Craftsman/Atlas 618 [page 17]
Thursday, Mar 16 2017
I need to cut an 8° taper. tan(8) equals 0.1406… When the compound slide is set correctly one inch of travel in the Z (parallel to the spindle) direction should result in 0.1406… movement in the X (perpendicular to the spindle) direction. And no, I don’t know why lathes are referenced as X and Z.
Friday, Mar 17 2017
I don’t have any metric drills. The spec calls for a 10.5mm hole. I drilled the piece to 3/8" then bored it out to the desired value. I’m ready to cut the taper. But first….
I though I’d check the compound 8° set up by comparing how it tracks an actual collet. I removed the 4 jaw chuck and put a 5/16" collet on the 5/16" shank of a reamer after checking it was straight on my surface plate. Since the 4 jaw chuck was in use I played around with the three jaw chuck trying to get the shank to run more or less true. I used a dial indicator to check the collet as I moved the compound slide. The collet did not match the 8° I’d configured yesterday.
OK, lets change the compound angle to match the collet. After some play I got it this close.
The X direction moves 0.146" in one inch of carriage travel or about 8.3° I’m not sure what’s going on. I’m going to bore the taper using this setting. I can make it less shallow if it turns out this is wrong. Plus, this is a test piece. I can always start over on a new hunk of steel.
Saturday, Mar 18 2017
I started cutting the taper using the setup from above. This was one of the tests I made with about 2/3 of the taper done. I’m getting good contact all around. The missing spots are mostly from taking pretty rough cuts – if you can call 0.005" cuts rough. That’s about the limit for this lathe when cutting steel. I was cranking on the compound slide pretty quick, though.
It’s hard to see in the image but at this point I’m finished and I have pretty even contact over the entire body of the collet. I put a piece of left over 8mm rod in an 8mm collet and tried to get it to move. It’s clamped good and tight. I’m going to call it done.
Now I’ve almost got something to hold small round stock in the mill and practice for making a collet chuck for the lathe. The reason for the almost in that last statement is I need to get another clamping nut. I borrowed the nut from the mill to test threads and operation.
That tube of prussian blue has got to be over 15 years old. A little goes a long way.