Metal work help

[crokett]

My mom got my dad a hand-cranked forge for Christmas that needs work. There is a large wheel with a handle that attaches to a smaller wheel via an axle. The smaller wheel uses a belt to connect to the blower. Problem is the axle is broken. The hub on the small wheel has already been drilled and tapped for a set screw. Getting some steel bar stock is not a problem. Problem is the ID of the small wheel hub is 1/2". ID on the large wheel is 5/8". I have a piece of the old axle that fits the large wheel. Is there a way to get it attached to the new bar? Maybe thread the stub and thread the new stock and add a coupler? Is there a way to sleeve the larger wheel down to fit the 1/2" bar?

[mpc]

Dig out your yellow pages and look up machine shops or welding shops. They should be able to reproduce the part fairly quickly. It probably won't be cheap but it'll be easy, dead-accurate - not a kludge - and probably won't be as expensive as you might think. Shafts can be press-fit into wheels assuming the wheel is reasonably strong - some metals will just fracture when stressed this way. A lot of stuff on your car is press-fit together with no other fastener. Thin sleeves can be used to build up a smaller shaft to make it press-fit into a larger wheel too. Depending on the exact setup of your parts, one option would be to use a shaft slightly larger in diameter than the largest opening... then just the end gets machined down - basically a metal tenon - to provide a solid shoulder for the wheel to ride against.

Any vocational colleges or high-school shop classes around? They're often looking for simple one-day projects to give to students.

mpc

[Stytooner]

Good advice above. The proper way is to have a shaft machined down to fit. It may need to be a 5/8" because of wobble issues. If you think you can get away with 1/2" shafting, it can be bought at Lowe's or Home depot and they also have bins with steel bushings that will bring the 1/2" shaft to 5/8". You would still need to drill for your set screws, but his is the quick and dirty way.
Another option is on a wood lathe with a chuck using 5/8" shafting, also available at the above locations. Get a very good file andyou can turn one end down the 1/16th inch needed. Shafting is generally cold rolded steel from the above locations. It will file down pretty easily with a good file and lathe.

[crokett]

Lee, the wheel with the handle takes a 5/8" shaft. The other wheel and the bracket that holds everything takes a 1/2" shaft. I have the original shaft that starts at 5/8 and steps down to to 1/2". I didn't realize Lowes might have the bushings. I will look for some bushings to reduce the size and also find out what it would cost to get one machined.