hornbow twist

[loon]

With heat + twisting, the chance of delamination is high.

I was thinking of clamping it on the vise at the handle, maybe clamping part of the limb, heating a smallish section to 45 or so and twisting at the ear opposite to the twist (rather than just pressure on the side..).
Of course, putting towels or cardboard at the clamping points..

My area is rather dry of course.

[mikekeswick]

No it isn't! You may think so but the only way you will damage it by heating/twisting is by either heating it too much or by putting a silly amount of pressure on it. Clamping is more likely to damage it.
If the corrections haven't held then either you relaxed the pressure before it cooled or you didn't get it hot enough. Heat gently for plenty of time.
Also remember that the maker would have balanced it one limb relative to the other when making it - you are trying to get that balance back. I strongly recommend you don't remove any material. to make the upper limb weaker. Tillering horn bows is quite different to wooden bows where the default action to weaken a limb is to remove material on a hornbow that is the last resort.

[loon]

"Also pay attention if you use heat and twisting - the danger of delamination is high." - Tc

A lot of bowyers use clamps when gluing up horn bows, though.. so I thought it'd be the same sort of thing

I think this is definitely true if too much heat is applied or in a humid climate, apparently hide glue liquifies more easily with higher humidity..

I'm thinking of just balancing it by pressing and then leaving it for a few hours with tepeliks on, or maybe with those straps you slip on (kemend?)

Though this kind of thing also looks good to maintain balance



I wish I had more time for all this. Maybe next year I can make revenue by selling arrows or something O_o

Thanks for replying

[mikekeswick]

These things are all relative....How much twisting, how much heat etc....this is the problem with computers and internet knowledge! Haha! If we were face to face and had the bow I could show you how to sort it out in a few minutes and there would be no confusion,crossed wires or terminology problems
Just stick at it. Be gentle, patient and don't get it too hot. I guess what I am saying is don't overthink it your bow can be corrected with simple heat and pressure. The magic in tillering hornbows is in making them stable and a lot of the ability to do that comes with practise and feel.

[loon]

thanks

I applied a lot of force, waited an hour and the twist is somewhat reduced but still there... limb has a bit of an S shape. It's hard to bend much of anything just with bare hands, especially the siyah I think, strangely enough. Pictures later. 1:33am and I have to get up for work at 5:20am or so ugh.

I think for siyah misalignment (I really screwed up the siyah when trying to adjust twist with clamps and stuff..) Adam mentioned clamping the ear to a table??

I took it to 29", heard a few tics but it didn't blow up!??

[loon]

It has barely changed, though I guess balance is a bit better now.

Previously, I used this sort of jig to try to fix the twist. A bit more heat and pressure than  I can by hand. Now I can't undo the offset on the top limb's ear. (edit - kind of managed just by adjusting when the bow was strung)

recommended



actual (I screwed up the ear by putting the center pressure point with that giant old clamp at the knee)

This was how it should've actually been - the twist appears to start mid-limb
This was months ago.



But whatever, it shoots. Although I guess it'd be significantly better without twist. Shot a few times with a 700 grain arrow with 29" draw (planned on 50 but got tired after 8 or so, only reached full draw on two). A tad of handshock, I guess the leather absorbs a little bit.

[loon]

I think it makes sense to just make a video showing the bow from many angles..






















What I fear is that shooting this bow with twist would put the limbs onto uneven stress and twist it further

[loon]

I apologize for the shakiness, hopefully it's obvious enough.

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

seem to have fixed ear twist a bit just by cold pulling holding handle & ear and knee on bow knee somewhat hard and holding just after stringing the bow

considerable bending limb twist..

[loon]

It's taken a while.. I'm slow

Walnut for tepeliks?

[loon]

I want to get new tepeliks made. Maybe walnut or butternut.. or a softer maple? I don't know what wood the Koreans use. Think I want one set of thick ones for bracing on the floor, and another of thinner ones to use one of those Korean benches.

Trying to fix twist... and the sinew damage. I don't know why it's black, if it's debris or voids or something. Used alcohol, then coated it with thin, then thick hide glue. I'll wrap it with sinew later. Blurry.. because I am so damn shaky. I should use my tripod.