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Precision Level or Precision Frame Level

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J BENNETT 122/01/2019 16:52:46
36 forum posts

I am considering buying a precision level to check the alignment of my lathe. In addition to the normal style of precision level I have seen square frame levels. Although there is very little difference in price, I cannot see any real advantage in the square frame level. In fact it may reduce ease of handling and actually be a disadvantage.

Can anyone advise on the relative merits of the two types.

Michael Gilligan22/01/2019 17:21:24
14011 forum posts
608 photos

The frame level allows you to check verticals in addition to horizontals.


Tim Stevens22/01/2019 17:58:41
1084 forum posts

That would be for setting up a vertical mill, then, would it?


duncan webster22/01/2019 18:05:02
2232 forum posts
32 photos

Whilst using a precision level is one way of checking alignment it's not the only way. Google 'Rollie's dad's method'. I certainly wouldn't go out and buy one just for this

Michael Gilligan22/01/2019 18:13:43
14011 forum posts
608 photos
Posted by Tim Stevens on 22/01/2019 17:58:41:

That would be for setting up a vertical mill, then, would it?


... or even a vertical slide on a lathe

Do you have a problem with added versatility as a bonus ?


not done it yet22/01/2019 18:59:52
3357 forum posts
11 photos

Exactly what are you wanting to check and for what/. If the lathe is cutting parallel, what is the point? Shirley, the ‘proof of the pudding is in the eating’?

Pete Rimmer22/01/2019 20:13:53
423 forum posts
18 photos

The frame levels have all sides finished square to each other so you can use it to check perpendicularity and parallelism if you like. They come into their own when working on a milling machine or other machine with vertical ways.

Paul Lousick22/01/2019 21:29:20
1168 forum posts
496 photos

The term "Level" in relation to a lathe is misleading. It does not necessarily mean that it has to be parallel (on the same plane) as the the ground, although this would be ideal. If one end or one side is slightly lower than the other, it will still produce accurate work.

What is important is that there is no twist in the lathe bed. The front and rear ways have to be parallel and in the same plane as each other and the ways are flat along their length.


Edited By Paul Lousick on 22/01/2019 21:30:23

Mike Poole22/01/2019 22:24:20
2111 forum posts
51 photos

Magnetic square levels are available to stick to vertical surfaces when gravity is not your friend.


Michael Gilligan22/01/2019 22:27:38
14011 forum posts
608 photos
Posted by Paul Lousick on 22/01/2019 21:29:20:

... What is important is that there is no twist in the lathe bed. The front and rear ways have to be parallel and in the same plane as each other and the ways are flat along their length.


... and one convenient way of checking that ^^^ is to use ... a level

Hence the name of the process is levelling


Ian P22/01/2019 22:59:34
2175 forum posts
90 photos

A precision spirit level has a very low level of usefulness in a home or ME workshop.

One could only use a precision level to check a lathe bed for twist if the lathe is not too small, if the bed is amenable to siting the level (although it could be used on the carriage), and if the lathe bed structure is mounted in a manner that allows it to be adjusted (4 points).

The OP did not say what lathe he wanted to check, it might be a watchmakers or it might be a 30ft Lang.

As far as I know precisions levels were extensively used in engineering and machine shops in olden times (even sometimes nowadays) as they were really the only instruments that were capable of checking and setting up work on large machines. Making large items of industrial machinery like turbines, generator, steam engines and everything else that drove the industrial revolution needed ways of measuring and comparing. A 15m (well it would have been 15ft) straight edge or steel rule was not a practical device so spirit levels were the instrument of choice.

Being pedantic, it might be that a lathe with a twisted bed produces more accurate and parallel parts than another lathe with a straight and perfect bed but with another defect, like headstock out of line in combination with a high tailstock. What matters is the end product and a large percentage of the product quality come from the skill of the operator coping with the quirks of his machine.

Ian P

John McNamara23/01/2019 00:47:43
1309 forum posts
113 photos

I have a precision box level bought second hand nice quality Wyler Swiss. an Asian 300mm precision 10 second level purchased new and a Starrett "Machinists level" also purchased second hand.

If you went shopping and paid full price a fair amount of cash would be needed, but that's not how I shop, like most of the tools in the workshop the items turned up unexpectedly. Its like fishing, The main thing is to not let them get away. Maybe you won't use the item straight away but sooner or later you will.

Other uses are setting your milling machine table perfectly flat, makes setting and checking angles easier.
Checking a flat surface for deviation from a true plane, the method is shown in most metrology books.

If your lathe or other machine machine is in good condition it should be set up with a precision level. that is what its manufacturer did when it was tested, Setting a good lathe up out of square will encourage out of square wear.

Rowleys method is for older worn machines, you are trying to correct errors by twisting the bed of your lathe by trial and error. Before I did this I would want to know how the machine performs when correctly leveled. On nearly all lathes the top of the shears or the top of the V's are used by the manufacturer as a datum. You can normally find unworn sections at each end of the bed. use these points to check that there is no twist in your bed.

I find the box level is my least used tool the short base length often requires a precision ground bar to extend the length. Its big advantage is that you can align vertically I don't often need that and you can always use a precision square with a plain level.

The Starrett USA with its black crackle finish and elegant chrome bubble housing is really nice to handle, It is less sensitive and is very useful for quickly rough leveling 1 division on the vial = .005" over 12" Still far better than any carpenters level.

Starrett also make beautiful precision levels with 10 second accuracy or even less! So far one of these fish has not come my way.

The Asian "Measuremax" brand level is 300mm long is very sensitive 1 division on the vial = .02mm per metre,

There is not much point using a level like this on a wooden floor they are flexible even if you can't feel or see it, the bubble can go off scale if you take a step. However if you have a concrete floor this is the preferred tool for setting up a machine.

Enjoy your fishing


Edited By John McNamara on 23/01/2019 00:51:01

Pete Rimmer23/01/2019 06:49:07
423 forum posts
18 photos
Posted by not done it yet on 22/01/2019 18:59:52:

Exactly what are you wanting to check and for what/. If the lathe is cutting parallel, what is the point? Shirley, the ‘proof of the pudding is in the eating’?

A lathe bed can be twisted and still cut parallel. The headstock might not be square with the bed and someone shimmed the legs/bed to make it cut parallel in the chuck then set the tailstock over to cut parallel between centres (for their test piece) but a twisted bed means that the saddle isn't sitting fully on the ways which means more wear in the ways and in the saddle and a less rigid machine overall.

It's quite important, though some machines are immune to it. Hardinge state that there is no requirement for levelling the HLV for example. The bed is spring-mounted to the cabinet.

mgnbuk23/01/2019 07:55:48
512 forum posts
13 photos

As far as I know precisions levels were extensively used in engineering and machine shops in olden times (even sometimes nowadays)

Not sometimes, pretty much all the time when building and installing machine tools. I have two precision block levels at work and use them during the installation of every machine that comes in to the works. Once set, regular checks as part of routine maintenance show if the machine has moved and requires adjustment. Level checks are the first checks specified in machine inspection records - correct levels being a pre-requisit of the following accuracy checks.

I would like to have box level as well as the two block levels - if I could only have one type, I would prefer a box level. At my last employment (CNC machine tool rebuild & retrofit) we had 2 calibrated box levels (one magnetic), a block level & a Talyvel electronic level (with block and box frames) and could not have functioned without them. Another area were the model engineering fraternity take a different view to industrial practice ?

Nigel B

Martin Kyte23/01/2019 09:10:35
1488 forum posts
24 photos

Yes adjusting a lathe can be done without a level but, it's a darn sight quicker with one.

You still need to do a turning test finally though.

regards Martin

Ian P23/01/2019 11:43:50
2175 forum posts
90 photos
Posted by Martin Kyte on 23/01/2019 09:10:35:

Yes adjusting a lathe can be done without a level but, it's a darn sight quicker with one.

You still need to do a turning test finally though.

regards Martin

'Adjusting a lathe' that could be anything.

Levelling a lathe using a precision level (in connection with bed twist) is fine (at the time it is carried out) but if the bench/stand/floor changes it will in turn alter the twist of the bed. Far better would be if the bed had three point mounting so it was unaffected by external forces.

If a three point bed has developed twist after manufacture then somehow one would need to add rigid brackets or metal work solidly fastened to the bed so that the twist could be corrected. If done properly the new metalwork would then become part of, and integral to, the original bed, which, still being three point mounted should remain straight for a long time.

With a four, or more, bed fixing system, adjusting the lathe bed twist relies on the stand/floor etc having enough rigidity and stability so that it can impart a constant restoring force to the adjusting points. It seems to me that a fabricated sheet metal stand especially a lightweight modern one, is not going to as solid as a rock so after levelling the bed and stand assembly are a complex bag of stresses and strains.

Its the turned products that matter but I feel that some users worry too much about this lathe levelling as if it was the be all and end all, of all lathe problems.

Ian P (rant over)

Ian P

Martin Kyte23/01/2019 12:39:55
1488 forum posts
24 photos

Well Ian I would have thought that as this thread was about setting up to turn parallel and because I talked about a final turning test it would seem pretty obvious what I meant when I said 'adjusting' so I am unsure what you are actually ranting about.

regards Martin

Emgee23/01/2019 14:37:22
1189 forum posts
206 photos

Martin, like many posts the original question seems to have been forgotten, it was requesting advantages or otherwise of 2 different types of level, no mention of turning parallel.


Edited By Emgee on 23/01/2019 14:38:48

Martin Kyte23/01/2019 15:07:06
1488 forum posts
24 photos

Well he does say he wants to check the alignment of his lathe.

I totally agree that a lathe bed does not have to be horizontal in both planes to operate correctly so long as it's not twisted but as Mr Bennett is considering buying a level he will then have the capacity to make such an adjustment. Once he has got the lathe bed 'on the flat' he could then use his level to set up material true to the same plane assuming the lathe has a boring table. Similarly he could level a mill table in the same way and one would immidiately see the advantages of the square frame type when setting up work.

regards Martin

Pete Rimmer23/01/2019 15:07:38
423 forum posts
18 photos
Setting the bed straight - level or not - is fundamental to the alignment of the lathe. It's such a trivial exercise (if you have a sensitive level) that there really shouldn't be any argument against it.

J Bennett - I'd you happen to be in N Kent you could borrow one of mine, then you can check your lathe without the expense of a seldom used tool.

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