I Decipher the Lathe Chart

Time for the world’s worst machinist to pose a stupid question.

I have been complaining that my lathe doesn’t tell me how fast the power feed moves. It has a threading chart, and I assumed the little measurements on the chart, below the thread pitch numbers, indicated the distance the carriage moved per revolution when threading. However, I didn’t bother to see whether the measurements made sense. Yesterday I realized they did not. For example, at 4 threads per inch, the measurement is 0.0367″, which is not even close to the 0.25″ each thread would require.

Are these numbers power feed speeds? They have to be. The manual doesn’t say, but it’s the only thing that makes sense.

I got amazing news from my rigger today. He says the mill should arrive at his place by 1:00 p.m. This is like waiting for the Second Coming. There have been so many false labors, I find it hard to believe that it will ever get here.

I wish I had some metal on hand for a project. I have lots of round stock, plus a little thin rectangular bar, but my only meaningful piece of milling fodder is my 72-pound chunk of mild steel, which is the size of a loaf of Wonder Bread. I had the chance to get a Jet band saw at a great price, but I failed utterly, so I have no practical way of making smaller pieces from the loaf. I can use the mill, but that would take a century and waste a lot of metal. I guess I could part it in the lathe! That would be pretty terrifying.

I was kidding just now, but I suppose it’s possible. Mount it in the 4-jaw chuck, center-drill it, stick it on my poor beat-up dead center, and pray. I’d have to back the tailstock off every time I got close to the center of the work, because you’re not supposed to part using a center. I’d also have to drill over and over, because each slice would take a drill hole with it, and then I’d have slices with drill holes in them, so I’d have to face the material down to the point where the holes disappeared, wasting metal.

I wonder how slowly I’d have to run the lathe. Like 20 RPM, unless I wanted to dodge a 72-pound missile as it came off the chuck.

No, this is not a great idea. I may as well get a band saw or find someone to cut this thing. If I pay someone, I have to decide in advance exactly how big the pieces will be.

I parted my pathetic hammer handle project with one end in a chuck and one end on a dead center, but I pulled the dead center out before I got close to the end. I hope that’s not insanely dangerous. It seemed to make sense. The center kept things working through most of the cut, and at the end, it wasn’t necessary.

The VFD is pretty great. Combine it with the back gear, and you could probably turn slowly enough to roast a pig. Helpful when parting.

VFD…pig roasting…help! I’m having an awful idea! I have a crappy 3-phase motor I’ll never be able to sell. How cheap can I get a VFD for it? I’d be the bull goose pig roaster of all time.

Thank God, the VFD is too expensive. It’s $144. There is no way I would do that. Tempting idea, though. Low frequencies for slow cooking; crank it up to throw excess grease off the pig. I guess the motor would burn up at 1 RPM.

I never followed up with my pig roaster idea. A long time ago I planned to weld one up, out of fence posts. But the motor I ordered never arrived. They discontinued it or something. I should check Grainger. Fence posts cost virtually nothing, and I already have a couple. The motor is the only real expense.