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.
wrote:
wrote:

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.

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. :-)