Leveling a Lathe on a floor that keeps shifting?

Hello all

I have a problem keeping my Lathe level in my shop. My shop is located in front of a major hi-way here in Toronto, and a few years back they added a few more lanes that come closer to the building I,m in. The foor in my shop has these big cracks all over the place, and I can,t keep the machine level. I can,t even keep my two car hoists level for anymore than about a month at a time.

I really need to find a way to stop this problem.
I have 12x37 chi-won Lathe,and need suggestions on what you guys would do in this situation, sort of moving of coarse. I was thinking maybe mount the lathe on a 1-inch thick steele plate, with some type of machine mounts under that. I don,t really know whats the proper method to remody this problem.

I have seen lathes sitting on wood planks in barns,and question how good that could be. I was in a guys shop this summer that was built like a boat house over the water. This guys repaired props for boats, and the whole place was made out of wood. The lathe in that shop was huge compared to mine , maybe so big it could resist twisting like mine.

Whats the fix for this guys? What would you do if you had this happening in your shop? Ever since this hi-way was widened, I having this problem.
Is there a fix, or am I just screwed?

Thanks in advance
Cheers Paul

yep... a steel plate would help, on top of a sand
pit cut into the slab to isolate it from the
resonance....

anyway , that's not a tank-sized lathe ...are you
having problems with runout/finish/whatever?

have you leveled it with an
.0005/ft master level? that sounds like a ~1500lb
machine, and the short bed suggests it doesn't
have much twist.

perhaps you could clue us in on the type of
problems you encounter from the vibes..

or ...maybe you have a crap floor to begin w/,
and there's no other fix but to repour.(in canada
it's probably 8"+ minimum thickness


good luck.......there's lots of answers here.
someone will have the right answer.

tnmg

Its not really a vibe problem, but a floor that keeps moving. I will first notice that I getting a slightly crappy surface finish,along with a few thou taper when turning down shafts. If ignored it just gets worse, till I re level it, and tweak it a few days later, then it fine again.

Its the worst in the winter months when the place is covered with ice and snow. In the spring is real bad too. I,m starting to feel like I,m sitting on top of a swamp.

With this hy-way so close to this building, I have been wondering if a big rig ever lost control could make its way through my front office.

cheers Paul

No machine has to be exactly level. It does have to have its precision parts in alignment and its principal axes is a single plane. We accomplich this be leveling.

I suggest you either find the three points (two on the head stock end and one on the tail stock ent) where the machine finds its own neutral
support and support it only from those points. Or pour an isolated reinforced concrete foundation (6" larger than the machine's outling by 1 ft thick) for it and level the machine on the foundation bolting it down afterwards. Then the foundation can shift and slide to the traffic, subsoil moisture, or frost heave taking the lathe with it without affecting the machine's alignment.

Don't bolt it to a piece of plate. 1" thick plate is pretty flexible compared to machine tools. If you want to build something good and stiff that would make your lathe independent of leveling, make a bulkheaded welded and stress-relieved steel fully enclosed box of 1/2" plate with boxed pedestals whose tops are machined and scraped to take the machine bed. But that's expensive. Better go with the isolated concrete foundation.

Paul,

And how about a law suit to your local highway commission (by whatever name) for "Severe, On-going, and Continious damage to your property."

Sounds like the engineers failed to take into account what road vibration would do to nearby structures.

My apprentiship was in an old (pre- Civil War (US version) brick building that had wooden floors made of stout oak boards, like, 4" thick by 12~18" wide by 40" or more in length. Obviously built back with original trees.

Anyway, over the years the local city had built roads around the place. In the prototype shop they mounted all the precision equipment on major-sized iron beam framse that had, for example, three leveling jacks on each side along the length of a lathe (going from the underside to the floor) with the "middle one" centered under the center of gravity of the lathe, not the mid-point of the beams. The Craftmasters did a general re-validation of the levelness (such a word) every two months and always check an individual machine before any major contracted job for that shop.

AS for the production shop, the three years I roated throught that company I never saw anything checked except a planer's bed and one really long-assed lathe bed.

If you do the law-suit or negoiation thing, consider having this (adjustable leveling frames) as a last-restort for negoiations.

i agree that machines don't have to be dead level.
don't know how big the machine you are talking about is but my smaller machines (mazak qt8's)
i drag around on skids for secondary work no leveling at all....if they ain't rockin' no worry.
sounds like your bed is twisting so the isolated
(and reinforced) cemant is the solution.
one other possibility is something between the bed and headstock or saddle is loose so the machine has to dead level or it starts to shift around 'cause the weight is not pushing straight down

Dont even try going after any DOT. My neighbors lost $100K worth due to flooding caused by 4 lane expansion and storm water handling problems. 1/2 doz. lawyers told him forget it, you cannot beat the state.

Thanks for the replys guys

After reading Forrest,s comments about mounting the lathe on three points, maybe that would solve this problem. My Lathe has a cabnet on each end, and a sheet metal thing in the middle welded to each cabnet. The cabnets have two ajustment bolts on each to level out the lathe. I have my spare chucks and lots of other stuff in these cabnets that add to the over all wt. With the 4-point ajustments on the base its hard to judge how much pressure is on each corner. Usually when I notice a change in surface finish I can grab the lathe and rock it, only to find that I have 3 out of 4 ajustment bolts touching the floor.

This lathe is a gap bed type, and because of this
maybe thats why its not as ridgit as other models without a gap bed. Do you guys think I should try and build a more solid stand for this lathe and see how that works out with a 3-point leveling set up? I have marked the floor around the corners of the cabnets, and the ajustment bolts have jam nuts. So I am sure that the machine is not skateing across the floor from vibration.
The jam nuts keep the bolts from backing out of ajustment.

Has anyone modded the stock stand , to make it a three pt, instead of the 4-pt it comes with?
Should I empty all of the heavy stuff out of the cabnets, so the wt doesn,t try to twist the lathe when the floor does shift?

On the last note, I don,t have ny interest in trying to sue anyone over the extra lanes put in on the hy-way. I am really starting to wonder if its a health concern being this close. In the summer months,at rush hour you can swear you have a car running , and the tail pipe is pointed at my office window the fumes are so bad. The fumes sometimes get bad enough that we turn the A/C off as to not pump it into the office.

Thanks for all the comments and suggestions guys

Cheers Paul

Maybe rigid is the wrong way to go since you say the floor is shifting. Maybe you want a "sandbox" on top of the present floor, maybe 6" to 8" deep and filled with pea gravel -- which won't compact. Then put the 1" steel plate on top of the pea gravel and mount the lathe to the plate. Leave a few inches clearance between the sides of the sandbox and the plate. Have no idea whether this will actually help, but the concept is based on the idea that a lathe mounted on the deck of a ship can maintain accuracy because the necessary parallelism is maintained even though the deck shifts. Good luck! Charles

This 'movement' of the slab suggests less than adequate sub-grade preperation. If you have frost heaving, then likely in the spring there is the potential for 'liquefaction' beneath your slab. Each condition will contribute to fractures and lateral/vertical displacements.

As a possible last resort consider four(4) footbearing or friction piers beneath the lathe mounting pads. With adequate depth (check with your local Soils Engineer), King Kong couldn't displace the individual pier X Y Z positions relative to each other. Regardless of slab movement, piers ISOLATED from the surrounding concrete will remain stable. Grout with a flexible material.

Is this same condition affecting your residence or other structures on the site? Are you on native soil? Engineered fill? Alluvial soils? High organic content? Do you have underground utilities to your shop that may present a problem with this shifting?

Each sub grade condition requires unique mitigation practices for a stable pad. Boring ! P J

Here's my idea of how to solve the problem. Don't take it as gospel, but if I had your problem, this is what I would do about it. I think to solve your problem you would need to use a triangular base with very short feet attached to the three corners. This base could be made from square steel tubing, and could have a square angle iron box fastened to the top of it for the cabinetry to nest into. I'm talking about the cabinets that your lathe is currently mounted to. You could put a plywood bottom within this square, that would be fine. The important thing is for the feet to be short, only enough to prevent the base from touching the floor anywhere. What will happen is that as the floor heaves, the base and the lathe on it will tilt left/right, and front/back, and may even rotate a little, but will not twist, except what little comes from the lathe leaning. I can't imagine the lean from your heaving floor being more than a degree or two, so this source of twist would be very slight.
What will also happen when the floor heaves is that the feet will have to skid to accomodate, because they are so closely constrained by the triangular base. Most all of the motion that would normally be sent up the stand as flex is relieved by this slipping of the feet on the floor.

Because this stand has only three feet, the two under the headstock should be as far apart as practical, front to back, to keep the whole thing vertically stable.

When levelling the lathe, the forces against the bed are transferred to and through the cabinets that hold up the lathe. The base will see some of this force, but an equilibrium will be obtained where the bed is correctly twisted or de-twisted as needed for alignment. This equilibrium isn't affected by the relative motion of the floor, but it certainly would be if the stand had four feet.

The third foot (under the tailstock end) would ideally be a wheel oriented to roll forward/backward. If it had some small room to slide left/right on it's axle, that would take care of the last possibility of the floor affecting your alignment.

As far as vibration goes, I think you'd want to make sure that the lathe's connection to the cabinets, and the cabinet's connections to each other and to the angle iron square on the base is very secure. Any motion of the cabinets within the base will definitely throw the alignment off. Other than that, I can't say what the long term effect on alignment would be. I know that the lathe needs to 'season' so as to arrive at it's own settled in condition, before any alignment can be anything long term.

I also would recommend a three point mount. Perhaps a frame or heavy plate under the lathe. I would put three levelers on that plate or frame to allow it to be leveled when the floor settles. The lathe is still mounted on that frame or plate in the normal manner (with four points of suspension).

Level the added frame. Then level the lathe on it in the normal manner. Now when the floor settles, you should only have to relevel the added frame to restore the lathe to proper level. It should not be necessary to do a perfect job of releveling the frame as any twist to the lathe on it will be much the same as when first leveled if the frame is brought back close to the original position.

They mount lathes on ships, don't they.

Paul A.

I would cut out a suitable section of the cracked floort...dig down a good bit BELOW reccomended "local codes" frostline...and install a fair sized footer, a nice big one. cement cylinder up to the new "floor", and have a nice reinforced thicker floow piece...leaving this small thicker floor piece de-coupled entirely from the surrounding floor.

The basic concept I am picturing is that everythign else can do what it wants, but this section will remain immobile.