Vibration isolation - machinery on wood frame floor
 

Old, wood frame office building needs 3-phase power to run the new elevator. The only space available for the phase converter is on the second floor. The electrician set the phase converter on a rubber pad and bolted it to the wood floor, which is now acting like a big sounding board. You can hear the vibration throughout the building.

I was thinking that some type of neoprene or rubber vibration isolating mounts would help, but I doubt that the mounts will solve the problem completely. Should we put pour a small concrete pad under the phase converter? I was thinking that the mass of the concrete would eliminate some of the vibration.

Any thoughts or suggestions?

There are accoustical consultants for just such questions. Thorburn Associates in Castro Valley, CA is one excellent one.

The Rectifier should have been placed on springs with the springs on rubber pads.

Danny

Brian Carlton posted a link to a company that does nothing but anti-vibration stuff, in any case he know mo bout vibratin than...

http://www.shocktech.com/products/products/products.html

I used a set of wire-mesh mounts on a crappy old washing machine that shook and vibrated like heck, in a manufactured home we lived in. Dampened things down pretty good. Bought them at Boeing Surplus, so you may check around at industrial supply houses in your area.

Some 20 years ago I worked for a guy that had a machine shop in his garage(it was a BIG garage), and all our machines ran off 2 converters that were mounted on the wall. Yeah, nothing like that 60cps drone on a wood frame building!:eek:

Here's an excellent source for advice.

Bot

http://www.eng-tips.com/threadminder.cfm?pid=384

The rubber mat undoubtedly helps to isolate the rectifire, but as soon as you bolt it to the floor, you provide a path for noise --rectifier frame to bolt head to wood floor.

Does the building have masonry walls?

If it does, it may be possible to mount it directly on the walls. To really isolate from a wood floor system seems a tall order if the motor is big.

The best way is to put a heavy pad of concrete under the machine and then probably also use the rubber isolation devices, I suspect.

If you have masonry walls and if you can put it in the corner, you may be able to add some steel beams and a concrete pad so that it does not bear on the wood floor system.

Tom W

All of the above.

Putting down a concrete pad works because it forces the vibration-causing unit to move the mass of the concrete. More mass = less movement.

Putting down padding eliminates or reduces frequencies in the range related to the mat density and transmits other frequencies (a sort of band-pass filter).

Springs act like padding but on a different frequency range.

John Doe devised a simple, elegant (and even sexy?) solution -- used breast implant gel packs to isolate vibrations from a turntable. Hydraulic dampers are extremely effective and can be made tune-able. There are commercial designs that combine springs and fluids -- on cars we call them, "shock-absorbers", but there are lots of designs for different functions.

I'm betting the problem you're looking to solve is 60 hz hum. I'd look for something hydraulic that attenuates the frequencies that cause the most problem.

First-pass guess.

B

Is this a roatary phase converter? Pages 1317-1320 of the McMaster-Carr catalog should have what you need. www.mcmaster.com

That's a nice website. Definitely worthy of a bookmark.

This site cost $7.00/month to join. And has alot of good info on engineering basics.

http://www.efunda.com/

I say you decouple it from the second floor and support the platform from the ground. So build some supports underneath, and then saw through the floor around it so you have it floating on the second floor. :D

Hell, just let it hang on the wiring.

Or do it like we used to when we had no money to fix our cars. Turn up the music until you can't hear it or feel it anymore.