Sinewed Ocean Spray

[DC]

I haven't seen one either. I'm hoping it won't chrysal but time will tell.

[Marc St Louis]

That is a good looking bow, well done.  If Ocean spray is not prone to chrysalling then it will be even less prone with the sinew.

[Onebowonder]

<snip> If Ocean spray is not prone to chrysalling then it will be even less prone with the sinew.

PLEASE help me understand this point, because I'm confused.  I don't understand how a sinew backing would manage to both increase the draw weight and tension strength of the bow, yet somehow decrease the propensity to form chrysals.   My understanding is that a given surface area or volume of wood on the belly of a bow forms chrysals when the compressive force applied against it exceeds the capacity that the wood can bare.  It seems to me that adding tension force resistance to the back of the bow and increasing the draw weight of the bow would necessarily increase the compression stress on the belly as the bow is drawn.  ...which should deductively increase the propensity to forms chrysals on the belly, - - - I think. 

I have been trying to noodle out a way to make the physics work for this, but I keep winding up in the place I started.  I went down several different rabbit holes trying to figure this out.  I contemplated differential curves of force being applied by sinew vs. wood.  I considered the resting brace state vs the momentary full draw load and how it might be different.  Materials science is one of my favorite curiosities, but there is MUCH of it that remains mysterious to me.   It just seems that if more force is applied to the same belly material, the probability of the fibers in the belly reacting to that force to form chrysals HAS TO be increased!  ...but I read frequently that the opposite is the case with sinew as the backing and cannot noodle out why it is so!

I know sinew is magical stuff, but I don't really get how it can do some of the stuff it is said to be capable of.  I'm sure I am missing some key little bit of understanding of how it works or the properties of the material, but I just cannot wrap my cerebellum around it yet.  Can anybody help me understand?

OneBow

[Marc St Louis]

<snip> If Ocean spray is not prone to chrysalling then it will be even less prone with the sinew.

PLEASE help me understand this point, because I'm confused.  I don't understand how a sinew backing would manage to both increase the draw weight and tension strength of the bow, yet somehow decrease the propensity to form chrysals.   My understanding is that a given surface area or volume of wood on the belly of a bow forms chrysals when the compressive force applied against it exceeds the capacity that the wood can bare.  It seems to me that adding tension force resistance to the back of the bow and increasing the draw weight of the bow would necessarily increase the compression stress on the belly as the bow is drawn.  ...which should deductively increase the propensity to forms chrysals on the belly, - - - I think. 

I have been trying to noodle out a way to make the physics work for this, but I keep winding up in the place I started.  I went down several different rabbit holes trying to figure this out.  I contemplated differential curves of force being applied by sinew vs. wood.  I considered the resting brace state vs the momentary full draw load and how it might be different.  Materials science is one of my favorite curiosities, but there is MUCH of it that remains mysterious to me.   It just seems that if more force is applied to the same belly material, the probability of the fibers in the belly reacting to that force to form chrysals HAS TO be increased!  ...but I read frequently that the opposite is the case with sinew as the backing and cannot noodle out why it is so!

I know sinew is magical stuff, but I don't really get how it can do some of the stuff it is said to be capable of.  I'm sure I am missing some key little bit of understanding of how it works or the properties of the material, but I just cannot wrap my cerebellum around it yet.  Can anybody help me understand?

OneBow

You are confused because of the idea that sinew adds tensions strength, it does not.  The magic of sinew is its elasticity.  Wood is somewhat stronger in compression than sinew is in tension so having a sinew backing allows the back to work more thereby reducing stress on the belly

[willie]

I'm sure I am missing some key little bit of understanding

adding sinew to a limb will make it stiffer, assuming of course that the wood that it is added to, does not get thinned.

adding sinew and retillering (thinning) the belly wood , makes a different limb, as Mark has described.

[Onebowonder]

You are confused because of the idea that sinew adds tensions strength, it does not.  The magic of sinew is its elasticity.  Wood is somewhat stronger in compression than sinew is in tension so having a sinew backing allows the back to work more thereby reducing stress on the belly

OK - I'm still confused.  I guess I think of a bow as a balanced system.  The belly and the back have equal and opposite forces acting upon them as the bow bends.  I.E. - A fifty pound draw weight bow when drawn has 50 pounds of tension strain on the back spread over whatever the surface area/volume of the back is and 50 pounds of compression force working against whatever the surface area/volume of the belly is.  Now both the back and the belly may have a greater degree of 'capacity' for tension or compression force resistance, but when the bow is drawn to 50 pounds of draw weight, neither the back nor the belly is holding more or less than 50 pounds, regardless of it's capacity.  Similarly, if the new backing of sinew is going to increase the draw weight of the bow, say to 65 pounds, then both the backing AND the belly are going to be subjected to 65 pounds of strain, the back in tension and the belly in compression.  I just cannot sort out how the 'elasticity' of the sinew on the back is going to relieve the compression force that has to be endured by the belly.

OneBow

[PatM]

]OK - I'm still confused.  I guess I think of a bow as a balanced system.

OneBow[/color][/size][/font]

Is it?  What about the neutral plane position?

[bradsmith2010]

ok maybe I am over simplifiing ,, but the sinew stretches more than wood,, so does not but the same compression force on the belly,, as a wood back does,,,, am I close,,?

ok for example, when  u put on a bamboo backing that is too thick it will crush the belly,,cause its too strong,

[bjrogg]

ok maybe I am over simplifiing ,, but the sinew stretches more than wood,, so does not but the same compression force on the belly,, as a wood back does,,,, am I close,,?

ok for example, when  u put on a bamboo backing that is too thick it will crush the belly,,cause its too strong,

I'm like Eric. I don't understand how you can have more tension and poundage without out requiring more compression to counteract it.
     I can understand how a sinew bow of same weight as all wood bow could be faster because of the elasticity of the sinew.
     I'm not saying it's not true, I like Eric just can't seem to comprehend how this works. I like to figure out how things work. In my mind it seems it would be like the thick bamboo and overpower the belly. Must be something I'm missing. Don't mean to get off track on this post DC. I think you post a comparable question once that went on for 12 or more pages.
    Nice bow D.C., I really do need to try sinew. I shot Paulsemp's at Elm Hall and was very impressed. For its physical size and weight it was a very nice shooting bow.
Bjrogg

[DC]

And even after 12 pages I'm not sure how it works but it does

[Marc St Louis]

ok maybe I am over simplifiing ,, but the sinew stretches more than wood,, so does not but the same compression force on the belly,, as a wood back does,,,, am I close,,?

ok for example, when  u put on a bamboo backing that is too thick it will crush the belly,,cause its too strong,

I'm like Eric. I don't understand how you can have more tension and poundage without out requiring more compression to counteract it.
     I can understand how a sinew bow of same weight as all wood bow could be faster because of the elasticity of the sinew.
     I'm not saying it's not true, I like Eric just can't seem to comprehend how this works. I like to figure out how things work. In my mind it seems it would be like the thick bamboo and overpower the belly. Must be something I'm missing. Don't mean to get off track on this post DC. I think you post a comparable question once that went on for 12 or more pages.
    Nice bow D.C., I really do need to try sinew. I shot Paulsemp's at Elm Hall and was very impressed. For its physical size and weight it was a very nice shooting bow.
Bjrogg

Because the belly is not storing more energy, it's the back/sinew.

[Onebowonder]

Because the belly is not storing more energy, it's the back/sinew.

...Mark - We should perhaps move this to a new thread, but how does the sinew on the back 'store more energy' without increasing the resistance force required of the belly?  How can you increase the draw force on the tension side of the bow, without similarly increasing the compression force pushed against the belly?

OneBow

[DC]

I don't mind if it's here, just don't move it to PM's. I'm hoping to learn something.

Does the added thickness make much difference?

[BowEd]

I've read that bow building will drive accountants crazy.

[bradsmith2010]

because the sinew is stretchy and magic,,