7x16 Mini Lathe [page 9]

I first turned down some O-1 tool steel to 4 mm with a 6 mm boss to make the retracting pin portion of the tap follower. This will fit in the body with the spring pushing against the boss. My target is for about 25 mm of pin travel. I put a 60° taper (approx) on the end of the pin. That is 1/3rd of the device.

The second 1/3rd is the shaft that will be used to hold the follower in either a collet or a chuck. I turned some 11/32" tool steel down to 8 mm and used a die to make the needed 8 mm x 1.25 threads. This shaft will screw into the body and capture the spring against the moveable pin. That’s the plan, anyway.

Before calling it a day I heat treated the pin to harden it and then brought it up to about 400° F for the desired temper. Don’t know if hardening this part is strictly necessary, but I don’t think it will hurt.

Tomorrow, time permitting, I’ll make the body.

I put some 1/2" 12L14 in the lathe and drilled a 4 mm hole a little more than 50 mm deep. The picture shows me checking that the pin fit the hole. I pulled the stock out enough to cut off the 50+ mm piece that I wanted. The cut off piece was flipped and mounted to drill a 6 mm hole about 44 mm deep. A check fit of the wide end of the pin was a no-go. Too tight. I changed to a 6.5 mm drill bit. Much better. Finally I drilled and tapped the end for about 8 mm worth of M8 x 1.25 threads.