Edward's S2 Enclosure

edwardrford
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Re: Edward's S2 Enclosure

Post by edwardrford » Fri May 09, 2014 4:24 pm

I'm working on a BOM and exploded view for anyone interested in building their own. I'll post them here once completed.

-Edward
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

Signals
Posts: 108
Joined: Sun Apr 06, 2014 2:52 am

Re: Edward's S2 Enclosure

Post by Signals » Sat May 10, 2014 6:21 pm

I do a lot of audio engineering.

If you want to deaden the sound of that bad boy substantially take MDF (more mass will always attenuate more as well as be more effective at lower frequencies), I think half inch is fine, because the sound of a router really doesn't put out any frequencies below about 200 hz ish anyway, you want high frequency reduction, not so much low.

Anyway, take a 1/2" MDF panel and attach it to the inside, and an 1/2" mdf panel and attach it to the outside of the frame. Cram as much Roxul Safe n' Sound into the crevice between the two sheets as you can to add mass - if you don't care what it weighs, fill in between the panels with sand. That would be ideal. That should give you some serious sound reduction. I wouldn't be surprised if it was nearly whisper quiet after that.

As for mechanical coupling, yeah, the two 1/2" sheets of MDF are still coupled to the shapeoko, but that's not going to matter much due to how much they weigh and the amount of force it would take to move them, especially if they were filled with sand. I would actually just use like 1/4" mdf if you're going to fill it with sand, so it doesn't get too bulky. Lots of high end speaker stands are filled with sand to add mass and kill structural resonances.

If you want it to look nice, make it out of "plyboo" bamboo panels, which is also great at dampening sound. I believe it also weighs less than MDF, and is a lot stronger. Put an acrylic window in one of the sides, and it'll look great and be whisper quiet.

Obviously this will take a bit of redesign to the enclosure for clearance of adding panels to both sides of the railing.

Ultimate in sound proofing would be to decouple the cage, build it filled with sand, then build an even bigger cage the same way, leaving an air gap in between the two cages. A lot of recording studios employ this room within a room technique, and you likely would literally not be able to hear the Shapeoko operating at all. I would test the 1/4" panels on both sides stuffed with roxul vs not stuffed at all (air gap) as an air gap may very well be more effective in this scenario, but seeing as how the panels are coupled together anyway I doubt it would be. Worth testing though. If you have any type of microphone at all I can probably point you in the right direction of being able to test different designs, since all you're concerned with is the relative differences in attenuation from one design to the next. Could just use a crappy usb mic, as long as it doesn't move between tests, you're good.

edwardrford
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Re: Edward's S2 Enclosure

Post by edwardrford » Sat May 10, 2014 10:22 pm

@signals - Instead of doing a box within a box, how do you feel about using isolation mounts between the shapeoko and the enclosure? Some inexpensive ones could be had for less than $20 (total for 4) and would decouple the machine from the enclosure. Which, if i'm hearing everything correctly would be the main reason this wouldn't work.

-Edward
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

Signals
Posts: 108
Joined: Sun Apr 06, 2014 2:52 am

Re: Edward's S2 Enclosure

Post by Signals » Sun May 11, 2014 2:43 am

Decoupling the panels from the box may help, but I doubt it will be significant in this case. Worth a shot though. I don't think the high frequencies would have the energy to move the panel anyway, but in theory if you decoupled it it could change some of the sound wave energy (mostly any low frequencies) into mechanical energy because it's turning the whole box into "limp mass membrane" absorber - I think that's what they're called. They're usually just a piece of heavy rubber suspended from a hook. It might be worth trying it out and taking another measurement, but I would think your best bang for buck is going to come from adding additional mass.

What will help you a lot since you're dealing with mainly high frequency is some type of sound deadening "sheet" material, for example something designed for the inside walls of speakers. Open cell foam and the like reduces sound by turning it's energy into heat.

Something like this (this is way overpriced, would probably knock a couple db's off.) http://www.youtube.com/watch?feature=pl ... qC_RQKE3no

Also you could look into peoples designs for guitar amp "isolation cabinets", since it's essentially the same design principles you're going for. http://en.wikipedia.org/wiki/Isolation_ ... 8guitar%29

Typical studio foam if you can find it for a good price would work well. You can see the noise reduction (NRC) of the materials on this page. Pretty sure these guys have an American store as well. 2 1/2 eggcrate would work well for your needs, especially if you decoupled it (which would help absorb some lower frequency energy) http://www.ebay.com/itm/Soundproofing-2 ... 1e78bbae98

Your current drop from 89dB to 82dB is already pretty good, considering decibels are a logarithmic scale. Essentially a db is the smallest change a person will notice, and between 6-10 db difference is the region where people perceive things as twice as loud as they were, or alternatively half the amplitude. So right now you've basically cut the sound level in half.

Llamas
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Re: Edward's S2 Enclosure

Post by Llamas » Sun May 11, 2014 8:38 pm

I don't think you'll have much of an issue with resonance as long as the panels are solidly secured. i.e. If they're slid into the extrusion channels and fit loosely, they might rattle around, but if it's all connected well, it's the mass of the entire structure that's resisting the vibrations. Since you're not slot-mounting the panels, it doesn't seem like this would be an issue.

Signals
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Re: Edward's S2 Enclosure

Post by Signals » Mon May 12, 2014 12:51 am

Agreed that the structure is too heavy to resonate in it's entirety, and I also doubt even the panels alone would, since they are secured and pretty stiff. Plus MDF is said to be a great material for dampening resonance.

You will definitely get specific resonance build ups inside the box, from frequencies that are high enough in frequency to reflect off the MDF panels instead of traveling straight through them. The resonances will be the speed of sound (around 1125 feet per second) divided by the width, length or height of the box depending on the resonance you are calculating for. I'm going to guess one of the dimensions is around 3 feet.

So your fundamental resonance is probably going to be around 375 hz or so if it's 3 feet. (if you have the box not square the resonances reduce because they are split amongst different frequencies instead of all building up at the same frequency. That's why typically if you build a speaker you build W x H x D all different to reduce similar resonances from building up).

If you look at NRC (noise reduction coefficient) ratings of this foam (http://www.ebay.ca/itm/2-Acoustic-Studi ... 0874656795), your best bang for buck would be 3" foam, which is way more effective than two inch in between 250-500 hz.

There's also going to be harmonics of that fundamental resonance of 375, the second and third harmonics being (375 x 2) 750 hz and then (375 x 3) 1125 hz and but the foam will make short work of these, since it's NRC for higher frequency stuff is really high.

I think it would be be cool and probably actually help attenuate bass frequencies a bit if you did decouple the box. Not really necessary though, as the bass frequencies are far less "annoying" than the higher ones, however they are more audible at further distances because the pressure waves are longer and they essentially travel through typical walls with little hindrance. Bear in mind though that a router puts out relatively little low frequency sound energy anyway, so you might not have any sound to attenuate in those frequencies anyway. My Bosch colt definitely sounds like the lowest frequencies it's generating are around 200 hz to my ears, while milling wood. Just a guess from hearing it operate in my garage.

Chrisprols
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Re: Edward's S2 Enclosure

Post by Chrisprols » Tue May 13, 2014 12:27 pm

Hi !
I saw another thread on the forum that might interest you ... part of it is about build and installation and another part is about the noise and how to reduce it.
thought this might help.

http://www.shapeoko.com/forum/viewtopic.php?f=5&t=2531


.
Shapeoko 2 #4852 with Bosch Colt
Location : Rouen, FRANCE

edwardrford
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Re: Edward's S2 Enclosure

Post by edwardrford » Tue May 13, 2014 1:38 pm

Indeed, Meanderbolt's enclosure and supporting data are impressive. It makes me envious of anyone who can craft things with commodity tools and materials. But, for me, the objective is to build a case that conforms to my 80/20 principle of design along with the 'no fabrication' requirement of Shapeoko.

Just so we are all on the same page, I want to share a little secret about my design style: When I'm designing something, I tell myself that I can't fabricate it. No saws, no drills, no tools other than maybe a hex key and a tap. It has to be bolt together, and it has to be repeatable by anyone with the same tools. People can say what they want about that design philosophy, but at the end of the day it's what brought Shapeoko into the world, and it's treated me pretty well, so I won't be deviating anytime in the near future.

If I didn't stick to this philosophy then when my enclosure was finished I wouldn't have anything to share other than some pictures of a cool enclosure. Instead it would be a one off built that more than likely couldn't be repeated by anyone in the community. And if it can't be repeated, then it can't be improved, and that would lead us to chasing our tails. My goal (always) is to release projects in the hopes that someone else will take my design files and build one of their own, or base an improved design off of my design so we can move the project forward.

But I digress....

OK, with all that said: I did some more work to the enclosure in CAD over the last week. Because of an oversight, I had to order a few more parts from misumi, one of which was the HSQN4-1570 panel. Because of that it took nearly a week for the parts to be delivered. They were delivered safe and sound yesterday, but I haven't the time to do anything with them.

I'm leaving for Makerfaire tomorrow and won't be back until Late Sunday, which means that progress on this build will be halted until late next week. This should give me enough time to get the plexi back from the laser cutter and be ready to bolt everything together for the final assembly.

The only thing left to do after the plexi panels are installed will be to figure out the front control panel button layout (and subsiquent wiring...). Once that's done I can (fingers crossed) call it done.

-Edward
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

Signals
Posts: 108
Joined: Sun Apr 06, 2014 2:52 am

Re: Edward's S2 Enclosure

Post by Signals » Wed May 14, 2014 1:50 am

I'm also go by the same philosophy, but it's more due to laziness on my part. :P

I'm excited to see the final design. Wish I had it in my studio to measure accurate attenuation!

Nigel K Tolley
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Joined: Sat Feb 08, 2014 4:06 pm

Re: Edward's S2 Enclosure

Post by Nigel K Tolley » Wed May 14, 2014 8:19 am

You can trivially download a frequency spectrum analysis app for your phone. It will give you a rough breakdown of the audio frequencies and powers coming off.

Simply mark the location and orientation of your phone so you get some repeatability.

That's the place to start. Otherwise this is like shooting for that 10th of a thou accuracy with nothing more than a tape measure.

Sent from my SM-N9005 using Tapatalk

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