Leveling machines

I have ordered my lathe and milling machine, when they arrive I know I will need to level them so that they run true. I have seen many use an engineers level to do this is this type of level essential or can I use a good spirit level.

I do know that if the machine is on a slight slope this does not matter as long as the lathe bed is on the same level from end to end and also across so that the bed is not twisted.

The key is to avoid bed twist. Levels are just a convenient way to do that. As they are relative measuring devices using gravity as a reference then making the bed surfaces horizontal at each end is convenient but not essential. Equally the bed doesn't need to be horizontal. But ordinary spirit levels don't have the sensitivity of an engineer's level, if they did they would be very hard to use. May be good enough to get close then do turning tests to finally trim the bed adjustment, this has been covered on here many times.

It's convenient, rather than essential, to have an accurately-levelled machine. It is not essential for true running (within reason). The idea is to be able to use gravity as a reliable external reference, to check, for example, the ways of the machine are aligned to each other, or to set up work accurately. If the work is accurately aligned, by the level, and the machine is too, then they are aligned to each other (within the limits of accuracy and sensitivity of the level). Of course, there are generally alternative methods available.

Machinists' levels are much more sensitive than builders' levels, and can be adjusted. This sensitivity can make life difficult if the machine is not on a very stable foundation - just walking around on a suspended floor near the machine will likely deflect a sensitive level's bubble massively. So, if you can get the use of one, fine, but it's not essential.

Edit - beaten by previous poster. We agree, so take heed!

Edited By Kiwi Bloke on 26/07/2021 11:07:16

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To answer the specific question, Derek:

IF you want to do machine “levelling” and remain sane, then yes you need the sensitivity of an engineers level.

Frustration-wise : To use a builders level would be like stabilising a table on the pub floor by sticking various bricks under the legs, instead of a carefully chosen coin under the short one

MichaelG.

Edited By Michael Gilligan on 26/07/2021 13:15:34

If I was installing my lathe again, I'd put down a layer of self-levelling floor compound (from any DIY store), just big enough for the stand to sit on.

What I actually did was assume my garage floor was level and plonk the lathe straight down on it. Turned out, although the floor looks flat, it has a few shallow bumps and dips, which are enough to twist the bed. I fixed that by putting roofing felt under the stand, the idea being it would squish flat underneath and fill the gaps. Which it did for about 6 months, before it became apparent the bed was twisting again. I fixed that with another bodge, steel wedges tapped under the stand, which for easy adjustment require a sensitive machine level. Tiny movements under the lathe can twist the bed enough to cause mild taper turning. Possible to adjust the lathe without a level by taking a series of test cuts but pretty tedious.

Lathes don't have to be level as such, but the easiest way to remove twist is to ensure the floor is flat (no bumps), so the stand isn't stressed (as mine is), so the lathe sits flat on the stand. If that's done there's a strong chance the bed won't be twisted at all, or a minor twist can be taken out by shimming one of the lathe's feel, which can be done without a level just by taking a few test cuts. This compares with my set-up, where the floor isn't level, and the stand is stressed, which is likely to twist the bed. Both my counter measures are bodges: I ought to move the lathe, flatten the floor and start again! Annoyingly my garage floor is mostly flat - it's only uneven where the lathe needs to go.

Similar problems occur on wooden floors if they sag. For example if one end of the stand is well supported by a beam underneath, while the other isn't. Good idea to support a heavy lathe with pillars under the floor, not so much because the floor will collapse (unlikely), more cause the bed might twist due to the floor flexing. A sensitive level will show this up if the bubble moves when the operator steps away from the lathe.

Over sensitive bubbles are a pain in the butt! They take ages to settle, and quite small movements take them out of range. Frustrating to use. As I say with hindsight, easier to level the floor with a flattening compound, where gravity does all the hard work.

Dave

Hopefully not a nice thick pound coin, Michael!

Bill

Some mills are purposly set slightly off level to allow better drainage of coolant, so I wouldn't worry too much. A large ball bearing sitting on the bed would be a cheap way to level, or an ordinary spirit level in both axes and double checked by turning it round.

For the lathe, it would be best to have a 20mm brass bar sticking out of the chuck about 100mm and take a very light skim and compare the diameters of both ends of the machined diameter. If the end furthest from the chuck is less than 0.010mm bigger, then you might as well forget messing about with leveling.

Nope!

Only way to stay sane is to use a clinometer like this one :

The vial, at 30 seconds per division, is almost as sensitive as a high end master precision level and there are 10° of tilt adjustment via a screw calibrated in minutes with a ruler on the side calibrated in degrees for rough setting. Less than 8 inches long so you can get it in pretty much anywhere. Easily turned end for end during final set-up to effectively double the vial resolution.

The trouble with precision levels is that you barely have to breathe wrong to chase the bubble right up one end of the vial. With a clino a quick tweak of the screw brings it back into view and you can carry on.

WW2 gunners type in that style frequently turn up on E-Bay at £60 ish or less.

Clive

Edited By Clive Foster on 26/07/2021 15:22:24

At the museum, we are working on a 12 X 14 atlas lathe on a welded up stand. Instructions for the lathe include leveling and the only way to achieve that would be to include some sort of adjustment. I fitted an aluminium block under the headstock to raise the lathe about 40mm. That enabled adjustable mounting bolts to fit at the tailstock end. We haven't finished the lathe yet, and I'm not sure my Moore and Wright level is sensitive enough to be used directly. As mentioned in my earlier post, leveling can be tested by a test turning.

Edited By old mart on 26/07/2021 15:32:00

Clive … I take your point, but do please note that I wrote :

you need the sensitivity of an engineers level.

not

you need specifically to use the instrument known as an engineers level.

The adjustment on your clinometer is an added convenience, but it’s the sensitivity [versus that of a builders level] that makes it suitable for use when adjusting a lathe by the process known as “levelling”.

MichaelG.

Whereabouts in the world are you Derek? I have a level you can borrow if you’re within a reasonable travelling distance from RH19 near East Grinstead, Sussex.

Questions: Are boats level, when at sea? If they needed to be precisely level to the planet Earth surface, how did the navy cope with all those Drummonds during the war?

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All aired previously, ad nauseam

You may note that I put quotation marks around the word “levelling”

There was a good reason for this, which I have explained previously on this forum

MichaelG.

From what I have read, before and now ,it appears that it would make no difference if the machine was standing on its head, like a vertical lathe, provided that it was not in twist.

Open to correction, as usual.

The "levelling" when used in relation to a lathe is a poor way of simply making sure that runs true whatever length of work is machined. As I mentioned earlier, it is best to do test turning as your lathe bed may be fine as it is

The "levelling" when used in relation to a lathe is a poor way of simply making sure that runs true whatever length of work is machined.

How did the machine tool industry get it so wrong for so long ? And as they continue to do so, they mustn't have a clue. I guess I'll be making work for myself when I use a level to check out the lathe I'm cuurently working on before it goes into production.

Questions: Are boats level, when at sea? If they needed to be precisely level to the planet Earth surface, how did the navy cope with all those Drummonds during the war?

I have a recollection that the lathes on ships are mounted on a "neutral axis" that is isolated from the usual twisting and other movement that ships exhibit while at sea. But the lathe would have been checked while it was being bult using a precision level. And as ships are built "out of the water" on supports in dry docks, it would not be difficult to check the lathe for twist with a level at the point of installation, before the ship was launched.

Nigel B.

Thank you all for your thoughts so it is wise to buy an engineers level for when I set up. I did use an good level to get my woodturning lathe so that there was no twists in it as it can throw the tail stock out of alignment with the head stock. I do appriciate that a woodturning lathe does not need the same kind of accuracy as a metal turning one.

For what it's worth ... The first time I tried to explain this was on 01-January-2015

**LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=102987&p=2

Basically "levelling" is a technique [involving the use of a level], not a target or an outcome.

... Just like "milling" is the process of using a mill.

MichaelG.

Derek, all depends what you want to get out of the machines. My shed floor was checked with 900mm and 1800mm Stabila builders levels and the lathe stood on top. I seem to be able to get running engines off it and the mill that has not had the bench it sits on checked with a level.

Clive's mention of a clinometer, reminded me that I have a gunners sighting level from 1944. To those familiar with the device, would this be sensitive enough for lathe levelling?

Andrew.