Double heating while bending

[Mo_coon-catcher]

I’m wondering if anyone has noticed if there is any benefit to heating wood twice while bending it. I don’t know if it helps or not but I’ve gotten into the habit of heating the wood a second time after I have let it cool from when I shaped it on te form. I doubt it’s true, but my thinking is that the second heating while still clamped in the form would release some of the stress that’s locked in the wood from the initial bending. And help it to hold the new shape once it cools from the second heating. Any one have any thoughts on this and think it’s work the time to do a second heating with dry heat before removing from the form?
Here’s what I was working on while having that thought. It’s a short piece of Osage I’m using for the backer bow on a Penobscot. I had too pull the one I’ve been working on apart to drop the weight as it was pulling well over 100# as it pulled 70# at 13” on te longstringgince I pulled it together. I decided it try putting a bit more reflex in the backer bow after seeing how it looked under a load, put together. Their piece of Osage has bent well for me. It started with as much deflex as it has reflex now and there is a knot about every 2” along its length and a bit drying check down the center of the belly.

Kyle

[Jim Davis]

I have neither experience nor opinion on that aspect of reheating . I have reheated to do some more shaping, but that's all.

I have to ask, are those grooves you have cut across the back of the bow?

[Mo_coon-catcher]

Nope, there just on the sides. They’re more shallow than they look, about 1/16”. I cut those in for when I tie down the string hooks for the bridge strings. I cut grooves so they are less likely to slide and move. If the glue busts and it relies on just the binding, it should lock up once tension is applied. I’ve had the bow fully assembled, but cut everything back apart once I realized how much wood I still had to remove to get the weight down.

Kyle

[leonwood]

I always heat my recurves a second time with dry heat while clamped in the form. I boil my recurves and found that especially with yew and hazel the recurves flatten out a bit. Since I started "setting" the bend with dry heat I have never had a curve flatten out anymore. I use a heat gun for about ten minutes so it does not take that much time.

[Springbuck]

  I don't know if it does, but I end up doing it sort of by default all the time.  I heat straighten stuff, release it from the form, and have to revisit areas later.

 Marc says you CAN do it twice in the TBB, as long as you don't over-do it either time, and he also says sometimes when he has really cooked the heck out of it, the bows are very fast if they survive.

  Doing what you are doing might help ensure every section got a good heat treating.  It definitely helps with stuff like  Leonwood mentioned.  I always bend with wet heat, and then temper with dry in the same forms.

[Mo_coon-catcher]

Thanks for the input guys. Sounds like I’d might as well keep doing what I have been. Seems like it won’t hurt anything and will help assure that I have gotten proper heat to the wood to hold it in place. Btw, the tips spring back about 1/2” after removing the clamps from that piece of wood. I can fit 3 fingers under each tip.

Kyle