What is the root cause of this level of extreme warping of the wood?

[mauser284]

Is this because the wood was not aged properly before the stock was cut fromt he blank?


I have never seen warpage this bad or this resistant to being steamed and rebent!


Bending wood with heat, boiling water and steam and some form of jig is pretty common and old method.

 

[Jonnyofalltrades]

That's an entertaining video, isn't it?
In my parallel universe of building self bows, we would call that reaction wood.
Sometimes it is because of where the wood grew in a tree that leans. Wood from the upper side is lighter, and has higher tensile strength. Wood from the lower side of the tree is more dense, has lower tensile strength, and higher compressive strength. A blank from either of these can have some very desirable properties, but may have hidden internal stresses after curing that can make them move unpredictably.
It's actually very similar to the movements of a barrel that has not been stress relieved.

 

[Will Henry]

Back in my sawmilling days, we called that "timber bound". Usually from a tree growing on a hillside and bent when young. WH

 

[shortgrass]

Possibly not dried and aged properly.

 

[pdhntr]

An old Master Alvin Linden would build a stock from the inside out so to speak. The first process for him was to square and then inlet the blank while it was still rectangular in shape. After inletting and fitting all the metal he would rough the outside with a big hatchet !!

Early in my stock making I thought this was the best way, (although I didn't use a hatchet) until I was working on a piece of claro that was pretty nice. The customer ordered it from California and it was supposedly dried for enough years that I wasn't concerned. I inletted it and started removing wood from the outside of the blank, the inlet started taking a walk to the right at the muzzle. The more wood I removed the worse it got. I finally had to abandon my efforts and call the customer. After some resistance from the supplier he finally got another blank. That was the last one I inletted first.

After that disaster, my procedure was to carefully cut off some outside wood staying a good ways away from the final contour. I would then let the stock sit for a couple weeks in my dry shop and measure occasionally to see if it was moving. If nothing happened I would remove a little more outside wood, creeping up on the final contour and then let it sit for a couple more weeks. If the stock behaved, I moved to the inletting.

I eventually started laminating my own stock blanks and have never done a non-laminated stock since.

Jim