Mulberry staves with many thorny like pin knots, please help.

[bowandarrow473]

That's true, but density can't be the only factor, it must be a willingness to stretch under less strain than the heartwood, and since different density bow woods can make the same weight at practically the same dimensions, then it can't just be density.

[Bowmonk]

I think i would at least take the sapwood down to one growth ring. The problem with over doing the sapwood is that you can then get too much compression on the heart wood belly, especially if it is less thickness in ratio to the sapwood... you still have to imagine that the neutral plane is going to be the center of the limb's thickness, and i think that the sapwood tensile strength may possibly be more than the compression properties of the heartwood on mulberry.

[Josh B]

That's true, but density can't be the only factor, it must be a willingness to stretch under less strain than the heartwood, and since different density bow woods can make the same weight at practically the same dimensions, then it can't just be density.

Pat pretty much nailed the reason.  It's true that the same front profile dimensions can be used for a wide variety of wood densities even though it's better to adjust the dimensions to best suit each particular stave.  However, you will find that the thickness will for the most part have to be thicker to get the same draw weight on the lower density wood than it will be for heavier woods.  Josh

[bowandarrow473]

Who am I kidding, you all are probably right, who am I to argue with people who have been doing this for decades. but in my head it works out that a wood can have lower density and still retain tensile or crushing strength( I'm talking about 3 or 4 SG, which is what I assume the density difference on sapwood is) but then again, I'm just a 14 year old who likes bows!

Cheers!!!

[Pat B]

B&A, I never give it that much thought.     From experience I know the finished product is thicker when using sapwood over heartwood. My brain doesn't compute the whys but it does acknowledge the reality.
 I've built mulberry bows that were all heartwood, heartwood with a sapwood ring back, 50/50 heartwood/sapwood and all sapwood and the more sapwood involved the thicker the limbs are for the same draw weight and design.
Bowmonk, I think all the pins on the back were of concern to Ameer so I was letting him know that if the sapwood is sound he could use it as the back. As it is now the sapwood is physically unblemished so therefore the best possible back for his bow...if the sapwood is sound.

[alwayslookin]

It looks like the mulberry I have in Florida. It grows very fast here. Growth rings are huge. I always use just under the bark for my back. In fact the biggest piece I've found was maybe 5 or 6 inches but I've never seen heartwood on this type of mulberry I have around here. The wood has good properties though (not Osage good) but good none the less.

[Ameer]

Does heartwood have to be a different colour to sapwood on Mulberry wood? Where exactly does the heartwood start on this stave?

[Pat B]

The sapwood is creamy color and the heartwood is caramel color.
 All of the mulberry I've seen had large growth rings.

[Ameer]

Wow Mulberry has a lot of sapwood.

[Pat B]

How big(diameter) was the tree?

[Ameer]

About 12 inches the bottom was thicker though.

[Limbit]

That is a very typical stave from my experience with mulberry. You shouldn't worry about those little pin-knots. Mulberry is resilient bow wood. Just be careful about it twisting. If it isn't fully seasoned before use, you might find your tips move on you...even in straight-grained wood I've seen it do some strange stuff while drying. You can heat treat it as well! It will end up very light and have excellent cast.

[Ameer]

Can I please see a picture of one your mulberry bows?

[Limbit]

Sure, I'm working on one right now. I am splicing it out of billets. When it is done, I'll send you some pics!

[Bowmonk]

I understand why you recommended that he use what he had for the back of the bow Pat B, and just looking at the surface of what he had I agree, it looked great already. I will still say though that if that is a photo of the stave he is using, considering the thickness of the rings and the depth of the sapwood, and the fact he has a nearly 3 to 1 ratio on sapwood to heart wood... I think it would still be advisable to work the back down to the last sapwood (white) ring leaving one growth ring of sapwood.