The purpose of leveling machinery

[blue_luke]

Hello all the good people at the Hobby-Machinist forum

I am am in the process of moving my machines to a new little shop in the basement of my new home.
The lathe is a Precision Matthews PM1127vf.
I built a base for it consisting of hockey pucks adjustable feet set at the ends of 2X4 steel tubing. The two cabinets making the base are resting on 1/4" aluminium plates bolted to the beams. This way it raises the height of the machine to what I feel is a more convenient height and allows me to set the base level to avoid any twist in the lathe bed. I use a precision level for this and the results are as perfect Ican achieve.

Now to the question: I will move my small mill (PM-25) wich also have a 4 point levelling system, and I am getting a new PM-833t (900lbs!) for which I have to build a base.
I will set those machine as perfectly level as I can, because I can and care, but I fail to understand how important it is to get the mills perfectly level.

In the same string of thought, how important it is to get a granite surface plate perfectly level?

hanks, Luc

 

[Bob Korves]

The only reason to get a mill or a surface plate really level is so round tools and workpieces do not roll off, and so you can use bubble levels for setup help. On a mill it might help to get oil where it needs to be. None of this is critical.

 

[Cactus Farmer]

Also being level helps the shiney bits direct the light right into you eyes at those awkward moments that can set the stage for your whole day.
Round tools like not bouncing off the floor too!

 

[Ray C]

When I setup my lathe, I made it ever so slightly un-level such as it was not noticeable but, would allow fluids, ball bearings etc that fell in the drip pan to roll forward for easy clean-up and/or retrieval.

It's quite possible that forcing your lathe to be perfectly level will interfere with it's ability to cut straight. The bed needs to be flat and coincident to the axis of the spindle; this means you may need to shim the bench legs to get it that way -and in so doing, the lathe might not be perfectly level.

The above mainly applies to lathes and not so much, mills.

Ray

 

[tjb]

Also being level helps the shiney bits direct the light right into you eyes at those awkward moments that can set the stage for your whole day.
Round tools like not bouncing off the floor too!

That's funny!

 

[Dan_S]

The reason you level any machine tool, is because you want to use level as a reference.

 

[Larry42]

Strange as it seems, cast iron will twist . So the bed of a lathe needs to be leveled both directions. It really isn't the level to the earth that matters, that's just a reference plane.
Someone commented that surface plates don't need to be level either, also true but they should be supported in the same way they were when ground. Usually a 3 point support so no forces are introduced into the plate. Look on the bottom side for the original support locations.

 

[Taborclock]

As stated above, cast iron will twist. Leveling will make sure pressure is distributed equally on an even plane. My question is; How is this done when installing a large lathe in a ship, as is often done ? Any Machinist Mates here ?

 

[Dan_S]

As stated above, cast iron will twist. Leveling will make sure pressure is distributed equally on an even plane. My question is; How is this done when installing a large lathe in a ship, as is often done ? Any Machinist Mates here ?

Some lathes only have 3 feet so you don't have to worry about twist.

On ship I vaguely remember my grandfather talking about about using wires pulled taught between bulkheads, and feeler gauges.

Edit:
Now days they probably just use lasers and optics.

 

[Taborclock]

I was wondering how it was done back in the day.... Thanks...