Quieting sheetmetal machines

[Wes Grass]

So when you swing that band saw, it'll really pack a punch

Or at least not bounce off the floor and hit you in the face.

[Wayne Cannon]

no subsititute for mass.

Two ways to minimize sound;
· More mass means the sound energy produces less movement, and therefore lower sound amplitude.
· Absorb the sound energy, I.e. convert movement into heat energy. For example, materials like rubber, soft gummy tar-like materials, or even a soft lead-like metal get warm when flexed, i.e., converting sound energy into heat energy.

For example, a common sound reduction strategy for rooms is walls made by sandwiching a thick rubbery mastic between two layers of sheet rock.

[Brian Holcombe]

The CLD took the tinniness out of the machines and feeling the panels provides that they are all ‘dead’ no more felt vibrations.

Next I think I will do the layer of mass loaded vinyl.

[Mark e Kessler]

interesting to know the results, I have a vibration issue in my panel saw i put 200 pounds of play sand in the base and it actually made it worse which I thought was weird so I took it out.

The CLD took the tinniness out of the machines and feeling the panels provides that they are all ‘dead’ no more felt vibrations.

Next I think I will do the layer of mass loaded vinyl.

[Brian Holcombe]

That is really weird. Worth trying this stuff out, not particularly expensive to line the interior of the machine with it. It's effective without covering the entire panel, so I think something like 50% coverage is good.

I used Kno Knoise from Knu Koncepts after coming across some 80 page thread on a car audio forum where the OP put together a test of practically every type on the market. This stuff was heavier than most of the other brands and more effective.

I lined the bandsaw (mm20), the jointer planer (FS41ES), the Omga cabinet, the router cabinet and the tables cabinet. I may also put rubber isolators between some of the motor bases and their pedestal on anything without a direct drive.

I plan to cover it with mass loaded vinyl just for a neater look, but if it helps with cutting the noise...even better.

[mike stenson]

CLD, sand, mass loaded vinyl, rubber isolation bushings.. starting to sound like an audio forum

All of these things make total sense to me, I'm totally interested in the results as you're moving along Brian.

[Erik Loza]

interesting to know the results, I have a vibration issue in my panel saw i put 200 pounds of play sand in the base and it actually made it worse which I thought was weird so I took it out.

I don't think it's as simple as just adding mass or even sand. Pretty much every Italian saw has a sizable block of concrete in the bottom of the cabinet (for ballast) and I never noticed it did anything about vibrations. Like Mike is saying, there is some science to the harmonics that probably can't be solved by just adding mass. I never thought of lining the inside of the frame with Dynamat/etc. but that's a great idea. Also, I think someone should try my lead shot idea. There are some aftermarket harmonic dampers for racing engines that use a series of loose rollers to absorb and dissipate crankshaft harmonics. I'm not an expert on any of that but the principle being that these rollers (or possiby lead shot) are free to move and vibrate, thus dissipating harmonics within themselves. Whereas play sand packs tight and might even transmit or amplify harmonics. Just thinking out loud.

Erik

[Brian Holcombe]

The play sand actually makes the column on the bandsaw not ring at all, just a dead ‘thud’ when I knock on it, I’ll be curious to see if it stays that way as it packs more tightly over time.
I’m sure Lead shot is probably the best in this regard but it’s a bit expensive at the moment (in high demand). On practical machinist one fellow suggested pea gravel and a few of them make a gravel/epoxy concrete or use non-shrinking grout, all seem viable.

I have a minimax T124 lathe arriving tomorrow so most of this thought has been due to that. I sold my T120
and one of my complaints was that once something started to vibrate on it, the machine did nothing to counter it. Bolting it to the floor helped by adding mass but it was never all that great. Whatever I fill it with has to be able to be undone later.

What I fill the bed with will depend on wether or not any bolts thread directly into it. I don’t want to setup a situation where loose sand that escapes the plastic bag basically locks every bolt in hard. So, a few hundred pounds of large caliber lead mixed in with some kind of filler material might be a better choice than sand.

[mike stenson]

FWIW, I use volcanic sand (the larger chunk version, not the fine stuff, about 1/4 the size of pea gravel(isn)) in speaker stands. It's cheaper than lead shot and is dry (dry being the most important thing). I think pretty much anything that causes vibrations to dampen works. So, pea gravel in stands sounds like an almost ideal cost/benefit mix.

[Bill Dufour]

Do not use sand use pea gravel or steel shot. If the sand leaks out it will get everywhere and abrade any moving parts.
I paint the inside and under the table tops with water based roof seal. Several coats can build thickness fast. I suppose you could mix in sand to add mass. Much easier to paint then to cut and glue sheets of anything.
Bill D

[Brian Holcombe]

I’ve been adding to to areas that it can’t leak into moving parts.

Mike, thanks those are some good ideas.

[Andy D Jones]

Two ways to minimize sound;
· More mass means the sound energy produces less movement, and therefore lower sound amplitude.
· Absorb the sound energy, I.e. convert movement into heat energy. For example, materials like rubber, soft gummy tar-like materials, or even a soft lead-like metal get warm when flexed, i.e., converting sound energy into heat energy.

For example, a common sound reduction strategy for rooms is walls made by sandwiching a thick rubbery mastic between two layers of sheet rock.

In many machines, excessive noise is caused by part(s) of the machine resonating at some frequency produced by vibration elsewhere in the machine. Shifting the resonant frequency of the part(s) so that they no longer resonate at the excitation frequency can dramatically reduce noise. That can be done by adding or reducing mass, increasing or reducing stiffness, etc.

Typical sound absorbing materials may not work well, especially if the excitation frequency reaches the resonator through the structure, rather than through the air. But properly applied, they can prevent the resonator from transmitting sound to the surrounding air.

You can often tell when a sheet metal piece is resonating, by holding your hand against it with some force. If that reduced the noise, then that panel is likely a/the resonator causing at least some of the noise you heard.

Stiffening a large sheet metal panel with wooden battens is simple and often effective. Try to span the middle of the panel with the batten(s), and keep the fastenings fairly closely spaced, if not continuous (i.e. adhesive).

-- Andy - Arlington TX

[Bill Dufour]

truck bed liner is also a good coating. tar based underseal, not in my shop!
Bill D

[Ed Edwards]

Thanks Tom Bain!!!

So many times I've seen posts that the author must think all readers have an infinite knowledge of all acronyms. Not knowing what it is, I waste time going to Google and searching through pages of possible results.
I would rather see the actual words followed by the acronym when used initially, and just the acronym further in that post, and subsequent posts.
Just my two cents worth, and, maybe helping other readers.

Thanks, Ed

Tom Bain
[IMG]file:///C:/Users/Ed/AppData/Local/Temp/msohtmlclip1/01/clip_image001.png[/IMG] Contributor

What is CLD? Not a 3-letter acronym I’m familiar with

[Tom M King]

I lined a tractor canopy with this, hood and other, smaller sheetmetal panels with similar heat resistant stuff, and it made enough of a difference to be worth doing, even wearing ear plugs.

https://www.amazon.com/dp/B07QW2RL2Q...v_ov_lig_dp_it