach to cut a keyway in the sprocket, so I would like to find one with a keyway pre-cut. That being said, I’ve checked everywhere (Mc-Master, SDP-SI, MSC, Grainger, Small Parts, Motion, and a few others), and I haven’t been able to find one.

If you know where to find one, please let me know. Alternatively, if you know of a good way to cut a keyway in a steel sprocket with basic shop resources (manual mill & lathe, a small arbor press - basic HS metal shop tools) or something I could buy relatively inexpensively, that works, too. Thanks!

Sounds like a familiar problem, I was going to try using the mill to cut a short, rounded top keyway in the thick part of the sprocket.

A file should also do the job, tedious but effective.

honestly i think the best bet is to buy the sprocket and buy a broach set because it comes in handy…if that is not an option theres no reason you couldnt mill it, it would just have a round in it, but hey, who cares

Robot MarketPlace has #35, 10 tooth, 3/8" bore sprockets…no keyway, but it does come with a set screw. Alternatively, you could get a sprocket with a 1/2" bore and keyway from the Robot MarketPlace and then use a nylon shaft diameter adapter with a 3/8" ID and 1/2" OD from Lowes (found in the section with all the drawers of nuts and bolts)


Martin Sprocket has been good to my team in the past. They have the right sized sprocket, but with no keyway. It says on their website that the do custom as well. (www.martinsprocket.com) You may want to check that out too.

It’s amazing the effort we will go to, to avoid spending 10 minutes with a file…


well my first thought was “hack saw?”…

Well you can cut in a key with the manual mill to fit a normal square key. All you have to do is cut in enough so that the centerpoint of the end mill is as deep as the deep part of the key will go. Then put a set screw in to push down on it.

If you want to have a picture just let me know.

A broach in that size is not very expensive at all. You said you have an arbor press. Problem solved?

Will a broach work with a small table-sized arbor press? My only experience with broaches has been on a pretty large hydraulic press, so I just want to make sure that is sufficient before I buy a broach…

Yes, I keyed some #35 3/8" bore 11 tooth drive sprockets the other day with a table top arbor press, worked flawlessly. We had a bit of a tough time finding a 3/8 broach though.

I just looked around, there seem to be a bunch of old Dumont small Minute Man sets for sale on ebay, or you can buy a new set of small broaches for under $200, or a single 1/8" broach and 3/8" bushing for about $50 from Mcmaster Carr. I didn’t look for “economy” new broaches, there might be something for less from some of the discount places.

Looks like the mill or a small file for us :slight_smile:

The small arbor press (No. 00, which is 1/2 ton I think) is on the edge of acceptable, not because of force generation, but the space to put the broach in the press. You want to make sure anything you buy will fit.

Jeff - you have a PM as well


Only $2, yes seriously.

JFK HS, Denver, CO

I’m not sure how much I’d trust a $2 sprocket…

On a side note, I found that the school auto shop has a hydraulic press. So, I’m going to buy a broach when I order my sprockets tonight. Problem solved! Thanks to everyone who offered suggestions!

These steel sprockets are made by Grizzly with hardened teeth. I’ve used them with good success. They are only $2 because they are a surplused item.

I’m sure having a broach set will come in handy though.

JFK HS, Denver, CO

To accomplish without a broach insert a steel shaft in the hole - center punch and then drill a 1/8" hole - insert a steel pin and voila’ keyed shaft that holds as well as square - we have used this technique successfully. I pulled it off of a machinist forum a few years back.