ERC Sinew bow in progress

[Fox]

Okay stave picked and trying to figure out the best way to lay this bow out... I've probably made 10 or 15 bows and im still never sure the best way to lay them out. I crudely layed this one out. 2" to 3/4" tips. 60" long, my draw is 26".

I am guessing this not an acceptable layout with that much grain runoff? Will I be able to heat that out if I follow the grain? This stave is somewhere around 100 years old.... it just has a few little dings in the sapwood, can I sand those smooth and call it good? Should I chase a ring so I have heartwood on the belly ?

Untitled by Livvydog, on Flickr
Untitled by Livvydog, on Flick

(The dings in the back)

Untitled by Livvydog, on Flickr

[Hamish]

I would be following the curve of the grain in the stave, rather than how you have it laid out. ERC is risky in tension, even with totally straight grain. Put a structural weakness in there you are really asking for trouble.

Heat bend it straight, when you get it floor tillered.

I would work the sapwood down to 3/16-1/4" thick. Following any dips. Otherwise you will end up with a mostly sapwood bow.

I would also back it with rawhide(or even sinew) to ensure that the tension strength is maximal.

[Fox]

I am backing it with sinew. Yeah I was thinking that was asking for trouble with that layout. I’ve heard a lot of mixed things about sapwood vs heartwood, one person said sapwood is better in compression and the other said heartwood. It seems odd that the sapwood would have better compression though…

[bownarra]

Trust me I've tested a few sinew backed pieces to destruction I can promise you the heartwood can take more compression - FACT! This isn't what I think its what I know!
Layout with the grain and bend straight.

[gutpile]

I built an all sapwood ERC sinew backed.. only heartwood is in the handle. bow is a screamer with no issues, extremely light in hand.... gut

[Fox]

Okay I’ll chase down a few rings and back it