Palm bow, take two

[wood carver 2]

Last spring I started making a longbow from a black palm stave that a good friend had brought all the way from Ecuador.
 As I started stringing it up for the first time, I heard some cracking sounds. There was a little bit of insect damage on the back that I thought might not be a problem. Turns out, it was.
So, a little while back I was looking at this stave again and I decided to make it work.
I sanded off the back, removing the insect damage and getting the back flat. Then I glued on a thin bamboo backing and a hardwood riser. During glue-up, I induced about an inch of reflex to counter any set it might take later on.
I have been very carefully tillering and bending it and things are looking pretty good. ( Knock wood!) I have had it on a long string which is about 2 inches shorter than the NTN length. The limbs are straight when it's strung like this and the string is tight up against the riser. Braced like this, I drew the bow to about 13 inches and the scale showed 40 pounds.
At what point should I get it on a shorter string? When I bend it against the floor, I can feel that it still has a lot of poundage.
I am being very cautious with this bow as I only have this one stave and I can't afford to mess it up.
The bow is 72 inches long, 70 inches NTN, 1 3/8 inches wide at the fades, with a straight taper to 1/2 inch tips. The limb thickness is 3/4 inch at the fades and tapers to 3/8 inch. The glued on riser is 9 1/2 inches long.
This palm wood is the springiest material I have ever bent and I think the bamboo back has only supercharged it.
Any insights are greatly appreciated.
Dave.

[mikkekeswick]

Black palm is funky stuff! The centre is the 'wood' you want. It is denser and has less of the light coloured weaker stuff.
What draw weight do you want? The first thing to do is start pulling it at the intended finished weight assuming tiller is good and you progress upto it slowly.
Once it is pulling intended weight at around 18 inches you should string it up but only brace it around 2 inches high. This will make the tips come around a little more compare to longstring.
Continue pulling full weight all the way through tillering unless you spot a weak spot etc.
Every time you unstring it check down the limbs to see where any set has occured. Your width taper will require a slightly elliptical tiller.

[wood carver 2]

The stave I have Is black all the way through. To say that it is dense is an understatement. This stuff is heavy and it has a ring to it if you hit it. The outside had a hard crust like bark. I removed that in order to get a flat surface that I can glue a backing to. The bug damage was in that crust.
I'm looking for a 50 to 55 pound draw weight. It's  already looking like a elliptical tiller and the limbs are bending almost to the riser.
I'll remove a bit more wood and shorten up the string when I get back to it.
Thanks.
Dave.

[fujimo]

keep us posted- this sounds awesome- any pics yet?

[wood carver 2]

I'll get some pictures up if I don't bugger it up.
Dave.