Turning accuracy with Engine lathes

[Optic Eyes]

Most beginners aspire to great accuracy with common lathes, if you need more accuracy just modify your techniques, turning on centers for making grinding spindles for example, turning on centers will give a straight product if you take an overall cut, mike it, and adjust the tailstock to correct the taper if any.
Turn your compound slide to 5 degrees 42 minutes this will give you a tenth indeed for every .001 on the dial, carbide radiuses inserts can give great finishes .
Better yet get a small tool post grinder, grinding will increase accuracy close to ten fold. I rebuilt spindles this way at work spray welding and turning and grinding journals. Tailstock offset is an old technique
somewhat ignored today as is grinding in the lathe. I rebuilt Sargent Welch vacuum pumps regrinding the rotors and stator body on a 14" Engine lathe saving the company $2000.00 replacement costs.

 

[graham-xrf]

Neat trick! This one, at least, is within my capabilities - a little trigonometry to help. I have read of it, but given the temporary parlous state of my compound, not actually tried yet.

There are others. If one is a fan of Robin Renzetti, and Stefan Gotteswinter, you note they decide that except for special occasions, you don't need the compound at all! Reap the benefits of stiffness in a small lathe that has it doing stuff it would fail at if the compound were there. The business of adding a block for the toolpost is not trivial! It includes dowel pins with pre-load, stops, kinematic location with certainty of non-rotation. Each has his own special build, all shown off on YT.

Then..
Stefan does his trick of engraving a special two-line vernier, that divides his 0.02mm cross slide dial to give him 0.01mm off the diameter, because he has a 200 division scale.

I am in awe of Robin, who designs spindles with verifiable run-out of only a few millionths, and laps things to insane flatness measured in fractions of a green wavelength. Most of us may not be able to get to their kind of machining accuracy and skill, but their stuff at least leaves us dissatisfied with what we thought was "good enough", and start thinking.. "could do better". They don't make non-critical dimensions better than they need to be, it's just that I have to pay lots of attention to even get mine to their "non-critical" level

 

[silence dogood]

Check out Tubalcain's "Machine Shop Tips #90 Splitting a hair...."