Primitive Archer
Main Discussion Area => Bows => Topic started by: sleek on September 15, 2019, 02:42:33 pm
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I have bamboo backing and belly glued onto an osage core with smooth on. The recurve twist at 20 inches and makes the string pop off. Can low heat be used to correct limb twist with smooth on?
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I have done it with West Systems 105/205. You could check the temperatures on their websites. I wrapped a heating pad around the area and stuck a cooking thermometer in next to the wood to make sure it didn't go over 150°f. I left it cook for a half hour and then twisted it and clamped/held it in the new position. Took the pad off and let it cool. It moved quite well. No problems.
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I can't respond specifically about smooth on, but I have used other epoxies and experimented with heat quite a bit.
if you want to be cautious with the temperature, you could always plan to use more time to accomplish the adjustment
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Check the thickness from side to side of the limbs. If one side is thicker than the other it will twist as it's drawn.
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Check the thickness from side to side of the limbs. If one side is thicker than the other it will twist as it's drawn.
Solid advice, but the belly is crowned on this bow. As I think about it, that mw be the problem.
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Crowned belly or not one side can still be slightly thicker. Slide your fingers along the belly side of the limb with your thumb on the back, just barely touching and back and forth across the limb along it's length. You will be able to feel a very slight difference in the thickness if there is any. I do this as I tiller a bow to help keep things even..
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Even if wood removal is equal from side to side the limb can still twist. Remove wood from the strong side. Jawge
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And / or your layout could've been off.
EA40 has all the information you need on the can or the datasheet.
To answer the question about the glue we would need to know - What ratio did you use? How did you cure it?
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I have done this with smooth on a few times, just needed minimal correction though.
I use my original recurve form for this. Just clamp it in as normal and bend the recurve a little sideways in the form. (a little more then the correction needed) Then heat the belly with a heatgun for 30 seconds. (You can repeat this a few times but wait a few minutes between sessions to prevent overheating the back) You will be surprised how effective this is! I have done this with bamboo backed bows glued with smooth on and titebond and never had the glue come loose.
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I tried a heat correction with smooth on and my glued on tip overlay popped off. This would have happened with urac.
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You can also try to just torque the twist out and "train" the limb to stay straighter.
Clamp the handle in a vise and manually draw the limb back while countertwisting it the opposite way.