Post For Tim Baker ( Sinew)

[willie]

A 7" sample of hide glue just dried to 6", another 51/4" sample dried to 4 3/8" 

Tim, can you tell a bit more about these samples? was it just a strip of glue laid down with a brush on waxed paper or cloth or something?

Interesting....I'm sure more experiments are needed....

I agree Ed. this past fall I recovered quite a bit of moose sinew and think I need to run some glue tests before I put it to use. I also bought some hide glue in three different weights 135 ,251 and 379. the mixing instruction for these three different weights call for 3:1 water ratio for the highest weight glue, and only 1.3 :1 ratio for the lightest
I have some fresh deer sinew on hand and some sample boards cut and intend to make a few tests and set them to drying this weekend.
At present I want to .....

1. mix each weight glue to the same consistency and compare shrinkage
2 . take some fresh (frozen) deer sinew and see just how much it shrinks on it's own as it dries.


I welcome any ideas from you guys for more experiments to undertake.

[DC]

With a 3:1 and a 1.3:1 I guess that means the lighter glue will "cure" quicker but maybe shrink less.

[Tim Baker]

BowEd:
"
" Do you think lower density type woods will reflex more than higher density?"

Yes, since for the most part, lower density wood is easier to bend.

willie:

"... can you tell a bit more about these samples? was it just a strip of glue laid down with a brush on waxed paper or cloth or something?

Strips of the cheapest 99-cent-store toilet paper was used, almost all air, were saturated with glue, allowed to gel hard then hung up to dry. A few hours later it's hard springy, dry, and shrunk.

[willie]

Strips of the cheapest 99-cent-store toilet paper was used, almost all air, were saturated with glue, allowed to gel hard then hung up to dry. A few hours later it's hard springy, dry, and shrunk.

as good a medium as any. will test my glue the same, tx

[BowEd]

It's my point exactly.The lighter density wood I've worked with has been compression strong/tension weak.Example red cedar.Don't know about others like redwood though.I have some redwood from building a green house with it.Very light weight stuff  but does'nt rot any.
Seems the wood would need to be sinew backed too.Which was probably your intentions too.
There are lightweight whitewoods like hackberry that is tension strong or compression weak like hickory that would benefit from the glue belly maybe,but it seems most times it does real well just sinew backed alone.Both doing well with just a heat treated belly and no sinew at all.
I might not be fully envisioning your intentions though.

[Tim Baker]

What test samples look like if hung up to dry wet. These used paper towel strips.
The top sample is a single layer saturated with glue. The bottom sample is three layers, saturated then put together. They didn't begin deforming till past the hard gel stage. To get flat dried samples, once at the hard gel stage, no longer wet to the touch, set them on several layers of PT, then several layers on top, then a not-too-heavy book. Replace the wet papers every couple of hours, then every day, till hard dry.

[Tim Baker]

BowEd:

" Seems the wood would need to be sinew backed too.Which was probably your intentions too."

Your posting hit a few seconds before mine...

Yes, it will pulled into a bit more reflex then sinewed, on a fairly high crown.

The reflex taken with that thin glue layer, would have been a bit more but the handle is stiff.

[PatM]

Are you of the belief that this bow will not chrysal readily?

[Marc St Louis]

One would think that sinew would protect a wood low on elasticity from chrysalling but it doesn't.  A sinew backed highly reflexed Black Cherry recurve I made many years ago chrysalled badly well before I got to full draw

[PatM]

It seems to me that even though sinew and glue is theoretically very stretchy is still acts like a steel strap when placed over weak wood.

 I had an Elm bow that I  sinewed and it chrysaled like pine just getting it back to a straight profile which didn't make much sense at all.  I pulled it back to 32 inches anyway and it still had remarkable cast for being a mushy mess.

[Tim Baker]

PatM:

" Are you of the belief that this bow will not chrysal readily?"

Hard to know. I can't find figures on the compression strength or elasticity of dried hide glue. This is a fist test. But judging by its elasticity and strength in tension it seems realistic to think the glue belly will hold up.

Marc: 

" A sinew backed highly reflexed Black Cherry recurve I made many years ago chrysalled badly well before I got to full draw"

If your cherry recurve had had a horn belly it would'nt have chrysaled; the idea here is to see to what extent this poor-man's version of horn will function like horn. Lots of possibilities if it even comes close. Several tests needed to know one way or the other. 

[sleek]

I believe very much that the hide glue will deform or crack under the compression forces. However, using a matrix of glue with a fibre in it should hold it better. I am orderung some horse hair next week to do a parallel test with you on this to see if a difference in performance is to be had. Id like my horse hair belly to be as thick as your glue only belly.

I am curious, what the specific gravity of hide glue vs different horns, and antler is.

[willie]

One would think that sinew would protect a wood low on elasticity from chrysalling but it doesn't.  A sinew backed highly reflexed Black Cherry recurve I made many years ago chrysalled badly well before I got to full draw

It seems to me that even though sinew and glue is theoretically very stretchy is still acts like a steel strap when placed over weak wood.

 I had an Elm bow that I  sinewed and it chrysaled like pine just getting it back to a straight profile which didn't make much sense at all.  I pulled it back to 32 inches anyway and it still had remarkable cast for being a mushy mess.

I dunno about these generalizations about sinew. How much sinew compared to the quality of the elm or cherry has to be considered

[sleek]

Now i wonder about repairing chrysles by putting hide glue in them. The weak spot would be beefed up by the glue filling the cracks.

[PatM]

One would think that sinew would protect a wood low on elasticity from chrysalling but it doesn't.  A sinew backed highly reflexed Black Cherry recurve I made many years ago chrysalled badly well before I got to full draw

It seems to me that even though sinew and glue is theoretically very stretchy is still acts like a steel strap when placed over weak wood.

 I had an Elm bow that I  sinewed and it chrysaled like pine just getting it back to a straight profile which didn't make much sense at all.  I pulled it back to 32 inches anyway and it still had remarkable cast for being a mushy mess.

I dunno about these generalizations about sinew. How much sinew compared to the quality of the elm or cherry has to be considered

 Those are just observations.  The quantity of sinew was a typical amount.  The quality of the wood is hard to really judge until you actually turn it into the bow.