9 Replies to “Build-Along: The Long Recurve Bow Pt. 1”

  1. well.. I don't think so. the stress in metal like steel is because it has impurities like carbon atoms in "sea" of metal atoms. pure polymer like pvc shouldn't have that problem

  2. It can-mostly if the heating isn't even as the stress-loads won't be evenly distributed. In theory, if the heating were perfectly even, and stayed even during shaping, it'd be fine. Honestly, I can't see there too often being significant concerns unless the heating was extremely uneven or there was significant reshaping at differing times while the limb cooled. If you curved it just heated, then flattened a lot of curve out with force after it lost heat, I can see there being problems induced.

  3. Thanks! Me too – they're looking very elegant trimmed up and all decorated. I need more clear coat, then to finish the bow up…

  4. Very true – so my question is: do deformations while semiplastic due to heating introduce stresses that could create problems down the road, like the stresses introduced into steel by machining?

  5. If you melted the PVC, it would break down the polymer chains and allow the material to flow. When it cooled, the chains would reform in the shape it was then in. Heat allows the chains to release from each other, offering some ability to shift. Some break every heat, which is why re-heating a lot can weaken the bow.


  6. The polymer chains remain connected. PVC is extruded, the polymer chains formed, in the shape of the tube. When you flatten them, they don't rearrange but stretch to meet the new shape you've imposed. Heat allows them to be stressed out of shape, but they store some energy like a stretched spring. When you re-heat them, it gives the chains the energy needed to shift again, and they release energy and return to the original form when extruded to begin with.

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