Primitive Archer
Main Discussion Area => Bows => Topic started by: ozy clint on April 21, 2025, 09:08:22 pm
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I finished tillering a mollegabet yesterday. It's made from an ironbark stave I cut some years ago. I left the back as nature made it and the limbs are mostly sapwood. Top limb is on the right and is longer than the bottom limb. It's an asymmetric bow. Turned out to be 64#@27"amo 66" NTN. I haven't shaped the handle or the levers yet.
Let me know what you think of the tiller. Brace is 6" this is my 2nd bow. I'm just happy it's not a 2 piece.
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Looking at the full draw photo it looks like the bottom limb bends more. Didn't notice that yesterday.
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Pretty solid stuff for a second bow! You could balance this a bit still if you don’t mind loosing a little draw weight. Take a few scrapes from the right limb and exercise the limbs then check again.
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Before you make any changes, check the amount of set between the upper and lower limb, and let us know. The set will tell you if you need to make any changes.
When you make a bow with a shorter lower limb, you intentionally bias it to be stronger and therefore not bending the same amount as the upper limb.
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I agree with everything said so far. Very nice work.
My only concern is the transition from lever to working limb left limb. My eye seems to think it’s bending a little more right at that spot. I wouldn’t remove any more there.
I’m just looking on my phone and didn’t see starting unbraced profile.
Like said though, really nice work
Bjrogg
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Here's some unbraced pics after having not been strung for 24 hours.
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Bottom limb is towards camera.
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Looks like it has recovered a bit since yesterday. Straight after having been strung it shows more set. The wave in the bottom limb is the original stave profile.
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Looks fairly even when you take into account the stave's natural character. Unless you think the lower limb has taken more set than the top limb, I wouldn't change it.
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Looks really good to me, looks like in may be setting on the tiller board a little lower at an angle on the lower limb side, that may be why it looks like the lower is bending a little more, I would see what it looks like in the hand drawing it. :)
Pappy
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I think Ironbark is my favourite of the Aussie hardwoods. I use it more than any other. The heartwood to sapwood contrast is really striking.
Great job, especially for a second bow!
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..., looks like in may be setting on the tiller board a little lower at an angle on the lower limb side, that may be why it looks like the lower is bending a little more, I would see what it looks like in the hand drawing it. :)
Pappy
Nice work!
I'd say Pappy is right, and that makes the tiller look strange to me.
Might be a good idea to have longer fades handle into the limbs on your next. These short fades work well for pyramid design.
And I'd say material could be reduced on the levers' belly sides, too, for better performance and less handshock.
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Well I'm not sure what's happened.
I haven't done anything to it since the last pics but now it's dropped a ton of draw weight. Now it's 47#@27" AMO.
The bottom limb has a huge hinge too.
This is nowhere near the target weight now.
Moving on to the next stave I think.
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I think Ironbark is my favourite of the Aussie hardwoods. I use it more than any other. The heartwood to sapwood contrast is really striking.
Great job, especially for a second bow!
Do you find the sapwood is ok for bows or should it be removed from the stave first?
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Would high humidity cause such dramatic weight loss? It's been drizzly weather here the last few days.
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That is a lot of weight to drop, with no apparent cause. Has it taken a lot more set than in the previous unstrung photos?
Are there any chrysals/compression fractures near the hinge(and or localized set). Moisture can cause a drop in weight, increase in set, but 17lbs is a heck of a big drop.
A pair of outside calipers can go a long way in helping to prevent a hinge. Checking the thickness taper whilst tillering makes sure you will pick up any thin spot before it's too late.
I have made stave bows from grey ironbark, sapwood limbs and heartwood on the handle, and also bamboo backed bows from heartwood. It usually makes a good bow, but sometimes frets even when the tiller is good.
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Would high humidity cause such dramatic weight loss? It's been drizzly weather here the last few days.
all of what Hamish mentioned above and I quess one other thing to suspect is if you you might have been making adjustments too quickly and without letting the adjustments settle in before further tweaking. Working slowly as you approach full tiller is prudent.
Some folks like to shoot the bow at reduced draw lengths before drawing it out further. A couple of times.
I know I can see one thing at the end of a tillering session, and see the limbs bend in a different way when I string it up again tomorrow.
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I think Ironbark is my favourite of the Aussie hardwoods. I use it more than any other. The heartwood to sapwood contrast is really striking.
Great job, especially for a second bow!
Do you find the sapwood is ok for bows or should it be removed from the stave first?
Sapwood is great. No need to remove it.
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I think Ironbark is my favourite of the Aussie hardwoods. I use it more than any other. The heartwood to sapwood contrast is really striking.
Great job, especially for a second bow!
Do you find the sapwood is ok for bows or should it be removed from the stave first?
Sapwood is great. No need to remove it.
What about on Brigalow?
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I've not used it myself but I understand that to be just fine too.
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Sapwood on brigalow is fine as long as it hasn't been attacked by bugs, or rot. Tree stave, thinned sapwood down to 1/8"-3/16" , with the heartwood belly makes a really pretty bow. I rate brigalow better than ironbark.
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Next question, unrelated.
I have a brigalow stave with about 2.5" of reflex.
Just approach it as normal? Seems the limbs would be more stressed than a straight stave.
The wood has to work a lot more.
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What style of bow do you want to make?
2.5" of reflex is manageable, pretty much tiller as a straight stave. The only potential hard spot is using a long string on a tillering tree. The bow will try and flip due to the reflex. This can be avoided by adding a clamp at the handle. This stops being an issue once you can get it to about 3" brace height or higher.
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Was thinking Mollegabet again. The clamp thing is a good tip. 8)