Lathe Leveling Foot Pads

[backyard_cnc]

Sorry accidental duplicate post!

[Toolmaker51]

Toolmaker 51 and Frank S,

Thank you for the advice. Both of you are far more experienced than I in the best way to set up machine tools. My lathe is a circa 1987 Taiwanese equivalent of the Victor and very well built with hand scraped surfaces. I like the suggested design of the extended leveling pads.

My lathe is located in my garage that has a slightly sloping floor. The lathe is located parallel with the floor slope. I use a 0.0005"/10" precision level (it took me almost two hours to first precisely adjust and self-validate this level on a surface plate - it is an extremely sensitive level and takes a while to settle in).

In my experience, the lathe ways have to be as close to leveled front to back (cross slide direction) and with the same reading at the headstock and tailstock in order to remove any minor twist in the lathe ways if you truly want to work within very tight tolerances. During the leveling process you have to take test cuts to verify the diameters over several inches from the headstock. The vertical leveling along the long axis direction of the bed is important because it makes doing cross bed leveling so much easier to set up. There are plenty of YouTube videos on doing this lathe leveling work. Don't assume the headstock is out of alignment until the lathe is very closely leveled and not an error due to lathe way twisting. From my experience, leveling the lathe ways makes the final and most critical cut along the lathe's long axis very predictable and consistently allows a constant cut diameter along the lathe long axis. The extra effort doing leveling for the lathe eliminates scraping parts and makes the final cut far more predictable and a less stressful operation when you have to hit your mark. Paul Jones

Paul, you are precisely correct about flat and parallel being critical to how a lathe will run. The plane described by the ways across X & Y has to be flat. But actual level is incidental, a great universal reference. A lathe would truly cut accurately if set on an incline, provided all other parameters are correct, it would look peculiar certainly.
A quick course on setting/ calibrating adjustable levels. Or non-adjustable, for that matter. Tape off a perpendicular area (right angle) of intended reference surface. Ideally the work should be draft free, clean surface, and stable temperature between plate and level. Set the level 'in' right angle boundary of tape and observe reading. Slide the level around and position as identical to before as possible. I've taped down all kinds of objects to be 'tooling stops'. If the level is accurate the reading will be the same; [emphasized] even off a whole bubble, long as identical both directions. Then slip two equal strips of clean feeler gauge, gauge pins, small dowels, needle bearing rollers, anything with a ground surface, under the level. The reading still should remain, after eliminating errors in contact of level and reference surface.
Or a user could send to a cal-lab for a pricey tab; betting they will not take the same pains to insure reading, and certainly not at standard temperature of your shop.
But the cert will look good in a frame...
Another trick for levels is a tapered leaf. Any angle will work, face mill (not grind) a decent strip of good steel (mine is A2) of around the width of your favorite level. I suppose mine is 1 or 2 degrees something, taper starts out .020 thick to just over 1/4" in 7 inches.
Put a small mark at convenient distance from end on your level, like an arrow point of masking tape, 10" and 12" work well on this side of the pond. So now you are setting up new mill, shaper, lathe, grinder, jig bore, broach, rotary head milling machine, plasma table, surface plate; Did someone send you a check$$!?
The first reading will be off. Slip the taper under the low end and move in until level is zeroed. Mark the taper with a pencil (why you don't grind it), remove and check with a caliper how thick that area is. Lets say it's .019 in 10". That equals more or less .0019 per inch. The distance between feet of the machine touching the floor is 91". One side is low .1729 inches, and very close to how much is needed to raise that end nearer to being level. You could even calculate thread pitch of the jackscrews and turn them close to the needed amount. What if the taper is too thick? Dang TM51 told me to make it too thick!
No it isn't; put a feeler under the 'high side' a bit more than its minimum thickness of taper, you can read down to a couple thousandths. Oh, that TM51!
When you are crawling on hands and knees leveling a 10-pad boring machine or lathe, you'll be glad you made that taper.
Of course it is usable to check any sort of opening or gap as long as it fits.

[Paul Jones]

Toolmaker51,

Great advice on leveling the machine tools. I like your advice on taping off the reference surfaces where I had just marked the lathe ways with a felt tip pen. Measuring the leveling correction with a tapered leaf will save a lot of trial and error iterations and your back. The bigger the lathe, the longer it takes on the iterations and this would be a real time saver before one ran out of patience on making it perfect.

The only reason I like my lathe to be level in all directions is because I sometimes use small levels in some of my cutting tool setups and I need a truly level reference to the lathe.

Regards,
Paul Jones

[Paul Jones]

Toolmaker,

Since my original posting, I check the leveling of this lathe every six months with a precision level with calibrations at 0.0005 per 10" and use sold 1-2-3 blocks on the ways to average-out any imperfections. It takes five less than five minutes because there is usually no change in the leveling over time but worthwhile checking. However, it takes some patience in doing the leveling because the precision level is very sensitive and the level takes several seconds to stabilize. It is worth the effort because the perfect leveling removes any slight twists in the lathe bed. The leveling results in allowing accurate and repeatable lathe machining work depending upon the wear on the machine. I sometimes use conventional bubble levels in my initial setup work on the lathe and this only works well when the lathe is perfectly level in the longitudinal and cross-wise directions.

I have not added the sections of 4"x4" angle bar at the headstock and tailstock ends to make the footprint of the leveling pads wider because the lathe remains stable over time. However, it is probably a good idea because we live in earthquake country and the lathe could topple.

I do wish I had spray painted the outside of the steel foot pads (but not into the inner holes) because the pads are starting to develop some rust after a few years of contact the concrete floor. It is not a big deal but a suggestion.

Regards,
Paul

[bigal001]

Thank you for a very nice job. Regarding the proposed widening of the rests, may I point out, that projecting the angle bars is going to create a handicap as you will be knocking your shoe every time going around the lathe. May I propose that you extend the angle bar only towards the back, leaving the front corners flush with lathe base. Just a thought...