Today's project went pear shaped on me, as my Irish friend Mick likes to say.
I started with intent to make (or at least attempt to make) a new elevation screw for Darren's Kondia mill. I first turned the diameters for the gear and the M12 thread, though metric threading would be the last operation because I'll have to change gears. The turning went as well as expected. I then turned the part around 180º in the 3-jaw chuck to start making the 18.62" long 1-1/4-5 Acme thread. I had a good live center in the tailstock end, but my lathe doesn't have a follower rest.
Here's a short video of the 3rd pass:
On the 4th pass, the cutting action didn't sound quite right so I pulled the tool out and stopped. It seems the cutting pressure with a .010" deep (per side) pass was a bit too much and it started slipping in the chuck. Because it was following the previous passes, the tool never left it's path so no damage there. The turned 20mm diameter I was clamped on didn't fare so well. It's scored and I'll probably have to start anew. No big deal, as I have PLENTY of stock.
BTW, it may appear in the video that there's runout of the major diameter. That's just an optical delusion, the fault of a little surface rust on one side of the stock.
I started with intent to make (or at least attempt to make) a new elevation screw for Darren's Kondia mill. I first turned the diameters for the gear and the M12 thread, though metric threading would be the last operation because I'll have to change gears. The turning went as well as expected. I then turned the part around 180º in the 3-jaw chuck to start making the 18.62" long 1-1/4-5 Acme thread. I had a good live center in the tailstock end, but my lathe doesn't have a follower rest.
Here's a short video of the 3rd pass:
On the 4th pass, the cutting action didn't sound quite right so I pulled the tool out and stopped. It seems the cutting pressure with a .010" deep (per side) pass was a bit too much and it started slipping in the chuck. Because it was following the previous passes, the tool never left it's path so no damage there. The turned 20mm diameter I was clamped on didn't fare so well. It's scored and I'll probably have to start anew. No big deal, as I have PLENTY of stock.
BTW, it may appear in the video that there's runout of the major diameter. That's just an optical delusion, the fault of a little surface rust on one side of the stock.