Epoxy Preference?

Discussion in 'Materials' started by die_dunkelheit, Feb 15, 2012.

  1. Yobarnacle
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    Yobarnacle Senior Member holding true course

    hrp=hemp reinforced but trp? t-shirt reinforced?
     
  2. die_dunkelheit
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    die_dunkelheit NA Student

    Yes he did mention hemp, but I was referring to his mention of hair a little past the tee shirt reinforced plastic.
     
  3. Yobarnacle
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    Yobarnacle Senior Member holding true course

    Oh, a Godiva bow!
     
  4. die_dunkelheit
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    die_dunkelheit NA Student

    The bow I made for myself is bamboo backed Osage Orange, with a high degree of recurve (very high..)
     
  5. Yobarnacle
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    Yobarnacle Senior Member holding true course

    I have a bear takedown/backpack bow. Magnesium handle with GRP limbs. 55lb draw 24 inches. I draw to 32 inches. 34 inch shaft. Don't know weight at that extension.
    Haven't bow hunted in decades. Probably needs a new string. Probably I'll need to make one. Maybe from spectra twine. About 4 or 5 bights, (8 or 10 strands) then wrap ends and center.
     
  6. die_dunkelheit
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    die_dunkelheit NA Student

    There needs to be some stretch in the string, spectra might be to low of a stretch material which could damage the bow. Lookup "Fast Flight", low stretch but not too low...
    Fast Flight
     
  7. Yobarnacle
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    Yobarnacle Senior Member holding true course

    thanks
    any idea of the draw weight at 32 inches? middle 18 inches is rigid. limbs are also 18 inches but socket 3 inches in handle. Strung, bow is 48 inches, designed for 24 inch arrows at 55 lbs
     
  8. die_dunkelheit
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    die_dunkelheit NA Student

    When pulling beyond it's tillered length it's almost impossible to estimate. Though it's a glass lam bow, it still has a wood core. The final draw weight will depend on much, what wood is in the core, how thick the glass is on each side and even to how straight the core grain is and it's orientation in the lamination. To be honest, it's a testament to the bow that it holds up to being drawn 8 inches further than tillered for. (To "Tiller" by the way, is to cut each limb to flex evenly. There are a couple nautical terms that mean something completely different in archery).

    Take it to an archery shop, they'll be able to put a scale on it and measure it for you, or you can buy one from the store I linked you to in the earlier post.
     
  9. Yobarnacle
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    Yobarnacle Senior Member holding true course

    the limbs are pure glass. I figure from the extra strength I exert beyond the 24 inches, I'm drawing 65 to 70 lbs. A guesstimate. Reasonable?
     
  10. whitepointer23

    whitepointer23 Previous Member

    thats scary. pulling solid glass limbs 8 inchs past there draw length, you should wear a crash helmet.
     
  11. die_dunkelheit
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    die_dunkelheit NA Student

    Possibly.
    How thick are the limbs?
    After the 24 inch mark you probably feel the effects of "Stack" which is the weight per inch drawn goes up exponentially rather than a smooth increase in weight.

    An easy trick to measure the draw weight: cut a shallow "U" shape out of the end of a 2x4 about 36 inches long, measure 32 inches back from the bottom of the "U" and mark the board. Place the other end on your bathroom scale and hold the bow in the "U" cut. Draw the string down the board until the mark you measured at 32" & read the scale.
    Works because the bow is pushing the 2x4 into the scale with the weight of it's draw. Simply subtract the weight of the board and bow at rest and you've got an accurate measurement.
     
  12. whitepointer23

    whitepointer23 Previous Member

    my hoyt compound got banned from our range because 1 limb developed a small crack, but they were laminated limbs which mostly split when they go but i was told solid glass limbs can shatter and you want to near when they do.
     
  13. die_dunkelheit
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    die_dunkelheit NA Student

    Had a buddy (well, acquaintance..) get stabbed in the shoulder by the tip of a limb broken off an English long bow. So, it went like: draw, bang!, limb sticking out of his shoulder...
    Laminated limbs in most respects are more efficient than solid glass because the wood is mainly acting to separate the back & belly glass. Back & belly under tension and compression respectively, the wood experiences a great shearing force and also compression (squeezed between the glass lams, not longitudinally like the belly glass). Which means it helps to isolate the tension & compression in the back & belly. It also makes for a lighter limb which means less static inertia that must be overcome in casting, and less dynamic inertia that must be stopped leading to less shock, whether that be shock to the bow or your hand...
     
  14. Yobarnacle
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    Yobarnacle Senior Member holding true course

    Limbs are oval section 3/4 inch thick and 2 inch wide where the insert into handle. Remain constant about 60% out toward tip. The width begins narrowing and the back becomes concave and the belly convex and recurves. At least surface fibers are running along length, uni directional, no weave. Tips are a hard smooth black plastic apparently glued on/over ends.

    Drawing the extra length only causes a couple or 3 inches more deflection in the tips. Mathematically, the extra draw is spread over 2 limbs and extra length in string pull also occurs as bow shortens by curvature. There is no sense of "over stressing" the bow. The bow was bought in 1975. By Bear. a good brand back then. Don't know current reputation. I strung it today for first time in maybe 20 years, been stored in a bow case in closet. The waxed multistrand string seems okay, though I'll not shoot it. Sorry for pirating the thread. Once I make a new string, I'll "weigh" it as suggested. Thanks!
     

  15. whitepointer23

    whitepointer23 Previous Member

    been a while since i was into bowhunting but bear equipment was top of the range back then.
     
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