Building an enclosure

Greetings all!

I haven’t purchased my CNC yet but I’m planning on doing it in a few weeks and I am already getting ready on building in the enclosure.

The problem is this CNC machine is going to be inside I’m going to be putting it in a 7‘ x 7‘ walk-in closet of mine.

My first question is how thick the walls have to be to cancel most of the sound? I was planning on making 4 to 5 inch thick walls With three-quarter inch thick Baltic Birch plywood and 4 inches of roxul safe and sound sound dampening Insulation, followed by a three-quarter inch thick hard foam that I will spray paint white. My goal is to remove much of the sound as possible so that during the day when I’m cutting things it’s not annoying everyone in the house.

Below that I will be making a similar style enclosure for a shop vac. I’ve seen some people do this but I have concerns about the shop vac overheating is this a valid concern?

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The thicknesses you cite are in-line w/ those of folks who have made perfectly quiet enclosures.

For the vacuum, yes, overheating is a concern. Most folks work up a baffle system and start with a quieter vacuum/dust extractor such as a Fein. Above all you need to bring in fresh (cool) air and exhaust hot air — could you vent into an attic space?

I was actually planning on using the suck and blow part of the vacuum at the same time. Have one part blowing on the workspace and one part sucking. Is this feasible?

My enclosure is 56” wide and will be 52” deep. This should give me enough space. All I built was the table legs and I could make an enclosure that hangs over the table slightly if I need more space. And those fein vacuums are expensive But they seem like they’re worth it. I’ll definitely get one.

Do yourself a favor and get a water-cooled spindle. Imho it’s not worth overbuilding the enclosure for the sole purpose of suppressing the sound. I’ve wasted so much money on different foams, plywood and what not to reduce the noise of a router and I could still hear it on the other side of a house. Don’t get me wrong, you can reduce the sound dramatically but the money you’ll spend on the materials would be better used towards upgrading a spindle.

This is the final version of the enclosure I built. Paid extra attention to making a VERY solid base that has as little flex as possible, but the walls aren’t thick at all. I can work all day cutting aluminum and the sound doesn’t bother me at all.

Also, while using a router in a very well sealed enclosure, I was noticing a dramatic increase in temperatures. Wouldn’t expect that to be safe.

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The problem is finding a good spindle. There’s just so many Chinese manufacturers selling the same product for different prices and reliability is kinda a shot in the dark. How much does your spindle cost? Do you have the link for it so I can purchase it?

I do want to get a water cooled spindle I’m just having trouble finding one. Should I just make 2 inch thick walls if I get the water cooled spindle?

What about the cutting noise? I know the router makes a ton of noise but doesn’t a lot of the noise also come from cutting the actual material?

It will recirculate and heat air and isn’t advisable for long cut sessions.

While a quiet spindle helps, the sound of cutting is invariable regardless of cutting tool.

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They’re usually around $400. There’s plenty threads on the forum - eBay and amazon are full of them. The quality is pretty decent these days so wouldn’t worry about that.

True, but speaking from my own experience - with extremely overbuilt enclosure, the sound of a router at 24K is comparable to the spindle at the same speed in the enclosure designed solely to contain the debris - not the sound. At 30k rpm it was obnoxiously loud.

Will getting the spindle also allow me to cut faster?

Also one of the things I wanted to figure out was how to add a double motor drive to the shapeoko. Is it as East as daisy chaining the connections from the second motor to the connection on the control board? Ie, wiring two motors for one axis To the same output on the control board?

As in replace each motor with two motors? You’d need to build your own controller for that.
Can I ask what the reasoning is for this?

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No, one on each side to drive the overhead Carriage more evenly. Having one motor means that there could be a tiny amount of flex on the side that’s not driven. I know this isn’t a huge issue but in the future I’d like to

There are already two motors on the Y-axis, which are automatically counter-rotating — where else would you want to add one?

FWIW, I put a drive shaft on the Y-axis of my Shapeoko 1.

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Wait that?

The entire overhead carriage is driven by one motor in each side? I thought just one side was driven???

The Y-axis carriage plates are mirror images, each w/ a motor which are set up to counter-rotate:

What you’re doing there is very similar to what people try to do with home music studios. Basically there’s two aspects to dealing with sound,

  1. Managing reflection and reverberation to manage the sound within a space
  2. Absorbing or isolating the sound energy to reduce the leakage out of the space.

I can’t recommend this guy enough as a starting point to understand how this stuff works, he’s a real pro and talks sense not expensive products.

I’m a bit of an audio nerd so I’ve already got some strategically placed audio panels and bass traps to clean up the sound in my room. I’ve also done the measurement and fighting in a friends studio to try to position the monitor speakers properly to avoid the worst 1/4 and 1/2 wave resonances and level out the sound as much as possible before electronic EQ. If you put the noise making device in any of the ‘wrong’ places in a room it will just resonate and nothing you do will usefully damp that noise inside or outside the room compared to just altering the resonance modes.

As for construction materials… Wow, that a rabbit hole, if you go look at forums like gearslutz you’ll find an easy years worth of reading and argument on that topic.

In summary…

Mass is what stops sound, then isolation, but it really needs to work, sound leaks through tiny gaps. Rockwool is really not that effective because it doesn’t have enough mass to do much absorbtion in realistic thicknesses, stud walls are mostly transparent to sound because they transmit the sound through their rigid frames. floating floors and stud walls with separate frames for each side of the wall start to isolate the sound.

For a sound absorbing material, foams and egg-crates are just useless, regular rockwool isn’t much better. There are much heavier grades of rockwool which are used to make sound deadening panels, GIK acoustics sell both the panels and the materials. The panels I have are GIK. You can locate the heavy duty rockwool but not at your local building supplier.

There’s also a whole plethora of domestic sound absorbtion products which you might want to look at. These typicall work on a mixed heavy layer and spongy layer sandwich approach. This is what you could put under a ‘floating’ bench top for your machine.

I made a box to keep my shop vac in, but it has an outlet which let me put a 4" hose on the exhaust to go out a window, I also put a cyclone settler on the input to keep the worst of the dust out of the vac. It makes quite a lot of difference.

If you want to keep the noise inside the room I’d suggest using something heavy as the supports for the Shapeoko, even concrete paving slabs would be worth considering along with one of those floor isolating products and then use proper industrial grade vibration isolating mounts to isolate that frame from the floor. A few people here have used vibration absorber / isolator mounts between their machine and the table too, that’s a good double strategy if there is enough mass in the table.

HTH

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I’m surprise no one mentioned dynamat it’s super cheap and very very heavy. It’s basically a layer of very thick aluminum foil and an asphalt adhesive. The result is a very sticky and heavy surface and these can be easily layered up. A 50 Sq/ft foot box which I would need to for my enclosure at least would weigh about 40 pounds each.

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Dynamat may help with some aspects but be careful which type you use. Just adding mass to the system may not provide the results we want.

The popular Dynamat (and similar other vendor products) are designed as constrained layer damping materials to deal with vibration energy in relatively stiff metal panels. The idea is that the metal skin on the mat and the metal panel of the vehicle form the sandwich for the deformable layer of goop. The goop goes into a shear mode as the panels flex and converts the sound energy to heat. This is very effective, if you have a thin metal panel which is flexing sufficiently to move the goop into it’s shear mode where it converts stress to heat and out of it’s nominal elastic mode. It’s hard to get this right and using a material designed for thin metal panels in vehicles on a sheetrock, plywood, MDF etc. wall is unlikely to work.

The common ‘knockoff’ clones which are just a heavy rubbery or bitumen material generally only serve to reduce the resonant frequencies of panels they’re attached to by increasing the mass without increasing stiffness, thus their use inside speaker cabinets to move midrange resonances to less objectionable octaves.

The multi-layer dense foams can work like the dense rockwool in terms of reducing transmission of noise, they’re also pretty good at reducing reflection of higher frequency noise.

Different frequency ranges;

Dealing with different frequency ranges requires different approaches and a combination of absorbtion and decoupling is generally required to get good performance across the audible range.

At mid to high frequency (router noise, spindle whine etc.) relatively thin sound absorbers such as the Dynamat foams on the inside of an enclosure can be very effective. Many folks have built enclosures for their Shapeoko with acrylic windows to view through and these still disrupt the high frequency elements quite effectively.

This is because short wavelength sounds are much easier to absorb and disrupt. That’s why when you close a door or go downstairs from the party you’re left with the thump thump thump, bass just wafts through most things due to longer wavelengths and reduced absorbtion efficiency. Bass sees wooden floors and joists as a propagation path, not a barrier.

Once we get to lower frequencies and longer wavelengths mechanical transmission becomes the issue. You could fill the enclosure with absorbing dense foams and the people downstairs would hear the axis moves and low frequency elements of the cutting noise perfectly because the sound is transmitted through the feet of the Shapeoko to the table, through the legs to the floor etc.

To deal with these lower frequency elements we need to find a way to stop the low frequency energy propagating from the machine to the walls, floor etc. There’s two parts to this, direct noise conduction through the frame and sound passing through walls etc.

Low frequency sound is normally mitigated by decoupling, which works best when a flexible coupling is carefully tuned between the two masses to not pass the problem frequency range.

We’re not really in a position to calculate this so what we need is something rubbery which will support the machine effectively but flex in the low frequency range rather than passing vibration to the floor. There are assorted anti-vibration feet and similar products out there, the key is flexible couplings between masses.

As for walls, there’s lots of stuff out there but fundamentally, the things that work in lower frequencies are decoupling, not absorbing, split stud is popular as it’s not much more space than a regular stud wall.

The key thing is to deal with the noise as close to source as possible so an enclosure around the Shapeoko, maybe double-skinned (without battens linking the skins across their faces to reduce transmission) and fill the cavity with Dynamat foam absorber etc. (not the aluminium constrained layer materials) would work for the higher frequency sounds. Next up, isolate the low frequency noise, vibration isolating feet under the shapeoko are an option but require some experimentation to not add lots of harmful vibration to the Shapeoko frame. Sound isolating feet between the table and the floor are likely the best option and I’d be tempted to use a few concrete paving slabs on the floor as the resting point for the vibration isolating feet.

You could also do a double table top with a small torsion box for the Shapeoko to sit on which itself sits on a layer of the foamy floor insulating Dynamat on top of the lower table top which is attached to the legs. Not sure how well this would work, depends on the effective tuning of the mass and the springiness of the foams but I’ve done this type of isolating for noisy air conditioning units to good effect.

HTH

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I should probably mention that I built speakers and I also have an 1100 page book on HIFI horn design so I completely understand everything you’re telling me about sound absorption and how lower frequencies tend to past and move through walls and higher frequencies act more like lasers are very direct and reflect a lot. I just made the table I could probably put some of that dynamat in between the top layer of wood that shapeoko sits on and the 2 x 4 frame that The table top is screwed onto. This should at least help dampen some of the vibrations. It’s sitting on a carpet floor so that definitely would help.

I already have a 1.5 kW water cooled spindle so I won’t have to deal with router noises the only problem is the cutting noises. What I’ll probably do is use three-quarter inch thick Baltic Birch or maple ply, add two layers of Dynamat, and then a 1” or 2” layer of rigid foam insulation. I think that that should pretty much cover the frequency spectrum and allow me to absorb most of the sounds. This entire contraption is all housed in a 7‘ x 7‘ walk-in closet so A lot of the sound won’t be leaving that room.

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first off, thank you for giving me such a detailed reply! ’

second, I think some of the things you’re mentioning are a little overkill. I can not get concrete paving slabs in my room and the table is in my closet, which is above the garage so noise below me isn’t a problem.

I just want a simple solution that will cover most of the frequency range. a “one size fits all panel”.

if you had to design a simple panel of layers/sandwiched materials (no split studs), how would you design it.

Im thinking two layers of 1/2" thick plywood with sound dampening glue in-between, a layer of dynamite, and some rigid foam spray painted white.

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That might have the opposite effect from what you’re looking for.
:wink:

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