Kara Kurszan hornbow from Tc log - twist.. sinew damage?

[pcoutin]

Continuation of previous page.

http://imgur.com/a/uSNsy

It happens quite often the horn surface develops fine, lengthwise fissures with use or as the bow dries after sinewing. This is most likely a result of the cross-limb contraction of sinew, which puts the belly under cross-tension. The cracking has no effect on the bow’s performance. Sometimes it is possible to fill the cracks with the cyanoacrylate glue, but usually the cracks can not be repaired.

Well, this crack is not lengthwise...

The crack did not get visibly worse after stringing and balancing.

Pretty sure this is due to my negligence. Unstringing it too fast, accidentally, clumsily hitting the bow against things, shooting too light arrows... guess it is a learning experience. Gotta be careful with these.

[pcoutin]

loctite 480 superglue should do. It is black. Bowyer said no sinew is needed. Nice.

Not "any cyanoacrylic glue" - Look for superglue marketed as "Super thin". You want something with the consistency of water if you need capillary action.

The viscosity of water is from 1.8 to 0.5 mPa-s. The viscosity of loctite 480 is 200 mPa-s. Sigh.

I think what I might do is apply super thin glue, wipe it, and then apply loctite 480 before it all dries or something.

Loctite 480 would likely be good enough.

[pcoutin]

Will just try loctite 480, seeing that it's rubbery and shock resistant etc and that's what the bowyer recommended. Pretty pricey... It will supposedly arrive here between Friday and some time next week.

Don't really want to bother with a more brittle superglue material.

Hide glue and shellac also arriving! Wonder how good of a black pigment charcoal is, when I get my tung oil bottle back..

With such a crack the only thing to save this bow is to replace the horn I am afraid. It will eventually destroy the bow if you keep on shooting it, and I have my doubts about superglue solving the problem. If it were lengthwise it maybe would not be a problem. It unstrung itself while shooting you say? That might have caused it

]Could be a old male horn they got lots of ridges and cracks. I am with Alex that limb will go sooner or later. And no sinew is not a fix all.

Scary to hear this from such experienced people.

Well, I hope the Loctite 480 will be sufficient.

Meanwhile, I don't know what to do about arrows. Maybe I should build a spine tester..

I think my thumb release is still not that good. Though I managed to shoot off the left side of the bow with the thumb today, the arrows went waaay to the left.

[pcoutin]

uh

I really doubt that it'll just suddenly explode after gluing.

I choose to trust Istvan. If it gets worse after gluing and then shooting, then I'll consider replacing the horn. If it just suddenly blows up at the crack... well, I guess that'd be another learning experience. At least it'd settle this dilemma.

[pcoutin]

Applied loctite 480, dried in a blob. I did file a tad because I tried to get to what seemed like a part of the crack that was covered by sinew, but didn't get to it. Hopefully dust didn't weaken the glue or prevent it from going into the crack or anything.

But I braced the bow, was pretty balanced, and drew it until it seemed to stack (my cheek, I'm probably 187cm armspan or so) several times. Probably 15 times. Nothing much wrong, just that the string loop was making a noise on the notch again. I wanna make a twisted string even more now. Though filing the notches to be rounder should help as well.

Getting tung oil, sand paper, etc. May make some black paint. Also getting some of that titebond hide glue, should help with the sinew wrappings in all my stuff.

Was more successful heat straightening bamboo today, although it's still annoying.

At the end of unstringing, still let it go a bit too quickly at the end although I tried to be careful and slow. I should avoid slipping the hands while I unstring, the video is a perfect example of how to do it right.

One of the ears seemed to make a cracking noise when I was trying to align it. but didn't break. was fine while I drew.

[pcoutin]

Found a few small holes on the sides of one of the ears which I plugged with loctite. Not sure if they were there originally. Probably not, what. Should I worry about horn eating insects?..

[pcoutin]

Today I strung kurszan again, did not balance except by changing the tightness of the tepeliks once strung until the limbs looked balanced and leaving it for a while. Did have to try to align the ears though.

Drew the bow as well. No blow ups at the crack yet! I wonder if I should file the sinew next to the crack on the belly and maybe side of the limb, and apply loctite 480 there as well. Just in case?

I only string it with the two person at the knee method now. Step through is awkward and feels like I'll twist the limbs. Though it looks like it could be okay if done properly..

No problems besides noises of the string at the notches. Gonna round the notches some. Also, managed to make a flemish string. Will make double loops for it. That should help. I think a tan (or white to imitate silk?) endless string with twisted double loops tied on like described here would look and work really nice:

https://www.youtube.com/watch?v=Cwp6UJOUfZY

The cool thing about twisted rather than served loops is that they should be softer and less noisy..

The strings Tc sent me with the bow should probably be fine anyway, if I round the notches some more.

[pcoutin]

pretty sure this bow will have 0 handshock at 10gpp... i think i've shot it at wayy less than that. now if only i had a scale.

what am i doing at 4:22am

no idea what the draw weight will be at 30" yet..

[pcoutin]

Planning to draw 29.5" from belly.
If my sense of smell isn't too off, filing or sanding horn makes a smell like that of burning hair, and this shellac smells like rum, brandy or something. Amber shellac has a beautiful color. Pretty sure I could get drunk off of it... but it'd likely be poisonous or cause all sorts of health complications, obviously. I mean, it's diluted in ethanol?
I had forgotten about the smell of tung oil. Such a strong nutty smell.

I hope the notches on the bow will act better after I filed and sanded them a bit, trying to make the notches "rounder".

Planing to make a quiver of layered, glued cardboard (leather later?) that may be a mix of Manchu (because small quivers and I want a small quiver, and I found an appealing looking one) and Turkish/Polish? styles.

Hopefully I can manage to heat straighten a few shafts tonight. I wetted them, sanded them down, and wetted them again for some reason. Hoping the moisture will help some with heat straightening. I had cut one down that has a bit of a snake/kinkiness near the nock end, and it's backwards (thickest place towards the nock? or just the bottom of the bamboo towards the nock...). Gave up on trying to straighten it more and just accepted it. I wonder if it'll act stiffer when backwards, or weaker.

I want to make two arrow straightening tools. One like the Japanese use (apparently the groove on the Korean one is more perpendicular to the tool which doesn't seem as desirable...) and a possibly more primitive stone one as described here:

http://www.primitiveways.com/arrow_straightening.html

All of this for tonkin bamboo from no more than "garden canes". That I have half a thousand of because I'm crazy.

I thought of finishing the arrows with shellac, then tung oil... but. it seems friction from targets can turn the finish into a glue. maybe I should just do shellac and oil the shafts before shooting.

[pcoutin]

Humidity is 68-75% tonight, so I'll pass on shooting. Most of the rest of the week is rather humid with some precipitation as well.. temperature is 18C.

Made a heat straightening tool. Tried to bend a cane at the nodes, ended up making a kink right next to the node. Now it's all wonky. Great. Guess I'll have to settle for snakey arrows...

[pcoutin]

Filed further notches, sinew wrapping, covered again with shellac.

Is this enough sinew to make a difference reinforcing? I think backstrap sinew would be so much better than this leg sinew with the short strands and difficulty processing...





Blob of titebond 480 that I am hesitant to sand off further. It doesn't stick out that much.

[pcoutin]

Ugh, twist? Maybe I made the tepeliks poorly and not evenly, maybe from stringing it badly, maybe it doesn't matter.

[pcoutin]

I sucked at making the tepeliks, now the bow is somewhat twisted. Though I think stringing the bow clumsily might've had something to do with it as well. All this with a non-contact bow, I don't think I'll ever be able to handle a contact ear bow.
May try 3d printing some.. if the printer here allows

[pcoutin]

unstrung few minutes after being strung for the entire night, about 12h. Twist seems a little less now, but only a bit




New string I made, twisted, flemish with double loops, brown D-10 material, 12-strands main (pretty skinny imo) and 24 for the loops. The only slight problem is the knot at the loops kind of gets in the way, acts as a "string bridge". May be a bit more unstable.

Brace height is a bit more with it...

The rough feeling of the string rubbing against the sinew/notches is much much less noticeable now.

[pcoutin]

maybe i'll start posting about this in primitive archer if I ever manage to fix the twist or something, or once i 3d print tepeliks since ATARNnet is so dead