Half Moon Key Hole Question

RC

I've welded a gearbox shaft and re-milled a keyway on a flail mower similar to F14's suggestion. The keyway in the shaft was badly worn and part of the shaft was broken away.

I welded the shaft oversize, turned it on the lathe, and then milled the keyway on a Bridgeport mill. It's been in use for about 4 years.

Alternately, if the hub doesn't need to come off, clean the parts of any scaly rust and grease, then use JB-Weld. It is an epoxy that is highly filled with metalic powder and has a very high stiffness. If you ever need to remove the hub from the shaft, use a torch and burn/soften the JB-Weld.

I've done this a few times to cheat on having to make a proper fix. Just don't use J-B Weld on an item that has to come off occasionally for maintenance repairs/adjustments.

I'm getting ready to JB-Weld a sprocket onto a shaft on a hay crimper. I just bought the crimper, and I have it running. As soon as I've discovered and made fixes to the rest of it, and I'm reasonably certain that it won't have to come apart very soon, JB-Weld is going on. The woodruff key is badly wallowed out like yours and the bore in the sprocket is badly worn. I'll clean up all the surfaces, puddy on the JB-Weld in the sprocket's bore and shaft OD. Then I'll re-install the sprocket and and make sure the run-out and alignment are OK then clamp in place while the epoxy cures. Sometimes, I'll use a little heat to speed up the cure, but have to be careful because the epoxy gets very runny and can drain out of the joint.

If you're working on a purist restoration don't go this route. If you're interested in regaining function, then this is a practical way to go.

Ken McWilliams
Dayton, OH

1 - Shim the part of the key where it fits inside the U-joint keyway. I like 0.020" brass stock - can cut to size with sheet metal shears. Cut and stack shims as required on one side of the key until the key is a tight fit in the keyway. I then like to solder the brass to the key to keep the shims in place while reassembling.

2 - If the key on a steering shaft and you have suitable drilling equipment, bore a 3/8" hole radially thru the U-joint housing collar and the shaft, 90 deg away from the keyway. Then drive a 3/8" roll pin thru the assembled parts. It'll lock the parts together nicely. Good idea to run a safety wire thru the roll pin, or apply a hose clamp to the U-joint collar over the roll pin so the pin cannot work itself out.

Mikey