Steam Bending Problems

[arachnid]

Hi Guys.

I have a white oak board that I want to make a set-back handle + reflexed tips bow from.
Since it`s the first time I`m steam bending, I`ve made a rig and steamed a piece of the board,
about 3/4" thick, just to get the hang of it. I steamed it for about 50 min.
I then took it out quickly and put it in the form. I started bending it slowly and about half way- the belly side cracked! 

Here`s the rig:


The crackes:
 



So....
1) Am I doing something wrong? Can it be a grain runoff in the side?
2) If this happens on the bow stave, can I scrape the cracks and glue a thin laminate piece on the belly? Will it hold?

Thanks...
Dor

[Pat B]

Being that you are using a board the splinters are happening along the grain lines. A metal strap along the back will support it and help prevent the splinters. Without seeing this first hand I'd say you could super glue and clamp the cracks and continue on. Looks like you will remove most of it when you educe the tips.
  A stave is unlikely to splinter like this because you will be bending un-violated rings.

[arachnid]

Thanks Pat.
I thought of a safer way to make the bow- steam bend a set-back in the handle area (that`s a small bend so it shouldn`t be
a problem) and instead of bending the tips, I`ll glue a thick piece on the back of the tip and cut it into a reflex shape with
a bandsaw. That should give me a static-reflexed tips.

Will it have the same effect or steam bending the tips is still my best shot?

[Pat B]

There really isn't one way being better than the other. If it works, go for it. You will still have o consider grain and make sure your scarf joints are long enough to support the bent tip.

[arachnid]

Ok, thanks man.
 

[Eric Krewson]

Like pat said you need a strap of metal on the belly of your stave to keep splinters from forming.

You also need to alter your bending form to have several c-clamps clamping the wood at arc of your bend, which also help put pressure on the belly to keep splinters down.

When I bent this bow I popped a splinter in spite of having a strap and several c-clamps. I bent a piece thinner osage on the same form as I bent my bow on and glued it to the back of the bow.

My thinking was I would reduce the cracked belly  and have plenty of wood because of the glued on piece.  Turns out I didn't need the extra piece after I thinned the tips to their final dimensions but I liked the look so I added some walnut to make a fancier effect.

[Blaflair2]

If u work the tips down before u bend it wouldn't crack as bad. 3/4" is a lot of wood to bend.

[Prarie Bowyer]

Metal strap makes %80 improved bending.  Also you may be loosing heat to the box also.  Try using a section of stove pipe.  the cheap shiny stuff. 

[RBLusthaus]

for small sections, like tips, I just make a tent out of tin foil in lieu of the whole steam box.  Works just fine.  Russ

[bradsmith2010]

you might try steaming a little longer also

[Joec123able]

I usually steam 10 mins and have never got a splinter like that but I use staves and usually can chase the spot to one Growth ring. Where you're reflexing looks like a lot of rings run of the edge which could be the biggest problem

[DC]

Somewhere in the back of my mind there is a little voice that says that steaming too much is as bad as not steaming enough. Has anyone else heard this? I've looked on the net and can't find anything.

[bradsmith2010]

i am sure there is a point where you steam too much,, but the wood needs to be hot enough to start to bend,,, just like dry heat,, if you dont heat enough it won't bend,,just break or splinter,, you can always bend a little at a time ,, and not make the bend all at once,, being able to steam the whole clamp helps,,it is easier to start bending before it cools,, I also found boards with run off more difficult,,,, i know it would take more time,, but try a piece 1/2 thick and steam for 30 minutes longer and see how she does,,,,the window for bending is not big time wise,,,, keep that in mind,,

[PatM]

If you soak the wood for a few days you will have much better luck.

[bubby]

Jo I'd like to see you bend a big static like he's trying and only steam it ten minutes, for those big bends I steam about an hour and bend all at once, about 5/8" thick and two clamps