big bends in vine maple

[aaron]

I'd like to hear some successfull examples of big bends in vine maple. I'm talking mostly about sideways bends for correcting string alignment, or bends in the handle. I have had success with recurving tips on VM, but when it comes to thicker and wider parts of the bow, i have trouble with the bow returning to nearly it's original shape after a few days. Here's my method: first, I reduce the bow to about 2X2 for initial drying for 1-2 months in unheated shed. Then I reduce to about 1.25 x 1.25 and bring it inside for a month.My previously (mostly) straight stave now looks like a bannana. Let's say the stave has a string alignment that is 3 inches off (3 inches from the string to the center line of the handle).  I boil a giant kettle of water, about 1.5  foot diameter (like you boil crabs in). I lay the stave across the kettle, cover with foil and a towel, and steam for an hour at a slow boil. I remove the stave and get it in a jig within 10 seconds. The jig bends it way past straight, until the alignment is off on the other side of the handle by a bit. This I leave outside overnight. When removed, the string alignment looks just about perfect, but over the course of a day or so, it returns almost to where it was. I have had success with small sideways corrections, but not big ones like this.
Lately, I'm working on a stave that was fully 4 inches off in string alignment, and after steaming sections several times, the bow is still almost 2 inches off. Am I doing something wrong? Or Am I just asking too much in trying for these big corrections?
It's not that I don't have any straight staves, but that I want to save the multitude of staves that end up crooked.

[Thesquirrelslinger]

No idea, never worked VM...
I think that multiple bends... e.g steaming it multiple times to make it bend more... might be doable. But I really don't know.
Leave it clamped for a LONG TIME- a week or so, and BOIL it. Supposedly it makes most woods bend easier. I read that on some traditional wood-worker's database.
Maybe dry heat?

[Gordon]

If you harvest a stave from a vine maple tree that is under tension, then there will be a definite tension side and compression side. The tension side of a split stave will curl into reflex as the wood dries. I have tried to steam bend out some of the reflex in such staves with no success as the wood always seems to return to its previous state in a few days. Normally I make the tension side of a stave the back of the bow - is it possible that you have oriented the stave such that you are trying to pull out some of the tension? If so, you are going to have a devil of a time of it.

[steve b.]

I've done about half a dozen lateral bends with VM.  I do what you do and steam.  I've done the bend where you secure the bow and hang weight on the tip to bend it just slightly past where you want it and leave it there for an hour or more.  Those have all been successful.  I've also steamed then put the bow between two poles and just bend it by hand and hold it there as long as I can, like 10 minutes.  I've had limited success as a couple of those tries cracked the limb.
But I'm never bending near as far as you describe and the limbs that are cracking are beefy and wide.  I'd probably have more success with thinner, more narrow limbs.
I did one recently where the limb broke open fairly easy and it was where the grain was swirly.  With straight, strong grain the worst I've had is just a splinter on the edge, one that could either be wrapped or removed during side tillering. 
So mostly I've had good success, but again, with small adjustments of an inch or two.
I've never reflexed or recurved VM.

[vinemaplebows]

Ive had mixed rusults, and clamping over night is what I would recomend.


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