Why do I want my milling machine to be level?

You mean:

"Why do I want my milling machine to be level?"

just so it is visible in the body for those whose newsreaders don't easily show the subject while reading or answering. (It is really a good thing to have the question readable in the body of the article.)

I can think of two reasons right off the top of my head:

1) If you use coolant, so the coolant runs out the drains back to the reservoir, instead of pouring over the lips of the gutters.

2) When setting up something awkward, and tying to get a plane on the workpiece parallel to the plane of cutting, you can use a level on that plane as you adjust the clamps and machinist's jacks and step blocks and other cribbing, instead of having to run an indicator over the surface after each adjustment.

Other than that -- it probably doesn't matter.

Enjoy, DoN.

You want your milling machine level so the oil doesn't run off of things, also because sometimes using a level is the only way you can figure out to do a tricky setup.

GWE

It's nice to have your mill level so anything you place on the table stays put........ DoN and Grant presented other good reasons. A carpenter's level is better than no level, although quite useless for a lathe.

Harold

I'd agree with #1.

With #2, I think that if the part required enough accuracy and precision that required you to use a master level (.0005"/foot or better) then you could probably set the part up faster using an indicator. Remember, you'd have to level on two axis and flip the level 180° (end for end) on each axis. And, that all assumes the head is trammed, and the table was previously leveled.

If the head were not trammed, and you used an indicator, you "merely" dial the part in to be perpendicular to the quill. Not correct, or best, but it would work for that set-up and be faster than using a precision level.

To the OP. Milling machines are mounted in ships at sea. They work just fine with the ships rolling around in rough water.

Connelly in _Machine Tool Reconditioning_ makes a big deal that the ways are precise only in the level orientation they had when aligned in the original factory (or any later reconditioning). Tilt introduces distortions.

To me, it seems like it would take a significant tilt to cause such a distortion, but I've never tested that intuition. On the other hand, it doesn't take much force to distort massive members by tenths of thousandths, which is where things start to matter in common precision.

When rescraping, precise leveling is important because the horizon becomes the reference for aligning parts that are otherwise unbridgable with measuring tools, or as a redundant reference for checking alignment. Also, the total range of a 0.0005/foot level is only a few thousandths/foot, so if you're trying to compare two surfaces for parallelism, the machine has to be carefully leveled to permit the measurement at all. It is a bit of a challenge to get the corners of the rough base of a massive 2000 lb machine like a Bridgeport mill at the right height within a few thousandths. But again, this is needed for alignment and scraping, not routine work.

I would expect that things like flatness, squareness, and overall precision are significantly degraded from what the same machine does when steady and level. Whether it is enough to matter would depend on the application, of course.

Simple...

It's so all your tools won't roll offa the table !!!

"Jim Dincau" wrote in news:26904$42bb6b1e$d1ddc120$15870 @QNET.COM:

Believe it or not, castings *will* twist and warp if not properly supported.

Because it's much easier to setup some jobs using a precision level or a clinometer.

This is only true if you have the right bits - the standard engineering levels are much too big to balance on small workpieces. I use a small 1 minute per division vial rescued from a war surplus gunsite epoxied to little magnet. Used slow setting epoxy and carefully monitored bubble position as it set.

I use three point mounting on my mill (Schaublin 13) with 1/2" adjusting screws on two of the three mounts so setting up is no problem.

I don't believe that reasonable deviations from level make any measurable errors in accuracy in machines of the size used in the home workshop.

Jim

So your beer doesn't fall off.

I agree. If they did...nothing that comes out of my dirt floored shop would be square

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

Honestly I've never found reason to use a bubble level to do setups.

I've always found that dial indicators and edge finders are sufficient for my needs.

Jim

I've been on about a dozen ships with machine shops and none of them had a mill. Most shipboard engineers wouldn't know what to do with one. The ships all have lathes, but they are for meatball work, no serious machining ever going on that I saw, matter of fact I was the only guy using the lathe, off watch just as a diversion. 4 months at sea can get quite boring.

Tony

Has anyone ever used a milling aboard a ship?!!!

Why would you _not_ want it level?