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!
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.
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.
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.
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.
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!
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.
