Question on Sinew backed ERC

[Danzn Bar]

Been thinking about a ERC that's sinew backed.  Sounds like a great combination. 
Done some research and not much has come up about sap 'vs" heart wood. 

Question:  how much sapwood should I leave on if I sinew back the bow?..............any at all?

Looking at for 50# @ 28" assuming it to be about 64" long with flipped tips starting with about 4" of reflex.

Thanks in advance for your responses.
DBar

[osage outlaw]

I've been thinking about making the same bow Bill.  Just some different measurements.  I'm in search of a good piece of ERC to use.

[Danzn Bar]

I've got access to lots of ERC...........I've got to figure out what is the best to cut, assuming the same as other woods/trees, straight, no knots and no small branches.  I'll check some out this weekend.

Clint,  maybe we can get some and make that bow.
 
DBar

[osage outlaw]

Sounds like a plan Bill.  The ERC trees on my place only have about 3' of trunk before the limbs start.

[Danzn Bar]

Clint
I'll do my best to get some cut before Marshall...................but you've got to understand that this is an old man talking 
DBar

[toomanyknots]

Sounds like a plan Bill.  The ERC trees on my place only have about 3' of trunk before the limbs start.

That's the only way I ever see em. Even when they are bigger.

[Danzn Bar]

I've got some real thick cedar thickets that has some 8" dia trees.

If I remember right no limbs for 8-10 feet ...   I'll confirm this weekend, but someone should remind me...
DBar

[mullet]

If I was going to sinew back it I would remove the sapwood.

[Josh B]

If I was going to sinew back it I would remove the sapwood.

+ 1

Also, forget the trunk wood.  Find the big limbs that are fairly clean and use the top half of them.  Much better wood.  Josh

[blackhawk]

Yeah if ya have enough room to remove the sapwood and have enough heartwood then remove it...but you can leave some if ya need to,or not thin it at all...but its preferable to do so IMO.

@Clint...if ya need a dry stave to work right away lemme know,n I'll bring ya one in a few weeks

[Pappy]

I have some also,just remind me. I don't like the stuff,to much excitement for this old ticker to take.  never tried sinew but have rawhided,it didn't damper the noise and violence at all.
   Pappy

[DarkSoul]

Also, forget the trunk wood.  Find the big limbs that are fairly clean and use the top half of them.  Much better wood.  Josh

ERC is a conifer and the wood therefore produces compression wood when it is under compression, and not tension wood when it is under tension. (Source)
So in theory, the lower side of a branch should contain the lignified compression wood, while the top half is nothing special (except that it has thinner rings). Considering that the bow will be sinew backed, you are looking for extra compression strength in the ERC. So I would, based on the theory, recommend the lower half of the branch.
Mind you, I don't have experience with ERC, but this is based on solid theory.

[Josh B]

Yes...that is the theory and its scientifically sound.  However my practical application has shown the top half to be the less explosive part of the limb.  The compression wood sounds like the logical choice in theory, but it doesn't account for how brittle the compression wood is in comparison.  As usual, raw numbers do not tell the whole story when it comes to bow wood.  Josh

[Danzn Bar]

Thanks all for the responses.................

Gun Doc, DarkSoul,  that some good food for thought.

I didn't get over to the cedar woods this weekend......fish were biting good and the turkey didn't cooperate for me like I expected them to.  Spent way to much time trying to find them.
 
Clint,
I'll get some cut in the next few weeks for sure. I need to get some drying.

Again, thanks everyone for the advice on the sapwood.
DBar 

[Bob Barnes]

DB~ how did the sinew backed ERC turn out?