Is the early wood the weak link to cause set?

[PatM]

Maybe some foamy epoxy? Well, now I wonder, do we even know why early wood is so crunchy? What are its actual properties?

   That might work but you'd have to do some tests to determine if you were actually mimicking it.

   We do know why, there's lots of info on the actual differences between early and latewood and why they are different.   Or not  really  in some cases.

[Pat B]

People have been making their living, obtaining food and protecting themselves for over 10,000 year with wood bows.  Apparently the early wood was never a problem for them even though many of their bows had set. Blaming the materials we use is the easy way out. Learn proper tillering, learn the properties of the wood you are working with, learn the affects of the design you use with the wood used and work with patience if you want a wood bow with minimal set and reasonable cast. 

[Selfbowman]

People have been making their living, obtaining food and protecting themselves for over 10,000 year with wood bows.  Apparently the early wood was never a problem for them even though many of their bows had set. Blaming the materials we use is the easy way out. Learn proper tillering, learn the properties of the wood you are working with, learn the affects of the design you use with the wood used and work with patience if you want a wood bow with minimal set and reasonable cast. 

I agree totally but I would be willing to bet they have been testing one another to see who shot their arrow the farthest for the same time. Had to impress the ladies somehow even 10000 years ago. 😁😁😁

[RyanY]

Tim Baker was attempting something similar to Sleek’s idea with some type of hide glue foam and a sinew back a few years ago. I don’t think it went anywhere though.

[sleek]

Tim Baker was attempting something similar to Sleek’s idea with some type of hide glue foam and a sinew back a few years ago. I don’t think it went anywhere though.

His idea was going a different route and he quit for whatever reason without reaching a conclusion. I reached out to him several times over it, but his interest in it had passed.

[Yooper Bowyer]

From an aviation stand point, the crunchy wood is just like the honeycomb core in composite skin structures.  We lay a piece of thin aluminum  the bond to it a layer of honeycomb and another layer of aluminum.  The resulting structure is very light weight and amazingly stiff. It has all of the properties we want in a bow.

I think the cell structure of early wood is not quite this well ordered.  Also, your honeycomb is not oriented in the direction of bend like it is in wood. 

I think that most ring counts are fine enough and even enough to treat the wood as a homogenous material so long as there is not excessive early wood near the back or belly.

[sleek]

Often, always, unless its a pyramid ( im hinting at Arvin success ) the early wood is found on the belly as the rings terminate through tillering.

your point about the orientation of the honeycomb is a well thought out one but not applicable. The grain structure does not matter in a core as long as it is a function of 90° to the stresses.

[PatM]

 Early wood on the belly surely just sits there passively.   About like roughing up a belly surface with a rasp.   It can't have any functional integrity.

[sleek]

Early wood on the belly surely just sits there passively.   About like roughing up a belly surface with a rasp.   It can't have any functional integrity.

It doesn't,  and that's why I think ( key word ) it going into the belly is detrimental to a bow.

[PatM]

 Maybe to the degree its  "mass" slows the bow   but that has to be minuscule on a typical bow.   A streak or  two of graininess amounts to nothing.

[willie]

I think you're sort of wondering if the crunchy layers are sort of like a bad glueline in a laminated bow and if they actually allow some creep in addition to the more common types of set caused by compression.

I believe energy is stored when when adjacent wood cells are subject to shear stress as well as tension or compression. Otherwise we would be able to build a thin skinned honeycomb cored bow from wood.

higher percentages of lighter early wood in the core can't help much.  energy storage is likely higher closer to the back and belly surfaces, but even though the contribution is less towards the center of the limb, total energy storage is a sum of the whole

[mmattockx]

Otherwise we would be able to build a thin skinned honeycomb cored bow from wood.

We can't?


Mark

[bownarra]

Arvin, I dont know what my opinion is worth to you but....


From an aviation stand point, the crunchy wood is just like the honeycomb core in composite skin structures.  We lay a piece of thin aluminum  the bond to it a layer of honeycomb and another layer of aluminum.  The resulting structure is very light weight and amazingly stiff. It has all of the properties we want in a bow.

If I can find one, I'd like to make a bow that has one ring in the back, crunchy wood in the middle, and one ring on the belly. I dont think crunchy wood is a weak link. However, a badly proportioned stave of that early crunchy wood could cause a problem easily.

   I wouldn't say we want that in a bow.  We need a bow to flex, not be stiff.

   You could likely test the  crunchy layer   theory by gluing  lams of bamboo stacked like growth rings with a thick layer of crunchy glue holding them each together.

 Hard to say if there is a glue that mimics early wood.
 
  One thing is  pretty sure, early wood is often not the greatest bond between rings when a piggyback split can often be achieved right down one.

I think gorilla glue is pretty bubbly?

Few types of branded gorilla glue Sleek what you are talking about is polyurethane glue. Expanding foam is basically the same stuff.

[bownarra]

For folks wanting to understand set a bit better. I strongly recommend building a quicky d-bow. Pull it too far to induce set......then take it to the bandsaw and cut it in half....so you seperate back and belly and end up with two lams
One thing I will say is remeber the balanced seesaw (teeter-totter?)....IF we manage to balance the force back and belly we get significantly less set. I wish somebody else would do this experiement.....you might find it interesting. Trapping may well be the way to better distances for you.

[willie]

Otherwise we would be able to build a thin skinned honeycomb cored bow from wood.

We can't?


Mark

it could be built, but I do not believe you will get the energy storage. for example
a hickory bow vs. an otherwise similar dimensioned bow constructed with a front and back hickory lam on a balsa core