POTD was repairing a hand wheel on my “new to me” Bridgeport CNC mill. The previous owner had installed hand wheels with folding cranks, but broke off the one on the X-axis. After running a few routines on the Anilam Crusader II in rapid feed (100 inches per minute), the rapidly spinning (over 8 turns per second!) stock crank got me a little worried! Get anywhere near that thing while spinning and it will definitely leave a mark!
I had the hand wheel and made a replacement handle. The handle is aluminum with an OD of 1 1/8”. Wish I had some 1 1/8” or even 1 ½” aluminum, but only had 1” and 2” on hand. So, went with the 2” and made a lot of chips. Used a contour gauge to get the profile of the existing Y-axle handle and did some rough diameter and length measurements.
The handle has a pressed in bushing with an axle inside of that which freely rotates. The axle is in turn pressed into an axle in a detail pressed into the hand wheel.
Started the handle by drilling/reaming the bushing/axle hole, then flipped it and turned down to 1.125”. Then very carefully used a parting tool to plunge close to diameter at a few measured points on the handle. I think the rule of thumb is don’t exceed about 1 ½ or 2 diameters of material outside of the chuck without a tail stock center. I had 3 ½” sticking out with just 1” in the chuck.
Then turned the profile by eye spot checking with the contour gauge. Lots of flat file and Pippin file work after that, followed by sanding with 220 grit. Parted off the handle and cleaned up the parted end on a bench sander.
Made the handle axle from a ¼” bolt. Turned the head down so it freely fit in the bored handle hole. Then made the press-in bushing from a CRS round. Drilled the center hole for the ¼” bolt axle and turned the OD for a loose flip fit into the handle. Knurled the outside of the bushing for an interference fit into the handle.
Set the bushing over the ¼” bolt/axle and knurled the bolt where it would be pressed into the hand wheel axle, then parted.
The hand wheel axle had remnants of the broken off handle which were Dremel tooled and milled away so the axle could slip out of the bracket. Then pressed out the left-over broken off handle axle.
Used a wooden block with a 1 1/8” hole for a handle holder and pressed the axle/bushing into the handle on my shop press. Slipped a bushing and washers over the axle for pressing so the force was on the bushing and not the axle.
Then hammer-tapped the hand wheel axle/bracket onto the handle handle. Loctited the aluminum bracket into the hand wheel and replaced the stock crank handle on the mill. Lots safer now!
Bruce