I need a 1-1/4" bore in a sprocket that seems to be hardened steel. I contacted the supplier and they didn't know what it was, and their supplier couldn't tell them either. It is a 28 tooth sprocket for #25 chain, do you guys have any suggestions on how to cut the center out or where to get one the right size without breaking the bank?
Thanks, Steve
Good possibility its of powdered metallurgy construction.
In this case, it will likely have a sort of hardened outer skin, from black oxide coating, otherwise not too difficult to machine--similar to cast iron.
I will have a sulphurous smell to it, new out of the bag, If I am to have a clue .
What kind of lathe do you have available?
Gunner
Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
Hey Steve,
Gunner very recently posted a site on Ebay for other purposes, but they do have this too, one of which is 1-1/4":
Take care.
Brian Laws> I need a 1-1/4" bore in a sprocket that seems to be hardened steel. I
Have you tried one of the Bearing/Power Transmission houses (Motion Industries / Applied Industrial Tech. etc.)? Martin Sprocket makes a wide variety of sprockets and their bored to size price is only a little more expensive than their rough stock bore price.
I just looked up motion industries, the largest they will cut a bore on a #25 sprocket is 3/4". I don't have direct access to a lathe but i have some friends who are in a machine shop. They said they'd cut it for me but then they decided it was too hard.
In response to the material, it is shiny metal, doesn't have a black oxide coating and doesn't smell like sulfur. We couldn't scratch it with the tip of a pair of pliers. I registered with applied industrial tech but they take a couple days to get back to tell you whether or not they will register you. I'm going to call martin sprocket on Monday, it looks like they will be able to help.
I don't have 80 dollars to spend on a drill bit for a 7 dollar sprocket because I don't have my own machine shop but thanks for the response.
-steve
The sprocket is probably case hardened. It should be possible to bore it with a carbide tool.
The hub on a standard #25 28T sprocket is 1-1/2 diameter, so a 1-1/4 bore isn't going to leave much of the hub. You could get a plate sprocket and attach your own hub, but be careful to check that the increased dia doesn't interfere with the chain.
Ned Simmons
it wont interfere. the sprocket is a plate sprocket, it is going to be mounted on the side of a differential.
It needs to have a 1-1/4" bore and a four hole mount with 3/16" holes
3/4" from the center. -steveHey Steve,
Of course we don't know what the situation is you need this for, but is there any chance of having a reducer bushing made? A round piece with a 1-1/4" blind hole bore to fit your shaft, and a stub turned to the size that the sprocket needs?
Isn't 25 chain pretty small? 1/4" pitch maybe, by 1/8" wide rollers? If so, for a 28 tooth sprocket, the OD would be VERY roughly 2-1/4", and to put a 1-1/4" bore in that would not be real easy as it would be getting pretty flimsy to hold I would think.
Take care.
Brian Laws>
Chuckle..I probably have one in the Stuff out back. If you want to come by..you are welcome to dig.
Gunner
Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
Motion (or Applied for that matter) won't cut the bore - they only buy from Martin or other manufacturers. Be sure they understand that it is an "A" (plate) sprocket as a "B" or hub on one side would have nothing left if you cut a 1 1/4" bore. They usually assume a keyway as well which would remove more of the material so let them know if you don't need a keyway.
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