View Full Version : Hush Box

03-02-2006, 08:24 PM
I wonder if it would do any harm to put this machine inside of a hush box, its quite loud :shock: , Any thoughts pros, cons?

03-03-2006, 10:43 AM
We put such a box together a while back in order to cut down on the noise during demonstrations at shows. It works extremely well -- you can have a normal conversation standing over the machine while it cuts. It's constructed from plexiglass and foam insulation (pic below).

One downside is that you're limited on the size of workpiece unless you put some kind of feed-through holes in your box. We didn't try this, so I'm not sure what effect it would have on the noise reduction.

Another downside is that it can be difficult to operate the keypad and the handles unless the box is designed to give easy access to these. Ours is a simple lift-away design, so we can set the machine in motion and then place the box over it.

We haven't completely explored whether a long-running project will get too hot inside the box. Since our box limits the size of workpiece, we've never cut for more than a half-hour or so. It does get warm (like in the 80's F), which is fine if it stabilizes there but could be a problem if a long-running project pushed it over 100F. If your box expels the exhaust from the cut motor then the machine itself could generate some positive air flow and could probably keep the inside of the box cool enough. Again, though, I don't know how much noise this would add since the cut motor is obviously the loudest part.

On the positive side, the box totally contains any expelled sawdust. One could get creative with a pegboard bottom and a shop vac in order to give some airflow and remove dust. Keep in mind, though, that although the machine is designed to run continuously for hours, many shop vacs are not.


05-11-2006, 03:20 PM
I wear ear protectors. Mine play the radio, so I listen to classical music while working. They cut out a lot of noise.

05-12-2006, 02:25 PM
I wonder if it would do any harm to put this machine inside of a hush box, its quite loud

01-02-2008, 10:40 PM
When I was having my shop built I had it fully insulated with 3 1/2" fiberglass. Before the drywall was installed I noticed there was absolutely no echo with in the building. :rolleyes:

So here's how I built my sound box. The box is made of 1/4" leuwan plywood and framed with 1x2's around the outside edges. The box measures 28"x28"x60" long. The side panels are attached to the rear panel with two screws, just enough to hold them together. The top just sits on the three sides. I lined the inside walls and top with R-11 fiberglass insulation. I attached the paper side of the to the wall and top with water base contact cement. So far the box cost around $30

Most of my CW projects are under 2' long so the box is big enough. For longer boards I just put a 5 1/5 block under each corner and raise it up.

When I get around 2-it I make a couple of doors for the front. Anyway fiberglass absorbs a lot of sound. Can't say how much but there is a big difference.

I also have a down draft system connected to my shop vacuum system. The vacuum is 2hp about 15' away from the CW. At this point I'm not sure which makes the most noise.

03-16-2008, 04:27 PM
This is the shorter of two threads I found on the hush box and mine seems to fit in better here.

The photo's I intend to include should be worth a few thousand words, but basically the box is a 1x2 frame with luan panels and a hinged front lined with acoustic foam (http://stores.ebay.com/Foam-Factory-of-Canada). The cart is made of 2x scrap ripped down to 2x2 with plywood shelves and stake material edges and braces.

I've not put wheels on the cart yet, or rather, my first attempt didn't work well so it's back to the drawing board.

After all that, the machine is still loud. My next step is draping the wood pass holes.

After that, I dunno. I'll take suggestions.

03-18-2008, 09:11 PM
Maybe line the inside of the box with egg cartons if there's enough room. I would think that they would absorb alot of the sound. Just an idea.

03-18-2008, 10:32 PM
You can add a wall of pink foam board insulator from homedepot.
It really help.

03-19-2008, 08:19 AM
I have operated my CompuCarve in the middle of the summer in Houston, Texas. I built a hush box and installed a blower on top of the box. In addition to the blower directing air on the top of the box towards the unit I normally use a fan blowing on the box.

I used the pink isulation from Home Depot, but I feel that the accoustical foam would be a better noise reducer. I also wear noise reduction headphones when I operate the machine. I have the habit of watching the machine work and it is noisy.

03-19-2008, 08:45 AM
Britt, seems the pic did not load.

03-19-2008, 09:09 AM
The box is already lined with egg-crate style acoustic foam which I would expect to dampen sound better than egg cartons. Anyone know what the technical parameters of sound damping are and where actual egg cartons measure out? If I add insulation panels it would be to the exterior of the box.

Thanks again for your thoughts.

03-19-2008, 05:47 PM
I doubt if insulation on the outside of the box will do you much good. If you are using the foam egg carton insulation I think you are probably using the most effective insulation made.

You might Google the web for sites that list the sound dampening characteristics of various insulations. I had done some research years ago, but with the technology of today they have accumulated a great deal of information.

I used the pink insulation from Home Depot and I don't think it is as effective as insulation that will absorb the sound rather than bounce it around.

Good luck!

03-19-2008, 06:26 PM
Here’s a thought for some of our electronics wiz kids out there.
How about a small portable unit that could be used to quiet down our carving machines,
like some kind of modern active noise control that is achieved through the use of a computer,
which analyzes the waveform of the background aural (http://en.wikipedia.org/wiki/Noise_%28environmental%29) or nonaural (http://en.wikipedia.org/wiki/Noise_%28physics%29) noise,
then generates a polarisation (http://en.wikipedia.org/wiki/Polarisation) reversed waveform to cancel it out by interference (http://en.wikipedia.org/wiki/Interference).
This waveform has identical or directly proportional (http://en.wikipedia.org/wiki/Proportionality_%28mathematics%29) amplitude to the waveform of the original noise,
but its polarity (http://en.wikipedia.org/wiki/Polarity) is reversed.
This creates the destructive interference that reduces the amplitude of the perceived noise.
Or something like that. http://www.carvewright.com/forum/images/smilies/icon_razz.gif

What'd I say http://www.carvewright.com/forum/images/smilies/icon_eek.gif

03-19-2008, 07:56 PM
I've spent alot of time studying soundproofing for home theaters. The purpose of foam is to break up sounds as they approach a surface, thus reducing reflected sound. This works better on lower frequency sounds.

To reduce or eliminate the transmission of sound waves, you need weight, lots and lots of weight. The heavier the barrier the better. One of the cheapest methods used is a double layer of drywall. Ideally, you want a rubber membrane between the two panels of drywall to "decouple" (seperate) the panels from transferring the sound wave vibrations from the 1st to the 2nd layer.


03-19-2008, 09:22 PM
My shop, which is made of 6" thick spruce double T&G house logs is very sound absorbing, has excellent accustics, but takes alot more light as the wood absorbs light too. I'm quite happy in there with the DC, CW & sometimes the TS or planer running with only foam ear plugs for hearing protection.

03-19-2008, 09:42 PM
I am getting ready to vent and sound prrof a room I have in the shop for the CC. Its 6'x 9' x 8' high. Its 2x4 construction with cedar T/G on the outside and a cedar door. I have acess to all of it right now so I want to do it right and really make it sound proof. I ran the machine in there for 3 hours today and when the door is shut you can hardly hear it in the house. But it louder in the shop and you can hear it outside in the driveway.

As I live in a pleasant 55+ park with the main population being retired area bussiness owners I don't want to tick any of them off. They have a lot of pull in the area and it would just take one to put a hamper in my activities. So I too am watching for any suggestions on sound proofing materials.

03-20-2008, 07:49 AM
I have my unit in the garage and even with the hush box I have to close my garage door to reduce the noise levels. I don't want to upset my neighbors as I am certain that they don't want to listen to the whine of my carver. I normally do all the prep work prior to closing the door. I am also considering adding insulation to the garage door.

Under no circumstances will I operate my carver without wearing protective head gear. I don't know the frequency of the soundwaves generated by the carver, but I do know that my hearing would be affected now or later.

03-20-2008, 08:07 AM
I was in the old BF Goodrich test center in Breaksville oh, They had a sound proof room where they listen to spinning tires, The room was lined with foam cones, It was an amazing experiance, you could her your heart beat.

There is some foam packing that looks allmost the same.


03-23-2008, 06:31 PM
Well, the low frequency sound is tamed a little, but the high frequency whine is an issue. I see the post where just plain weight is a secret to noise isolation but I'd like to avoid installing a ceiling hoist for my hush box. I'm also not ready to tackle a noise cancellation electronics box (Holy speakers, Batman!)

I, too, have stood in an amazing sound dampening room. We stood in a corner while the techs fired off an attitude adjustment thruster for a space payload - completely quiet even though we could feel a general air pressure increase. Impressive.

Any more good ideas out there?

I guess that this is becoming a science project.


03-02-2009, 08:16 PM
Well today the police gave me my last warning for the noise the CW is making.:(
Has anyone found away to reduce the noise?

03-02-2009, 08:32 PM
is there a way to build an oversize box using 2 inch or 3 inch hard insulation
(foam) that you can put over the machine and your stand or on all 6 sides?
are you carving all night long or what??

03-02-2009, 08:37 PM
just talked to Jason at LRW and he suggested the same thing. build a hood for the machine to quiet it up....:D

03-02-2009, 09:53 PM
Well today the police gave me my last warning for the noise the CW is making.:(
Has anyone found away to reduce the noise?

you never told us about the first warning? that would have been interesting. do you live in an apartment building, community house, or what's the deal?

03-03-2009, 05:06 AM
As I live in a fairly dense part of NYC, I built a box for indoor carving here, as well as to lower the noise when carving out on the roof deck if the weather permits (which it has not since the fall). It's still fairly noisy but using a soundmeter it shows a drop in noise from 97 dB while carving out in the open to 78 dB inside the box - that's in an environment where it's normally 59 dB with regular city noises up on the deck, no carving going on. A pretty drastic difference, and it certainly takes the annoying higher frequencies off. As Britt mentioned, the sealed box also keeps in all dust, so it's actually allowing me to carve inside our apartment without total dust takeover.

I built a rectangular 1/2 plywood box, a bit like giant shoebox, rather long to accommodate feeding in and measuring the 28" pieces of wood I was carving for a specific project. I have considered adding doors to either end but everything is fine for what I'm using it for now.

I used several hinges and locking clasps to hold the top lid piece tight against the felt weatherproofing I used along the open top of the box. I used an expanding spray-foam to seal all corners and the opening for the AC-grade extension cord. I put a square hole in with a rotozip and created a double-paned window with a square of plexi siliconed to either side of the plywood at the height of the control panel/data screen, which allows me to see the thing while the box is closed - however, it's totally dark inside the box when it's shut up, so I need to use a flashlight to read the screen through the window... I have definitely considered getting those backlit screen kits that Jeff Birt sells! That would be helpful and certainly cool-looking. The whole thing sits on foam mats to minimize vibration and floor damage.

If I were to do it again, I would have the box's control-panel side open downward to the floor rather than having the lid-open-upward option, to allow easier access to the control panel and easier removal of the machine. I built the box the first week I got my carvewright, and I didn't think I'd need to lift the machine out so often to maintain/fix it.

Under a carve, the machine does tend to warm up the air in the box, so I try to open it to check in every hour or so.

As for the guy who's getting warnings from the police, I'd suggest building something like the boxes discussed in this thread right away, as well as picking the hours you carve carefully. Maybe even consider a double box to isolate it even further.

It can be really stressful worrying about that noise - I live in an apartment building in a urban environment and I've felt the stress of just hoping the carve would finish soon. I now only carve during the day from about 11am until 5pm, while all neighbors are at work (I work at home) and I only once got a question about the noise, more of a curious question rather than a complaint. It sounds like you might just have a sensitive neighbor.

Good luck!

Hexe SA
03-03-2009, 12:31 PM
still trying to talk my husband out of his sanding/paint booth. With the lid and the collection system it should work like a charm. It is large enough for the machine and a 3ft board. He keeps telling me to buy my own. The sound when he uses it is very quiet. He grinds metal in there too. If needed a layer of foam could be added to the outside. Guess I'll have to go to HF. That's where he got his.