Printing Press Footing
Printing Press Footing
(OP)
I'm looking at a possible project for a printing press that would require an insanely small deflection tolerance (0.03mm/m). I think there's so many things that could go wrong. Heck, the natural shrinkage of the footing concrete could exceed this. How would one go about getting a geotechnical recommendation to satisfy?
Not that I'm going to go after this one, but I am interested if any of you have actually designed for something like this and how you have approached it. Almost seems impossible with structural engineering tolerances.
Not that I'm going to go after this one, but I am interested if any of you have actually designed for something like this and how you have approached it. Almost seems impossible with structural engineering tolerances.






RE: Printing Press Footing
RE: Printing Press Footing
RE: Printing Press Footing
Would it be total settlement or differential settlement thats the problem.
I would think as long as the entire printing press and surrounding equipment settled at the same rate that might be acceptable.
RE: Printing Press Footing
RE: Printing Press Footing
RE: Printing Press Footing
I do agree that the temperature would need to be stable. The foundation has a CTE of about 10 so even a 10 degree temperature change would put it out of spec.
RE: Printing Press Footing
Maybe you can talk to the guy who wrote the specification and find out what he is after.
RE: Printing Press Footing
You could maybe put the equipment on a large skid with shim points where it sits on the foundation, then leave clearance underneath for a jack. Then you can jack the equipment a tiny amount up and shim it to make fine adjustments.
If the press isn't insanely large, you could probably attach some sort of screw jacks directly to the support points and adjust those directly.
RE: Printing Press Footing
Some advice if it's just a differential settlement issue. Put survey points in corners of the foundation. Survey the foundation right after the manufacturer balances the machine. That way, if the machine goes out of balance, you can resurvey and eliminate the foundation as the cause.
RE: Printing Press Footing
I hear what you're saying about getting a surveyor to measure the foundation. Even if I could find one willing to measure to that degree of accuracy (which I cant) I still see it as a can of worms that could be dragged into litigation.
The press manufacturer would come out and relevel once if there was a problem. But any more than that, it would be on the owners dime and the press would not be warranted. Crazy! One would think the press manufacturer would design their own rigid platform that could sit on some sort of pads that could sustain normal movement.
RE: Printing Press Footing
BA
RE: Printing Press Footing
1/33,333
instead of say
1/360.
Is that right?
If you could design a structure that stiff, settlement in the substrate would not affect it; it would just rest on the highest three points.
Mike Halloran
Pembroke Pines, FL, USA
RE: Printing Press Footing
It's a matter of timing so that shrinkage can occur as well as size for stiffness. There is a real premium for high strength concrete (a balance between Ec and shrinkage), low slump, low w/c and possibly superP, mass and delay in doing the work to let shrinkage occur.
It's a challenge and very costly... unreasonable specs have a price.
Can the proper elevations be maintained using a flowable grout under the equipment?
Dik
RE: Printing Press Footing
http://www.eng-tips.com/viewthread.cfm?qid=264282
RE: Printing Press Footing
Precision equipment is set by millwrights that make sure the equipment is aligned and functional according to the equipment manufacturers specs. It can be re-leveled later if there is a problem that affects the process operation, but the foundation must be rigid. The manufacturers specs are to make sure there is a satisfactory base to install and operate on even if the is some long term settlement, plus they get paid for adjusting the equipment of the rigid foundation.
Mass, minimal foundation deflection are the keys in the end. Concrete is cheap and rigid. I had a project where the proposed foundation (16'x40') for a heavy (40,000#) piece of equipment which had very strong cyclical vibrations. It was supported on piling and the foundation was originally about 3' thick and both the owner and the equipment supplier insisted on at least 6' thick because it was just some cheap concrete.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Printing Press Footing
Bob G.
RE: Printing Press Footing
I think just designing a huge hunk of concrete is a risky approach because at these tolerances nothing is rigid. Concrete shrinks even if you use SRA's. Look up self dessication. High strength concrete is VERY bad in this respect.
My approach would be steel H piles down to bedrock, to heavy honkin steel structure connected together with slip critical connections, and make the owner temperature control the entire environment.
RE: Printing Press Footing
Is there an elevated press platform?
Typically, the mat foundation is supported by drilled piers or auger-cast piles.
The Press Manufacturer always makes (crazy) claims/requirements which the contractor cannot reasonably meet. I can go on and on, but it is beyond this single post.
Basically, it needs to be reasonably stout (carry design loads, minimal deflection and settlement) and contractor has to meet the tolerances. In all the ones we have done, the worst case is the contractor may have to come back and grind some areas - but even though the Press Manuf. won't admit it, they have 'adjustable' bases that can tolerate some construction differences.
RE: Printing Press Footing