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Cutting Polyester Panels
Old 1st March 2018
  #1
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kotsaris's Avatar
Cutting Polyester Panels

I bought 20 polyester panels from Euroacoustik,to make bass traps.The problem i have is trying to cut the polyester.I tried with knife,scissors,saw but nothing.It is very difficult!
Does anyone has success with it?
Old 3rd March 2018
  #2
Gear Addict
Wow polyester?

Never heard of polyester bass traps, what are the Gas Flow Resistance figures for this material? Can you share your design? What frequencies are you targeting?

Are you sure these are for acoustic treatment and not soundproofing?

I cut my materials (Knauf earthwool) with a hand saw.
Old 4th March 2018
  #3
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kotsaris's Avatar
Well,there is no Gas flow resistance for this material.I thought that is similar to Caruso Isobond and tried it for some broadband absorbers,that worked quite well.So,as an experiment,I try to make some bass traps with it.My frequency target is around 90-100 Hz.My design is based on DP panel:Acoustics Forum • View topic - Studiotips Corner Absorber
I can confirm that the material it is very nice to touch and breathe near it as opposed to common rockwool.As for the absorbing qualities there is a data sheet: https://www.eurokustik.com/files/fib...da_tecnica.pdf

Originally I thought it would be easy as earthwool to cut,but it's fluffy and the teeth of the saw don't work well on it.
Old 4th March 2018
  #4
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I used polyester, it’s a nightmare to cut.
Depends on the thickness too, mine was 50mm, so not as bad as the 100mm stuff.
I used a heavy duty stanley knife. I had to change the blade regularly, as they went blunt quick.

I did some research, some people recommended an electric kitchen knife, and also an angle grinder (I was too chicken to try this!)
Old 4th March 2018
  #5
Gear Addict
Details please

Without a GFR number it is a total gamble whether you are using the right material to optimise the absorption of particular frequencies.

What density do you have?
What frequencies are you trying to target?

If you are making standard porous absorbers and were trying to target say 50Hz
even a 1 meter thick trap is not very efficient at that frequency IF the density is 45Kg/m3 and this material has a GFR of 14755Pa./s/m2 (we don't know)

(according to this porous absorption calculator)
Porous Absorber Calculator

On the other hand a Limp Mass Membrane trap with a 5Kg [email protected]
Attached Thumbnails
Cutting Polyester Panels-1-meter-thick-porus-absorber.jpg   Cutting Polyester Panels-limp-mass-membrane-50hz.jpg  
Old 4th March 2018
  #6
Gear Addict
Ah I see 90 - 100Hz

Ah I see 90 - 100Hz
Mmmmm even those frequencies are hard to touch with standard porous traps
Old 4th March 2018
  #7
Gear Addict
Absorption

BUT they are good at absorbing the other frequencies above.
You will get some action at 90Hz as they will be in the corners but still even when calculated with a random incidence it is much less than say 1kHz. @100mm thick with 100mm air gap there is a steep roll off before you get down to 100Hz
(according to the calculator).
Attached Thumbnails
Cutting Polyester Panels-100mm-thick-porus-absorber.jpg  
Old 4th March 2018
  #8
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kotsaris's Avatar
Quote:
Originally Posted by TheBrightSide View Post
I used polyester, it’s a nightmare to cut.
Depends on the thickness too, mine was 50mm, so not as bad as the 100mm stuff.
I used a heavy duty stanley knife. I had to change the blade regularly, as they went blunt quick.

I did some research, some people recommended an electric kitchen knife, and also an angle grinder (I was too chicken to try this!)
Thanks for the recommendations!I can borrow an angle grinder and try with it.
Old 4th March 2018
  #9
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kotsaris's Avatar
Quote:
Originally Posted by Carl Freeland View Post
BUT they are good at absorbing the other frequencies above.
You will get some action at 90Hz as they will be in the corners but still even when calculated with a random incidence it is much less than say 1kHz. @100mm thick with 100mm air gap there is a steep roll off before you get down to 100Hz
(according to the calculator).
Thanks for the calculations!
I'm using panels with density 30Kg/m3 and 100mm thickness.More likely the air gap will be 50mm.Also,they will be floor to ceiling.Like you said it's a gamble.I''l make a measurement afterwards and post the results.
Old 4th March 2018
  #10
Gear Addict
If the GFR is

Pretty fluffy then. 7619.46 (probably a mute point, excuse the pun) @100mm 50mm Airgap
then... it really is NOT a gamble it is a dead cert that there will be not much action @90Hz

Treat the corners but if there is still a problem then you maybe need a bunch of tuned traps.

I don't want to discourage you. You will get some improvement.

I have 250mm + 250mm air gap in my corners. With the help of careful speaker + sub positioning I am pretty happy from 20 to 150Hz. Could be smoother but the room is a horrible shape with partial pitched roof in half the room and low ceiling.

I am on a mission to reduce a 10db lump at 165Hz. Not put up my ceiling cloud yet. (Very punchy sounding, means my mixes will end up not punchy enough)

It seems an awkward area to get right. Thick porous traps not in corners seem to me to give unpredictable results. For example I did a test with 10cm cloud panels over my speakers and listening position 10cm air gap and it gave me a dip after the frequency I was hoping to reduce. It got rid of flutter echo and reduced the decay at other frequencies but not the modal ringing at 165Hz
Attached Thumbnails
Cutting Polyester Panels-100mm-thick-porus-absorber50mm-airgap-.jpg  
Old 4th March 2018
  #11
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I cut polyester panels with a table saw. Works great.
Old 4th March 2018
  #12
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Soft

Quote:
Originally Posted by DPower View Post
I cut polyester panels with a table saw. Works great.
Which densit?. OP has 30Kg so is really soft.
Old 4th March 2018
  #13
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Quote:
Originally Posted by Carl Freeland View Post
Which densit?. OP has 30Kg so is really soft.
I think 45kg. Fairly hard, but like the others, I found they resisted all knives.
Old 4th March 2018
  #14
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kotsaris's Avatar
Quote:
Originally Posted by DPower View Post
I cut polyester panels with a table saw. Works great.
I gave them to wood worker to cut them with table saw,but he feared his machine will crash!
What disk did you use?
Old 4th March 2018
  #15
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Quote:
Originally Posted by kotsaris View Post
I gave them to wood worker to cut them with table saw,but he feared his machine will crash!
What disk did you use?
Bog standard cross cut. 80 tooth, if I recall correctly.
Old 5th March 2018
  #16
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kotsaris's Avatar
Quote:
Originally Posted by Carl Freeland View Post
Pretty fluffy then. 7619.46 (probably a mute point, excuse the pun) @100mm 50mm Airgap
then... it really is NOT a gamble it is a dead cert that there will be not much action @90Hz

Treat the corners but if there is still a problem then you maybe need a bunch of tuned traps.

I don't want to discourage you. You will get some improvement.
I guess you 're right about minimal absorption at low frequencies.Still,I'm not sure that the DP panel design can be modelled by porous calculator.It seems that is mostly for classic panel design.
Anyway,it's just the beginning of the acoustic treatment...
Old 5th March 2018
  #17
Gear Addict
You are right. The quoted efficiency is much better than I am stating. Can anybody tell us how they reach down as far as they claim in the studio tips
Acoustics Forum • View topic - Studiotips Corner Absorber
"When built and installed properly this device exhibits a large increase in performance in the low frequency band between 63 and 125 Hz where typically porous absorption panels begin to drop off in effectiveness. This rise in low frequency performance [frequently referred to as the 100 Hz peak] is apparent in the graphs shown in the above linked 4 devices thread and is a perfect match for the treatment needs of typical small rooms."
I want to see your measurements before and after! Good luck with the build
Old 30th July 2018
  #18
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Hi, are you looking for cutting solution for polyester acoustic panels? we are the manufacturer of digital flatbed knife cutting machines. And we have the machine for cutting such materials. Here is the video link for your reference. YouTube For more details, please kindly contact [email protected]. Thanks.
Old 4th August 2019
  #19
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capoeira's Avatar
 

Quote:
Originally Posted by kotsaris View Post
I bought 20 polyester panels from Euroacoustik,to make bass traps.The problem i have is trying to cut the polyester.I tried with knife,scissors,saw but nothing.It is very difficult!
Does anyone has success with it?
How did this turn out?
Topic:
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