Leveling the lathe for twist

[PWF]

Looking at the pics. What is the correct way to level the lathe for twist?

A,b or c?

 

[Technical Ted]

I use method B because typically the tops of the V ways are not worn (as the flat ways might be) and should be close to as built condition. I would touch them lightly with a hone to remove any possible burrs.

Ted

 

[benmychree]

I would use A, the tailstock ways would not be worn at the headstock end, or the very tail end of the bed, and yes, stone the surfaces to eliminate any burrs. On some lathes, the tops of the prismatic ways may not be at the same height.

 

[Cadillac]

The V’s are not the same height at least on all the ones I’ve seen. You will need to use 123 blocks or parallels to get you off the the V,s. You can do like C but you need to remember any variance can be within saddle or cross slide fitment. Check your blocks or parallels for errors so you know what your dealing with.

 

[Technical Ted]

Well, I guess it depends on what lathe you have. On my South Bend lathes, I only have one flat way with 3 V ways (which are all at the same height).

Level it with whatever method you choose, but then check/verify by a two collar test.

Ted

 

[rogerl]

What is a "two collar test"?

Roger L

 

[benmychree]

You chuck up a piece of stock of large enough diameter to be stiff, say an inch or more, and 6" plus long, you want to end up with a piece that is relieved on the diameter, leaving a short distance of full size at each end, say 1/4 - 3/8 long, then with a sharp tool, light cuts and fine feed, take a light cut on the full size ends without adjusting the cross feed; measure the resulting diameters to determine whether or not the lathe is cutting a taper; if, say it is cutting taper large at the head end, lower the tail end leg in the front or raise the head end in the back. I would tend to truly level the headstock end, and make adjustments at the tail end.

 

[darkzero]

I also use method A. Not that it matters but I lay my 123 blocks flat instead of standing up like in the photo.

 

[Technical Ted]

There's a lot of discussions on this list and others about leveling lathes. The only reason I level my lathe is to get it in the ball park for cutting true as benmyhree described. Things will move over time and if I find my lathe is cutting a taper while only holding a piece in the chuck/collet (not using the tail stock) I will tweak the tail stock end lathe leg levelers to make my lathe so it cuts true.

I don't really care if my lathe is level (within reason of course). I want it to turn and bore true.

Ted

 

[PWF]

THANKS to all.

I have found that A and B are essentially equal just a bit offset.

Meaning that they measure the same tilt on both ends, but absolute value of A and B are different.