"Crossing the grain" - help!

Discussion in 'General Slingshot Discussions' started by SpraveRocks, Jan 1, 2014.

  1. SpraveRocks

    SpraveRocks Junior Member

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    Hi, so i came across this thread (https://www.theslingshotforum.com/f4/tragedy-warning-not-faint-heart-31996/) that said that "slingshot would break because the grain is not crossed".

    Being new to woodworking, i dont really understand what that means..

    With reference to the attachment, if i want to glue wood to the core, does that mean i can only do it like in A and not in B? Or did i misunderstand what "crossing the grain" means? I could not find clear explanations anywhere :(

    Thanks so much, happy new year.
     

    Attached Files:

  2. Arturo Borquez

    Arturo Borquez Administrator

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    crossing the grain is the A (90°) option but must be full overlapped and glued before cutting the shape ... several crossed layers at 90° is better, with several layers depending on the shape of the slingshot some layers at other angles (in example 45°) can be combined with 90° layers to optimize strength ...
    cheers
     

  3. kohlqez

    kohlqez Accident-Prone

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    That was because I made all the grain go horizontally. As Arturo said ideally you would have several layers making almost a 360° (vertical, horizontal, and diagonal making an X with a + overlapping, like an *) the worst case scenario is what I did, all horizontal, because wood is most prone to breaking along the grain. So if I had pulled back wit any reasonably strong bands one or both fork tips could have broken off and lodged themselves firmly in my face.
    Hopefully you (and others) can learn from my tragedy and avoid the same thing happening to you, because I promise it isn't fun.
     
  4. Moin moin,
    You hate but such lines on your drawing ....
    This will probably be the wood fibers, right? (Suggest remember times with an ax on a piece of wood, on the four sides of a piece of wood, and you'll see the differences ....)
    So now if too much train, or a fork hit the danger that splits the wood along these lines ....
    Is advantageous when several layers one above the other, and these fibers were glued always rotated by 90 degrees so as to handle your ....

    But what is the fork transition to the handle ..... here are short wood fibers that can be cleaved rapidly ..... or?

    -http://de.wikipedia.org/wiki/Multiplex-Platte#Ausf.C3.BChrung

    Du hasst doch solche Striche auf deiner Zeichnung....
    Das sollen wohl die Holzfasern sein, oder? (Schlage mit einer Axt mal auf ein Holzstück, auf die vier Seiten eines Holzstückes, und du wirst die Unterschiede merken....)
    So, jetzt ist bei zu starkem Zug, oder einem Gabeltreffers die Gefahr, das das Holz entlang dieser Linien spaltet....
    Vorteil ist dann, wenn mehrere Schichten übereinander sind, und diese Fasern immer um 90 Grad gedreht verleimt wurden, so wie in deinem Griffstück....

    Aber was ist am Gabelübergang zum Griff..... hier sind Kurze Holzfasern, die schnell gespaltet werden können..... oder?