heat treating/tempering question

[jimmy]

Forgive me if this has been asked before.  I just recently started using a form to heat in reflex and temper limbs.  Should the limbs be slowly heated and worked down into clamped position?  I am asking because I clamped the limbs into reflex on a narrow osage bow and then heat teated them, ending up with a good size fret about 2" out of the fade.  I have used heat a lot, but never a reflexed form.  I think I overstressed the wood by clamping first and it just couldn't take the exteme heat being bent like that.  Thanks for any input.

[blackhawk]

You actually have a tension crack on the belly and not a fret....

Theres many ways to skin a cat...the safer way is to clamp down as you go....BUT you can do it the way you did it,but you must be more careful and pre thought out about it...for example the bow should have a nice even tiller and bend in it prior to heating cus any hinges will want to lift up off the form there and possibly pull a tension crack,and you have to be careful around knot areas where theres usually an island of grain there and ittl want to lift the grain there,and you need to be careful of deflexed kinks and shimming them(it adds stress there),and if you do preclamp youll have to run the gun slowly up and down the limb heating the whole limb at the same time so no one spot is heated up(which makes it weaker than any other area and will want to lift there as the heat releaves the stress in that one area,which happened to you)...well..you get the point......just clamp as you go man if your not a gambling man.......me im a gambling man and preclamp if the stave allows me too

[Del the cat]

Sounds like you are confusing two things. Using heat to bend the wood and using heat to temper/heat treat the belly.
The two can often be combined, but bending the bow needs heat applied firt.
If you think about it, the heat is appled to make the wood pliable so it can be bent into shape. Therefore you can't bend it into shape and then heat it without risk of damaging the wood.
Generally clamp one end nice and firm and heat it, you gradually bend it down as you feel the wood 'give'.
I've done it with a brick tied to the far end of the bow, after a fair while warming it suddenly started going down under the weight of the brick.
For tempering/heat treating the bow is often clamped to a former (maybe under a little tension) but that's more to hold it in shape during the process rather than to bend it.
(Just my take on it of course, others may have a different view).
Del

[jimmy]

Thanks for the input.  I was actually tempering and bending all at once.  The tiller was already good, and it was a light weight bow, so I thought it was safe.  I just bent the wood too much too fast.  I won't make the same mistake again.  The bow turned out pretty good, and it is around 40 pounds with about 1 1/4" reflex.  However, that fracture scares me a little so I probably won't be shooting it much.  Everytime I make a bow, I tell myself that I'm gonna really take my time on this one, then I get excited and rush through some part of the process (of course I won't admit this to myself at the time).  There is always more wood begging for some attention.

[PEARL DRUMS]

I temper and bend at the same time myself. Those "stretch" cracks you have wont hurt a thing. Fill them with super glue. The bow isnt bending away from them, but towrads them and that wont be a problem. I have a static recurve that did that and it has been oodles of times with zero ill effect.

[Del the cat]

Hey Jimmy,
The first Osage with flipped tips I made got a few cracks on the bend, I built up the belly side with a thin sliver of Osage and pretended I'd done it so I could go narrower on the tips .
Excitement and impatience is fine, it'll ease off a tad by the time you hit 60, but it'll be a sad day when we don't get excited to do our thing
Del