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is my project doomed from the start?
JW_Halverson:
--- Quote from: Zugul on February 02, 2025, 04:04:54 pm ---So, I've tillered this bow a bit more, now it's 35# at around 19.5" of draw lenght. I tried something new to see if I'm on the right track: I've made a realistic model of my bow (for what I could) on VirtualBow and then I "tillered" the virtual version to get an even distribution of stress across the bow, maintaining the front profile and changing only the thickness of the limbs. My reasoning is that, for a ceartain front profile, there's only one particular shape (tiller) the bow can have to spread the load evenly across the limbs, wich should minimize set. Feel free to correct me if I'm wrong, I still consider myself a complete newbie! :BB Here are pictures of the bow and the model from VirtualBow at the same brace height and draw lenght.
--- End quote ---
Glad to see you back and still working on this bow. I think it has real potentional to be a bow that works for you!
willie:
--- Quote from: bjrogg on February 02, 2025, 09:44:14 pm ---Whatever you are doing it looks really good to me so far and it seems like your unbraced profile is holding its shape well.
Bjrogg
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agreed, and looks like you have that knot area neither to stiff or weak which can be tricky
--- Quote ---for a ceartain front profile, there's only one particular shape (tiller) the bow can have to spread the load evenly across the limbs, wich should minimize set.
--- End quote ---
very true. and the best approach since you are concerned with getting 40# out of a short and narrow stave.
when width and length allow, having a stiffer (lesser stressed) handle area and tips can improve performance and feel (dampness) in the hand.
Zugul:
--- Quote from: Pappy on February 02, 2025, 08:43:53 pm ---Still looking really good to me. :)
Pappy
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thaks, it's really heartening to hear it!
--- Quote from: bjrogg on February 02, 2025, 09:44:14 pm ---Whatever you are doing it looks really good to me so far and it seems like your unbraced profile is holding its shape well.
Bjrogg
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It did take a bit of set, around 1/2" for now, but I'm fine with it considering the sub-optimal design I chose
--- Quote from: JW_Halverson on February 03, 2025, 12:48:32 am ---Glad to see you back and still working on this bow. I think it has real potentional to be a bow that works for you!
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Thanks! I hope this piece of wood thinks the same! ;D
--- Quote from: willie on February 03, 2025, 01:11:03 am ---
--- Quote from: bjrogg on February 02, 2025, 09:44:14 pm ---Whatever you are doing it looks really good to me so far and it seems like your unbraced profile is holding its shape well.
Bjrogg
--- End quote ---
agreed, and looks like you have that knot area neither to stiff or weak which can be tricky
--- Quote ---for a ceartain front profile, there's only one particular shape (tiller) the bow can have to spread the load evenly across the limbs, wich should minimize set.
--- End quote ---
very true. and the best approach since you are concerned with getting 40# out of a short and narrow stave.
when width and length allow, having a stiffer (lesser stressed) handle area and tips can improve performance and feel (dampness) in the hand.
--- End quote ---
I'd say the knot area is still a tad stiff, but I don't want to weaken it too much... I'll keep a close eye on it while tillering. Since a bit of set already happened I dropped my target weight to 35# and even if I come a couple of pounds uderweight I won't be mad as long as I get a functional bow. For my next project I already have a much longer and wider floor tillered stave waiting on wich I'll try to leave those areas stiffer.
I did not make any progress with the tillering process yet but I took off the tip overlays since they were made out of a not strong enough wood (Sorbus torminalis, wild service tree) wich was getting dough into by the string and made new ones from heat treated black locust, wich should be strong enough and should look good. I hope to finish up the tip overlays this afternoon and then get back at tillering in the weekend. Thanks to all of you for the kind replies!
Zugul:
just a quick update on the tip overlays: I sanded smooth one of them up to 280 grit and then burnished half of it, this is the result. It's still unfinished but I'll get to it when the bow is complete.
I think it looks pretty neat!
Zugul:
little update: I got down to 35# @ 22".
precise measurements (since it seems I did not post them before):
handle section: 34 mm wide, 15 mm thick
end of the working limb: 17 mm wide, 10 mm thick
total mass of the bow (without string): 378 g ( 13.3 oz)
The bow is getting scarily thin and light, but it doesn't seem to have taken any more set. I've started running a caliper down the limbs every 20-30 scrapes to be sure I don't leave any thick spot and to check that I have the same thickness on both sides of each limb.
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