Thick Enough?

Discussion in 'General Slingshot Discussions' started by Withak, Jan 2, 2014.

  1. Withak

    Withak aka Whitehawk!

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    A question for all my slingshot buds:

    I'm working on my first slingshot using birch multiplex. It's 3/4" (19mm) and I'm making a copy of a Bill Hayes target shooter that's been scaled down by about 20%

    My question is, now that I have it shaped, rounded and rough-sanded, it seems like it might be a bit thin, but maybe I'm just imagining things. I know that multiplex is pretty strong stuff, but I didn't laminate anything additional to it to make it a bit thicker. So, my question is to the folks that have made slingshots from a single piece of 19mm multiplex, will this be strong enough for at least one layer of TBG? Maybe two?

    I will be certain to test it, but I'm wondering before I go there if anyone else already has experience with this. And, just FYI, this is the stuff with a lot of layers, not the cheaper stuff.

    Thanks!
     
  2. VWscooby

    VWscooby Senior Member

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    Ive got the equivalent of 1 layer of TBG on a piece of 10mm plywood with no problems so far so I would go with 'Its fine' :)

    EDIT: It is a PFS though so probably not a good example thinking about it
     
    Last edited: Jan 2, 2014

  3. Arturo Borquez

    Arturo Borquez Administrator

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    I guess 19mm is more than enough, of course it depends on shape, if the forks are long and thin could pose a risk ... bench stress test first x 3 force ...
    cheers
     
    Last edited: Jan 2, 2014
  4. BeMahoney

    BeMahoney Builder of things

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    Depending on the width of the forkarms:

    Yes

    and

    Yes

    .. depending on the width of the bands.. 2 times 18mm will work

    .. depending on the weight of the projectiles

    summarizing:

    ..depends!.. :)

    Greetings,

    Be
     
  5. Withak

    Withak aka Whitehawk!

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    Good responses from everyone so far - Thank you!

    The general shape is very similar to this model:

    [​IMG]

    Compared to the photo, the forks on mine are a bit wider. It's sounding like I'm probably fairly safe. This multiplex just feels light in my hand compared to the hardwood naturals I'm used to handling. I'll be sure to do a vise test, just to be safe.

    I really appreciate the feedback guys.
     
  6. Achso_42

    Achso_42 Senior Member

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    Just for the physics: if you make the arm twice as wide, the strength will be doubled.
    if you make it twice as thick, the strength will octuplicate(I never heared this word before:))
     
  7. Lars

    Lars The Evil Genious

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    it´s enough
     
  8. Ravensbull

    Ravensbull New Member

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    If you want to really get busy try laminating 3 blanks big enough together and work out a recurved or raked back grip like Master Hays' favorite Scorpion models. You can shoot a strait wrist for TTF with forks curved back towards you. LOTS more work but I bet you won't put it down once it's done! I think you should be good other than watch where the forks meet the grips and try to keep that as thick that is comfortable seeing it's a critical spot. If it's strictly for TTF, I considered how the forces are applied like a torque trying to twist the fork off, as apposed to OTT... If you want, I will post a pick or two of how I did my fork tips on this maple laminate?
     
  9. dolomite

    dolomite Banned

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    E, 3/4 is quite thick enough. I've got some board cuts that thick from mahogany, they're plenty strong without crossed grain.

    Sent from my ME173X using Slingshot Forum mobile app
     
  10. Withak

    Withak aka Whitehawk!

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    Some more great input! Thanks guys! I can't wait to get it in the vise and put it to the test. Sounds like I'm good to go ahead and try to finish this bad boy.

    @Ravensbull - sure, go ahead and post your photos. All are welcome here :) and I'm always looking closely at the work of others to try and improve my own.
     
  11. Jeremy

    Jeremy Senior member who totally rocks a pink Scout! Pink

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    I can't wait to see the finish product.
     
  12. Withak

    Withak aka Whitehawk!

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    Patience grasshopper - it's for a trade, so it may have to wait, though I'm not up against the global trade rules, so I may just post it before I send it out. Not sure just yet.
     
  13. Ravensbull

    Ravensbull New Member

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    I had decided to avoid the hole drilling as it looked like if would make my parallel laminate maple way too week there. It turned out I broke it on purpose to see where it was weakest. With my wood it was at the bottom of the throat. That shouldn't happen with the cross ply Baltic birch though. Oh, this was 3/4" so now I'm cutting it 1" thick when I split the thickness for heavier duty frames. These boards are 1-7/8" thick and like 27 or 28 ply.
     

    Attached Files:

    Last edited: Jan 2, 2014
  14. Will

    Will Thread Hijacker

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    This should be plenty strong enough, Withak. I have cut this design (and variations of it) about 15 times, and the only one I broke lost the battle to the infamous 'truck test':D
     
  15. Flipgun

    Flipgun Well-Known Member

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    I made one recently as a gift with 2 pieces of that thickness even though 1 would have been enough. I just like chunky.;) 1 piece will be fine in my opinion.
     
    Last edited: Jan 2, 2014
  16. Withak

    Withak aka Whitehawk!

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    I had to go back and search - I forgot about the 'truck test'. Perhaps I should try that myself sometime :)
     
  17. Withak

    Withak aka Whitehawk!

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    I like how you've finished the fork tips. Nice work.
     
  18. Withak

    Withak aka Whitehawk!

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    I've seen one like that Flip, a very nice piece of work. I got inspiration to try one off a similar model :)