Table with wood properties

Discussion in 'Materials' started by gonzo, Sep 20, 2015.

  1. gonzo
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    gonzo Senior Member

    This is a table with some common species available at the local lumber store
     

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  2. TANSL
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    TANSL Senior Member

    The following properties are used in the calculation of scantlings:
    • Weight:kg/dm3:0.52:
    • Ultimate flexural strength:N/mm2:74:
    • Ultimate compressive strength:N/mm2:41:
    • Ultimate inplane shear strength:N/mm2:8.99:
    • Modulus of Elasticity:N/mm2:121000:
    Could you please give this data to the woods of your tables. Thank you
     
  3. SukiSolo
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    SukiSolo Senior Member

    Useful mainly for the US, we don't see much hemlock over here in Europe!, or southern pine....;)
    In fact Doug Fir is specialist and hard to find. We get a lot of European Spruce species and some pines, used to be a lot of Russian timber, certainly we get Swedish and Finnish stuff. There is some larch as it's grown for telegraph poles, I believe.
     
  4. gonzo
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    gonzo Senior Member

    I've only worked with larch on a couple of folkboats. It seemed very similar to some fir and pines.
     
  5. TeddyDiver
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    TeddyDiver Gollywobbler

    There are different kinds of larch too, with very different properties..
     
  6. Petros
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    Petros Senior Member

    this list is not practical for boat building, that is a list published by the western wood products association for group of species of visually rated mass produced lumber. each one of those has several species in it, and safe allowable load is for the weakest one in the group, statically verified (19 out of 20 exceeds it), for visually rated dimensional lumber. that means is is slinging down a conveyor belt and a trained guy with a rubber stamp looks at it and stamps it as it flies by (that what "visually rated" means). It also has a lot of complex adjustment factors allowed by the timber rating guildlines. I use them daily in my line of work, they are useuful for designing wood buildings, but of limited use for boat building with hand selected and finished boat wood.

    If you hand select, cut out to get a clear vertical grain specimen from a larger piece, from western hemlock, you will get as high a strength as 10,000 psi. doug fir similar. yet these tables show safe working loads of about 1000 psi. the category "hem-fir" includes a lot of wood besides western hemlock, but also silver fir, balsam fir and a number of other trees that tend to grow together (the loggers do not separate them when they are logged). it takes a wood lab to study the grain structure in a microscope to properly identify the wood once is it cut into lumber.

    The rating also includes defect size, type and location (run out, sap pocket, knot, etc). So if you take a #1 2x12 and cut it into two, you have two pieces of unrated lumber. Also, smaller pieces that you tend to use for building small boats are not rated from a lumber yard since there is no standard for lumber under nominal 2x2. When you rip them from a larger piece, you could end up with something far stronger than the rating implies because the chances of a hidden defect deep within the wood is much less. that is BTW, why larger timbers have lower allowable loads than smaller 2x or 4x lumber.

    The table has value in determining relative strength, but it not really useful for designing say a wood mast of lumber you select, rip into smaller clear paces and laminate together. best way to deal with that is to set up your own test jig and back calculate ultimate strength. somewhere on the internet this a government publication on how to rate aircraft lumber, giving species, grain size, defects, run-out, etc and you can determine your own working loads. but I think actually doing your own tests are the best way to know what you are working with.
     
  7. gonzo
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    gonzo Senior Member

    Hand selecting will give you better quality for home building too. We use to pay a 30% premium on delivered lumber so we could return anything we didn't want.
     
  8. SamSam
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    SamSam Senior Member

    If I don't pick it out myself, I just order more than I need, use the best stuff and return the rest for a refund, with no premium involved.
     
  9. gonzo
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    gonzo Senior Member

    If you were to return about half of every order like we did, any lumberyard will either charge you a premium or stop delivering to you.
     
  10. SamSam
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    SamSam Senior Member

    I probably wouldn't buy from a lumberyard where half the material was unsuitable for a house and on top of that they charged you 30% extra because their stuff was so bad.
     
  11. TANSL
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    TANSL Senior Member

    I've never bought wood but I bought other things and I think to pay an extra 30% because gender is so bad you have to return half is crazy, plus hard to believe.
    Perhaps I misunderstood.
     
  12. gonzo
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    gonzo Senior Member

    You said it: You never bought wood.
     
  13. waikikin
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    waikikin Senior Member

    It comes from a forest and is made of trees as grown.....
     
  14. gonzo
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    gonzo Senior Member

    Some customers want matched grain, which takes a lot of sorting through.
     

  15. whitepointer23

    whitepointer23 Previous Member

    So your you think he is lying. Whats gender got to do with it ?.
     
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