Lathe Leveling Requirements

[pcmacd]

I've a newly acquired King TD-45AA lathe.

The previous owner probably never cleaned one bit of scarf off the sucker.

It is a mess, and it truly did break in my new Craftsman shop vac?

Lathe is on a solid concrete floor. It is not perfectly level either fore/aft or left/right.

Tried using the "BUBBLE" app on my android, but what do I calibrate THAT against?

Using a conventional Craftsman 24" level, I am a wee bit off left/right, and about 2x more, fore/aft.

1) I'd like to know how to absolutely measure how level the machine is?

I can likely afford any reasonably priced tool.

2) what are reasonable level requirements?


I have no lathe experience, and no clue.

I'll be taking some community college classes this fall to get my head screwed on right.

I'm not a mechanical dummy. Just don't know much about lathes and mills.

tanks.

mac

[Illinoyance]

The lathe really does not have to be level to work right. Level is just the easiest way to make sure the bed isn't twisted. You really should have a level sensitive to .0005" per foot. Check for level (front to back) close to the headstock and again at the end of the bed. Shim the feet until both ends are level. If your lathe has only 4 feet there is not much to worry about about level in the longitudinal direction. Squatting to adjust shims or feet, then standing to check the level and doing this over and over again is going to be rough on the legs. Get a helper so one person can make the adjustments while the other reads the level.

[johansen]

if you download an app that can log the output of your phones accelerator, you can take an average of 10,000+ datapoints (upload the data to your computer) and get better than the 16 bits the accelerometer outputs.. maybe. worth a try, it seemed to work on my phone.


anyhow your lathe doesn't need to be level. just turn a rod between centers and either adjust the tailstock or shim the bed until you get the same diameter at both ends.

[darryl]

This is a pretty deep subject, and it sounds like you're not ready for it. Level it up in the traditional sense, using the carpenters level, and at the same time shim the legs of the stand until it doesn't rock. Then I'd say make some chips. In order to even turn a test bar, you will need to have correct tool geometry so you can get a decent cut without deflecting the bar. I would just play with the lathe for awhile until you start getting some feedback from what you're doing. If you seem to be getting a decent cut, then chuck up a piece of 1 inch bar, leaving perhaps 3 inches sticking out. Get your best cut across that to true it, then measure the diameter near the chuck, and near the outboard end. If you're within a thou over 3 inches, then note the error but keep using the machine as it is. You can tweak it later as you get to know more about all this by reading (and asking here). You aren't going to be making high precision parts right away, so don't sweat this leveling thing right now. Amongst a ton of other things, you'll need to learn the proper use of calipers and micrometers so you can get consistent and accurate readings from them.

[mihit]

illinoyance got it. doesn't need to be LEVEL. just not TWISTED.

I would not use a phone app, though the one on mine looks supremely accurate, and gives numbers to a tenth of a degree (and would calibrate by gravity - which is a pretty reliable thing to measure against)

The test, is a test-bar. turn two collars on a bar, one at the head and one at the tail stock and compare them.

[MattiJ]

anyhow your lathe doesn't need to be level. just turn a rod between centers and either adjust the tailstock or shim the bed until you get the same diameter at both ends.

You should adjust the lathe bed/feet with test bar supported only by chuck and after you don't get taper you can start worrying about aligning the tailstock.
Otherwise your lathe bed can be like a pretzel. (even getting no taper on test bar doesn't guarantee that the lathe bed is not twisted but it's reasonably good assumption..)

[J Tiers]

Do not bother with 0.0005" sensitive level. Just a nuisance.

Level as closely as you can with a good level, at most 0.005" per foot or equivalent. THEN do the turning test. That will make reasonably sure it is not a pretzel, and works fine.

[Mcgyver]

I prefer an accurate level like the Starrett 199, but until you get the right level, use what you've got. Use short parallels (good 123 blocks work) on the two flat ways (not the top of the V's) on the (mostly) unworn sections are the extreme left and right. Then turn something held in the chuck only and tweak the tailstock end leveling bolts until you turn parallel. Do not use the tailstock as work holding as then you have no idea whether the tailstock or bed is out. You could have the tail stock off and end up putting more twist in the best compensating for it. One thing at a time, process of elimination.

Lathes have wear and concrete moves so perfection is elusive and if you find it doesn't last. Get it as good as you can and tweak when necessary. I've managed to get long parallel turnings to tolerance with the adjustment of the tailstock side leveling bolt.

As the guys have said, level is just a convenience to check for twist. Twist isn't a flaw, just that the weight of the lathe sitting on an even surface (any concrete floor is uneven) will induce twist in the bed. That matters - picture looking at the bed from the end that is twisted. as the carriage travels along the ways, this twist will change the distance from the tool to the spindle centre

[SLK001]

Get a PRECISION level, like a Starrett 98-6 (also available in 8" and 12"), or even this 300mm long one:



The Starrett has divisions of 0.0005" per foot (1:24000), while the 300mm long one has divisions of 0.02mm per meter (1:50000). The 300mm long can be had on ebay for less than $100US.

As has been said, a lathe doesn't have to be level, it just has to have planar ways to get the best results. Lathes on ships are almost never level, but they are carefully set up to be planar. Doing work near the head, a non-planar lathe is nearly undetectable. Only when you try to do long shafts to close tolerance will the leveling be necessary. People actually put their lathes on casters (I cringe every time I see one on casters), so they are never in level.

[Planeman41]

I have often wondered why bench lathes don't have three bolts holding it to the bench instead of four - two at the headstock end and one at the tailstock end. This would avoid twisting the bed. When I mounted my Maximat 7" I just tightened down one of the bolts on the tailstock end and dropped a bolt into the other hole to make it look pretty. It has no nut on it.

[Mcgyver]

I have often wondered why bench lathes don't have three bolts holding it to the bench instead of four - two at the headstock end and one at the tailstock end. This would avoid twisting the bed.

agreed, it would be so much more sensible, factory alignment and accuracy just be setting it down. Should be defacto. Schaublin does it, a little lathe that bolts to big cast iron tray and the tray has three bosses that contact the bench. A Monarch 10ee also does it, obviously isn't a bench lathe but sits on massive cast iron base - with three points of contact to the floor.

Get a PRECISION level, like a Starrett 98-6


The Starrett has divisions of 0.0005" per foot (1:24000),

The Starrett 98 is a machinist level, graduations are .005" per foot. The 199 Master precision level is .0005" per foot. New, they're a fortune, used still a lot of money but doable. They're (or comparable) are almost a requirement for scraping work, but if I wasn't doing that, not sure I'd ever buy one...but if you have one they're the deal for leveling. Sans a 199, the machinist level and test bar is how I'd go.

[lakeside53]

If you are really trying to correct a "twist" (the type caused when the casting has moved since factory grinding) you aren't going to do it with a typical freestanding (lathe mass and gravity acting) lathe - it needs to be bolted down to the concrete (not on a wooden or sheet metal base) and have the type of adjuster that both push up and pull down. Larger lathes have this - mine has 6 adjusters. If it's own mass is causing a twist because of poor or uneven supports, then maybe.

If you really want to do this, get or borrow a real machinist level.

For the OP with a 36 inch lathe... get it about right and use it, or just use it and see the results.

[mickeyf]

Don't even worry about "level" yet. Make chips. If you had a perfectly set up lathe you would still need to put in a number of hours learning how to do anything with it at all before worrying about making things to a meaningful degree of accuracy. Learn how to hold work in it correctly and solidly, in both a three jaw and four jaw chucks, and between centers. Faceplate, also. Learn how to set up your tool so that it does not grab or rub but cuts. Learn how fast to run it and how deep a cut you can take on different materials. If you are grinding tool bits rather than using inserts, learn how to do that.

When you are reasonably comfortable with all these things, and discover that your work is not as accurate as you'd like, then think about levelling and setting up your lathe so that it is not contributing to your deviations from perfection.

[BCRider]

First off WELCOME ABOARD to the forum ! ! ! !

As you can see there's a couple of different options that can work. But one of them (the machinist's level) requires that you buy a piece of gear that is not cheap for a home shop and which will mostly sit in the drawer for much of its life if you don't have any reason for using it other than the lathe setup.

I'm with the other camp that says you can do a lot with a test bar cut if you already know how to correctly use and read a good micrometer.

My own lathe is also a 12x36 lathe and a couple of years back I leveled it with a builder's level like you've done so basically round things won't roll off when I set them down. Then I used a piece of heavy round stock (2" if I recall correctly) and did the test cuts mentioned and shimmed the bed until it cut the same size at both ends of the bar.

HERE IS A LINK to a web page of a guy that did this with pictures and diagrams.

In my case I was no longer using the tin box base pedestals. Some years back I did some built up pedestals out of construction blocks filled mostly with small gravel and the top course and a half filled with concrete that I used to set "J" bolts made from 1/2" threaded rod. The lathe and chip tray sits on nuts and washers then additional nuts and washers hold it down. So when I did the test bar measurements I actually found it to be pretty easy and fast to dial it in until the 8 to 10" spaced measurement bands were within a tenth or so.

And because your lathe and mine also have 6 mounting points there's a risk of removing any twist but having a crown or sag in the bed. With the test bands at the same size I rand a dial gauge on a stand to look at the tops of the bands. I then equally corrected the two of the head stock bolts to remove this crowning/sag. So now I had the lathe bed twist and bend free to as close as my dial gauge and Mk I eyeballs could muster.

BUT WAIT! Order now and you'll also get..... Since the test bar and tail stock ram are roughly the same size you can also use the dial gauge to step from one to the other. Measure the diameters and look for half of the difference on the gauge. You can use this for two things. First is from the side you can use this to set the tail stock side to side adjustment to zero. You can also use the same reading from the top of the bar and ram to check for any sag of the tail stock ram due to wear.

So do this test in all ways as described you'll need a micrometer large enough to measure the fairly big diameter test bar measurement collars. So a 1-2 inch or 25 to 50mm size. You'll also need a dial gauge on a magnetic test stand. Both things you will use a lot in the hobby so they are money well spent vs a machinist's level you will rarely use and which will cost as much as the mic for a good brand name or the mic, dial gauge and magnetic stand if you go for the inexpensive import models of each.

[pcmacd]

Thanks to you all.

I have micrometers, indicators and magnetic stands galore, and well know how to use them.

First I need to get the motor wiring figured out, but that is for another thread.....