Bridgeport Mill Leveling

[Marc M]

We often overdo a project just to make it look good and us feel good...

Uhh, yeah.
Besides, since when do home shop guys worry about overdoing a project? I knew a guy that would make pipe nipples out of bar stock rather than buy one for a tenth the cost. When I asked him why he said "Cause then I wouldn't have gotten to make it".

[Timleech]

Uhh, yeah.
Besides, since when do home shop guys worry about overdoing a project? I knew a guy that would make pipe nipples out of bar stock rather than buy one for a tenth the cost. When I asked him why he said "Cause then I wouldn't have gotten to make it".

Guess what I was doing earlier this evening?
Yes, making a 1" pipe nipple out of bar stock
Actually with good reason, I wanted one in bronze & reckoned it was quicker to make it than hunt around to find where I could buy one etc.


Tim

[Steeltoe]

Anything with 3 legs is much more stable than 4.That's why camara tripods,lathe beds have 3 legs.You cannot unbalance things with three legs,unless you tip them over.All of my mills just have little wooden wedges under the casting to keep them from rocking.

[Timleech]

Anything with 3 legs is much more stable than 4.

That's why Sir John is so fond of Reliant Robins

Tim

[pcarpenter]

I know that level is not that critical, but not having a 2000# rocking horse is what I really want to accomplish. Solidly mounted machine tools cut better in my opinion....plus I am just anal and hate to work on rickety stuff.

I agree that tripod mounting would probably be the best provided the three points were in correct orientation with what I will call the moments of inertia (God forbid it ever really rotates ) of the mill. The thing is a rather unwieldy shape and its balance changes as it is used, further making having a stable mounting useful. I am not sure the relatively small base footprint on this mill really makes it a good candidate for tripod mounting, however.

The base of the Bridgeport has 4 "high spots", one at each corner that are unfortunately several inches wide. The trouble with shims as I have been using them is that because each corner is actually a long contact area that wraps around in two dimensions in a plane, there is no good place to stick a shim and not make the whole works a little tippy in yet another direction. Forget square and plumb....you still end up chasing the ability to rock the whole thing, around in a circle, as you insert a shim in a new location. The problem exists because the shims are not tapered to exactly fit the pretty much unmeasurable tapered gap at the corners....and because it is four point contact instead of three. I think this is the reason that mortar is often used on these once they are positioned.

Mcgyver's three point barstock wedges (if I understand it correctly) is probably the wisest way to deal with this, but I will likely go ahead and drill and tap the existing bolt-down holes and use the bolts minimally to just make the whole works stable. I was just paranoid about having the mill standing on what amount to 5-6 inches of unsupported bolt. They have to be that long due to the thickness of the hollow base. I don't even have the thing fully assembled, and already I have moved it a small amount three times to make it better fit its space. The ability to quickly re-stabilize it as it occupies a different section of uneven floor will be nice.

thanks for all the help!

Paul

[ralphe]

I installed leveling feet (see photo)under my mill some years ago. The plate is made of 1/2 inch aluminum and has grooves which accommodate the base of the mill milled in the surface. The socket head cap screws are used to do the leveling. They "bite" into the concrete floor and have kept the mill from moving.

[Virgil Johnson]

The holes in the base should already be the correct dia. to be tapped 3/4-10. Tap the holes 3/4-10 and use all thread rod to make levelers with a jam nut on top. You will have to make an extension for the tap in order to drill the rear holes. I don't worry much about level I just can't stand for a mill to rock back and forth on a high spot.

[kap pullen]

When I level a Bridgeport, or similar mill, I set the level
diagonally in line with the two OPPOSITE leveling screws or pads.

This allows me to work opposite sids togather, similar to using a four jay chuck.

I find the high screw or pad, jack, or shim it solid to the floor.
Then shim, or jack, to bring the opposite pad up level.

Now your machine is like a see-saw, and a simple job to align the other sides level. Shim, or jack, the low side level, and pack, or jack, the remaining pad solid with shim.

You may, or may not, have to re-shim the first two pads.

I pulled this stunt at work leveling four machines over lunch break to piss off the mantainance crew.

They would drag this job out over a couple of days.

Try it, you'll like it!

-------------------------------------------------

I would not use rubber pads if you want your machine to remain level.

Each move of the table will change the weight distribution, resulting in changing the level of the machine.

Kap

[pcarpenter]

Kap-- that's a hugely good idea (levelling across two dimensions simultaneously) and I much appreciate it! That in conjunction with getting point contact for adjustment instead of the problem I mentioned should really help in not chasing level in circles.

Ralphe-- that is a really clever design that also deals with the problem I mentioned about the way the base contacts the floor, and if I can round up enough material, I may go that route at some point. It offers the advantage that the mill is a bit up off the floor in sitting on the plates. If I need to move it, this makes getting bar stock under it even easier.

I'm an amateur and haven't had the volume of experience levelling machinery you can get in industry, but sure did spend a while levelling my import lathe. It was a real exercise in frustration. It had 6 feet--4 under the headstock and 2 at the tailstock end of the base. Getting consistent contact without pulling it back out of level was really difficult.

This thread has produced even more information than I had hoped. Thanks to all who offered suggestions.
Paul

[Karl H]

My Bridgeport vertical mill has been moved around the shop so many times I've given up count. The simplist method I use to keep the thing from rocking is to make two or three aluminum wedges. .750 thick about 3 inches long and 1 to 1 1/2 inches on the high side. While rocking the mill; I just stick these wedges under the open spots under the column and bang them in with a hammer. They stay this way for a good while. -K-