Selecting an Engineer’s level

[Howard LewisParticipant @howardlewis46836]

Really what we are actually talking about is adjusting the mountings so that there is no twist in the bed, so that the lathe turns parallel.

My ML7 was very sensitive to the torque applied to the holding down fixings.

Its successor, a BL12 – 24, on the same bench, seems to be most affected by the two fasteners, of the six, beneath the chuck.

The Raglans probably overcome the problem by having only one fixing, under the Tailstock, so that it effectively has a three point retention.

Aligning the Tailstock with the Headstock should produce parallel turning between centres.

ASSUMING that the Headstock and Tailstock centres are at the same height!

Howard

[Bo’sunParticipant @bosun58570]

I suspect, unless your lathe stand is extremely rigid, shimming the feet may not correct any twist. Many lathe beds are quite likely more rigid than the wooden benches they're sitting on. As well as some of the cheap sheet steel stands available from the Far East.

[thaiguzziParticipant @thaiguzzi]

Posted by peak4 on 17/04/2020 00:06:18:

If you still decide to purchase one, good brand name ones are often available on ebay for less than £30; e.g. Starrett, M&W, Rabone etc.

Bill

THIS!

+1.

Even 50 quid for something nice and beautifully made is surely better than paying double for something that looks a bit kack with no brand name or engineering history.

[old martParticipant @oldmart]

I wish the 70 year old lathe I use had less than 0.025" wear in its ways, but nevertheless, it can still cut parallel, and has never been levelled by me in the last ten years.

[old martParticipant @oldmart]

I wish the 70 year old lathe I use had less than 0.025" wear in its ways, but nevertheless, it can still cut parallel, and has never been levelled by me in the last ten years.

[Martin KyteParticipant @martinkyte99762]

Posted by Bo'sun on 17/04/2020 14:49:56:

I suspect, unless your lathe stand is extremely rigid, shimming the feet may not correct any twist. Many lathe beds are quite likely more rigid than the wooden benches they're sitting on. As well as some of the cheap sheet steel stands available from the Far East.

This assumes that the bed is twisted as a permenant feature. This is not the case. You are not trying to correct a twisted bed but correct an unevenly supported lathe.

The lathe should be 'twist free' when unstressed. It's the uneven mount that introduces the 'twist'. By definition when in the stress free 'untwisted ' situation the mount is imposing no 'torque to the bed but merely evenly supporting the feet. Thus a light wooded bed can correctly support a lathe in it's proper configuration to turn parallel.

This does not however mean that sturdy mounts are not better than flimsy mounts, they are.

regrds Martin

[Pete RimmerParticipant @peterimmer30576]

I was trying to keep out of this, Martin … but I do feel the need to re-state my understanding of the semantics:

Levelling in this context [as in surveying] is the process of using a level to compare heights.

… The ambiguity comes from the assumption that it must mean setting something horizontal.

MichaelG.

Quite right Michael. Add that to the fact that the most expedient way to to check for twist is the ensure that the ways are actually level both ends. They need not be and it might not even be possible, but why complicate things?

The Colchester alignment check sheet calls it a 'transverse bed level' measurement. Seems like a pretty intuitive description.

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