Heating belly of Osage

[bigcountry]

Well all this talk of belly heating has me thinking.  I have a bow that came way underwieght from a year and half ago.   I keep planning to sinew it.  But I figured it would be a nice experiment.  Before I sinew, should I heat temper?  I figured after I sinew, I would have to retiller anyway.  

Does tempering gain much if any wieght?  Or is it the induced reflex where you get the wieght?

[Hermann From Bavaria]

only with heat its about 5-10pounds i think(depends on type of wood)

greets

[bigcountry]

I suppose heat treating does come with a downside?  Like more chance for belly to collapse?

[Don Armstrong]

I think just the oppsite would be true. The belly would be stronger and be less likely to fail but some the good bowyers on here would know for sure. I am just a rookie. Don

[b.glass]

Just don't get carried away with reflexing with heat if your thinking of doing any of that. I'm new to heat treating and reflexing and I hope I've learned my lesson. I put to much reflex in and collapsed one limb of an osage bow.

Bona

[Pat B]

Heat tempering will help strengthen belly wood. It is more noticeable on whitewoods with weaker compression strength but it does work well with osage. It really depends on how much damage(cell collapse) was done on the bow. Heat treating compliments the belly by adding a bit of compression strength but it is not a miracle worker.
  Generally I will add no more than 3" of back set to a stave and as I do this, I heat treat it; scorching it to a chocolate brown color.Then I leave it in the form for at least 3 days but a week is better so the wood can rehydrate.
  The combo of the reflex and heat tempering should get you a few more pounds...but that will depend on the bow.

[bigcountry]

Thanks guys, I wonder if I didn't add any reflex or setback (pretty well now, no set), heat treated, and sinew backed later (this will add some setback) if heat treating will gain me much.

Guess I am trying to figure out if the performance gain is mostly the setback, or increased compression.  Of little of both.

this is just for experimenting.

[ranger 3]

I heat tempered a Osage bow and it gained about six pounds and I had to re tiller it and it is still shooting,like Pat said make sure it sits about a week before you do anything to it....Howard

[talkingcabbage]

I just saw this thread and had a question.  I have maple selfbow I've been working on and it's developed a prop twist in the lower limb, and I was nearly done tillering.  If I heat treat the belly, taking the twist out and add a little reflex at the same time, will it hurt to finish tillering afterwards?  Scorching the belly to a chocolate brown, then scraping and sanding.  Will I "undo" the tempering?

PS. Sorry -- not intending to hijack your thread.  It just got me thinking.

[Pat B]

Joe, If your bow is developing a twist as you are tillering it, the limb thickness is probably uneven. It is common for this to occur while tillering and especially if you are working from a vise mounted to a work table. This set up doesn't allow you to remove(or see) wood from the table side as evenly as from the side away from the table because the table is in the way.
  I would venture, if you used your thumb and forefinger to feel the thickness from side to side of the limb you will find a difference in thickness. I use this method throughout the tillering process, not only from side to side but the entire length of each limb. You will be able to feel even the slightest difference way better than you can see them.
   Heat treating(tempering) is not a miracle that will fix a mistake but a method to increase the compression strength of weak in compression woods. Heating is also a way to remove natural twists and bends and to add reflex and or deflex when wanted...but before the limbs were trained to bend. You may in fact remove the twist with heat but if it is mechanical(because of uneven wood removal) it will return and possibly even more so because you haven't eliminated the problem.
  Scraping and sanding the char from a "toasted" stave will not remove the tempering. The tempering is in the viable wood cells and not in the top "char".