Need a sprocket to fit a tapered shaft

I would think I could find what I want it I knew how to phrase what I was looking for...
I am needing to repair a drive sprocket on a home-made feed cart. It was originally a flat chain drive sprocket that was on a keyed shaft that tapered from 3/4 up to 7/8. It drove a sprocket on a shaft that was tapered from 1/2 to 3/4. My grandpa had made it with parts from a deere 12a combine. The sprockets were cast and broke. I would like to convert it to roller chain while I am rebuilding it, but I can't find any sort of hub to fit a tapered shaft. Anyone know where to look? I realize I could have one machined if it came down to it, but was hoping for a ready made part. If anyone has any ideas I would appreciate it. Thanks!

i doubt you will find the correct taper off the shelf. I would buy a sprocket the size you want with a bore the size of the small end of the taper. Then have a machinist bore the taper to the desired size. Use the old sprocket to get the dimension for the machinist.

Adam. Our local welding shop carries a large selection of products like that. You might check with one close to you

DrAllis wrote: Use your tapered hub. Grind/machine off all of the old sprocket. Weld on a new bare sprocket onto the existing tapered hub.

I would go with the machine shop route, they will need the old hub to set up the correct angle I think.    Thirty min setup and five to cut the taper .

I'll check on an old allcrop we have laying around. The old sprocket broke into half a dozen pieces when it went so using it as a center would be hard to do. Trying to make the shafts a straight shaft would be difficult too. Grandpa had used parts of 2 12a john deere combines and their bins to make a feed cart decades ago, and though I don't need it, i don't want to part with it either so would like to make it usable. Thanks for the suggestions. I hadn't thought about a taper not being standard. That's probably part of why I can't find one... Thanks again!

As the DR said:

Put the tapered hub/sprocket in lathe... cut off the sprocket.  Turn a concentric land, and fit a roller-chain sprocket in it's place.  You could probably face the old sprocket, and drill it to make the new sprocket BOLT on, which would save work and prevent distorting the new sprocket, and in the case that the hub is not-so-weldable, you're not welding it...

If you have the shaft, then collet the shaft into the lathe, and put the sprocket hub back on the taper, so it all runs true in-situ.

I'm thinking the old sprocket and hub may have been cast iron. Anyway, Adam said it broke into half a dozen pieces, so I think he meant the hub with the taper is broken up and therefore not re-useable.