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Poplar ply - any good?

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infrasound View Drop Down
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    Posted: 05 March 2021 at 3:04pm
Nope, only for personal toys

IMO it would be hard to commercialise, specifically due to the cost, assembly complexity, tolerance, wear and definitely overall strength.

I'm happy to manage these personally, but wouldn't scale well upwards from there
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Post Options Post Options   Thanks (0) Thanks(0)   Quote stevie Quote  Post ReplyReply Direct Link To This Post Posted: 05 March 2021 at 2:27pm
And did all this FEA and physical validation result in a commercial product?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote infrasound Quote  Post ReplyReply Direct Link To This Post Posted: 05 March 2021 at 1:48pm
Originally posted by stevie stevie wrote:

Originally posted by infrasound infrasound wrote:


Stiffness is determined by the bracing primarily, thickness second.

With proper bracing, "just" 9mm of poplar ply can exceed the stiffness of 24mm birch plywood in cabinet.


How exactly did you reach that conclusion?
]

FEA and some physical validation Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 05 March 2021 at 12:16pm
Originally posted by stevie stevie wrote:

Originally posted by infrasound infrasound wrote:


Stiffness is determined by the bracing primarily, thickness second.

With proper bracing, "just" 9mm of poplar ply can exceed the stiffness of 24mm birch plywood in cabinet.


How exactly did you reach that conclusion?

deflection of a panel is proportional to the width^3 and inversely proportional to the thickness^3.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote stevie Quote  Post ReplyReply Direct Link To This Post Posted: 04 March 2021 at 1:08pm
Originally posted by infrasound infrasound wrote:


Stiffness is determined by the bracing primarily, thickness second.

With proper bracing, "just" 9mm of poplar ply can exceed the stiffness of 24mm birch plywood in cabinet.


How exactly did you reach that conclusion?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote VECTORDJ Quote  Post ReplyReply Direct Link To This Post Posted: 18 February 2021 at 8:02pm
I am basing My choice of Finland 4 x 8 sheets as to what is stocked in Maine USA. The Poplar cored ply here has very thin Birch outer layers and is not water proof. Sort of soft too.  Go Finland. Like a Rock.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 17 February 2021 at 9:19pm
Originally posted by VECTORDJ VECTORDJ wrote:

Why send all the time and work to make custom speaker cabs and use cheapie ply??? The best I have found is "Finland" 3/4" 4 x 8 foot 100 % birch exterior...........Like a Rock....


the good poplar isn't cheap - if anything it's more expensive than birch.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote VECTORDJ Quote  Post ReplyReply Direct Link To This Post Posted: 17 February 2021 at 9:05pm
Why send all the time and work to make custom speaker cabs and use cheapie ply??? The best I have found is "Finland" 3/4" 4 x 8 foot 100 % birch exterior...........Like a Rock....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote infrasound Quote  Post ReplyReply Direct Link To This Post Posted: 17 February 2021 at 6:13pm
Thanks for the link snowflake! Just what I'm after.


Stiffness is determined by the bracing primarily, thickness second.

With proper bracing, "just" 9mm of poplar ply can exceed the stiffness of 24mm birch plywood in cabinet.

Add a CF/GF skin to that and you're fixing that wear resistanceParty


Nb. 'Proper bracing' involves multiple rounds in FEM analysis & isn't a walk in the park. With guessing the bracing, you can go surprisingly far though.





Edited by infrasound - 17 February 2021 at 6:16pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 17 February 2021 at 1:15pm
anyone looking for poplar ply I think I have FINALLY found somewhere that will deliver small quantities for a reasonable price. And they have a cutting service.

https://www.atlantictimber.co.uk/efficency_ply_int_18mm.html

commenting on the above thread:

poplar surface is not as hard as birch but is better than spruce or pine. hard surface can be achieved with high quality resin/paint/liner/fibreglass. poplar takes paint very well.

poplar is not quite as stiff as birch but it is 40% lighter. If you want really stiff panels then use 24mm poplar instead of 18mm birch - it will be lighter and twice as stiff. If you want heavy cabs then replace some of the wood weight with bigger drivers!

poplar machines very well and reduces tool wear.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote nickyburnell Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2014 at 8:45pm
Originally posted by MarjanM MarjanM wrote:

I wonder what kind of cardboard wood is used in the JRX range.


Have some here, made from MDF, screwed together OK, wood screws holding drivers in, although I have seen VERY high end cabs do that in the past.
As I mentioned before, worst I've seen is OSB in EV cabs of old, apart from chipboard of course.
It's everything, not everythink!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KidCreole Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2014 at 5:02pm
You can have string and stiff but if its light it will go walkabout
 
I like bass bins to stay where they are
Speakers don't pay bills
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