Staves with concave backs

[Weylin]

My main concern with a rounded belly would be the force trying to flatten it out. That being said, hollow limb bows seem to deal with that stress just fine. Thanks for the wisdom, all!

Well, I think that the stress gets applied differently on a concave back vs a concave belly. In my mind a concave back would have more force trying to flatten in out than a concave surface under compression. I don't have any hard science to back that up, it's just what my logic is telling me.

I don't think it makes any difference.  I heat-treated a very wide, relatively thin limbed HHB bow many years ago.  The process made the belly go concave.  On first stringing one limb split from fade to nearly the tip of the bow

That's interesting. I wonder if it had to do with the fact that it had been flat and became concave do to the heating as opposed to being concave because of following a high crown.

[RyanY]

I wonder how much the strength in that direction depends on wood species.

[Marc St Louis]

HHB has interlocking fibres and is very hard to split. 

The split was right down the middle of the limb

[SLIMBOB]

My experience is much like Marks. Early attempt at one with a fairly deep Concavity failed in less than spectacular fashion. It just broke right along the high edge. Leaving the belly rounded seems to lessen the strain on the edges, making the center do a little more. Or so I figure as it has worked on several.

[Selfbowman]

I’ve had failure and success with this before. Yes with Weylin on matching the thickness from back to belly. I can’t give reason for failures but I suspect the wood did not want to bend there. I do think that concave backs do put more tension on the outer edges causing the bow to have more tension.they seem to have good cast if they hold together. A good test would be have a real straight grain stave and reverse it. Belly split to the back of the bow. Arvin