If making guns were that complicated for me I would have quit before I started.
And this comes from a man that works with buckets of molten metal.
...after the spindle is aligned and corrected, what steps are you going to try to improve the run out of the chuck?...
Jonathan, i find it simpler to diagnose the issue in two steps: First check the back plate after removing the chuck. It must be dead center and machined perfectly perpendicular to the spindle. The holes for the chuck mounting bolts (bolt pattern) must be centered to the spindle center line. If the plate is warped or off center then if not fixable it must be replaced. An off kilter bolt pattern can be fixed if not too far off by offsetting each hole a tad. Make 'em egg shaped in other words to allow some "wiggle room" to bring the chuck into better alignment. That was the case here. The bolt pattern of the back plate was off just enough to cause the chuck to sit off center to spindle center line. By reworking the bolt pattern the run out was reduced to an acceptable level. The second step, if the back plate is determined a-ok, involves thorough inspection of the chuck. This is best accomplished using a CMM. Luckily we didn't have to do that.
And now (drum roll please) I'm happy to announce a lathe is born. Date and time of birth: March 30, 2023, 2:05 PM. Birth weight: 750 pounds. Give or take a few pounds. Length: 62 inches. Place of birth: United States of America.
Got the spindle set true and the chuck adjusted to give +/- 0.0015” run out. Bearing tolerance and chuck precision stack up to 0.001”. Looks like that’s as good as it will get without installing high precision bearings and chuck.
Eager to try it out, a short length of schedule 80 black iron pipe was clamped in the chuck, tooling adjusted and the drive powered up. The machine ran incredibly smooth up to 2000 RPM. Harmonic vibration set in above that indicating an unbalanced spindle. We’ll have to work on that later.
Made several light passes along the pipe to get a feel for the rigidity of the carriage, cross feed and tool post. Aggressive cuts gave considerable chatter, some of it due to the crappy cutters in the tool post. The majority is caused by deflection of the carriage feed, the ball screw to be specific. Was not pleased with the ball screw when first installed. We’ll have to replace it.
Cut a few rings into the pipe to see how it does with making bands. It did ok. Turned a tapered flare into the end of the pipe. That did ok too. As you can see in the pic below, there will be no problem keeping the barrel wall concentric to the bore:
This will be even better with the addition of the tail stock to turn a blank on center.
All in all i’m satisfied with the machine so far. Except for the ball screw and spindle balance. Here’s the test piece compared to the drawing of the Bailes barrel:
It doesn’t look anything like the drawing but it’s not supposed to. It’s a piece of black iron pipe used to test the new lathe. And guess what? It's a working lathe.
Hank