concave back?

[uncleduck]

I am about to start into a osage stave here that is going to end up with a concave back. Are there any additional design considerations I should be thinking about here compared to a normal flatter back?  Any advice or experience with this would be appreciated. Thanks.

[JW_Halverson]

I got an osage bow with a concave back, has always shot like a dream!

[half eye]

I am just finishing up the last of 5 yellow birch bows (2 staves and 3 board) the one stave bow has a concave back that comes and goes and varies in depth. I did not allow anything for this fact as these bows are tests of the parameters of the wood. It's 50" ntn, just shy of 50# @ 25" and is stressed pretty hard but shows no signs of distress at all. The stick is 1=1/8" wide in the center 12" and straight tapers to 3/4 " tips.

Was going to post the bows and the working properties of the yellow Birch which will surprise a lot of folks. Dont know if that helps you or not because it's not Osage.
rich

[SLIMBOB]

Busted a few Osage bows with concave backs.  Tension breaks on all of them.  A minimal amount has never mattered, but the ones with serious dips have caused me problems.  Marc addressed this on a bow he made last year with this characteristic, and he said he leaves the belly crowned if the back is concave.  Thought about it and that made sense to me.  I've used it a few times since and it seems to work.

[half eye]

Just took some pics of the one I made if you would like to see them, dont know if yours has more or less so you could see if it makes a difference.
rich

[Blaflair2]

Can I just make the concave part the belly like a regular bow and chas a ring on the inside

[WhitefeatherFout]

I was just getting ready to suggest that Blaflair.  It should be fine if you want to reverse the back and belly.  I've only done it once and it worked.  I've seen others do it with good success.  If you elect to leave the back concave I would allow for a more rounded belly as mentioned earlier to keep your thickness the same across the width of the bow.

[Will H]

I've made a few like that, just do like a few others have suggested already. Crown the belly to match the back in order to keep the thickness even. Otherwise the sides of the back act like rails putting most of the tension in two small parts of the back upping your chances for a tension failure. Good luck with it! Look forward to some pics

[uncleduck]

Thanks for the replies. I will be sure to get some pics up when I start on it. It might take a while to chase a ring on this thing having to use the rounded scraper for the whole back, I suppose there plenty of worse things I could be doing though