hornbow twist

[loon]

I've been planning on making a jig for fixing my hornbow's twist..

Will heat from the horn (belly) side, also have an infrared thermometer, may take it up to 48C or so , and then heat the whole bow to 40C?

Should I take a video of the top limb while drawing it to find out where the twist is, and then try to correct it.. it looks like it's mostly the upper 1/3 of the sal/bending limb but begins a bit below the middle of the sal. Should probably try to take picturs/video perfectly frontal as well ...

The top limb's ear is also tracking to the right viewed from the back from when I tried to correct it..

[BowEd]

I can see that.Not much though really.It doesnt throw the string off though correct?You got Adam's instructions on that procedure.

[loon]

I can see that.Not much though really.It doesnt throw the string off though correct?You got Adam's instructions on that procedure.

Thanks
Yeah it doesn't (almost seems to) but I can tell the siyah is really not in line more easily at brace
Adam Karpowicz? I only saw text about twist correction, no pretty pictures, and I didn't see anything about using special jigs to correct twist or offset. I don't recall if he mentioned that it should be heated from the horn side, which I noticed in Adam Swoboda's book



Sorry about the crappy drawing. This is what I'm planning to do... dowels or pegs in a pine board. Instead of wrapping for the supports, I could put on blocks of wood. but hopefully wrapping would work fine. Was thinking either twisting twine or using a clamp to apply force

[mikekeswick]

Forget the jigs!
You can easily correct that twist by hand. Simply heat then over correct and hold there until cool. Then leave it for a few hours before stringing it. Check for twist again and repeat if necessary.
Hornbows just don't lend themselves to jigs and clamping etc.

[BowEd]

Yes Adam Karpowicz's book.Heating limb at the twisted area from the horn side not over 50 degrees centigrade.He used little heart blankets at times for more control of temp.Using a heat gun will work too[waving it slowly back and forth] letting the heat slowly penetrate but then I moniter temp with a laser temp gun too.Then like what Mike mentioned over correcting and holding till cool.All by hand.You'll see results.Your almost there and done I'd be patient and don't do anything drastic now.....lol.Look forward to seeing the final bow done.

[mikekeswick]

Yes I forgot to add that...be very careful not to overheat it! Better for it to take a few attempts than get it too hot once.

[loon]

Thanks Mike and Beadman!!

I hope I didn't overheat it already when I didn't have an infrared thermometer. From the sinew side, no less. Though I nearly took it to full draw... (this is few days ago, haven't done anything yet), and that area doesn't really bend much



Good to hear that I don't need to sweat making any jigs. I thought I would because I could give it propeller twist otherwise, which it doesn't seem to have..

old pic, pretty sure it is different now but not that much (just the ear should lean to the right more now)


P.S. this bow is from Tc.. stringing with tepeliks in the floor is hard and I screwed it up, hence this twist. Shipping back and forth from Hungary is too expensive.

I've still got a long way to go before I start making hornbows

I'll just make one of those Korean style bracing things, or just put the teplik on my vise at first.

[loon]

Bow is quite wide though - 42x11mm ~ 1 2/3" x 3/7", so it seems rather hard to bend it sideways, especially the maple core

[BowEd]

I see.It's ok if the tips look out of line a little at rest.Just so it's dead nuts at brace and full draw.

[BowEd]

Your gaining on her.You'll make it.

[loon]

I put it lightly on a vise, heated it until the reader registered 46-50C and pressed it down against the side of a pine board, hands on mid-limb and at the knee and the pine board in between for a little, pressing from the side.. about how much force should be used?

Maybe next time I'll try a more twisting motion

[loon]

pictures

Yup. Unbalance..










I should make some leather strips for the kemend or whatever. May have to heat the other limb.. wouldn't that make it stronger though? The top limb is the weak one that I've heated. While unstrung, of course.

[loon]

putting on tepeliks on the floor

and... it's the exact same bow.. Kurszan.

Code: [Select]

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

[mikekeswick]

If one limb is stronger than the other simply squeeze the string into the weaker limbs belly thus putting more strain on the weaker. Make sure you keep the string centered as you squeeze. You can also cut a section out of an inner tube (like a thick rubber band). Don't heat the sals with the bow strung.

[loon]

If one limb is stronger than the other simply squeeze the string into the weaker limbs belly thus putting more strain on the weaker. Make sure you keep the string centered as you squeeze. You can also cut a section out of an inner tube (like a thick rubber band). Don't heat the sals with the bow strung.

I do that and I also put the knee on it and pull with one hand on the tip and another on the knee to balance. That top limb just really wants to be weaker..