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My horn bow build-a-long

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DC:
OK bring this up to where I am
I spread the limbs to about 24" apart on the pegboard. I heated the kasan eyes(at least I think it's the kasan eye) Used a hair dryer so I wouldn't overheat it. Heated about 3" to 50°c (125ish f) and held it there for 30 minutes. Heat was checked with an infrared thermometer. Did both limbs at the same time. Waited 2 hours for it to cool off. Took it off the pegboard and it went right back to where it was :( :( Put it back on the board and spread the limbs to about 30" apart and repeated the whole procedure but used a little more heat, 55°c and same time. This time I left it on the pegboard overnight and when I took it off in the morning it didn't look too bad but not as open as I thought I wanted. There was 15" between the tips. Went and did a few chores for an hour, came back and it had closed down to 12". I just looked at it about 5 hours later when I took these pics and it's closed down to 10". I don't think I made any progress with the heating at all. Is this supposed to happen? The picture showing me heating it was just staged, I actually heated it yesterday. I haven't done any actual tillering yet. Makes me wonder why I didn't keep it from reflexing so much when I was sinewing it. Very frustrating, especially when the damn thing is probably going to break anyhow.

bownarra:
If the bow has been in 35% rh it will be hard to correct. I have no problems with my electric element. For the sort of corrections you are attempting it would take about 20 - 25 mins per limb.
As I said above if you don't get the core hot enough you won't change a thing.
So your heating cannot have got the areas hot enough.
I wouldn't heat it on the pegboard either- it will lead to uneven heating. You should be heating it with the tillering stick in place. Don't try to re-invent the wheel!

DC:

--- Quote from: bownarra on February 23, 2020, 01:26:54 am ---If the bow has been in 35% rh it will be hard to correct. I have no problems with my electric element. For the sort of corrections you are attempting it would take about 20 - 25 mins per limb.
As I said above if you don't get the core hot enough you won't change a thing.
So your heating cannot have got the areas hot enough.
I wouldn't heat it on the pegboard either- it will lead to uneven heating. You should be heating it with the tillering stick in place. Don't try to re-invent the wheel!


--- End quote ---


When you say 20-25 min per limb it sounds like you're doing one limb at a time. Are you?

I'm not trying to reinvent the wheel, I know my limitations and I could see myself overheating this thing if I tried to heat it over a stove. The hair drier seemed like a safer way. I'm going to put it in a plastic bag with a wet rag for a few days.

I'm making a tillering stick. I realised yesterday that the pegboard was less than optimal for showing twist.

bownarra:
I meant by heating it on the pegboard.  You need to be able to move it.
A normal stove is likely too hot. The hotplate elements I mentioned are very gentle and don't dry the bow out too much either.
Heating with the tillering stick in place must be done on both limbs equally or else things will start going south. I heat each limb for 30 secs then swap, 30 secs, swap.
I like wrapping both limbs in heating pads first to pre-warm them, then go to the hotplate.
This part can be frustrating but patience is key. You need to develop the feel for a lot of things before you can do the corrections quickly. Over heating is easily done and non reversible so much better to work your way upto things slowly.

DC:
Just to clarify things. If I get this thing open into a "C" shape should it hold that shape forever? I had it out to 19" between the tips, left it overnight and within a few hours of taking the tillering stick off it was down to 15" and the next morning it was 11". Should I be leaving the stick in. I'm heating it on the stove, doing everything I should, I think. I'm heating the horn side until the sinew is about 120°(50c) and holding it at that temp for 20-30 min. That's actually overheating the belly side a bit. Adam says to spread the tips to about 24" and I'm spreading them to 30". I left it in a bag with a wet cloth overnight. I'm about out of ideas.

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