Engineers level

Good grief Bob!

What are you going to make in your shed - space ships?

Norman

Edited By NJH on 03/01/2015 10:18:32

In a dream last night, the simple answer came to solve the lathe levelling problem! It was a technique to eliminate even the sag of a test bar and dramatically reduce any bending effects on the lathe bed due to is weight. I was thinking about Bob's large diameter tubular test bar and realised that if his tube had unequal wall thickness it would sag different amounts depending on its rotational position.

Unfortunately the technique will not work with all makes of lathes (Myford's with the little oil reservoir gadgets on the headstock bearings would be tricky but sealed for life rolling bearings should be OK), Long bed lathes in workshops with limited headroom would be a challenge too, but otherwise all we have to do is change the lathe orientation so that the main spindle rotates in the vertical axis.

Who is going to be the first to try it?

Ian P

Ian P,
Were you perhaps dreaming about MEW 224? By some strange coincidence there is just such a vertical lathe on the cover, courtesy of Jock Miller. Unfortunately its the wrong way up as its sited down under in New Zealand.
If you don't get MEW there is a preview description of the lathe on this site's home page.

Bob D

I tried that today but my major issue was how to find a center point for suspending the lathe end. Finally I tried a long bar through the lathe spindle with a monomolecular strand fixed to it's centre (a challenge in itself) but even then the tiniest draught causes the ways to deflect. I'm also waiting on local magnetometer readings in case tere might be some side load effect I need to allow for.

pgk

I have an early model Southbend lathe and this is the original instruction for mounting it on a bench.

A 3-point mounting system seems like a good idea, unless you can guarantee the accuracy of the lathe set-up. Bolting it down at 4 points will twist the lathe if it not completely level.

Paul.

Hi there, all,

I have a Rabone Chesterman engineer's level with a broken vial.

Thanks to this thread, I am now aware of a potential source for a new vial.

However, I can't see how to get the old broken vial out! The inner metal tube (that houses the vial) has end caps (or plugs) with flat extensions that are secured to the cast iron base by a screw one end and a stud and a pair of nuts at the other end.

My first thought was that the end caps (or plugs) are screwed into the metal tube but trying to unscrew them gave only an ominous creaking from the glass vial.

I'd prefer to get the old glass vial out in sufficiently large pieces to enable me to correctly specify the replacement!

If anyone here has trod this path before me, please, please, lighten my darkness?!?!

Just to clarify - I do mean Rabone Chesterman, not the one pictured up-thread one page.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 07/02/2015 19:41:00

Edited By Swarf, Mostly! on 07/02/2015 19:47:00

Swarf ...

Many of the old vials were 'potted' into the protective tube with a mix of Plaster of Paris and [sorry, I can't remember what ]

MichaelG.

If its only plaster of paris would soaking it water for couple days allow it to come out?

Hi there, Michael and Ian,

Thank you for your inputs.

I know about the Plaster of Paris but I haven't reached that yet!

I've got to get one or both of the metal end caps (or plugs) out first!

I need to know how they're attached - threaded, press-fit or what?!?!

Best regards,

Swarf, Mostly!

.

On most of the ones I have seen, the caps are threaded ... but you might also find some tiny grub screws [three per cap].

MichaelG.

It looks like Ketan has been monitoring our conversations as I see he's just started stocking 0,02mm/m levels!

**LINK**

Neil

The little 'Frame Level' looks rather nice.

MichaelG.

Without doubt the end caps of the tubular level will be fixed with threads and maybe a grubscrew to lock it in place. The bubble itself will as Michael says will be set in plaster of Paris. Under the bubble you will find a folded paper like a concertina. This presses the bubble gently to the aperture where you view it. The replacement bubble will have a dimple on one end and when you set it in the tube the dimple must be clear of the plaster of Paris so no lateral pressure can snap it off. Allow plenty of time for the Plaster of Paris to set hard, maybe a week or so as it will move the bubble as it dries. Clean any threads carefully and put the lightest smear of grease on them. To set up the bubble you will need an adjustable table to end for end the level as you adjust the bubble to stay in the middle when you end for end the level.Allow plenty of time for the bubble to settle as you adjust and do not touch the bubble ( Thermal shift)

Clive

Gentlemen,

Thank you for your inputs. I'll have another go and report back.

As to grub screws, the outer cover tube extends right to the flanges on the end caps - I didn't see any signs of grub screws.

Thanks again and best regards,

Swarf, Mostly!

If you are going to be so pedantic as regards getting your lathe bed level [ why I don't know, industry used the time honoured formula of a straight line drawn between two chip shops ] then just float it on a bed of mercury.

But this then raises the question if you get 4 points on the bed to within a eyelash of a gnats left bollock, who's to say the bed is actually level after 40 years being moved from A to B and then Milton Keynes.

The real reason is that it's actually more informative to talk about it than go out into a cold workshop and actually use the machines.

Edited By John Stevenson on 09/02/2015 00:08:06

A simple and cheap method to level a lathe with a plumb bob

https://www.youtube.com/watch?v=2qIdsnl5vpg

I always understood the point of the exercise was to get the lathe to turn parallel rather than being worried about its relationship with the local gravitational field. So I would expect to see it done with a test cylinder and dial gauge rather than a precision level. I would comment that one of the comics has described how to make your own precision level, I think it was ME but can't recall. I think also it was using the technique where a straight tube is bent slightly by applying pressure. Cheap glass tube may of course already be somewhat less than straight anyway.

There was also something written many years back in ME about the virtues of actually leveling machines, I think possibly by Tubal Cain. (Tom Walshaw) The advantage was more in the context of milling machines and shapers, where a workpiece can then be set up with the level. The level may not be on the face to be machined, it may be on some other face, perhaps even vertical. Or with a suitable sine bar arrangement, at some other angle. While I can see that this would be a workable method, I've never attempted to apply it.

John

Good morning,

A progress report concerning my Rabone Chesterman engineer's level:

I have now removed both the end caps (or plugs), the outer tube, the two end caps (or plugs), two small not-quite-flat leaf springs, sundry glass fragments, a folded strip of paper and several teaspoons full of powdered plaster of Paris from the inner tube.

The end caps (or plugs) were a tight press fit in the inner tube - no threads, no grub screws. Their flanges retained the rotatable outer tube with the two leaf springs providing friction to the outer tube. The springs seat in shallow slots milled in the back of the inner tube, one near each end.

I found no trace of a 'pip' on the wreckage of the vial - if there was one the p-of-P wasn't clear of it! Maybe the vial I've just removed was, itself, a replacement, fitted by an un-tutored repairer?!?!

Plaster of Paris seems to be readily available - I've sought a quote for a replacement vial. (The smelling salts are to hand!)

Pressing in the end caps (or plugs) when the repair is complete promises to be fun - the flanges need to be accurately in line with each other and when I wrote 'tight press fit' I meant it; the metal (chrome-plated brass?) inner tube was flexing!! I hope the mice haven't eaten my tallow ......

I've included the maker's name - other manufacturers' levels will be different.

Best regards,

Swarf, Mostly!