Levelling a lathe?

Michael,

To measure +/- 10 degrees at .02/m you need a vial about 7m long (depending on how much measurement you want either side of 10 degrees! (Vial has an internal radius of 10m more or less for).

Mark

That's about where I got to, Mark

... But John's definition of 'sensitive' may differ from ours.

MichaelG.

.

Ref: .... "It wouldn't surprise me if that one was ok at 10 degrees at as described. I'm not sure what it was doing with the Pultra." [Ajohnw]

Edited By Michael Gilligan on 28/08/2016 11:42:41

Did you get as far as finding out the tube would be about 1200mm ID at the thickest section?

Mark

I suppose a 7m diameter spherical (bulls eye) with concentric markings would be useful for seeing exactly what was going on?

Mark

Its also going to be heavy (if filled with ethanol) at roughly 3.8 tonnes without the vial glass or housing.....

(4.8 m3 internal volume for anyone wanting to know how I worked that out)

Edited By Mark C on 28/08/2016 12:02:09

What temperature would that be at?

.

Apologies for for my temporary absence, Mark

[pies and mushrooms had to be procured from the market]

At that weight, the natural 'sag' would be phenomenal

... a very well-designed supporting structure is required

... does anyone here have decent Finite Element Ananalysis tools and/or plans for the Forth Bridge ?

MichaelG.

Yes Michael, I do have a pro FEA package but I have no intentions of trying to set it up for that let alone wait around for the results! Sag might start to be dealt with by perching the thing on it's Airy points for longitudinal deflection but hoop stress etc might be more of a problem especially if the vial is constant section? This could be an interesting problem for an engineering course (perhaps not beginner level)

Hopper, 20 Celsius? or perhaps it might be different on whatever planet we are working on - this is clearly not of this planet....

Mark

PS. Hope the pies and mushrooms are nice or are they a reference to the way this conversation is going?

.

The pies are real, Mark

... But unfortunately the seller doesn't do Desperate Dan's favourite.

**LINK** https://goo.gl/images/0w5X8S

MichaelG.

You adjust it for 10 degrees in one direction and if the vial is large enough it wont matter if it's tilted 10 degrees in the other direction.

I would have thought that was pretty obvious and did mention adjustment. It really would need adjusting if there was a 10 degree slope across the bed and probably wouldn't go that far.

John

-

John,

I think you are missing the point.

... Let's just call it a day.

MichaelG.

Not according to DSG, they do like it level and you only have to fix it if you are a purist/ heavy duty man and then it requires 6 holes in the garage floor 12 inches deep by 4 inches square.

I have spent sometime with a too short 22mm spanner levelling a lot of lathe and indeed its now test bar time. Not sure if the image below will be the right way round - usual problem.

How do you level the bed of a well used 30-year-old lathe that inevitably has a few thou of wear more on one shear than the other at the headstock end where the saddle is mostly used? It's not uncommon for  the front shear to be worn down by five thou in this area, enough to send a sensitive level absolutely loopy.

Edited By Hopper on 31/01/2017 23:31:24