How Quiet Can I Get From Boxing a Noisy Shop Vac?

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snipped-for-privacy@hotmail.com wrote:

Yes, the motor's in the normal place. It's a Genie. And it's LOUD. Can't remember the model but it's not nearly as wellbuilt as the one Woodnet tested here: http://www.woodnet.net/reviews/archive/shop-vacuums /
The only thing it does really well is suck. This thing really sucks, and takes a long time to fill up. I got one of those red superduper hoses for it. In that box, with that hose, it's great. :-)
There's 29 1/2 inches of height in the box and the vac is about 20 inches high. I believe that's way more than I need. I just built the box from one sheet of ply and it ended up being about 21 inches square and 29 1/2 deep, AFTER the carpet was in.
In my opinion, it's the air flow, not the amount of space available. If the unit can vent the air fast enough it'll be fine no matter if there's no extra space at all. Heat does not seem to be an issue - I've had it running for over an hour and it's no hotter in there than it is after ten minutes.
I've got about ten one-inch holes drilled in the top along one side. You could hear the vac through those holes. Then I fastened a 3/4 strip above them and down the sides, then put a sheet of 1/4 ply over that, so the air was vented almost to the bottom. It made a big difference.

Not this one. They'd hear it. But I think the idea could be taken to a new level if you spent the money and started with the best stuff - a quiet vac and sound-deadening box liner material - you could get your hands on, instead of being like me and spending the least amount of money possible. :-) My budget was much slimmer then.
With mine, if I was in the garage and also shut the garage door, that might work.
But I would have to try it and then ask the neighbors. Actually, I've never run ANYTHING in the shop at that time of day. I know that the neighbor next door - about the same distance as yours - knew when I was using the planer with the doors shut but said it didn't bother either of them. I always take care to do my planing between noon and about 7 PM. The planer is the only one that anyone has noticed - the dust collector, table saw, router, etc, they don't care about. Lawn mowers make more noise than that, and we have a reel mower. :-)
I also note that neighbors really appreciated me asking them which tools they could hear. I got cookies. I like this neighborhood.
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snipped-for-privacy@gmail.com wrote:

Thanks for pointing out that air flow is more important than the head room above the motor. Great, this means I don't need to reserve so much head room for the motor. I need to make sure the air outlet is pointing right at the motor area (very near the blower hole); then I can sure that the air flow will go around the motor and cool the motor.
I will also make sure the air passage way out of the box will be insulated and loop around before it lets the air out to keep the noise down.
I will use particle board instead of plywood to construct the box. I am under the impression that dense material is better in term of keeping the noise down. If this still cannot keep the noise down enough, I will need to consider getting the expensive and quiet shop vac from Fein.
I am hoping that this setup without using a Fein will be good enough. My neighbor always has the windows closed, and use central A/C all the time. I have a feeling that I may be OK. But I will surely ask him to make sure he will not hear anything.
Thanks.
Jay Chan
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snipped-for-privacy@hotmail.com wrote:

Make sure you pad the bottom nice and thick. I don't know about density as noise abater but I know solid wheels on a solid surface really increases the vibration.
The better the lining is at sound deadening, and the thicker it is, the better. The more room you give it to add soundproofing, the better. The more I think about it, if you baffle the air flow out, and you really pad those walls, you could probably get the noise down low enough so it didn't make any more noise than an idling car.
I'd check it every few minutes to see how hot it was getting in there, though. Best o' luck with that. :-)
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I would like to make the following comments concerning my noisy shop vac
1. I used 3/4" thick mdf to make my box because, in general, its higher mass will deaden the high frequency sounds better than plywood. I have a Sears shop vac and it gives off mostly high frequency sounds. Also, a thiner plywood or partical board would not have worked as well, but it would still reduce the noise considerably. 2. Cooling of the vaccum motor is dependent on the movement of air into the cubical box(suction) and movement of air out of the box(exhaust). The air comming out of the box will be warmer than the air going into the box. The vaccum's cooling is dependent on a sufficently large volume of air passing out of the box since the cube acts as a thermal insulator surronding the vaccum motor. In use, the temperature of the vaccum cleaner inside the cube will depend somewhat on how large a volume of air the suction hose is able to pick up and pass into the inside of the cube that the electrical motor is operating in. You need to be sure that the suction is not completely block for long periods of time. A portion of the electrical energy the vaccum motor consumes is converted one way or another into heat that must be exhausted to the exterior of the cube for long term cooling of the vaccum motor. snipped-for-privacy@gmail.com wrote:

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I have already partially finished building the body of the box (except for the baffle air outlet). I am using 3/4" thick particle board. I use particle board instead of MDF because particle board is cheap and seem like it is dense enough; moreover, it is what the dust-collection book recommends. Not sure if it is any better for the saw blade than MDF though. But this box is really heavy (3/4" particle board). I guess my idea of carrying it on and off the boat is not quite practical afterall. I will have to leave it on the ground and use a long extension hose to reach inside the boat.
Thanks for pointing out that the air flow volume is the key to keep the motor cool. Would you please tell me how large the air outlet hole that you have in your box? Then I can have something to base on.
How much quiet your shop vac is after you have housed it inside the box that you built?
I will finish the body of the box quite soon. But I probably cannot finish this project for quite a long time because I cannot find any free carpet underlayment. Buying new carpet underlayment from home center for three layers of insulation will cost me $75 -- this is more than what I really want to spend on building the project. I will have to wait until I come across a dumpster full of carpet underlayment to finish this project. Meanwhile, I will have to make do with using some left over fiberglass insulation as sound-dampening material.
Jay Chan
snipped-for-privacy@verizon.net wrote:

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On 28 Aug 2006 07:16:49 -0700, snipped-for-privacy@hotmail.com wrote:

Check the dumpster's behind any REAL Carpet store that does installations.
I have so much of it I use it in front of my tools to stand on, (Great for the feet) when it starts to wear I throw down another chunk.
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snipped-for-privacy@the.shoppe wrote:

Yeah, what he said. Or find a carpet seller/installer and check their showroom to see if they have remnants for sale. Top dollar carpet and underlayment, brand new, for peanuts. Fill the truck with the stuff for twenty bucks. Our cats have one really fancy cat tree. It's got the most expensive carpet in the house.
Around here they actually chase you away and maybe even give you a ticket if they catch you around somebody else's dumpster. :-)
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Our carpet place encourages dumpster diving during business hours. The installers fill them up pretty fast. You can't get at them after hours as they are in a locked compound.
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The box I made initially had five 1 1/2" holes in the back of it for exhaust ports. My vaccum exhaust its air from the canister into the upper part of the space in the cube and I located the holes along the bottom edge of the cube thinking that the interior air in the cube would have to be more completely exchanged this way. It works pretty well this way for me. Heat build up inside the cube is completely acceptable with what I have. I think the thing to watch for in your box is if there is much back preasure buldup in it when the vaccum is running. I am sure different vaccums will have different air flows through them when setting in an open room. I discovered that if there is a large back preasure inside the cube the peformance of the vaccum's suction in the intake hose will be degraded.
The cube I am using actually has had two different vaccums in it. The first shop vac was a 12 year old Sears that was on its last noisy leg when I first tried reducing the noise by putting it in a box. I built the box with more interior room than I needed for this vaccum because I knew that this vaccum was not going to last too many more years. I wanted a box that would not have to be rebuilt for a change of vaccums. The first vaccum is now dead and I have bought another noisy Sears 12-15 amp shop vac. For some reason, the new vac sits much lower to the ground than the old vaccum did and probably passes more air through it than the old one did. Because it is much lower to the ground, it was necessary to drill a new hole in the side of the box for the suction hose to pass through. The hole I drilled in the side is the outside diameter of the 2 1/2" hose that is standard for this vaccum. This new vaccum probably needs the extra hole since I have observed that there is air under very low preasure passing through it. Just check your exhaust ports on the box you are building and make sure that the air passing out through the holes (or through the port) you are building is under very low preasure and that there is no signifigant preasure buildup inside the box when the vaccum is running.
Conderning your question on the noise reduction. My box has worked so well that as I said It has had two vaccums in it. The carpet on the interior of the box probably contributes signifigantly to the noise reduction. For me, the high pitch whine that is so typical of a cheap shop vaccum is almost totally absent. What I hear is some noise from the lower pitched sounds that the vaccum gives off. I do not have sound measuring equiptment and am unable to give any science based accurate measurements of the noise reduction. But, I maintain that you will be able to talk to someone in your shop in a normal tone of voice or listen to the radio without having to increase the radio volume signifigantly nor will you have to turn the volume on the radio down when you turn the vaccum off. I often use my vaccum attached to my random orbital sander for long sanding sessions and the sander makes much more noise than the vaccum. The 1 1/4" vaccum hose that is used to attach to the sander makes somewhat of a high pitched sound whistlening sound when it pulls lose from the sander and the whistlening sound of the vaccum hose is much louder than the shop vac running.
Because the cube that the shop vac is in is somewhat heavy, I have purchased 18' of 2 1/2" vaccum hose and I move the hose to where I want to use it instead of moving the vaccum. My cube is on casters, but experience has shown that for me, I am more comfortable moving the hose than moving the vaccum box. I also have adapters to attach various tools to the 2 1/2' vaccum hose or a short length of 1 1/4" vaccum hose to attach to various tools
I liked this arrangement so well that I have build a cube to put my Grizzley dust collector in. I have been disappointed in how large the noise reduction has been for the dust collector. The box reduces the noise but not nearly as much as it does for the shop vac Thinking about why the dust collector noise reduction was not as dramatic as the shop vaccum, I have come to several conclusions( None of which as of this date have been proved). 1. The dust collector box was built out of 5/8" birch plywood, 2. The primary noise frequncies of the dust collector are much lower, more energenic and more likely to pass through the box one way or another, 3. I failed to line the interior of the dust collector box with carpet or other sound deading material, 4 Because of the signifigant weight of the motor and fan, I am sure that both of them will need to be futher isolated from the bottom of the box in a way that lower pitched sound vibrations are not transmitted to the box. They are currently bolted to the bottom of the box.
I am sure I will eventually go back and make an attempt to reduce the dust collection noise futher using improvements that are outlined in the four unproven reasons above. When I do I will report on the results if there is a large noise reduction in the dust collector.
snipped-for-privacy@hotmail.com wrote:

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snipped-for-privacy@verizon.net wrote:

If I understand you correctly, the air outlet hole of the box is actually far away from the actual air outlet of the shop vac itself. I thought this might not help the air flow around the motor to cool the motor. But now I think of this, I have a feeling that this probably doesn't matter: The shop vac forces air through the motor to cool the motor down and not depends on natural air venting; therefore, having a shorter path between the motor and the air outlet probably is not critical. On the other hand, having the motor far away from the air outlet may have helped reducing the high pitch noise. I am just guessing...

I guess we can fix this "excessive back pressure" problem by enlarging the air outlet, right?

I am very glad to hear that the noise of your shop vac is now comparable to the noise from your random orbital sander. I find that the noise from a random orbital sander is quite low and is quite acceptable. Sound like I can keep my hope high in term of getting a great reduction of noise from my shop vac.

Glad to hear that the suction of your shop vac is not impaired by the 18-ft long extension vaccum hose. I will definitely try a long hose like yours; hopefully, I can keep the shop vac inside the garage and run the extension hose to my boat (that is parked right outside the garage).
You must be much stronger than I am. I find the box that I am building _very_ heavy (it is made from 3/4" particle board). I have splitted the box in half (a body and a lip) in order to minimize the weight of each piece that I need to man-handle; but I still find it to be very heavy. Anyway, I am pretty much giving up of the idea of moving the shop vac and the box onto the boat -- too heavy to do this often. The shop vac and the box will have to stay on the ground.

I think you are right to say that the low pitch noise from a dust collector is hard to reduce.
You may need to suspend the entire dust collector inside the box to keep the virbation from transmitting out of the box. I think I read something like that in one of the very popular DIY dust collection web site (from Bill?).
Hope you will find a way to reduce the noise from your dust collector.
Jay Chan

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