Quieting sheetmetal machines

[Brian Holcombe]

For no reason in specific I’ve decided it times to find a way to quiet down some of the machines in my workshop. I feel that my bandsaw (MM20) is needlessly loud, though it’s not due to anything mechanical that I am aware of.

I started this process so far by filling up the bottom of the main column with playsand, (poured into a plastic bag and sealed off). Knocking on the bottom of the column produces a nice dead thump. Next I will be lining the saw with CLD on all sheetmetal panels. Apparently even 25% coverage should reduce or eliminate the ringing produced by these panels when they are knocked on.

I also plan to line the interior of my jointer/planer and tablesaw. These machines are pretty acceptably loud but I’d like to see if I can knock them down a touch.

Perhaps it will do nothing, but perhaps it will do something. I’ve been spoiled by the few full cast iron machines that I have, but my understanding is that weldments can also be made exceptionally quiet.

Ive seen various approaches taken: granite epoxy is one, filling with pea gravel or sand is another, also filling with grout that doesn’t shrink and finally filling with silicone.

[Erik Loza]

What about cutting a hole or holes in the frame and filling with Great Stuff foam or something like that? Probably deaden just as well, without adding any weight.

Erik

[glenn bradley]

I happened on to some sheet magnet material. Not super strong but, has plenty of grip when in 1 foot square pieces for example. I stuck sheets of this to the inside of my jointer's cabinet, tablesaw and other machines with good result. CLD would undoubtedly do an even better job. I used the sand in a plastic bag trick on an old contractor saw and it moved the performance of that machine up a tier as well as deaden a lot of noise.

[Tom Bain]

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

[Brian Holcombe]

Constrained Layer Damper.

Erik, my understanding is that a damper has to have mass, so a foam probably won't do much.

[Warren Lake]

no subsititute for mass.

General jointer and bandsaw sound rinky dink compared to my old stuff. I lined the bandsaw with Dux seal long ago, never did the base figured id make a new one. Stuff comes in pugs or did I think about 5 lbs in a pug. Used it for other stuff as well. Dont remember which supplier it came from nearly 40 years ago but want to do it to some of my older stuff with 1/4" thick bases. They are quiet enough but could be more so, bang on stuff and listen for a tone. We also used stuff called Bituminus felt but its not right for the machines.

[Richard Coers]

Hotrodders use stuff like this on the floors. https://www.amazon.com/Kilmat-Deadening-Automotive-Insulation-dampening/dp/B0751G6TMV/ref=pd_lpo_263_t_2/189-9488967-7844438?_encoding=UTF8&pd_rd_i=B0751G6TMV&pd_rd_r=fd5dbb74-dc46-434f-a42e-94eb9a28ce44&pd_rd_w=yv5f6&pd_rd_wg=0KeVp&pf_rd_p=7b36d496-f366-4631-94d3-61b87b52511b&pf_rd_r=EB6QGS7CPP8W6GJWTV5M&psc=1&refRID=EB6QGS7CPP8W6GJWTV5M

I bought a lathe that had been set in machine setting grout. It almost took dynamite to get it out of the pedestals so I could reset the machine. Miserable crap!

[johnny means]

Plus one, on the mass thing. Sound is nothing more than our ears sensing movement. Make it harder for things to move and they make less sound. Foam has some ability to change acoustic properties, like resonance, but it doesn't really absorb energy as much as redirecting it.

[Frank Pratt]

The self adhering ice & water shield that roofers use works well to deaden sheet metal panels. It's quite dense & can be applied in multiple layers. If you buy it by the roll it's pretty cheap.

[Erik Loza]

Constrained Layer Damper.

Erik, my understanding is that a damper has to have mass, so a foam probably won't do much.

Gotcha’. The sand idea makes sense. Just thinking out loud: What if you poured a bunch of lead shot into the hollow frame? Not to the top, but maybe a third full? Basically, a dead-blow hammer for your bandsaw.

Erik

[Frank Pratt]

Gotcha’. The sand idea makes sense. Just thinking out loud: What if you poured a bunch of lead shot into the hollow frame? Not to the top, but maybe a third full? Basically, a dead-blow hammer for your bandsaw.

Erik

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

[Brian Holcombe]

Gotcha’. The sand idea makes sense. Just thinking out loud: What if you poured a bunch of lead shot into the hollow frame? Not to the top, but maybe a third full? Basically, a dead-blow hammer for your bandsaw.

Erik

That would probably work really well.

[Bruce Wrenn]

3M and others make sound deadening tape. Lots of up scale appliances use it. Same machine, only with sound deadening tape sells for a couple hundred dollars more, because it sounds sturdier. Wish the rear door on my wife's Suzuki had some in it

[Warren Lake]

go to home depot or a wholesaler better and buy 5 lb pugs of Duct seal. I did this 39 years ago to my first general bandsaw, with an audio back ground I couldn't stand the noise. This took the reverb time away.

Bandsaw is the same now as it was then, This stuff will do corners your other stuff wont. you can put it on 1/16 or 3/4 or whatever you choose you cant with the other stick on tape or roofers stuff.

13.00 for 5 lbs, Buy as many as you want to add

Or just sell it and buy a 50 year old Wadkin.

440619 440620

[Brian Holcombe]

Narrowly missed a nice Zimmermann saw recently....

[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 (https://sawmillcreek.org/member.php?116636-Tom-Bain)
file:///C:/Users/Ed/AppData/Local/Temp/msohtmlclip1/01/clip_image001.png 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/?coliid=I3RH0JMEMPKC7B&colid=2P8GBP5SU4LS7&psc=1&ref_=lv_ov_lig_dp_it

[mike stenson]

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

constrained layer damper. Basically it's a viscoelastic sheet that's constrained on both sides. You see this very commonly used in automotive audio applications, since sheet metal rings.

[Wayne Cannon]

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

I don't know what it is, but cars use something similar to deaden road noise.

[Tom Bain]

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 (https://sawmillcreek.org/member.php?116636-Tom-Bain)
file:///C:/Users/Ed/AppData/Local/Temp/msohtmlclip1/01/clip_image001.png Contributor

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

It’s funny because my Dad used to say in non-politically correct way “There are no stupid questions, just stupid people ... and the only way to not be stupid is to ask questions”.