Primitive Archer
Main Discussion Area => Bows => Topic started by: Prarie Bowyer on December 28, 2014, 01:57:28 am
-
First time laying sinew with Knox jellatin.
Broke most of the tendons down fairly far bu the ends of each strand were tapered and or feathered.
Most were combed when dry to break them down further to get more glue between them
It is strange because I combed the first row and tried to keep the rest orderly but by the end I have some spots where there were small voids. Do you guys fill these?
-
It has dried too quick. A fresh sinew back is just like a green stave. Get the majority of the moisture out slowly then increase speed of drying once it's hard all the way through.
-
Ok...it is not nearly as thick this morning as it was when it was fresh. I laid it yesterday afternoon in my basement (finished but cooler than the rest of the house). Those little gaps were showing up as it first started drying. It looks much more normal now. And i'm wondering if I do in fact need a 2nd course. I can't tell where my seams are but I kinda have 2 courses now. The 2nd was done 2 strings at a time.
Is it OK to just add right over the of what is already drying? Or can I call this enough?
I hasn't started pulling the bow in to reflex yet but I didn't clamp in any either.
-
You can poke bits of short sinew soaked in hide glue into the cracks, using the point of a knife or a needle. Just don't do like I used to....fill 'em with glue! All that does is add a lot of weight with no benefits.
And then when it is fully cured, you hear lots and lots of cracks and pops when you are first excercising it in for final tiller! Bad for the old ticker, trust me!
-
Another first timer that missed my how to get smooth sinew build along...
A properly applied sinew job with the right glue and ratio of glue to sinew shouldn't make a peep throughout the draw.
You can have this if you want. Smooth as can be.
(http://i399.photobucket.com/albums/pp78/pat_05/IMG_0056_zps46691090.jpg)
-
it wont hurt to add more, ,and you should bend the bow into reflex,, if you are using minimum amount of sinew it may not pull the bow into reflex,, and a sinew bow with no reflex can shoot well,, but will probably shoot slower than you would like,, :)
-
As it has been drying it has lost alot of thickness. My sinew isn't even 1/8" thick.
is it too late to add more? What about putting in some reflex? Too late for that also?
It is Yew from lumber so I don't want to overpower the belly.
-
Many Asian sinewing techniques involve drying time between layers and increasing reflex with each layer. You can add sinew years later if you want since hide glue can be reactivated centuries later.
-
Bigger problem!
Cracks forming along the side of the bow! What the heck! Is this fixable or fatal?
-
On a sinew backed bow I built I added one course, let it dry for a few days to a week and added the second course concentrating on where it was needed. I've let them rest for a month between courses. I had no problems with the two courses adhering to one another.
-
Cracks in the wood or between the wood and sinew
-
In the wood. 1/2 way down the thickness of the limb.
-
That sounds like win checks. Pics!
-
I'll try to get them up tonight. I picked up some thin locktight but I also have TB3. Or more of the Knox.... and clamps. And epoxy. And or wedges and glue. . . . .
-
What wood is it?
-
Yew.
heart wood.
-
The sinew is just shrinking and pulling the wood apart. Pretty common for yew bellies to do this when sinewed. Osage as well.
-
(http://i235.photobucket.com/albums/ee59/scottnlena/imagejpg8.jpg) (http://s235.photobucket.com/user/scottnlena/media/imagejpg8.jpg.html)
(http://i235.photobucket.com/albums/ee59/scottnlena/imagejpg7.jpg) (http://s235.photobucket.com/user/scottnlena/media/imagejpg7.jpg.html)
(http://i235.photobucket.com/albums/ee59/scottnlena/imagejpg6-1.jpg) (http://s235.photobucket.com/user/scottnlena/media/imagejpg6-1.jpg.html)
Pics of one layer of Sinew.
-
Oh no! I do NOT like the look of that!
-
Dang it! I was working so slowly and methodically! What a craptacilar result!
-
Yeah, but on the plus side, the crack is longitudinal and right down the middle.
Keep Calm and Carry On !
Sinewing isn't my thing, so I may be talking nonsense, but Yew is tough stuff.
I'm just finishing up a boo backed Yew and noticed a couple of "scratches" except they are some sort of very fine crack, can't feel 'em with a fingernail and CA doesn't even soak in... bow shoots fine... sometimes you just have to press on... it's how we learn.
There is a difference between pressing on knowingly to see what happens and being in denial.
If they were chrysals I'd say you were dead in the water... but they ain't so... who knows.
Good luck
Del
-
As I said before you dried your sinew too fast.
Sinew doesn't just shrink in length it shrinks in thickness and width also. This puts tensile stress on the belly of the bow.
Was the yew 8 - 10% dry before you started?
Use a comb to straight the sinew out when laying it down.
You definitely should have added a few inches of reflex BEFORE glue up then added more once you had the sinew applied and the glue had gelled. Sinew bows with no reflex don't shoot particularly well.
-
So. How to fix these cracks? So far they seem to be getting worse. Eventually it will stop.
I'm going to try clamping and gluing them out.
What kind of glue. Knox? Tb3?
I'm inclined to do the tb3 thn use thin superglue in the tiny ends parts.
-
Wondering if this might be an instance where you would squirt super thin crazy glue into the crack and hit it with a heat gun?????
-
I decided on tight bond 3.
The cracks are kinda like laminations and tb3 can be used for that. I think it was the Knox more than the sinew. My leftovers were cut into pieces and allowed to dry. They shrank from the jelly cubes that were cut by almost 75%!
The sizing coat was my problem. Other hide glues have "stuff" in them preventing such shrinkage I think?
-
So far clamping with TB3 seems to be working.
-
I've only sinewed two bows, but I've never had a problem like that. One was juniper and on was osage. The juniper came out nice, light but nice, and my dog ate the osage :0/ what ratio did u use for the glue? I got a bow I'm getting ready to sinew. Then it's gonna sit till I bring it to the classic to get some help not messing it up. Lol.
-
What do you mean other hide gluse have "stuff" in them, ?
-
They're all the same. Knox is what most people use from my understanding, I mixed mine until it was a polyurethane consistantcy. The second would have been better. The one I'm planning on now has been awhile in the works. I may try pats wrapping technique. We'll see. Hopefully urs can be helped
-
I think and this is just my speculation here, that the knox stuff is highly refined and "pure" (hence it's clarity inthe useable form).
I'm not certain that the consistancy matters that much since it is water and the "stuff". The water evaporates out but I mixed it to the consistancy of warm syrup. It coudl be that as teperatures dropped right after I did it the humidiy in my house dropped also. BUT my basement was cooler so thta should have slowed evaporation and I had no fans or anything like that running.
By "stuff" I mean organic material. if you grind fish bladders or odd bits of sinew and hide you get that hide glue that is opaque... which is opaque bercasue there are particles that are suspended in the colagen. These particles may nor may not have the same capacity to shrink as much as the knox...
I could be way off base also.
-
Cruder hide glue actually seems to shrink more.
-
:-\ WELL.. there goes that thought. Why did my wood split so badly?
-
I think mike got it. Ur ainew dried too fast and it shrank so much it pulled the wood in different directions and split
-
??? What do you guys do to slow it?
-
Wrap it with cloth and place the bow in an cold dry area.
-
I put it in the coolest room in my house.
-
Basement is the coolest area. :-\
evaporation is affected by air flow and heat. No "wind" to speak of.
I hydrated the sinew in water then dipped it int he glue. Should I not have used the water soak (2-3 min tops).
-
Well I've chased around several small gaps and clamped them out with tb3.
Now the biggest one? Should I clamp and squeeze or fill with something?
Also I have a few tag ends that stick up. What to do about those? If I did another course with just wet sinew would it stick? Or is the damage done?
-
Use 220 grit and sand it lightly. Then wipe down with a barely damp cloth. If any more bits lift up, sand again and repeat with the damp cloth. If it is nicely smooth when dried again, thin a little bit of hide glue down until it is really runny syrup consistency and use a finger to fingerpaint a very thin coat. Done with the hide glue and sinew...start thinking about your sealing coat.
-
Second coating down.
This time there doesn't seem to be any cracking going on......or only tiny amounts.
When I snake skin this is it necessary to fill all the little gaps and valleys? I planned on sanding or scraping a bit to help level it.
-
you dont have to have it that smooth to put on the snake skin,,, every thing I have read suggest that sinew will make checks in the wood as it shrinks,, I think it is pretty normal,,, I do experience a bit of checking, I usually leave a coat of glue on the belly side and that seems to reduce it,,
-
The new layer of sinew has been on for about a week. It feels and looks dry. How long should I give it to be sure?
-
a couple of weeks,, and when you put the snake skin it will introduce moisture, ,so you need to wait again till dry,,