Plywood?

Discussion in 'Wood Construction' started by cdlwingnut, Oct 20, 2017.

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  1. Oct 20, 2017 #1

    cdlwingnut

    cdlwingnut

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    My plans call for baltic birch or finnish birch, I see Aircraft Spruce has finnish birch and domestic birch both meeting aircraft specs, the domestic birch being cheeper, can domestic be used or is finnish birch that much better? Also a local lumber yard (not a big box) has baltic birch in the 5 by 5 sheets.

    what to pick whats the pros and cons.
     
  2. Oct 20, 2017 #2

    TFF

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    Most of the time it is not going to matter. Make sure the glue used at your local store is what is used in aircraft ply. What kind of plane?
     
  3. Oct 21, 2017 #3

    MikePousson

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  4. Aug 25, 2019 #4

    John wadman

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    I see that this is an old thread but I'm going to add to it in case someone looking for alternative birch happens across it. I found a good looking 1/8" Birch ply at a local lumber supplier and thought whoa, this could be great. So I bought a single sheet and took it home. I cut a couple of 3 x 3" pieces off a corner and boil tested them. They lasted about 35 minutes in a pot of boiling water before the outer skin started to delaminate. I let them go a bit longer and then took them out and cooled them under cold water from the faucet. I then peeled the three layers apart. Not happening!
     
  5. Aug 25, 2019 #5

    Speedboat100

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    What is this to say John ?
     
  6. Aug 25, 2019 #6

    John wadman

    John wadman

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    Boil test your ply if its anything other than stamped aircraft ply. If it comes apart, don't use it! If it's not put together with waterproof glues, its going to eventually come apart.
     
  7. Aug 25, 2019 #7

    Speedboat100

    Speedboat100

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    I have to try cook the pieces I have..definitely some looks to have whole lot more layers than others.
     
  8. Aug 25, 2019 #8

    John wadman

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    don't cook them speedboat100, you have to boil them. cooking them will probably only post cure the glues even more. They may not fail if you cook them. Boiling water will seep into the grain and if, the glues aren't waterproof, the layers will come unglued. If this happens it "no bueno" no good man!
     
  9. Aug 26, 2019 #9

    Speedboat100

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    Sorry John...boil them. I will boil them to see if some of the plywood I am using ..is no good.
     
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  10. Sep 3, 2019 #10

    MadProfessor8138

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    I had started a thread a while back about aircraft grade plywood that returned no valuable answer to my question of : "where can you get aircraft grade plywood other than ACS or Wicks ? "
    ACS & Wicks do not manufacture the plywood....they are only retail distributors for the product.....and surely,they are not the ONLY distributors of the product.
    I cannot see a manufacturer or manufacture"s" of the plywood relying solely on 2 companies to distribute their product...that's a hell off of a lot of faith in 2 places to keep you in business.

    Who manufactures and supplies the plywood to ACS & Wicks & who else do they sell to ????

    Kevin
     
  11. Sep 3, 2019 #11

    Speedboat100

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    Mohogany and Koskisen OY in Finland will provide aviation grade when requested.
     
  12. Sep 3, 2019 #12

    AdrianS

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    What is the difference between aircraft ply and marine ply?
    Proper marine ply uses water (boil) proof glue, and has standards regarding allowable defects etc.
     
  13. Sep 3, 2019 #13

    Speedboat100

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    Construction grade and aviation grade can be seen externally as the aviation grade has double amount of layers in it.
     
  14. Sep 3, 2019 #14

    BJC

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  15. Sep 3, 2019 #15

    TFF

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    The ply quality is higher on the airplane ply. Any inside ply is as nice as the outside with same quality of finish of the plies, and the guaranteed that the boil test is of higher quality than the marine. Airplane ply looks like modern furniture ply but better inside. The fudge factor is gone with modern manufacturing. In the 60s-70s stuff ended up better because the fudge factor and materials quality. As resources got scarce, manufacturing tightened up to the point you only get what you pay for. No free quality. It’s one of those things that if you had samples of both, it would not be a guess to figure out which one is which. The first plane I know of to use marine ply was the Flybaby, ribs mainly. I think spar reinforcing plates and like are still airplane ply.
     
  16. Sep 3, 2019 #16

    Aerowerx

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    I looked into this myself, several years ago.

    As far as I could tell there is only one company in the USA that makes aircraft plywood to the military specification. When I contacted them they said they only sell in large quantities. Read that as Wicks and ACS.
     
  17. Sep 3, 2019 #17

    MadProfessor8138

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    AdrianS.......I've done a lot of research on plywood in the past year and the general consensus seems to be that marine grade plywood actually "ISN'T" waterproof.
    Dont ask me why.....it would seem that marine grade plywood would be constructed specifically for wet environtments/applications....but it's not.
    I'm just relaying information that I have collected across the internet on the products....

    Kevin
     
  18. Sep 3, 2019 #18

    narfi

    narfi

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    I don't think that is true.
    I think your problem is in labeling... anyone can say 'this is aircraft plywood' or 'this is marine grade plywood'. But unless it has been tested to meet a specific standard, then what does that really mean?

    https://en.wikipedia.org/wiki/BS_1088

    Here is the standard for the marine plywood I am using to build my boat with. Are you claiming that stamped BS1088 would not pass a boil test?

    Here is the company I purchased it from, they are a great ma and pa feel business with excellent customer service and do their best to get you good shipping rates etc...
    https://boatbuildercentral.com/wp/proddetail.php?prod=PLY-PL_Okoume_BS1088
     
  19. Sep 3, 2019 #19

    MadProfessor8138

    MadProfessor8138

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    narfi.....no,I'm not stating that at all.
    I'm just simply relaying information about plywood that I have found on the internet.
    This is information from the EAA publications and from various "well respected" builders from around the world.
    Just a quick screenshot pertaining to the BS1088...it seems that the BS1088 "standard" is not held in high regard.


    Screenshot_20190903-161209_Samsung Internet.jpg
    Screenshot_20190903-161109_Samsung Internet.jpg

    Kevin
     
  20. Sep 3, 2019 #20

    MadProfessor8138

    MadProfessor8138

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    Quick screenshot from the EAA pertaining to marine grade plywood in aircraft.....

    Screenshot_20190903-160558_Samsung Internet.jpg
    Screenshot_20190903-160548_Samsung Internet.jpg

    Kevin
     

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