Dust Collection Noise

[matthew lippel]

Hi All,

I feel I've read all I can find on the dust collection noise but I haven't been able to replicate some of the community's successes. On to my setup: I built a shed outside and lined the area in between the studs with Roxul's Safe'n'Sound rockwool batting. I do NOT have any filters coming off the exhaust as I'm venting outside. I did not stagger the studs. While I could have, it seemed people were achieving my desired level (mid 70s) without employing this technique.

The structure is a 3 x 6 x 8ft (LxWxH) lean-to constructed with 2x4s and 3/4's exterior barnboard ply. I have 6" pvc pipe running through one side (inlet) and 8" 24 gauge (I believe) HVAC metal ducting through the other side. Any seams (as few as there were) were sealed. The doors have weather stripping and appears to be airtight. Again, the walls and ceiling are covered with rockwool batting. With the doors open I'm reading about 86db and with the doors closed I read about 82-83. I was hoping for more. My target is somewhere in the 70s as I do no wish to disturb the neighbors who are only 10 feet away. Having seen some videos...it seems possible. The DC cannot fit in the shop so it must be stored outside.

Let's make this baby silent. Thoughts?

-Matt

[Erik Loza]

I don't have a specific answer for you except to say that customers would always tell me they were worried about machine noise in their homw shops and I would tell them, "Wait til you fire up the DC". Table saws and so on might be louder on the high-pitched end of the spectrum but the low-frequency sound of air rushing through the dusting of the DC system always seemed to be the most prominent sound in any shop. At the big trade shows (IWF and AWFS), our voices were always hoarse and shot from trying to talk over the DC systems. SCM had a special "room" that held the actual DC units but all the sound came from the ducting.

Getting back to you question, I think it's going to be loud that there won't be much you can do about it. My air compressor is the loudest thing in the shop and I sort of have a gentleman's agreement with my neighbors not to run it in the early AM or late at night. Good luck with a solution.

Erik

[John K Jordan]

Hi All,

I feel I've read all I can find on the dust collection noise but I haven't been able to replicate some of the community's successes. On to my setup: I built a shed outside and lined the area in between the studs with Roxul's Safe'n'Sound rockwool batting. I do NOT have any filters coming off the exhaust as I'm venting outside. I did not stagger the studs. While I could have, it seemed people were achieving my desired level (mid 70s) without employing this technique.

The structure is a 3 x 6 x 8ft (LxWxH) lean-to constructed with 2x4s and 3/4's exterior barnboard ply. I have 6" pvc pipe running through one side (inlet) and 8" 24 gauge (I believe) HVAC metal ducting through the other side. Any seams (as few as there were) were sealed. The doors have weather stripping and appears to be airtight. Again, the walls and ceiling are covered with rockwool batting. With the doors open I'm reading about 86db and with the doors closed I read about 82-83. I was hoping for more. My target is somewhere in the 70s as I do no wish to disturb the neighbors who are only 10 feet away. Having seen some videos...it seems possible. The DC cannot fit in the shop so it must be stored outside.

Let's make this baby silent. Thoughts?

-Matt

Your design is not clear to me. Maybe make a diagram and provide pictures?

Is this a big cyclone? Did you mount it on the outside of the shop wall? If so, sound can be transmitted directly through the wall which can act like a big sounding board. Sound can also be transmitted through a floor or ceiling.

Just guessing in the absence of details, but you may be able to add mechanical isolation/dampening. If sound is transmitted through the studs an isolated secondary wall with insulation might help, either inside the closet or inside the shop. If the return air is entering piped back into the shop baffling might decrease the sound entering that way.

I built an interior closet for my 5hp cyclone. I chose a 6" thick staggered-stud insulated wall faced on both sides with 1/2" plywood, insulation in the ceiling, and a baffled return duct. I used a 5' wide insulated steel double door for access but it does not open onto the main shop - it opens in another room that I never use when running the DC. I don't remember my dB numbers but I can hear whispers and carry on normal conversation in the shop with the cyclone running. The loudest thing is the air rushing into the dust pickups, especially the open pickup at the lathe!

JKJ

[matthew lippel]

Sorry I should provide pictures. I'll post them when I'm back at the shop.

But it's a 5hp, 16" impeller, clearvue cyclone

[Jim Andrew]

My cyclone vents outside, and the exhaust seems to exhaust noise as well as air. No problem, it is far enough from the house my wife does not complain, and no neighbors nearby.

[Jim Becker]

When you exhaust outside, you need to take into consideration "direct sound transfer", so if you're outlet isn't taking a turn toward the ground, etc., you're going keep sound levels "up there" simply because of how sound is transmitted. Baffling and muffling the exhaust should be helpful around that. There's actually a recent thread on this very subject here in the Workshops forum area...

[Peter Aeschliman]

This is a long post, so I'll start with my recommendation first:

(1) start by trying to muffle your exhaust. If still too loud,

(2) build a free-standing frame for DC so it's not attached to the walls (assuming you have a cyclone). If still too loud after that,

(3) then I'd at least recommend double drywall and green glue. If you really want to go hard-core, use noise isolating clips + furring channel + double layers of 5/8" drywall with green glue between. This worked surprisingly well for me, but was definitely a PITA and wasn't cheap.

--------------

A few things from my experience, which I understand doesn't completely relate to your situation.

I have a 3hp grizzly motor and impeller on an ebay cyclone in a sound "proofed" closet in my basement, venting outside with 6" ducting.

I read up on soundproofing techniques for home theater, and found everything I learned to be spot on. I staggered the studs, insulated, used these sound clips and resilient channel, two layers of 5/8" drywall with green glue in between, and acoustic caulk to seal the drywall joints at the corners. Also, I built a free-standing frame to hold the cyclone in the closet, which is only bolted to the concrete floor. It was a ton of work and quite a bit of extra expense, but worth it in the end. I didn't want my wife to be any more annoyed about the time I spend in my shop, so it was money well spent.

I have an air return for my furnace right above my dust collector (which I covered with 3 layers of dynamat), and with that monster running, I can barely hear a hum, even when I stick my head into the return upstairs.

The big thing I'd like to stress, that I think often gets missed on this forum, is that roxul safe and sound, or any insulation for that matter, only helps attenuate the noise that gets into the stud cavities. That's only a fairly minor part of the noise equation. In order for noise to get into the stud cavities, it has to first vibrate through your drywall or interior wall board. But if that's happening, then those same vibrations are being passed through your studs and then to your exterior siding. So you can't have high expectations for insulation alone.

It's all about minimizing the vibrations that get into your stud cavities in the first place. You do this with decoupling and mass. Decoupling is done with the use of the sound clips/resilient channel and the green glue between the drywall panels. The mass is handled by the double drywall.

Those two things are FAR more important than insulation in the walls.

All that said, Im willing to bet that most of your noise is coming from your exhaust. I just got my DC up and running. I expected to only hear the sound of rushing air outside, but it sounds like a jet engine out there. So I have another problem to solve.

There are some commercial exhaust mufflers you can buy, which are essentially just extra large sections of pipe with insulation packed into the sides. Most claim about 3db of noise reduction, which won't get you all the way to your goal. So my plan is to build a sealed box out of 3/4" MDF, lined with egg crate foam, with a few baffles inside of the box to disrupt the air flow and force sound to hit them.

This will of course introduce turbulence and resistance. So to help at least reduce the static pressure impact, it will have a 10" exhaust with a 6" inlet, and the cross sectional area of the cavities inside will have the same area as the 10" exhaust (~314"). I've read about people having success with this approach.

Good luck!

[Bill Jobe]

I've started assembling everything with rubber pads between parts bolted together. When I replaced the fan in the bathroom I mounted it with rubber pads and you can hardly hear it.
I bought a HF Dc and going to take it apart and put 45mil liner between all the parts. I think a lot of the noise is amplified simply by going back and forth between mating parts. Maybe not much, but some. I'm convinced the base alone acts like an amplifier. JMHO

[Andy Giddings]

If you're only dropping 3dB with the doors closed are they solid core or hollow? Doesn't seem like they are helping much and you might try green glue and panels with those as suggested by Peter. Also, as stated by others, either build a muffler for the outlet or a baffle. There are a number of threads on here and the ClearVue forum covering best practice. Some have had success with an insulated duct so it doesn't have to be rocket science

[matthew lippel]

Awesome guys thanks for the replies. This is driving me nuts. I'm on my way to the shop now so I will provide pictures shortly but I have two major concern that I'm not sure how to take care of:

How do I sound proof the inlet and exhaust?

And...how do we provide cooler air for the motor? There have to be vents no?

[Bill Dufour]

Your target of 70 db outside is way to high unless you live next to a freeway. If it is 70 db outside you neighbors are going to call the police when you run the dc. You need to be in the 50's outdoors.
Are you using flex duct on intake and exhaust to isolate the dc? I would mount it all on rubber isolators. paint the casing with grafting seal. and blanket it in rockwool. How many horsepower? is it air starved and cavitating? Can you feel the vibration when it is running?
Bill D.

[matthew lippel]

I'll post pictures tomorrow. It's a 5hp clearvue cyclone. I have safe n sound 3" rock wool in between the studs. I have 6" inlet going to the cyclone through the side of the shed and an 8" exhaust leaving the shed.

[Robert Payne]

Not sure when you got your ClearVue cyclone, but if you add the small block shown in the attached picture inside the blower, it should reduce the noise created by the impeller by about 10 dB. Has to do with changing the acoustics created by the impeller. Hope this helps.

Noise%20Reduction%20Blower.jpg

[Ole Anderson]

How are you measuring your sound level? Phone apps can be quite erroneous. dBa or dBc? It makes a difference. They seem to work fine for relative levels, but not always so accurate at matching a calibrated sound level meter. I like to use dB Meter by Vlad Polyanskiy. I also have a (uncalibrated) Radio Shack meter and they don't agree very well.

[Chris Parks]

DB in the end means almost nothing as there is no standard to use in measuring like a set height, distance etc and most of the non professional meters are not accurate as Ole notes. If you can't have a normal conversation standing next to the exhaust when venting outside then I reckon it is too loud. I walked into my workshop yesterday ready to ask my son to turn on the DE because he saw using the BS and it was already on and I was only about three meters away from the outside exhaust when I thought it wasn't.