Primitive Archer
Main Discussion Area => Bows => Topic started by: MattZA on July 21, 2018, 02:54:39 pm
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Hi all!
Working on a new bow, but it's my first time using steam, so have no idea what to look for in tillering.
Design: Pyramid shape with static recurves/levers. I want them to effectively be 'mini holmegaard' tips in shape (thicker than wide), but with a slight reflex to them. Not aiming for a crazy angle.
Specs: Aiming for 40-45# at 28". 62" ttt. Massaranduba board. 4" handle. 1" fades. 4" levers/statics. 1 1/2" of setback already steamed into the handle. I intend to leave the bow unbacked.
Am I building something that'll work?
Here's a photo after roughing it out and a tiny bit of tillering. I know it's out, but I'm more looking for advice on the shape I should be aiming for.
Any advice would be welcome!
https://www.reddit.com/user/MattYoungZA/comments/90qwy2/rough_tillering_of_a_massaranduba_pyramid_tips/?utm_source=reddit-android
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Oh, I should also mention I haven't even touched the tips since cutting the shape out. Someone (Del, perhaps?) once recommended only starting on them once you've got a basic tiller (to keep them from twisting).
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Both of the limbs are bending in the middle and not inner limb or outer limb. The right limb is bending more than the left.
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Yea I see that, Pat. Thanks for the advice. What kind of shape do you think I should aim for in the end? Elliptical?
Does anyone think I'll have any trouble with limb torque from the narrow outer limbs with statics on top of them?
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Keep the tips wide until you get to brace then be sure everything is even before narrowing the tips.
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I broke it!
My first time trying to bend wood, and suddenly the clamp was turning too easily...
Does anyone think it's salvageable?
https://photos.app.goo.gl/LFbop74H757TT24x8
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It's natures way of telling you created a weak point.
As you move outwards along the limb the increased thickness section has to start before the limb narrows, it's a tricky transition that has to be smoothly blended. If you narrow the width too abruptly with no extra thickness.... well you can see in your pics what will happen.
It may be salvageable and even if it isn't it's good experience.
1. Plane off all the extra thickness, where the split has started, leaving a thin lever.
2. Stick the end in boiling water, steam or dry heat and pull it back in line.
3. Make a new vertical section, with one wide end and glue it onto the belly side of the thin lever, with the wide end overlapping onto the full width limb.
4. Blend in the new lever... leave the glue twice as long as necessary, then test it.
5... you may want to do the other lever too.
Even if it fails it will improve your patience and your skills.
I've done that repair before, but I did it before it failed ;D .Details here:-
https://bowyersdiary.blogspot.com/2015/10/stitch-in-time.html (https://bowyersdiary.blogspot.com/2015/10/stitch-in-time.html)
Del
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That's an impressive repair job Del!
Yea I was thinking the same thing as you. Chop off the broken bits to make a really thin lever and then build it up again. You reckon wood glue will suffice? Or is it epoxy or nothing?
As you say though, either way it sharpens the skills. Impatience and inexperience were the dangers here.
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I've noticed this a few times. Peoples first bow turns out OK and the second one breaks. I little bit of "this ain't so hard" sneaks in. Now that you've been humbled by the wood gods you'll do better :) :)
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I use Resintite (aka Cascamite) it's relatively cheap, easily available has a good pot life and cures at room temperature. It's a fine white powder you mix with water. It says only apply glue to one surface... ignore that and apply to both!
I measure it out accurately by weight.
Del
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I've noticed this a few times. Peoples first bow turns out OK and the second one breaks. I little bit of "this ain't so hard" sneaks in. Now that you've been humbled by the wood gods you'll do better :) :)
Haha actually it's my 4th. The first 3 are functional (although certainly not amazing). Your point still stands though.
Great thanks Del, I'll have a look for it. I haven't seen it here in SA before, but then again, I've never looked!
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Did you break that trying to heat a bend in? I beleive massuranduba behaves a bit like ipe and does not like to bend with heat much
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Hmmm, just looked at those pics again and it looks like it's been bent the wrong way? The Back should be a continuous straight line... the belly should become narrow and deep at the levers.
I've read your post again s-l-o-w-l-y and...
Ah, got it ::) you tried to flip the tips and have molle' levers? If so it's a lesson in trying to do to much... Keep it simple.
Do the suggested repair, but have it straight, or put the curve in while the lever is thin and then add a shaped curved lever to the belly side.
Del
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Gotcha Del. That's what I'm going to do (option 2). The other option was to chop the whole bugger off and make some levers to splice in.
Leon, I was actually trying to steam bend them in. Strangely PatM and others reckon massaranduba bends extremely well, despite its similarly to ipe. Only one way to find out, I suppose.
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Update:
On the last episode of "Making fancy firewood"...
During steam bending I managed to break my bow right at the outer fades where the limb flips into the holmegaard type levers.
I was originally going to cut away the broken section of belly and glue in some replacement wood.
After much deliberation, I decided to saw the whole levers off and glue them on the back as siyahs instead.
Once I've wrapped the limb/siyah joint in silk, we'll proceed to tillering and hoping it doesn't explode!
Any comments are welcome, as always...
https://photos.app.goo.gl/5G1omP9dtBhzHhPz7
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On the early tiller.
Pulling 30# at 7" of tip bend. Aiming for 40-45# at 28".
Haven't wrapped the siyahs yet.
Thoughts?
https://www.reddit.com/r/Bowyer/comments/969pjl/tiller_advice/?utm_source=reddit-android
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The way I tiller is from the tips towards the fades.looks good so far!
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Thanks!
Its only bow number 3, so I'm really feeling around in the dark here. I think I've still got lots and lots of wood to shave off that belly if I want 45# at 28". I'd go heavier, but I'm not sure if the unbacked wood will take it...