Router Enclosure Experiment

[Brian Kent]

I am working on a box to enclose my PC 890 ubder a router table. My primary motive is dust control. I'll slant the bottom towards a 4" blast gate to the dust collector.

But I am also experimenting with sound control. An acoustic box should enclose the unit, but if it is an all wood box with firm connections to the table, it would work as a resonance chamber like the box of a violin or a drum.

I want to try 2 layers of 3/8" baltic birch ply, with a layer of rubber router mat between them. I'm trying to figure out the connections between layers.

I thought about building 2 boxes, with the inner box covered by the mat and fitted inside the outer box. The bolts or screws that connect the boxes would have rubber washers.

Any other ideas for attaching the sound-insulated box together?

Other sound control: I bought PC 890 because it's unloaded decibel rating was one of the two quietest tested. I am trying Whiteside bits and others with a smooth cut in hopes of reducing chatter. I am using fittings for the dust collector instead of the shop vac because the dust collector is a little quieter and a lot lower tone.

[Greg Cole]

Brian,
I built mine out of scrap 1/2" MDF. The sound doesn't really reverberate or resonate up though the table or anything even close. I have a Woodpeck RT that is 1 1/2" thick that I directly attached the router DC box to.
Same idea as you are talking about, slanted bottom and a 4" port to a blast gate.
The vibration from the router isn't affected by boxing it in, since the router is attached to a lift that simply drops in place with my set up anyway.

Greg

[richard poitras]

You could also use Styrofoam between the ply for soundproofing? I have 1’’ on the out side of my house and it sure does make my house a lot quieter than some of my other ones I have had..

[Jim Heffner]

You could also use Styrofoam between the ply for soundproofing? I have 1’’ on the out side of my house and it sure does make my house a lot quieter than some of my other ones I have had..

I'm with Richard on the styrofoam panels. Just cut to fit inside of the box
and use spray contact cement to hold them in place. Should make it quiet enough to suit you this way.You can buy that stuff at one of the BORGs
or at a siding supplier for a few bucks. Jim Heffner

[Brian Kent]

That's right. I could just glue the panel inside a box rather than between two layers. I wonder if my table saw blade could handle the stuff?

[Bruce Page]

Brain, it'll make a little mess but your TS blade will cut it like butter. I have had excellent results gluing styrofoam with plain old PVA (yellow) glue.

[Fred Craven]

Think speaker box. MDF is one of the best materials for speaker boxes. Nice and dense, and not as prone to resonate. Now throw in some sort of sound sucking material on the inside of the box...uh, not insulation.

Sandwiching different materials is a good idea, but any mechanical fasteners, such as screws or bolts which go from an inside layer of wood to an outside layer, will defeat your purposes. (like a 2x4 in a wall).

During the Dallas Opera's production of Billy Budd several years ago, the entire stage had to open up (like a big mouth) with 20-30 (40?) guys top of it--with another 40 or so coming underneath it. Sorry can't find the photo right now.

The point is that we had a very big hydraulic pump just off to stage left which operated the lift. The pump...was very noisy (going up) So they floated it on thick sound absorbing feet, boxed it heavily, and lined the box with very expensive stuff.

We still heard the pump, but the noise was greatly reduced, oh, and the sound was covered by the massive men's chorus, orchestra in the pit, and several drums on the stage.

----
Let us know how your experiments come out!

[Randy Denby]

Remember a couple of things when designing it. The top needs to be flat and not sag over time from the hanging weight of the router/lift , so dont go thin there. Dust collectors need air movement to operate efficiently, dont choke it down. I drilled air holes/slots in the front bottom of my box to entrain the dust and allow more airflow.The opening around the bit aint enough .
Good luck

[John Young]

Here are a few of my thoughts:
If your dust collector is capable of pulling 500 cfm and you port it into a sealed enclosure, you are going to get no flow. You need to allow opening(s) in your enclosure to allow air to flow into your collection port. If noise is a concern, these opening(s) should be located and sized properly to minimize the noise yet allow proper air flow. Noise will come out of these openings. So, you could cover the opening(s) with a filter of some sort that would allow air to enter and at the same time silence the noise trying to escape. The openings could be like speaker ports with rounded edges to minimize air flow noise.
To minimize your enclosure resonance, think thick and high mass panels. In speakers, bracing is also included to minimize panel vibration. I think you are on the right track by installing some type of sound deadening material on the interior. Traditionally this would be an acoustic foam. Styrafoam would not be a good choice. It does not absorp sound/vibration very well.
Make sure you seal the rest of the enclosure well.
Sorry, but this is what happens when an engineer starts brainstorming.

[Mike Heidrick]

I have the woodpecker enclosure and it is not very noisy or resonating at all.

If you really want to deaden the sound look for Dynamat or a product called BrownBread accoustical sound dampener. These are commonly used in competition car audio installations and come in either mat or peal and stick forms. The Dynamat is almost like a firm rubber sticky tar like consistency with a thick foil surface and once applied will not come off. It will sound dampen your enclosur no problem. It is best to use a wooden roller to apply the dynamat. Also you do not have to have 100% coverage to control the sound.

go to dynamat.com

[Tyler Purcell]

I personally would use MDF as it is so dense and not prone to resonating. Also, I would line it with sound absorbing materials. They commonly use these in computer cases, military items, and even recording studious etc.

Check out this great site for recycled material scraps etc. They have plenty of great sound absorbing materials:
https://www.materialscraps.com/Merchant2/merchant.mv?Screen=SFNT&Store_Code=M

[Brian Kent]

After a trip to the Borg…

Acoustical Ceiling tile and 1.5" insulating styrofoam sheets are both reasonably priced.

MDF looks like a good idea for the box. I haven't used this very basic material before. Do I use glue and screws in rabbets?

Between the box and the table, I want to isolate vibration. I am thinking 1/4" bolts surrounded by vinyl tubing with rubber washers, and rubber strips between the surfaces.

I like the idea of the stuff used to isolate sound in cars, but the acoustical ceiling panels actually have about the same decibel reduction ratings (.4 to .8).

In musical settings I would use the specialized foam panels, but these are so soft and porous they would be extreme dust collectors.

If I am putting holes in the box for airflow (with filters - good idea there!), is there an advantage of drilling them at an angle to encourage a whirlwind the same direction as the bit spins?

I appreciate all of your expertise and imagination. Hope something fruitful comes of this.

[Randy Denby]

Brian,
The router will need to be hard coupled to the top, otherwise you could introduce movement in the bit . So , that will be a negative for sound transmission, but in reality, my setup with enclosure for dust collection is not that loud. And I usually have ear plugs in most of the time due to other tools that are REALLY loud....planer, Sliding compound miter saw, etc.
I'm sure a little creative drilling might help with vortex, but I wouldnt think enough to be measurable. I do like the idea of a filter on the holes, mainly because it would help on noise transmission...but as I said, even with that missing on mine, I am not bothered by the noise too much. Maybe I've already lost my hearing :eek: ? I have designed the return air chase on central heating/ a/c units to quieten down the sound alot of times. (Especially mine that is near my living toom.) It is just a series of stepped lined baffles to stop sound transmission. I'll try and draw an example as best I can with the keyboard

[------- .

. ---------]

[------- .

. ---------]

This would be looking down on the return air chase with the baffles meeting the wall on every other side and going from top to bottom solid. Sized in between for the airflow requirement. Might help on designing your intake holes . Of course, just one baffle with the intake from the bottom would probably be enough

Randy
edit....dingdangit, no matter waht i do the lines are supposed to be offset more, but when i go to the post it brings the dashed lines back toward the beginning of the line.....I hope you get the jest of what I'm trying to show. Good luck!

[Brian Kent]

Randy,

I got your idea. Looks like your typing baffled the computer:p .

The router will for sure be tight with the table top. It's the box around it that could be connected with a gasket.

I know a lot of this is overboard, since I will use ear protection and since I already am so much happier with the new router. Just seeing how far I can go with the idea without a lot of expense. And since I'm going for dust control, why not sound too.

What do you use for table top and router plate insert? I was thinking of a base of 3/4" mdf, well supported, with a 1/2" phenolic coated Baltic Birch for the surface and to hold the miter slot and t-slot.

I have no idea what matters for an insert plate.

[Randy Denby]

Randy,

I got your idea. Looks like your typing baffled the computer:p .

The router will for sure be tight with the table top. It's the box around it that could be connected with a gasket.

I know a lot of this is overboard, since I will use ear protection and since I already am so much happier with the new router. Just seeing how far I can go with the idea without a lot of expense. And since I'm going for dust control, why not sound too.

What do you use for table top and router plate insert? I was thinking of a base of 3/4" mdf, well supported, with a 1/2" phenolic coated Baltic Birch for the surface and to hold the miter slot and t-slot.

I have no idea what matters for an insert plate.

Finally...I've got one over on this computer....cause its always baffled me :D
I respect what your doing and am gonna hold you to keeping us in the loop! I have done similiar things on my other tools. One big one was removal of the orange plastic baffle just inside my Jet 15" planer. This made a huge difference as it was like a reed in a horn,still loud, but not intolerable.
I used 2 thickness of mdf for the top and single layer elswhere, Also laminated the top for durability and slickness. Gotta be careful tho, as the contact cement will cause problems with bubbles/ buggers underneath. Not good for flatness. I also have one of the first lifts offered, its a Jessem/ Jet Exzacta Lft
They have refined them alot since and check out woodpeckers quick lift.

[Tim Marks]

I wonder if my table saw blade could handle the stuff?

Styrofoam? Just score the top with a knife and break it on the edge of a table. Or just cut it all the way through with a knife or a handsaw.