Styrofoam Enclosure

Hello all

I was just wondering, has anyone considered building an enclosure out of styrofoam insulation?

I have no idea how the sound insulation would be vs plywood.

At some point I’m going to have to move my shop and I’d rather not make more gigantic things that are heavy to move.

Something like this?

Sounds like an interesting idea. Let us know if you proceed. I’m still looking at options for my enclosure.
Reduction in noise is a key factor.

One thing to consider is the static electricity that could potentially happen and affect the machine.


Hey Paul,

I have also been looking into the possibilities of suppressing the noise emission, because I recently had to consider whether to set up and test the Onefinity CNC during the remaining time that I still live in this apartment building. For the neighbors, it is not so much the direct sound that is generated in the room by the air (and which can be well shielded with an enclosure with sound insulation panels) that is disturbing, but the structure-borne sound that is spread into the building by the machine base and its feet. Against this, I have considered separating the machine base, to which the Onefinity is bolted, from the substructure, which stands on the floor, with a thick sheet of very dense rigid PU foam between the two. I have some of that around, and it already reliably decouples my speaker cabinets and an air purifier from their base.

By the way you know that polystyrene is highly inflammable.

Fire hazards

Like other organic compounds, polystyrene is flammable. Polystyrene is classified according to DIN4102 as a “B3” product, meaning highly inflammable or “Easily Ignited.” As a consequence, although it is an efficient insulator at low temperatures, its use is prohibited in any exposed installations in building construction if the material is not flame-retardant.[citation needed] It must be concealed behind drywall, sheet metal, or concrete.[117] Foamed polystyrene plastic materials have been accidentally ignited and caused huge fires and losses of life, for example at the Düsseldorf International Airport and in the Channel Tunnel (where polystyrene was inside a railway carriage that caught fire).[118]

Source: Polystyrene #Fire_hazards – Wikipedia

Reaction to fire

Polystyrene burns with a bright yellow, heavily sooting flame. The styrene released in the process has a flowery-sweet odor; in practice, however, the vapors often have a pungent odor due to additives.

The fire behavior of expanded polystyrene is dominated by the fact that it softens at temperatures just above 100 °C and then drips off, whereby the droplets (also due to the low mass and the associated poor heat dissipation) can catch fire and then drip off while burning. Above about 300 °C, the material decomposes into styrene, among other things (flash point of about 31 °C). Residues of the propellant pentane (flash point approx. −50 °C) may also be released. This can lead to the polystyrene burning off and dripping off on its own. [18] Flaming droplets of polystyrene can spread fire by igniting underlying materials.

The flammability of (expanded or extruded) polystyrene can be reduced by using suitable flame retardants . In the past, polybrominated diphenyl ethers or hexabromocyclododecane were often used as additives , the use of which in the raw material is no longer permitted, but can still be introduced into the end products through recyclate. Today, a brominated styrene-butadiene copolymer is mostly used. During combustion, these flame retardants split off gases containing bromine , thereby breaking the radical chain reactions by scavenging the oxygenand thus inhibit combustion; this can result in polybrominated dibenzodioxins and dibenzofurans .

The reaction to fire of flame retardant polystyrene foam for building applications is classified according to EN 13501-1 and classified in the European reaction to fire class E. When installed, the fire behavior depends on the specific structure of the insulation system. For information on the fire behavior of thermal insulation composite systems and controversies following media reports about facade fires, see Thermal insulation composite system#Fire behavior .

– Source: Polystyrol #Brandverhalten – Wikipedia (DE) → autotranslated

YES for sure, I’ve built things with this stuff and its a static nightmare that never ends. If you do it, I would sandwich it between 2 sheets of 1/8" Luan board to stop the static.



Hey Onefinity Support, hey all,

this could be avoided by lining the enclosure (the polystyrene foam panels) with a fine steel wire mesh which is connected to ground (earth).

Also a good EMI shield by the way.

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I had researched this topic as I have my CNC - for now - set up in my basement. Although I have not yet decided on my own solution, the article below is one I had originally found, and thought was informative:

Is Styrofoam good for soundproofing?


Mass is what will stop sound. Density matters most in controlling sound. There is a youtube video with an insulation enclosure and it was dust focused. It didn’t seem to mitigate sound any at all.

For sound control in my below table enclosure I’ve enclosed in ply, with a double layer of quilted and sewn moving blanket panels. the soft irregular material absorbs and doesn’t reflect the sound of the vacuums under my table. one for dust the other motor for holding. The wood holds it in mostly. I have a muffler built into a panel for air circulation.


Something like this might be what you are looking for. Not designed for this application specifically, but an enclosure lined with these panels might significantly yield sound reduction. Additionally, they are generally fire resistant. I can’t speak to the susceptibility for static build up though.

There are also thin mats that are attached with pressure sensitive adhesive used by the automotive industry. However, I think they may be geared toward lower frequencies than those created by the CNC. Both products reduce sound by converting the mechanical vibrating energy to heat on a cellular level.

Just a thought.

Those help reduce reflected sound and reverberation but will not stop it or absorb it. It prevents small spaces, like an enclosure from becoming a megaphone as sound bounces off the hard surfaces. There are lots of great videos on sound control and absorption on YouTube.

Pro Tip if you get these panels for any enclosure or wall, put the stack in the dryer for 10minutes. The heat will re-expand the foam to full size. They don’t have any structural rigidity so need to mounted to a firm surface.

I don’t know if @ [paulmcevoy75] reason for an enclosure. If its dust or sound or both.

If its dust only and you want light weight. You probably can’t get any lighter and cheaper than 7-10mill painters plastic stapled to some 1x1’s mounted on the corners of the machine. Tarp it side over the top and down the side, and the same front to back, leaving the front like a flap.

Something up the line that can convert to do both in the future. I’d suggest looking into Quick Frame Tubing or Ready Tube from 8020

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Hey Tom,

useful document. It is important to understand that preventing sound leakage and sound absorption in the meaning of annihilating sound reflections are two different things.

Two distinct soundproofing problems may need to be considered when designing acoustic treatments—to improve the sound within a room (see reverberation), and reduce sound leakage to/from adjacent rooms or outdoors (see sound transmission class and sound reduction index)

– Source: Soundproofing – Wikipedia

There are 5 elements in sound reduction (absorption, damping, decoupling, distance, and adding mass)

– Source: Soundproofing – Wikipedia

I HATE the sound of a vacuum cleaner in the first place so sound absorption was a priority for me. I just repeated the same system I had used for my hella loud air compressor,enclosed it in a cabinet of 3/4" MDF lined with 1 1/2" standard white styrofoam. The doors are left without lining and actually have a fair sized gap. This combined with a muffler from big orange has reduced the noise considerably, down to where I can easily talk at conversational levels right beside the machine. While probably not the best solution or the highest performing, it does improve things substantially and has the benefit of being relatively inexpensive and using materials I had lying around anyway. As for my enclosure, for space reasons there is nothing lining the inside at all and I can confirm what others on this forum have stated that enclosing the machine contributes VERY little to the abatement of the sound without some kind of lining. There is a difference, but not enough to satisfy a disgruntled significant other if the noise issue has been brought to your attention.:smirk: On the other hand I haven’t found the sound of the Mikita to be quite as loud as some of my other machinery but then again, I don’t operate any of them as long either. Listening to music in the shop when it’s operating is a thing of the past.:worried:

I also hate the shop vac noise so tried a few things in my enclosure. A layer of soft materials like those acoustic panels or even cheap moving blankets would help take the boom out of the enclosure noise. I’m considering put a layer of boom mat around the inside barrel of my canister on my shop vac or maybe a cut to fit bit of moving blanket. that said it won’t stop the high pitch whine, only thick dense materials will do that and I’m not paying for mass loaded vinyl.

Sorry, Ultrafox, but did you mean putting sound deadening 'inside ’ your shop vac? I can’t see how that would accomplish anything.

Yes or the outside. The canister is open on the inside to the motor and so lots of sound blasts into that drum and makes a significant part of the noise, because its reverberates. I’ll test it soon and report back if it works. My thinking is a layer blanket to line the inside bottom and around the bag is easy and reversible. I did pattern the outside with masking tape to cut boom mat but decided the square footage was a bit much to justify, at least for now.

I don’t want to derail the original focus on a Styrofoam enclosure so will leave it there. But do plan to share workbench enclosure, sound control, and vacuum holding table with this forum when I’m done.

I’d be really interested in the results of this experiment. Still have a large shop vac that can’t be stationary for the rest of my machinery that I’d like to ‘shadupalready’.:shushing_face:

I saw a product last week called “Green Glue” that’s supposed to help with sound deadening by putting it in between a couple of pieces of 1/2" MDF. I wonder how well it works. Could be helpful for a vacuum enclosure.

I watched a lot of videos on sound control and green glue came up quite a bit and most seemed to believe it wasn’t worth the expense. Mass loaded vinyl was the one thing that almost everyone agreed did the most next to thicker wood.

Here’s a video out there of a truly silent cnc build and the walls are doubled and the enclosure appears to be nearly 6" thick.

I just want to cut the edge off the sound travel its the bass, not the whine that gets out past my garage. So I mostly do what I can to address the boom of reverb and air moving. That means walls as dense as I can get and a layer of soft textured material to disrupt the waves.

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Yeesh, 6" thick walls!!! While I would love the silence that grants I haven’t got the space to do that or I would have gotten the Journeyman. As it is I just managed to shoehorn my Woodworker enclosure in the shop and that was with about 1/2" clearance on all sides. Makes maintenance a bear but I found a home surveyors mirror helps out a lot.