If you have a levelled machine you can use a level or angle setting device clinometer etc on a job which has no way of using the bed to work off. If you are using coolant it should run off the correct way if the machine is level.

David

Well I would say yes, but only because I sometimes use “gravity” as a handy reference for some set ups. When I am not going for a very high level of precision, it is handy to use one of those electronic level gizmos on the work to indicate that you are more or less horizontal or vertical or at any desired angle.

I am also working on some tooling for cutting valve seats where I am going to use a circular spirit level located in the valve guide to indicate that the valve guide bore is vertical – if the mill is also properly levelled, I can assume that the valve guide is then aligned with the mill vertical axis……more or less.

If you set everything up from the table i.e. the mill only references itself, then it doesn’t matter.

Ian

I've never even thought about it let alone measured it, so for me it's of zero importance. The CNC mill sits on a welded steel tube stand. The base is shimmed to the stand so that mill is trammed. The manual vertical mill (Bridgeport) sits on the concrete floor but isn't bolted down. The head is trammed. The horizontal mill (A&S 2E) just sits on the concrete floor; at nearly 2 tons it's not going anywhere.

Andrew

I gave that a lot of thought, so 1st thing comes to mind is a ship with a workshop.

My mill is level for coolant reasons and ease thereof(Not 100% accurate), if coolant design is to flow with mill table level, but I will not use that for any accuracy achivements, seeing the indicators will be more specific and accurate and more easy, than using spirit levels. Using spirit levels(Digital) you zero it and work relatively,

I think any reasonably flat and level floor would be good enough for a mill.

As Michael points out mills don't need 'levelling' in the same way as a lathe might to straighten the bed, and I've never set a workpiece with a sensitive level. Partly because I didn't know until now it was a way of working, but mostly because my mill is trammed relative to the table, not the floor.

Starting by levelling a structure is always a 'good thing' whether it's a house, factory chimney or machine tool. They're designed so the forces due to the weight of the structure itself and whatever loads are applied to it are transferred to ground without causing the structure to bend or topple over. When a machine tool is set up for accuracy, making sure it's level on installation ensures any further adjustments aren't distorted because the machine is tilted, which saves a lot of fiddling. But I doubt levelling is a priority in a home workshop.

Dave

I have to agree with other comments, on the mill a sensitive indicator is the way to go. If you want to use a level and the mill has moved then everything has to be put on hold until the mill levelling is rectified. On a floor with any give then a heavy vice or rotary table with a large workpiece mounted in it will change the levelling as the masses are moved from one side to the other. A suitably sensitive level will detect this and it will soon become an annoyance.

Martin C

Dave, Andrew, Martin

I only mentioned it because it was demonstrated to me by one of the tool-makers at KODAK, best part of 40years ago … IF the machine is suitably massive and stiff, AND the foundation adequate, THEN it can be a useful time-saver.

I have no intention of promoting the idea, I have simply seen it in use.

MichaelG.

Glad you did – most of my learning comes off the forum and the magazines. Still plenty more gaps to be filled!

Dave

Having adjustable jacking screws is a great help to stop any rocking about, but its up to the individual whether to get it exactly level or not. Some mills are deliberately tilted to allow faster coolant draining. Both of the mills at the museum are fixed to the concrete floor using studding and chemical anchor resin. They are raised about 4" with wood and bolted. The relatively high centre of gravity is a factor, and they both are close, but not exactly level in either plane, so a cutter laid on the bed would not be in danger of rolling off. I have recently got one of those little square electronic levels to set things at an approximate angle. I do have adjustable angle plates with scales that have had their zero marks added by using a spirit level, I just matched the bubble deviation to that of the bed.

I would suggest levelling any equipment on a wooden floor is a waste of time. My whole shed expands and contracts with the weather so I’m sure this affects the wooden floor as well, even sat on a concrete base. I’ve not bothered levelling any of my machines over the years and it doesn’t seem to have affected my work. I suppose if you demand extreme accuracy levelling might well be important though, that being the case I’d mount through the wooden floor onto the concrete.