2D qrd difusser with round wells?

Banjo · 9th November 2009

I have a hair brained idea the make a diffusser by drilling 50 dia holes into a 300mm thick block of mdf or simlar, hole pattern would be 60degree honey comb style, holes would flat bottomed to depths calculated by any of the available software. Has any one tried this or have any idea if it will be better or worse than a skyline style with 4mm dividers? I have a large CNC machine at my disposal hence the idea of drilling the holes. Any help will be apreciated.
Thanks, Denis House......

terry j · 9th November 2009

well I have thought of using blocked pvc pipe, never thought of drilling holes out of solid!!

And I don't imagine going honeycomb would be particularly bad either.

It will do something I am sure. Hey, break the mold and go ahead with it!!

300 deep will be good, but why not use something other than mdf, bond a few layers of hi density foam together and use that perhaps.

where is somers?? I know of somersby, but not somers....

BlueSprocket · 9th November 2009

I can't think of any reason why it wont work. You will have a different resonant frequency of the wells based on the diameter and depth of the holes. Otherwise it will function in a similar fashion to a standard QRD. The same basic equations and rules should apply. Bottom freq will be determined by well depth and the high freq will be determined by Well diameter. Actually being round, you may well get more resonance in the device due to the round roles, which if done properly could be a good thing. In fact, if you offset the holes just right you could get to having very very thin walls between wells, which is ideally what you're looking for.

Give it a go and see how it turns out.

Banjo · 9th November 2009

Somers, Victoria , Australia. Quite a nice spot. Thanks for the replies, won't take long to glue up a block and give it a try, using the drillng idea means you could go quite small and deep with little more effort, think I have some more reading to do.......

Nordenstam · 9th November 2009

Page 262 in The Book:
"It has also been suggested by Pollack and Dodds that the wrappig can be carried out in a hexagonal configuration.

Sn,m = (n^2 + m^2 + nm) modulo N"

which is the same as the normal square 2D except for the added "nm" inside the parenthesis. Note that this is not the same 2D sequence as normal square 2D QRD's. The hex stacking would make the round hole packing lots more effective!

9th November 2009	#1
Banjo Gear nut Join Date: Oct 2007 Posts: 148 Thread Starter	2D qrd difusser with round wells? I have a hair brained idea the make a diffusser by drilling 50 dia holes into a 300mm thick block of mdf or simlar, hole pattern would be 60degree honey comb style, holes would flat bottomed to depths calculated by any of the available software. Has any one tried this or have any idea if it will be better or worse than a skyline style with 4mm dividers? I have a large CNC machine at my disposal hence the idea of drilling the holes. Any help will be apreciated. Thanks, Denis House......

9th November 2009	#3
BlueSprocket Gear addict Join Date: Feb 2008 Location: Harrisonburg, VA Posts: 396	I can't think of any reason why it wont work. You will have a different resonant frequency of the wells based on the diameter and depth of the holes. Otherwise it will function in a similar fashion to a standard QRD. The same basic equations and rules should apply. Bottom freq will be determined by well depth and the high freq will be determined by Well diameter. Actually being round, you may well get more resonance in the device due to the round roles, which if done properly could be a good thing. In fact, if you offset the holes just right you could get to having very very thin walls between wells, which is ideally what you're looking for. Give it a go and see how it turns out. __________________ "No stone throwing regardless of housing situation."

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9th November 2009	#2
terry j Gear maniac Join Date: Jul 2009 Posts: 296	well I have thought of using blocked pvc pipe, never thought of drilling holes out of solid!! And I don't imagine going honeycomb would be particularly bad either. It will do something I am sure. Hey, break the mold and go ahead with it!! 300 deep will be good, but why not use something other than mdf, bond a few layers of hi density foam together and use that perhaps. where is somers?? I know of somersby, but not somers....

9th November 2009	#5
Nordenstam Lives for gear Join Date: Aug 2005 Location: Norway Posts: 1,735	Page 262 in The Book: "It has also been suggested by Pollack and Dodds that the wrappig can be carried out in a hexagonal configuration. Sn,m = (n^2 + m^2 + nm) modulo N" which is the same as the normal square 2D except for the added "nm" inside the parenthesis. Note that this is not the same 2D sequence as normal square 2D QRD's. The hex stacking would make the round hole packing lots more effective!