Doh! Heat treating error!

[Willibow]

Okay gang,

So I had a bow that was working great, but of course I just couldn't resist trying my hand at heat treating the belly.  Well, my first pass at a form didn't seal up tight against the back of the bow and the back  of the bow became a bit browned.  Will this be a problem? Should I get the 400 grit sand paper out and try to ever so gently clean this up? Or is it simply cosmetic and shouldn't pose any problems?

[Willibow]

The belly side of the same limb.

[Ryan C]

I have accidentally Burned the back of a hickory before and it broke there but then again I've burned an Osage and it's still shooting so I don't really know for sure.

[Willibow]

Yeah, I'm pretty worried I killed this one. Definitely going to use masking tape or similar to avoid this sort of thing in the future.

Guess the only way is to let it sit three or four days to rehydrate and take it out back to shoot 

[Willibow]

Lessons learned during this heat treating session.

1) use several layers of masking tape or similar to cover the back of the bow with.
2) Clamp slats to the sides of the bow to stop hot air flowing around to the back during heating. I saw this on Del's blog, so thanks for that trick Del! Hopefully it prevents future newbies like me from making the same mistake and compromising an otherwise great bow.

My attempt found the back light to medium brown with the belly relatively unchanged in one section of a limb. I will wait four days and string the bow before pulling to full draw. I'll flinch every step of the way.

Question for those who know more than me: should the browned section (about 2" worth approximately 6" from the limb tip) be left alone at this point?  Or, would it be worth it to try to clean the (hopefully) surface browned wood and rehydrate what remains of the back? Would this attempted fix compromise things even worse?

[Slackbunny]

Yeah, I'd scrap off some of the burnt stuff and give it a week. Then I'd go back at it as planned and hope for the best. What have you got to lose?  It may not be as bad as you think.

[bushboy]

If your tips are. Stiff you should be ok,i'd worry more if the charred section was part of the working limb.

[DC]

Something about this isn't making sense to me. The first picture shows the back, right? The second is the belly? How did the back get blacker than the belly when the heat gun should be aimed at the belly? Them later you say," My attempt found the back light to medium brown with the belly relatively unchanged in one section of a limb. I will wait four days and string the bow before pulling to full draw. I'll flinch every step of the way. "

It sounds to me like you're heating the wrong side of the bow. The belly is the side toward you when you're shooting and that is the side you aim the heat gun at. If I'm out to lunch here I apologize but something just doesn't look right.

[Willibow]

Understood DC. You're absolutely correct; the back became darker than the belly, though I was actually blowing hot air directly on the belly with the back down against the form.  Granted, the form is a little rough with some gaps and an imperfect curve.  The only thing I can think of is there was some hot air eddies hitting the back of the bow and somehow getting in between the form and the bow.  I'm pretty confused as to how this happened too, I just hope it wasn't too damaging!

[DC]

Can you post a picture of your setup, the way you were treating it. I just can't see how the side you weren't heating got blacker than the side you were heating.

[bushboy]

Quite normal because the form is wider than the tip,trapping the heat on the back side.the narrower the form within reason the better.i keep the heat gun at least 4" from the wood,moving it back and forth towards the tips

[alwayslookin]

I'm confused too. Never had that issue and I do it on a stainless table.

[Drewster]

Willibow, I use a 2x6 for my form turned up on edge.  The middle 8" is flat and then it's radiused to a 4" drop for reflex.  I have 1 1/2" holes drilled in it for my clamps.  I usually clamp the handle in the center then heat treat each limb.  I think Marc St Louis starts at the tips and works to the handle.  In any case, the form is usually as or more narrow than the limbs so that helps greatly with NOT heating the back.  I also coat the edges of the limbs with Crisco so they don't scorch.  I keep the heat gun pointed slightly in towards the center of the limb and that helps eliminate the heat wrapping around the limb too.......works well for me.  Hope this helps.  Keep at it.

[Willibow]

Thanks for the info Drew. I try and learn from my mistakes, so hopefully next time will go a little better

I've attached an image of my setup. To heat I basically held the heat gun about four inches off of the belly and aimed it straight down at the center of the limb.  Constant slow movement in about 4" lengths with heat applied for four minutes per 4" section of limb.  That was enough to get a good golden color to the belly and the induced reflex held very well (only lost about 1.5" of 4.5" reflex).

Not sure how much of that will stay after its string and drawn again. Or how much draw weight will increase. This is my second time attempting to heat treat a bow, and the first using a form. Last time I hung a 1 gallon water jug off of the limb tip and heated the belly to induce reflex. That worked well and didn't cause any scorching of the back, though not nearly as much reflex was induced or

retained after.

[Jim Davis]

Scraping off the darkened wood will not improve anything but the appearance. The charred wood will not be involved in the tension formula, on or off the bow. Suit yourself.