Post For Tim Baker ( Sinew)

[willie]

if there is natural glue in the tendon and it can be reconstituted by chewing and saiva, is there a possibility of modifying the modern application process to more closely resemble a "chew and glue" method? utilizing what is already there, and not having to add so much hide glue?

[sleek]

if there is natural glue in the tendon and it can be reconstituted by chewing and saiva, is there a possibility of modifying the modern application process to more closely resemble a "chew and glue" method? utilizing what is already there, and not having to add so much hide glue?

I have no clue if thats possible, but I love the out of the box thinking. It would be nice to find a way to extract the glue without having to cook it out, as Im sure that degrades it.

[willie]

From

https://babel.hathitrust.org/cgi/pt?id=aeu.ark:/13960/t7br9bh8j;view=1up;seq=50

some techniques not often talked about with the application methods passed down from the old world. pretwisting strands and using a glue ball to rub the glue on

[Springbuck]

willie:  "I assume that each bridge is well anchored to the limb so that the tension can step down as you move out the limb?"

  Yes, that is what I assumed.  Either tied down hard with Boy Scout style lashing, or even set in slight recesses, something.

  Are you planning to just add bridges, or back with the linen cloth first?  Which version?  I'm afraid that any flex will splinter the bamboo from a small diameter

willie: "This time, I think I can "mess with the bridge height" and keep the same bend."

   I think so too.  There is a great example of an arctic bow from the Smithsonian North American Ethnographic Collection with a cable that rest against the limb, except where a tiny spring bridge rests right in the deepest part of a recurved angle to prevent the recurve flattening out.

[PatM]

if there is natural glue in the tendon and it can be reconstituted by chewing and saiva, is there a possibility of modifying the modern application process to more closely resemble a "chew and glue" method? utilizing what is already there, and not having to add so much hide glue?

I have no clue if thats possible, but I love the out of the box thinking. It would be nice to find a way to extract the glue without having to cook it out, as Im sure that degrades it.

   Not all glue is actually cooked out like homemade stuff.
   Gelatin for example is reduced by other methods.

[Springbuck]

 Like this....  sorry that pic is so tiny.

[Springbuck]

if there is natural glue in the tendon and it can be reconstituted by chewing and saliva, is there a possibility of modifying the modern application process to more closely resemble a "chew and glue" method? utilizing what is already there, and not having to add so much hide glue?

  Could be.  The thing is that, chemically, hide glue and sinew are ALMOST exactly the same thing, which is collagen.  The sinew also contains fibrin.  Boiling out hide glue is just denaturing the protein one step back, When it dries it essentially goes through dehydration synthesis, which is not EXACTLY the same process as the living cells use that laid it down, but results in a very similar product.   Saliva does the same thing chemically through an enzyme.

The real difference is that we may damage the protein during extraction (over-boiling, etc.) and we lack the precision alignment, matrixing, and perfect placement the living cells are capable of.    But, there is glue (collagen) still in the sinew, and when we add more and remove water, hide glue BECOMES part of the sinew, part of what is already there, in a way no other glue does.  We just can't do it as well as biology. 

[Springbuck]

Not all glue is actually cooked out like homemade stuff.
   Gelatin for example is reduced by other methods.
[/quote]

 Yes, lots of chemical methods.     

I just read an entire three page article on the process in "Uncle John's Bathroom Reader."  Since they are using industrial food scraps there are a lot of steps, and purity must be very high, the process is really involved (acid baths to dissolve ground bones, saponification and skimming of the fats, etc.) but the article mentions extraction by boiling.   That may have been to remove the chemicals from the previous step in the process, or whatever.   

[PatM]

  To illustrate the difference in the actual structure of glue and tendon you could try backing a bow with a strip of jello and letting it dry.

 How do you suppose it might fare as a backing?

[Springbuck]

  To illustrate the difference in the actual structure of glue and tendon you could try backing a bow with a strip of jello and letting it dry.

 How do you suppose it might fare as a backing?

That's what I'm talking about.

  Sinew has fibrin in it as well, and I suppose hide glue must have some denatured fibrin as well.  Using collagen by itself would be absurd, of course, and we can't get denatured fibrin to lay itself out longitudinally without the help of cells.

But, you can extract glue from sinew by slow cooking, and you can essentially put it back by letting soaked sinew dry, just not as well as nature.

[willie]

Are you planning to just add bridges, or back with the linen cloth first?  Which version?  I'm afraid that any flex will splinter the bamboo from a small diameter

not sure why it should splinter?

making the bridges the same height as the limb is thick directly underneath the bridge seems to work to keep tiller, at least to  the 10" draw curve I referenced yesterday.  It keeps the same taper going I suppose. the first pull added 30% to draw weight but I have not started to twist the cable yet. Need to add a few more bridges and glue them all down well before cranking on the cable and making big full draw pulls.

[willie]

Using collagen by itself would be absurd, of course,

I have read where hide glue left on glass to dry, can shrink and lift a flake. never seen it tried, though.

[Springbuck]

  I'm just afraid it would, is all. 

 I understand the theory of the neutral plane, and how raising the cable or backing changes it.  But, we are using a stetchy backing and there are spaces between the bridges, etc..   Hard to know until the first pull.

[Tim Baker]

willie: 

Especially when approaching full draw, friction of the cable against the bridges might be great enough to drain measurable amounts of energy.  Originally I thought that making the bridges toggle a bit  would solve that problem, but later decided to let them roll instead. But never tried either. Your setup looks pretty friction free, so likely not worth the bother, but if ever curious, just replace the present bridges with same-height no-friction rolling ones and see if there's a performance change.

[Ryan Jacob]

I wonder how well black palm “heartwood” will do as a core?