Thread: More on dust extractor noise

Originally Posted by Arron

I read Zelk's long thread below on Reducing d/e noise and realise I need to do something like this. One thing that I noticed though was that his d/c (like mine) is sitting on a pressed steel platform. I was wondering if this contributes to the noise - like siting your d/c on a steel drum. Would it help to replace the steel base with a timber one ? Anyone tried this?

It probably won't make much of a difference in the overall volume (but it probably will change the frequency spectrum emitted) as the majority of the sound radiates directly into the air from the DC. There is a chance the steel platform might resonate with the DC vibe. If that is the case try adding a dozen bricks to the top of the platform as that will change it's resonant frequency. Don't rely on your eyes (yes I do mean eyes) to determine a difference. Ie go out of sight and get someone to randomly load and unload the platform and see if you can detect a difference in the noise from where you can't see the DC, say from outside your shed. Or better still used a sound level meter.

I noticed this effect when I decoupled the DC from my DC enclosure and placed it on a wooden frame in direct contact with the ground (rather than the enclosure). It reduced the low frequency rumbling that the enclosure was emitting and dropped the sound level by a couple of dB.

i notice that you say 'radiates directly into the air from the Dc' . What part of the dc exactly is making the noise. I suspect its the impellor/rotor thing, right? If that's so, is there something that can be done to the impellor to reduce this noise. would remaking the impellor housing in heavy timber help - or maybe building a sound-deadening box just around the impellor (excluding the electric motor)'. I have some very heavy gauge rubber sheet - old conveyor belt stuff - could I fix that directly to the outside of the housing as a primitive kind of sound insulation ?

I'm looking for quick fixes because I dont have the space or time to build a decent cabinet like zelks. I'd love to improve my dust collection effectiveness but it always founders on the same rock - the noise the damn things make.

Arron

For a quick and effective reduction in noise from the DC try one of these:

Suppressor Dust Collector Muffler at Penn State Industries

I have one, acquired with a 2hp DC, and the difference it makes is amazing.

I was about to put my DC outside, mainly because of the noise factor, when my DC motor blew up.
I bought a used 2hp DC from another forum member and it came with one of these.
I was rather sceptical, in fact I almost didn't pay the extra for it, but I'm glad I did.

Only downside is that the DC now still lives inside and I really should put it outside

Now that is what I call a quick fix! One question though - what does it do to air flow?

Seriously considering it regardless.

Cheers
Arron

Originally Posted by Arron

Now that is what I call a quick fix! One question though - what does it do to air flow?

Seriously considering it regardless.

Cheers
Arron

It does nothing to restrict the air flow, in fact it is a straight through the same size as the outlet of the DC with a surrounding cylinder with what appears to be a sound deadening material.

Originally Posted by Big Shed

It does nothing to restrict the air flow, in fact it is a straight through the same size as the outlet of the DC with a surrounding cylinder with what appears to be a sound deadening material.

According to BP It will restrict air flow but only to the tune of about adding it's own length of ducting.

Originally Posted by BobL

According to BP It will restrict air flow but only to the tune of about adding it's own length of ducting.

All 12 inches of it?

And if one really wanted to be pedantic, it could replace 12" of the flexible hose, so it would actually be more efficient as it is 12" of smooth duct as against 12" of ribbed flexible duct.

What is the internal pipe like - does it have holes in it. Seriously considering making my own if its not available locally.

Originally Posted by Arron

What is the internal pipe like - does it have holes in it. Seriously considering making my own if its not available locally.

From memory, no, it is just a smooth galvanised steel duct (ie much more efficient than the exising ribbed flexible duct).

But I will check in the morning and if it is different from what I remember I will post to that effect.

Many thanks
Arron

Originally Posted by Arron

i notice that you say 'radiates directly into the air from the Dc' . What part of the dc exactly is making the noise. I suspect its the impellor/rotor thing, right? If that's so, is there something that can be done to the impellor to reduce this noise. would remaking the impellor housing in heavy timber help - or maybe building a sound-deadening box just around the impellor (excluding the electric motor)'. I have some very heavy gauge rubber sheet - old conveyor belt stuff - could I fix that directly to the outside of the housing as a primitive kind of sound insulation ?

I'm looking for quick fixes because I dont have the space or time to build a decent cabinet like zelks. I'd love to improve my dust collection effectiveness but it always founders on the same rock - the noise the damn things make.

Arron

The majority of the noise will be generated by the impellor, the majority of the noise will be heard at the exit of the of the fan housing, and this is where a muffler acts to absorb this noise as in the link big shed provided, I would think it will have holes in the inner pipe, the holes then allows the pressure waves to penetrate into the sound absorbing mat'l.
Design of the impellor in conjunction with the housing certainly will determine how much noise it makes, any sort of noise absorbing mat'l that surrounds the housing will also absorb noise that is generated by the fan and eminating from the housing itself, noise absorbing mat'l is usually porus, (full of air) not sure how your belting will do give it a try tho if nothing else, every little bit helps

My DC is outside, I have the motor/fanhousing surrounded in it's own box (no motor overheating issues) (yet) made out of freezer panel, also note the muffler on the exit (points down) pointing the muffler down also helps to redirect the noise down to the ground rather than at the nieghbors
overall view of DC.jpg


Pete

Originally Posted by Arron

What is the internal pipe like - does it have holes in it. Seriously considering making my own if its not available locally.

Hi Arron, just checked the internal pipe, it does indeed have holes in it, very small holes (about 2-3mm) failry close together. Looks like they used some sort of perforated sheet metal.

OK, thanks.
I did some research last night and it looks like they generally do. I find it puzzling though - doesnt the insulating material just get immediately clogged up with dust that has entered through the little holes.

cheers
Arron

I used BP's quick and easy muffler on my JET DC1900 blower/homemade cyclone: a 2.5 m length of 6" insulated HVAC flex-tube from the blower to the elbow taking the air outside to the DC bags/ Not too bad.