Heat Bending

[Newindian]

Working on a gull wing bow 49" ntn d section, and I don't  know what it is heat treating has never worked for me, I'll heat the wood till its to hot to touch, but I've never been able to move it more than an inch. Any ways I got the handle set about an inch and started making a second atempt at it when it pulled a splinter off the bellie right in the middle of the handle so I decided to leave it as is thinking it would come out to light. Now with a flat profile tillered out to 20" I think it will be a high 50 to mid 60 at 27 before sinew so Im considering making another go. Any sujestions at what I might be doing wrong.

[soy]

First, what wood are trying to bend?
Second what type of heat sorce...gun, steam, MICROWAVE???
I'm just guessing, but if it is only hot to the touch on the belly side and not the back you need to heat it a bit more throughout the entire area you intend to bend to get your desired results, and i have herd that different woods respond differently to different heat ...hope someone clears up the water i just muddied up

[DarkSoul]

I can't tell you what you might be doing wrong, since I don't actually know what you have been doing so far. Could you describe the exact process you follow when doing the heat bending?

- Different wood species react differently to heat bending. Some species are just easier to bend than others.
- You need to heat the wood thoroughly for a long period of time. Try not to darken the wood too much (color is irrelevant to the heat in the deeper layers), but heat the wood until it'll burn your fingers when you touch it for more than one second.
- Clamp it in shape QUICKLY. You have about twenty seconds before the wood cools down too much. That's right; twenty seconds. Do a count down and a test run before you actually heat the wood. Make sure everything is nearby, within reach.
- Thin wood is easier to bend than thick wood. Bending a 1½"x1½" handle takes quite some courage and patience.
- Dry wood or green wood? It makes a difference.
- You have to leave the wood clamped for at least a few hours before you remove the clamps.

[dwardo]

I try to heat and bend at the same time, this way you can feel the wood starting to give. You shouldnt have to force it.
I use a heat gun at about 6 inches from the wood and heat slowly. If i start to see a colour change i reduce the heat a little as i am after bend not temper.

I have recently started to cool the stave quickly after heat. Not because i think it has any greater effect its just i want to get to doing the other limb or correction quicker. To do this i cool with a frozen bag of peas (dont tell the missus) sweetcorn would work equally well better yet a bag of ice. Once cold to the touch, usually an hour i remove it from the clamp and form.

[crooketarrow]

    First off use dry heat to seasoned wood. So if you've tiler your bow some straight it had better be seasoned.  I built 3 gull wing bows. 2 SINEW AND 1 BONE ,stick with sinew. My sinews were SWEETTTTTTTT better that the bone I think no I know. The bone had more hand shock than I like. Weather it was the bone on bad tillering I don't know but the tiller looked good. I did one been at a time, slow down I used a heat gun on low heat and leave it until the woods starting to discolor. Then move it a inch or two and heat this area.
     I build all my bows slowwwwwwwwww. I never make myself go out to my shop and work on a bow unless it in my heart and mine to do so. It take me days or even a week on the one if I remember right.    I takes alot of time to heat your beens this way but you heat all the way through. Only heat from the belly. You heated your bows quick ,the reason your beens don't stay. You only heated the outward belly wood quickly you need a slow pentrating heat.
  I tiller my bow to a 5 or 6 inch's of finished as close to the weight I wanted (straight bow) at this stage. Added my sinew. Never been your limbs after you heat and but sinew and leave to dry a couple a 3  weeks. Before you even think about retillering or pulling on your bow. With the added weight the sinew will add give you enough room when you retiller to where you can get the weight you want and tiller you want.
   Do your bow this way and your beens will stay.

[Newindian]

Osage, seasoned, and I use a heat gun. I do keep every thing within reach and heat the bellie for about 40 minuets ( untill bellie is to hot to touch but i dont think the back is quite as hot) befor clamping and continue to heat after clamping ill push the wood down as much as I think it can take then leave it for a couple hours. Thanks for all the replays every bit helps

[blackhawk]

Seasoned osage is the easiest wood to dry heat bend and keep its bends. If its not staying then your not getting it hot enough....its as simple as that. The BACK needs to be too hot to the touch not the belly. And when osage plastisizes it'll take lil to hardly any force for it to bend. You'll know when its ready cus it'll bend like butta,and if your trying to push hard/clamps tight n hard,then its not ready. And also don't try making any bends where there's a knot,sharp grain swirls,or tight snaky turns and kinks cus it'll wanna splinter there.

[osage outlaw]

I totally agree with Blackhawk.  Are you using any kind of form or angle iron while heating?  40 minutes seems like a long time to make a heat bend.  I think how you heat and bend the wood makes a big difference also.  When I first started I would clamp the stave in a vice, heat it forever, make the bend, and then rig up some kind of contraption to hold it in place.  It would usually take me a few tries to get it where I wanted it.  Once I got a piece of angle, I couldn't believe how much easier it was.  First, the time required to heat the wood was drastically reduced.  The angle reflects a lot of the heat back into the wood.  The bend corrections were easier also.  I was able to clamp it exactly where I wanted and was able to make several corrections at once.  As far as getting it hot enough, the way I do it is to hold a little pressure on it with my free hand when I think I am getting close.  Once you hit that sweet spot on temp., you can feel it start moving.  Then you know you are ready to make the correction. 

[Gordon]

If you are using a heat gun, you need to make the bend slowly while constantly applying heat. This is unlike using steam where you make the bend all at once.

[lostarrow]

I find if you use a stave with natural reflex , tiller it out ,and then flip the tips , the set that it will naturally take is what creates the "deflexed " bends from the fades to the tips. I wet the tips ,and keep a moist paper towel close by . Heat with heat gun on high untill water evaporates. Rewet the area, and heat some more . After about 4-5 times the water will evaporate as soon as you put it on the wood . I keep constant pressure on the wood with a "wrench" I made for the curve I want. The water keeps the wood from scorching while adding any moisture that might be needed for a too dry to bend stave. When I have my curve (plus a little to compensate for spring back) I toast the belly side of the curve to "dry it out "again ,and for the added benefit if heat treating . Just toast untill it barely starts to turn  brown. Let it cool completely before stressing it.  Go make some arrows for a day. Take a scrap piece of the same woodand shape it the same as the last 10-12" of your bow. Test your bending on that before you ruin something you've put a lot of work into already . Once you've perfected your technique you'll know exactly how to approach your bow. You can bend a tip this way in about fifteen minutes.

[Oglala Bowyer]

I'm making the same type of bow with the same dimension, but i'm using hickory.  The exact same thing happened.  I think it is because of the tensile strength.  It would rather crack than bend at least that has been my experience and I've heated a lot of bows.  I agree with blackhawk it needs more heat.

[DarkSoul]

(...)
I wet the tips ,and keep a moist paper towel close by . Heat with heat gun on high untill water evaporates. Rewet the area, and heat some more . After about 4-5 times the water will evaporate as soon as you put it on the wood . I keep constant pressure on the wood with a "wrench" I made for the curve I want. The water keeps the wood from scorching while adding any moisture that might be needed for a too dry to bend stave.
(...)

I honestly don't see how this could be beneficial in any way. As long as you keep the wood moist, it will cool the wood down to 100 degrees centigrade, which is way too low to make wood plasticize. The water keeps the wood from scorching, because it doesn't reach the critical temperature. You'd better use some veggie oil, which will get MUCH hotter than water, and will spread out the heat. But you can also do without any oil.

[tom sawyer]

Hedge doesn't need oiling, but moving an inch at a time isn't a bad idea.  Sometimes you'll get a crack if you really try and bend something a long ways all at once.  I sometimes heat whole limbs but you're better off correcting a small area at a time, and working your way out from handle  to tips.

[osage outlaw]

Here is a picture of my best heat correction.  Dry osage, heat gun, no oil. 

[tom sawyer]

Outlaw if I'd tried that the thing would have cracked right at that knot.  Nice job.