Precision Level or Precision Frame Level

[Howard LewisParticipant @howardlewis46836]

Made mine from a casting from College Engineering Supply, using their most sensitive vial.

Set it up on a surface table in the Standards room.

Don't know if the new owners still supply castings and vials.

Howard

[Clive FosterParticipant @clivefoster55965]

For normal mortals the adjustable clinometer type is far more useful than a standard precision level. This is mine, a WW2 era gunners clinometer, about the only sort I'd give shop room. Hilger & Watts square frame ones are relatively common. Less sensitive than mine and a right royal pain to use in my view.

Although the vial isn't quite as sensitive as the very high end precision levels its more than adequate for any normal task. A thou per foot is quite easily seen. 10 degrees of adjustment means you can actually use the thing to bring something level without mucking about with by guess and by God shimming and waiting ages for a precision level bubble to stabilise. I have, albeit out on permanent loan, a couple of super levels which take the best part of a minute to stabilise. Never had much patience with them for the specific jobs they were made for. As general purpose devices a spectacular pain in the butt. But friend Mike wanted some really good levels to set up his lathe!

The small clinometer is a little over 6" long so easily switched round to zero in from both ways.

Clive

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[Paul LousickParticipant @paullousick59116]

I have just found a good demonstration of levelling a lathe on Youtube (fast forward thru the first minute). The simulated model of a lathe shows what happens if is not aligned properly.

Paul

**LINK**

[Michael GilliganParticipant @michaelgilligan61133]

Nice find, Paul

MichaelG.

[not done it yetParticipant @notdoneityet]

If one subscribes to Joe’s channel (like I do), one does not need to search, to find – they notify you when he puts up a new video.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by not done it yet on 30/04/2019 07:36:33:

If one subscribes to Joe’s channel (like I do), one does not need to search, to find – they notify you when he puts up a new video.

.

But if one had never heard of Joe's channel; it's nice when someone shares a useful link.

… Thanks again, Paul

MichaelG.

[AdrianRParticipant @adrianr18614]

I recently bought a level from arc euro, I chose the straight level not the frame one to save money. I wish I had bought the frame one. I am in the process of levelling my lathe now and don't regret getting a cheep one.

I read the spec 0.02mm/m and I understand it is pretty sensitive, but when i started playing with the level I truly appreciated how sensitive it is, a piece of tin foil is a mountain.

The level is too short to bridge the bed, and it is slightly too wide to sit along the slide way. It is not flat bottomed, it only has ground edges. Initial levelling I can use the cross slide. To do the full levelling need to make a bridge across the bed, with one end using a V slide way the other using the flat slide way. Some thing to think about if you buy a level.

[mechman48Participant @mechman48]

I subscribe to Joe's channel … https://www.youtube.com/channel/UCpp6lgdc_XO_FZYJppaFa5w

He has a lot of good videos to watch, very easy & simple explanations for just about anything that Model engineers would need in the home workshop.

George.

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[JasonBModerator @jasonb]

Yes, you can get different speed bubbles, faster on builders levels as you can't sit there all day faffing about with a slow bubble as your mortar will have gone firm or you will only have fixed a couple of studs in a day.

I think they are all barreled to some extent, the more sensitive the bubble the less barrel shaped it is see here

Edited By JasonB on 30/04/2019 13:30:58

[not done it yetParticipant @notdoneityet]

My lathe is supported at only three points – well, two firmly bolted-down points and one which is nearly free-standing.

It just requires a shim or two on one side, or the other, of the tailstock fixing point (which is effectively free-floating because it is fitted with a spiral spring washer which should not be pulled down fully). I have never cared for the slope along the machine – it is what it is. The drip tray is also only 'levelled' to drain coolant/cutting oil/ lubricant away towards the drain.

As the lathe is adjusted as per manufacturer's instructions, I expect it is as good as those, with similar models, that go to great lengths to achieve a perfectly level lathe in every axis.

I think that too much technology is attempted to be applied to these small lathes. I can understand the need for more precision with a large lathe (one, where I worked was used for fairly precise shafts – probably over 6m long at times).

Or are the more modern lathes so far out of true that they need heaving back towards straightness?

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[Martin KyteParticipant @martinkyte99762]

Posted by Barrie Lever on 30/04/2019 15:39:28:

My experience is that a well levelled small lathe will out perform one that is bolted down badly, I would go as far as to say that a small lathe just sitting on a bench top is better than one that is badly mounted.

B.

True, but not better than one that is well mounted and set up.

regards Martin

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[not done it yetParticipant @notdoneityet]

Posted by Barrie Lever on 30/04/2019 15:39:28:

NDIY

The small lathes have beds that are elastic bands in a model aeroplane, they twist that easily due to clamping forces.

I think three point mounting is great.

My experience is that a well levelled small lathe will out perform one that is bolted down badly, I would go as far as to say that a small lathe just sitting on a bench top is better than one that is badly mounted.

B.

Barrie,

Mine is a hobby lathe, not a commercial one (although doubtless many have been used for business purposes). I class it as small, it being 5” centre height and 24” between centres. It is not, however, built like some of the pathetic chinese offerings. When it was made, it was built up to a quality – not down to a price.

[PlasmaParticipant @plasma]

My lathes turn parallel and are not dead level as I deliberately tilted them slightly to improve coolant drainage from the drip tray.

If being dead level is a requirement, how do engineers on ships and submarines manage? They use lathes for repairs and I czbt see any level being of use on the open oceans

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[Martin KyteParticipant @martinkyte99762]

Lathes don't have to be 'level but they do need to be supported in such a way as to not impose a twist to the bed.

In order to do this each of the supporting points need to sit on a plane just as the bed did when the ways were ground. The plane need not be horizontally orientated but if it is then a level can be used on the ways in order to check this. In order to eliminate twist using a level the supporting plane only needs to be 'horizontal' across the ways, the longitudinal or spindle axis doesn't really matter.

If I could comment on the subject of bolting down or not as I see it and using the Myford as a 'test subject' there are a couple of points.

The lathe bed was originally ground flat and true by bolting upside down and grinding the feet level. The bed was then flipped the right way up and bolted down to the bed of the grinding machine and the ways brought true, by definition in relation to the feet.

When the rest of the lathe is assembled which includes having a large motorising 'lump' bolted over the back of the headstock this imposes a twisting force as much of the weight is transferred to the rear foot under the headstock. Correct bolting to a suitable stand counteracts this force and further stiffens the bed casting against cutting forces. It will also add mass to some degree which will help with vibration. This is a good enough reason as any for bolting down in my book. The main thing though is without some positive means of adjusting he support arrangements, in my case levelling jack feet there is no way to actively bring the lathe into 'perfect' alignment.

You would be surprised at how 'flexible' small lathes are. The Super 7 bed is quite a sizeable cast iron lump but just try taking a finishing whilst leaning in the headstock and then take the same cut standing clear and you will see a fraction go missing from the diameter.

I appologise to all who know all this already but I hope this helps those who are still figuring it out.

regards Martin

 

 

Edited By Martin Kyte on 01/05/2019 09:19:09

[Rod RenshawParticipant @rodrenshaw28584]

Hi all

After reading many of the contributions to this thread I am thinking of buying a level to use for "leveling" my lathe, and also for setting work up on my mill.

There has been much input on this thread about the sensitivity needed for these tasks and I find myself confused by all the different "Units" quoted by manufacturers and advertisers.

There seem to be units based on angles such as degrees, minutes and seconds of arc, and also degrees and decimal fractions of a degree. Then there are units based on offsets, and here there are many different lengths of baseline and some use Imperial measures and some use Metric units.

So how sensitive does the level need to be? and can the answer be quoted in many units so that levels from different sources can be compared? It is almost as if we could do with a conversion table, anyone know of one?

Thanks to anyone who can clarify this.

Regards

Rod

[Clive FosterParticipant @clivefoster55965]

Rod

The Starrett Master Precision Level sensitivity is quoted as 10 seconds of arc per division. This corresponds to a slope of 0.0005 inches (half a thou) per foot or 0.04 mm (40 microns) per metre.

In my vernacular a total pain in the butt to use as the slightest touch takes the bubble out of view.

My old gunners clinometer, picture about the middle of page 2, is slightly less sensitive at 30 seconds of arc per division, 0.0015 inches (one and a half thou) per foot or 0.120 mm (120 microns) per metre. The divisions are approximately 2 mm apart so its easy to estimate 1/4 of a division. Being so small the clinometer can easily be reversed end for end so the effective sensitivity is doubled. In practice it runs a Starrett Master Precision level so close that any difference is more likely to be operator error than real.

The huge practical advantage of my clinometer that it has a screw adjuster calibrated in minutes of arc over a 5° range. Keeping the bubble in sight for any rational error is easy and tracking changes in level due to adjustments is almost trivial.

By far the easiest way to level a machine. If you can find one grab it and don't loan it out.

There are other styles of sensitive clinometer, most significantly less easy to use for this purpose, but all far less frustrating than a master precision level.

Clive

Edited By Clive Foster on 02/05/2019 21:53:44

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Barrie Lever on 30/04/2019 19:27:38:

Ah Plasma …

Level is not the best description, twist is what we are really talking about …

.

It may be useful to note that, in this context, 'levelling' is the process of using a level

[ rather like 'milling' is the process of using a mill ]

The term originates with surveying, where a level is used to quantify slopes, not to flatten them.

MichaelG.

[HopperParticipant @hopper]

And once you have got your lathe perfectly level, you should then do a turning test by taking a light cut over a piece of 1" diameter bar sticking four to six inches out of the chuck, with no centre in place. Any variation in diameter between the two ends of the bar can be adjusted out by shimming or raising either the front or rear "foot" of the bed at the tailstock end. See the Myford users manual for details on this. (Available free online as PDF).

In fact, might as well forget the whole level thing and just do this test. Especially with even a slightly worn lathe that is not going to have a perfectly flat bed surface to rest a level on anyway. 

At the end of the day, all that matters is that the lathe turns parallel, which this test establishes better than any other. In fact, it's the only test that establishes this.

 

Edited By Hopper on 03/05/2019 07:10:04

[not done it yetParticipant @notdoneityet]

Hopper is spot on. Levelling to the ‘n’th degree is clearly time wasted if the lathe then needs ‘unlevelling’ to make it cut a uniform diameter.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, yes the term "level" is a bit misleading in this context, the lathe will turn just the same upside down (just ask them down under) if fact it will be the same in a vertical position. The point being that the bed shears are on the same plain as each other, from the headstock to the tailstock, whether the lathe itself is tilting forwards or backwards or sideways. If you are using a level, all you need to observe is that the bubble reads the same at each end of the lathe bed when placed across the shears and the bubble doesn't even have to be within the central two lines. The turning test will tell you if it is correct.

Regards Nick.

[JasonBModerator @jasonb]

Coplanar ( in the same plane) is probably a better description of how each end should be.

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