Dampen Workshop Noise with Paper Pulp and Kool-Aid — OH YEAH!

noise dampener

If you’re fortunate enough to have a garage and a workshop, you probably also have neighbors. The truly blessed must work within the confines of an HOA that restricts noise, porch couches, and most types of fun. [Mike] is among the truly blessed, and when he decided to design a cabinet for his CNC equipment, he took noise dampening into consideration.

[Mike]‘s design isn’t a blanket noise dampener; it’s specifically designed for the high-pitch symphony of his router, compressor, and vacuum. He also sought to avoid vibrating the cabinet. To achieve this, the sound-dampening panels are hung on eye hooks with a 1/2″ gap between them and the frame. The backer boards are cut from 3/4″ plywood. [Mike] considered using cement board, but thought it might be overkill since he plants to shell the cabinet in a layer of 3/4″ plywood.

The deadening material is paper pulp made from various shredded papers. After soaking the shreds in water and blending the mixture to an oatmeal consistency, he drained most of the water through a cloth bag. Then he added just enough wood glue to hold the pulpy goo together. The tropical punch Kool-Aid powder isn’t just for looks; it provides visual confirmation of even glue distribution.

[Mike] made some tape walls around the edge of his backer boards to hold the mixture in place and painted on some wood glue to hold the pulp. He spread the tropical concoction to 1/2″ thickness with a tiling trowel to avoid compressing it. The peaks and valleys help scatter any sound that isn’t absorbed. Pudding awaits you after the jump.

http://www.youtube.com/watch?v=6-X-6becj-M

Comments

  1. Sven says:

    Another even cheaper colorant is actual color, with the added benefit that you can find out exactly what it is and if it will interfere with the glue… I thought “Kool Aid” was a hackaday joke, didn’t think anyone would actually add a drink mix with unknown contents to glue…

  2. bigbob says:

    Or he could use any number of other things that don’t contain sugar to add color. I’d be concerned with ants, mold, etc…

  3. David says:

    Seems like a lot of time and work to go through when you could just buy sheets of foam and cut them to shape… I understand the poverty effort, but how long is this going to last? Most wood glues are organic in nature and tend to start crumbling after a few years.

  4. pcf11 says:

    In the daytime folks should be able to make as much noise as they want to. Although I suppose if one wants to pursue a noisy activity at night then some sound proofing might be in order. If you think about it the whole disturbing issue is somewhat ironic. Someone thinks nothing of disturbing someone else, to inform them that they are being disturbed.

    Get off my lawn!

    • mincedmincemicemuttonmeat says:

      Night shift exists.

      • pcf11 says:

        The majority must take precedence. Folks working odd hours need to adjust their lifestyle accordingly. This is so blatantly obvious I cannot believe I even have to say it.

        • Xyroze says:

          …And someone running loud machinery all hours of the day, every day of the week is going to get repeated noise complaints.

          Just because the majority of the people are awake doesn’t mean you get to bother everyone. Other people deserve to be able to use their yards to entertain friends and not be drowned out by the constant buzz of your stupid tools.

    • static says:

      Build in any style you want and paint it any color you want; I can’t care because I don’t have to stare at it. However I can’t escape any noise or odors you might make. Neither can those who work the morning tower. Take such operations to the industrial area where where such noise is the daytime norm, pack along a kitchenette, sofa bed TV etc., you’ll be fine as long as you don’t complain about any nighttime noise that may be the norm as well.
      Stay out of my ears and/or nose.

      • pcf11 says:

        I’ll take you into consideration just as soon as you start paying my way in life. Until then get stuffed.

        • Markey1979 says:

          @pcf11

          I will let you know when there is a house for sale on my street. I live about 30 minutes north of Philadelphia. You can make all the noise you want, until about 10pm, then people care, but it can’t be more noise then my neighbors garage band……

    • Mike says:

      I live in a nice neighborhood with nice neighbors that maintain a quiet atmosphere that I appreciate myself. I doubt my neighbors would mind occasional noise from power tools for projects here and there but I intend to get more routine use of my CNC and air compressor and for long periods of time. I’m just being considerate.

  5. Even though you’re using a material that needs dampening prior to application, the intended effect is to damp the noise in the workshop.

    Dampening is the result of a liquid leak, damping is reducing and/or controlling a process’s intensity, ie: http://en.wikipedia.org/wiki/Damping

    But despite the naysayers, I think it’s a simple solution to reduce the impact of a noisy tool. :)

  6. Waterjet says:

    Uhh, isn’t this a huge fire hazard?

  7. To hell with the neighbors, just to cut down on the noise within the work shop for your own benefit. I know that part of having power tools is dealing with the sound they make but come on! those things are loud and any reduction would make using them a little less taxing in the long term.

  8. belg4mit says:

    White glue and borax would have worked. The borax would serve three functions: cross-link the PVAc (will do this with wood glue too, but that’s thick enough as is), serve as an anti-pest agent, and depending on concentration a flame reatardant; it’s used blown celluslose insulation for properties 2 and 3.

  9. modmanpaul says:

    I just built a sound proof enclosure in my dog grooming bus and while I opted to just buy roxul safe and sound for the major deadening part I also learned a few things along the way. One was that mdf is a million times better at sound deadening than plywood. Rigid foam is useless, and a decoupling layer of rubber sheeting or similar is even better than air gaps.

  10. Seems like a lot of work for not much effect (check out the video).

    A much easier choice would be fiberglass insulation with the fuzzy side turned inward. You’ll need something fine-weave (cheap carpet works) to keep the fibers from shedding into the space but I guarantee it will absorb enormous amounts of noise, especially high frequency noise.

    But HF noise dies out in the air quickly, I doubt that’s what would set off HOA alarms. But simply making it airtight will kill most HF noise. He’s also got a low frequency noise problem. That buzz that rumbles out of the space in all directions will be the thing that drives the neighbors nuts. So I have one more trick: leave an inch or two air gap between the paper and the outside wall and it will absorb a ton of low-frequency noise, too.

    I built a recording booth with these tricks and was able to record my guitar amp at insane volumes, even at night, without bothering the neighbors.

  11. t-bone says:

    He’s still using the plywood frame of the cabinet as a speaker. I agree, a lot of effort.

    I work next to a big air turbine whose scream is literally deafening. My door is covered by maybe half an inch of foam and then a quarter-inch rubber mat facing the noise. Don’t have more exact information because I’m not at work, but it works like a charm.

  12. Pirate Tom says:

    Noise dampening. Heh. I’ve been reported as a terroist event. Ah, good times.
    (and no local noise ordanances thankfully)
    Anyway, it looks like he had a lot of fun figuring out a unique way to accomplish what he wanted to.

  13. Jelle says:

    “[Mike] considered using cement board, but thought it might be overkill since he plants to shell the cabinet in a layer of 3/4″ plywood.”
    Too bad, as weight is one of the components of a good sound deadening setup. Heavy walls will not vibrate as much as light (foam) ones. A layer of foam or other flexible material to mount it to your frame or walls should be there to absorb the vibrations before they transfer into the structure.
    So, if he had used cement instead of glue to bind his woodpulp together I think he might have had something far more useful.
    There is always next time I guess.

    • Blue Footed Booby says:

      He can always just pile more soundproofing material over the paper. Then he could put more on top of that until the room is totally filled. Can’t be noisy if you can’t get into the room to do anything. :V

    • Mike says:

      Cement board instead of plywood would make the sound dampening much better because of weight but I opted against it because I already had a heavy wooden cabinet around it. The panels work on two separate principles with the two layers though, the heavy layer (plywood or cement board) are used to absorb heavy vibrations from lower “shaking” tones and is why the boards are free hung. The cardboard layer is more effective on high freq noise and cant be too firm or it will just reflect the noise making it an echo chamber so I dont think using cement in the pulp mixture would have been a good idea.

  14. You can use foam rubber like used in upholstery, it is very dense and its construction blocks noise well. Speaker makers often use polyfil , sold in craft section for stuffing teddy bears, and that works great but hard to apply to a walled area. Quilt batting is another option, basically polyfil in a roll.

  15. gradyplayer says:

    I would have liked to have seen some sort of fire retardant … commercial cellulose insulation is pretty cheap, and is inspected by people who have jobs inspecting insulation (for flammability, pest edibility, etc )… also the most important thing in sound proofing a room from the outside is a mechanical de-coupling of the 2 walls… google staggered stud wall…

    • pcf11 says:

      I worked with some fireproofers as a laborer once. One guy said the stuff is safe, then started eating it. I wouldn’t consider him a pest though, he was a pretty likeable guy as I can recall.

    • Mike says:

      Gradyplayer; are there any mix-additives or post-install additives you would suggest for flame retardants or are you just saying fiberglass and rockwool only? Just for note; The mix, once dry is fairly dense and although it does burn, does not burn very well but I am definitely not against adding another layer of protection. Also, the reason I hung the panels is the mechanical de-coupling you mentioned.

      • pcf11 says:

        Stay away from rock wool. That stuff burns! I do not mean in the flame sense either. Rock wool is like the nastiest material from the seventh circle of Hell if you get it on you, or breathe any in. It is so friable it is like weapons grade anthrax that way too. The stuff makes asbestos seem positively benign. I guess when it is not old it isn’t too bad, but it seems to get brittle over time. We called it rotten cotton on the job site. Sometimes we’d go home with our noses bleeding because of that crap. Some of the worst material I have ever had the distinct displeasure to work with. I learned to handle bats of that crap like it was nitro glycerine for fear of getting any of it airborne. I swear it was like someone had a blowtorch and they were passing it over my body. It would get into my pores and then I felt as if I was on fire. I am not joking, or even exaggerating. I can’t even believe that stuff is legal it is so horrible. But I never installed it, I only ripped it out. So I only messed with the old rock wool. I figure new it can’t be as bad as what I’ve experienced. I mean it just can’t be, or no one would install it in the first place.

  16. Thinkerer says:

    I’ve built sound deadening cabinets as well but find that fiberglass insulation is the best/cheapest/simplest route – a layer of screen over the open face typically keeps skin contact down and noise damping up, and anything you can do to provide acoustic impedance mismatch (eg. air gap mentioned in other comments – think of a hollow core door and how it really does reduce sound pretty well).

    All arguments and trollage about materials aside, here’s the usual problem, and particularly with compressors as in the video (and eventually CNC machines): heat buildup. The equipment is air-cooled and you have to have air exchange or nearly all of the wattage going in through the power cord is going to turn up as heat in the cabinet. Then you have to provide a cooling fan and/or some ports to manage the cooling, and to damp the sound coming out of *that* you have to get into ducting and baffles. Simple with the HF sounds coming out of a pocket sized CNC mill, but bigger tools not so much (remember 1 Hp = 746 watts, so a 5 hp compressor will turn the cabinet into a sauna and fire hazard in no time).

    Also, think about damping on the feet to get rid of LF noise transmission – nice squishy mounts/material of any sort help here so long as you don’t have resonance in the structure.

    • Mike says:

      I have powered ventilation in the back of the cabinet, it is very important as you say. I’m trying to find a good source for some rubber feet too, do you have any suggestions? Recycled tires? I thought about shoving some rubber wheelbarrow tires under there but wanted something a bit nicer/long term.

  17. Dave Thunes says:

    I hate to be a nitpicker but the correct verb is damp, not dampen.

  18. modmanpaul says:

    I deaden the noise coming through the feet of my generator by placing it on those pads you kneel on they sell at lowes etc. They’re surprisingly stable at high temps and resistant to most liquids. If heat becomes an issue consider an online duct fan of the fantech variety hooked up to a used muffler! Another muffler for an inlet if needed. If you do, pls bend them upward like horns on either side and post a pic lol

  19. jim says:

    I’ve used two layers of acoustic “drop ceiling” tiles for sound deadening. They are really cheap – especially if you buy the damaged ones (crushed corners), and provide a lot of acoustic attenuation.

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