The objective in levelling is to ensure that the lathe bed is not twisted; if the bed is twisted then everything you cut on the lathe will be tapered to some extent.

Perhaps the easiest way is by the use of a precision level. You place the level, at right angles to the bed, somewhere convenient on the saddle which you then carefully move from one end of the bed to the other while observing the bubble. There is no requirement to centralise the level, but you must ensure that it doesn't vary along the bed. Any movement in the bubble indicates a twisted bed. You adjust the bolts and or shims until you are satisfied.

Unfortunately, precision levels are not exactly cheap, and are not needed very often, so its probably best to borrow one if you can.

There are methods that don't need a precision level, but they are not so straightforward.

This has been covered a number of times. When I have done it I have turned a test bar and measured the diameters at each end. Google "Rollies Dads method" for a way to do this with a minimum of kit or look at Harold Hall's site who explains how he does this. I used both these methods and got good results.

The divisions on a typical precision precision level are marked as 0.05mm/mtr. or 0.0005"/10". A plumb bob displacement of 0.5mm (which is about as accurate as you could hope to be) would need a suspension string about 10mtrs long for equivalent accuracy.

Maurice, you could make a modern version from a bit of box section aluminium extrusion. Ian S C

£50 delivered for a 200mm 0.02/M level on Ebay (291067274469)

Or for £55 delivered a 150mm box level (271385670211) – will be more useful when you get a milling machine.

Neither are that expensive when compared with a new machine.

If "Rollies Dad's Method" is so great, why does industry use levels ?

Regards,

Nigel B.

Terry,

Looking at the photo , it doesn't really appear that they had levelling in mind.

The headstock, with a bolt at each corner shouln't move far, and the support at the tailstock end [despite having only two bolts] has an uncommonly large footprint.

… Sorry, that doesn't really help; it's just an observation.

MichaelG.

Hi Terry,

I have a 290 lathe and used two 15mm thick steel plates with holes for bolting to the bottom of the headstock and tailstock. At front end rear end I drilled a hole and tapped MF 14 x 1 and made four leveling screws.

The first photo shows a sketch (not my lathe, just to illustrate the idea):

Here are a couple of photos from my 290F lathe:

The height adjustment is done with a suitable spanner underneath the grey steel plate – the head of the leveling screw is underneath the steel plate and has a square head.

I drilled 8mm dia. holes through the leveling screws and use M8 bolts to tighten them down after adjustment.

Thor

Edited By Thor on 24/02/2014 05:55:55

Do you all want to know a secret ???

The majority of small and medium sized lathes delivered to industry are just plonked on the concrete floor and put into immediate use . The more conscientious types might try a feeler under each leg to see if theres a bad contact anywhere – in which case they will either adjust or jam in a bit of sheet . Recorded instances of lathes not performing to spec as delivered – nil .

Edited By MICHAEL WILLIAMS on 24/02/2014 09:13:52

Lathe beds coming from better class makers are usually supplied in neutral stress + neutral distortion condition .

That is in their free form without any inputted strains they are undistorted and perfectly true .

Also not quite all but most lathe beds have a true surface on the underside such that if laid on a surface plate the top surface of bed would be true and the bed stress neutral .

With a four bolt bed support system a person with some sensitivity can set up a new smaller lathe by feel – just adjust each of the supports to a condition of uniform feel on each one .

The note on industrial lathes above does not suggest sloppy working .

Experience has shown that most lathes perform well straight out of the box . Any problems would in any case show up immediately in crooked work and remedies could be applied .

Situation is different on lathes and other machines with long beds and especially with sectional beds – these have to have special treatment during installation .

Michael Williams .

Edited By MICHAEL WILLIAMS on 24/02/2014 09:47:53

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Bazyle,

I think we're on the same wavelength [see my earlier comment]

Your approach seems entirely reasonable, with one small caveat; When the headstock end is first bolted-down, there needs to be a small gap under the foot at the tailstock end [otherwise the bed might already be being stressed].

If it were mine, I would first insert a thin spacer [a piece of Gauge Plate with four clearance holes] under the headstock.

MichaelG.

A machine bed can in principle have twist , sagging/hogging or lateral distortion in it .

If bed has multiple mounting points then each section between mountings can have different combinations of the various types of distortion .

Beds can of course in principle have cross section variation errors as well .

If any of you are going to ‘ level ‘ a lathe fully then you have to check EVERYTHING .

OR

You can reasonably assume that manufacturer made a good job of the bed and that it has no intrinsic faults and set it up in a very simple way .

Bit different with a used lathe with bed in unknown condition . Oft advocated procedures of correcting problems by twisting lathe bed cause more troubles than they solve . A used lathe bed has to be accepted ‘ as is ‘ and make the best of it OR corrected by grinding or scraping and then set up properly as for a new bed .

Michael Williams .