Ash Flatbow- problems and questions

[hallifox]

 I am making an Ash Flatbow. Pretty amateur at this, though with lots of wood experience. It's 70" long. While tillering it i ran into a problem; it developed a crack across the back (this also happened to my previous, first effort). After looking at the wood very closely, i realised that the ash had a weak, brittle layer under the bark, about 5mm deep. This may be a layer of weak summer growth, as the limb was felled in the autumn. I find this quite interesting in itself- it's not something that any of the resources i've looked at have mentioned.
Anyway, i managed to scrape this layer (and the crack) off. This has made the limbs quite thin, about 3/8" the entire length (at thickest- there is some curve across the back). So i now have a nice looking, flexible, but very underpowered bow. Any ideas how to stiffen this baby up? I would quite like to try steaming in some reflex (it has a tiny bit of natural reflex anyway). I could shorten it? String it tighter? stick on a rawhide backing? At the moment it has quite stiff ends, but i don't want to take more off it. It draws further back than i can pull (33" or so).

[JW_Halverson]

Ok, great, if you have succeeded in taking it down to the next growth ring, you may be in the safe zone. 

At 70" you should be able to "pike" it shorter and gain some draw weight. Shortening your string will not change the draw weight of the bow, so just play with that once the bow is finished in order to find a brace height that works for you. Backing with rawhide will not change your draw length either, BUT it might add a measure of insurance against the next crack developing.

[hallifox]

Here's a pic or 2

[bjrogg]

Welcome to PA hallifox. I'm kinda wondering if you may have been talking about the cambium layer? Right under the bark is the cambium layer. On white woods like ash if they ar harvested during the growing season both the Bark and cambium will "slip" ( can be fairly easily peeled off). After the end of growing season the cambium starts to get tighter to the first growth ring. I have actually had success using hot water pressure washer to peel cambium off without damaging first growth ring. Or you can carefully scrape it off but must avoid damaging growth ring.
    You could shorten or "pike" your bow to gain draw weight. You could also reflex the tips to gain weight. I'm sorry to say that your tiller looks less than ideal. If you look at your pictures it seems that almost all of your bend is just out of the fade in the first third of your limbs. The rest of your limb look quite straight. This will put a tremendous strain on that area of your bow. If it doesn't break it will probably crush your belly in that area and you will end up with excess set. I would shorten your bow and try to get more of the limb bending. Good Luck and don't give up. There all a learning experience even after you've built many of them they still have something to teach you.
Bjrogg

[loefflerchuck]

I had the same problem in the past first with green ash and years later with white ash. It is the only wood that has fooled me in that way. It really appears to be a ligit ring. Rawhide will not do much. Tighter string will only make it worse. You can shorten it or add sinew. Depending on how thick you lay down sinew, a simple 2 layer backing will add 10-15# to the bow.

[hallifox]

Thanks for the information.
This wasn't typical cambium, it's a deepish layer, hard, brittle, fully attached; maybe that's what happens to cambium after the growing season. And no immediate danger of it cracking again, it's very flexible now that layer has gone.
Short bow seems the simplest answer, but i've just made a good little 50 incher from another stave off the same log, so not really looking for another shorty.
I think i'll experiment with some steamed-in reflex, this might make more sense with the stiff tips. And steaming ash is fun. Thinking of tapering the tips more Holmegaard style too. This might be a bow just to experiment with, and forget about actual performance! I'll be interested to see how well steamed bends last in ash anyway. Anyone know about that?

[Jim Davis]

Just be  aware that it's much harder to be sure what made a difference in a bow if you make several changes at once, such as shortening, reflexing and recurving.

If you do all those, the most likely outcome is a bow broken by straining the limbs too much. It's often more work trying to salvage a mistake than to just start over.

Just my $.02 and 20 years of making bows.

[hallifox]

Thanks, just going to try a bit of reflex for now!

[hallifox]

Or recurve, never quite sure which is which 

[loefflerchuck]

Your tips are already stiff. Just a few " will increase it a bit. You could back only the near handle section. Or I like the idea of nothing to lose experiments.

[Morgan]

You should be able to do 64” easily. That will bring your weight up, I don’t know how much. You would still be stiff midlimb out though, which would require more meat taken off there, in turn making it light again maybe.

[joachimM]

You can shorten it, and toast the belly. If that doesn't work out immediately, I'd just start over with a new stave.
Will be less work than backing a so-so stave that still might break on you.
 
With all the bend in the inner limbs, you'll want skinnier tips. Or else get the mid and outer limbs bending too.

[hallifox]

The recurve works really well, it has certainly tightened it up quite a bit.

Here's a picture of it with it's little brother (which is a much more powerful bow, despite having a safe-feeling draw of only 16" or so!)

The right hand limb needs to be re-steamed, i unclamped it too soon.