Heat treating and then gluing lams

[willie]

Regarding lower temperature and longer.... it needs about 200C (390F) degrees to heat treat, and that's more than any glues I'm found can cope with. It would need extreme care to keep the heat off the glue line.
Del

Del, my comment to use a lower temp for longer was not phrased well. The thought was to treat the belly stock before glue up.

As far as the heat, 200C should work fine, the idea was to avoid excessive heat that might cause scorching of the surface. one could get heat thorough out the belly lam no matter what the thickness if the heat was delivered in some sort of hot box or oven and  the temps were raised slowly, The belly stock could be resurfaced before glue up if needed, and reduced any amount if required, as the treatment would be the same throughout.

this would be a treatment that would certainly over dry a back, if the back were involved, hence the post heat treatment glue up. one might even have a different finish on the belly than the back if they wanted to try to maintain different drynesses in the overall limb, the glueline serving as a moisture barrier of sorts.
 

[Del the cat]

@willie.
Yeah, I get it, a big oven/temperature controlled hot box that could cook through the whole thickness without scorching would be good.
Now if only I had a bigger workshop 
Mind it would just get filled up with more machines and I'd loose the fun of doing stuff by hand 
Del

[willie]

you could probably pull it off with a couple of pieces of stovepipe and some insulation. just something I have always wanted to try.

often I read comments about how heat treating is supposed to operated on a different principle from drying,
but of course any heat treatment job is going to involve some of both. heat treating might be a process that could be explored more.

[DC]

Maybe heat treat the whole belly lam in an oven like they do for bamboo. If the oven was set for 400°f you could leave it in there for an hour or so and the heat treat would go all the way through, hopefully. You could do the billets before any glue up. I just measured my kitchen oven and its 27" diagonally. That would have accommodated the billets that I used on the Molles with spliced on tips. I may try a test piece

[DC]

I think we all had the same thought at the same time.

[PatM]

The use of a pizza type oven is well known as a heat treating method.

 What actually happens with heat treating is as well documented as we need it to be and it's certainly much more than just super drying wood.

[DC]

And here we are reinventing the wheel-again In a fully treated belly is there any danger that having heat treated wood past the neutral zone would cause cracking under the backing?

[willie]

Any links to that documentation Pat? I have read opinions based on subjective experimentation, but don't think I have ever seen anything quantitative

[PatM]

It's out there but every time someone links to it others tend to  try to shoot it down or it's quickly forgotten.

[PatM]

And here we are reinventing the wheel-again In a fully treated belly is there any danger that having heat treated wood past the neutral zone would cause cracking under the backing?

Bamboo flyrods indicate no.    All bamboo bows like those made by Schulz and Miller have fully heat tempered lams.

[DC]

One hour at 400°f. Before and after. 3/8"thick, same colour all the way through.

[PatM]

Here's the one on Bamboo.
http://www.powerfibers.com/BAMBOO_IN_THE_LABORATORY.pdf

[willie]

Thanks for posting that Pat.

DC have you independently verfied the temp? Oven dials can be quite a ways off. And what wood is that?

[DC]

No and it's Yew. I took a slice off each piece with my pocket knife. The cooked one is noticeably harder. It did make the house smell a bit burnt woody. I'm going to try a bow sized piece at 350 tomorrow.

[Del the cat]

No and it's Yew. I took a slice off each piece with my pocket knife. The cooked one is noticeably harder. It did make the house smell a bit burnt woody. I'm going to try a bow sized piece at 350 tomorrow.

Good experiment, watching with interest.
I might Have to persuade Mrs Cat we need a bigger oven 
Del