Need advice on heat bending a bow

[shawn]

I purchased an osage blank some time back from a fellow TradGang member. I decided I would try to build my 13 year old a selfbow with this stave. Fortunately for me, John Scrifes had the bow drawn out with instructions on the back of the bow. I went ahead and removed wood to the scribe lines he made on the stave. Prior to any tillering, I put a weighted string on both limb tips to see where the string bisects the handle. Here is what I saw.

 
Handle area
 
Top limb
 
Bottom limb
 
 

It looks like I need to bend both ends of the stave. My concern is that there are knots where the bending needs to take place.
 
bottom limb
 
Top limb
Can the stave be bent where the knots are without causing undo stress to the stave?

I plan on using dry heat. Do I need to put something(crisco?) on the stave to prevent it from being damaged from the heat? I do not know if this info is needed, but it is a Torges style bow.

Thank you for any input.

Shawn

[Pat B]

Shawn, Will the knot be eliminate by the time you get the limb to a bending stage or does it go deeply into the limb or through it? If the knot will be a problem later you may try bending the bow in other places to get the string to track better. You may also be able to tiller the bow so the string tracks correctly at full draw, where it is most critical. Having the string off center to the correct side for the shooter acts similar to a center shot bow.
   When I use dry heat to bend wood I use oil to help prevent scorching, distribute the heat more evenly and hold the heat longer.  Pat

[ONE SHOT]

Shawn from the looks of the photos looks like you have cut thru or removed the radiused portion of the knots, or in other words the base of the knots in which case I doubt if the Bow will ever make it thru the tillering stages. You should have left wood all the way around the knots.

If you still want to proceed with the project, then I suggest bending the last six inches of each limb in opposite directions so that the string will be in the center of the handle....ONE SHOT...              :D

[Dano]

One Shot, I think that's the belly we are looking at.

Shawn, it looks like you have plenty of limb to work with after the knots, I would support that area, so you don't put any pressure on them and bend past there.

[John Scifres]

Hi Shawn.  I would bend the area between the handle and the knots.  Leave the dogleg in.  It won't take a whole lot of bending and will be a lot easier than bending the snaky part.  I don't use anything on the bow like Crisco or oil.  Just take your time, heat about 6" of the limb by using a heatgun.  Keep it moving and at least 4" away from the wood.  I really prefer to use a caul.

Here's a little heatgun tute I did a couple years ago:    Heat Gun Tute  

Have fun.  Let me know if you need anything else on this.  You realize you must post finished pics now.

John