Power Cross Feed Repair/ Miter Gear Replacement

Are you saying that the keyway in the gear is 1/8" wide and 1/8" deep? If that is the case and if the keyway in the lead screw is 1/8" wide by 1/16" deep, then the mating key will need to be 1/8" x 3/16".
 
I think he means the other way around.
He dropped a 1/8 x 1/8 keyway into the Lead Screw Slot and it went to the bottom with nothing showing.
 
yendor said:
I think he means the other way around.
He dropped a 1/8 x 1/8 keyway into the Lead Screw Slot and it went to the bottom with nothing showing.
Click to expand...

This is what I meant, but I made a stupid mistake. I was looking at the leadscrew for the Logan lathe I'm restoring which was on the bench next to the Craftsman one. The depth on the keyway on the Craftsman leadscrew is 0.07, so making the keyway in the gear 1/16" deep will work nicely with the 1/8" square key moving just above the bottom. All is well.

I got the first part of the machining finished today for the replacement gear. The steel part of the shaft on the old gear measures 0.997, so I made a counterbore of 0.995 on the new gear. Holding it backwards was achieved by making a ring with a internal bore that was a slip fit with the OD of the Boston gear and then splitting it. Then I could indicate the ID of the gear to get it on center.

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I finished the back side of the gear to length by turning a quick mandrel to the 5/8 ID of the bore and tapping a 1/4-20 hole for a cap screw to secure it.
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Next step is to turn the new part that will become the shaft. I plan to do the inside bore once the two have been fit together. Then broach a keyway and get it soldered in.
 
Looks like you are making good progress.
 
It's getting closer. I turned the shaft portion so that it was a press-fit with the counterbore created in the gear. I kept going back and forth on if I should press it or silver solder and ultimately decided to press it.
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Once the two were pressed together, the center bore could be enlarged to accommodate the 3/4" leadscrew. I went .005 over so that it would slide over. The final machining op was to cut the keyway with a series of cuts from a boring bar.

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Here's where it stands now. The key is a good fit in the slot and the whole thing fits over the leadscrew nicely. I only wish I had been able to center the cut on one of the teeth...
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Hopefully tomorrow I can solder the key in place and try it out!
 
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