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black locust flatbow build
Zugul:
So, I've started this new project after srewing up a cuple of bows in the last year. All the bows I have mede to this day fretted or came out very low poundage. My goal with this one is to get 40-45# at 28" with low enough set and no frets, hopefully. Since I'm not very experienced I opted for a safe design: 68 1/2" TTT, 67" NTN, 2" wide at fades and 5/8" at the tips. I've made some tweeks to its shape with a heat gun since it was a bit out of alignement and had some twist where the grain flowed around a knot. I could not take off all the twist so should I leave the side where the belly "dips" a bit thicker to avoid the wood getting pinched or not? I've used my fingers to gauge the thickness taper until now, in the future I'll switch to a caliper and try to make it as even as possible. should I leave a little extra wood where there are bumps on the back to avoid the belly getting pinched or do I have to chase the perfect thickness taper? I want to take it super slowly with this stave since I don't have meny left, and this is the best one :BB Feel free to make constructive criticism about my work, I know it's far from being perfect and I'm willing to learn ;). Wish you all a good weekend and a lot of good bows!
before straightening
20220906_103808 by Mattia Zuccolo, su Flickr
after straightening
20221014_171715 by Mattia Zuccolo, su Flickr
how the twisty part appeared before, now the twist is approximatly half as much
20220906_103712 by Mattia Zuccolo, su Flickr
same spot, viewed frontally
20220906_103743 by Mattia Zuccolo, su Flickr
on the tillering tree, the string is loose and hanging just shy of the 6" mark (top limb on the left)
arco a riposo by Mattia Zuccolo, su Flickr
now the bow is drawn, 40# at the 15" mark. I felt pretty confident since I spent a cuple hours to get a decent thickness taper, scraping all the obviuos thick spots I encountered.
arco teso by Mattia Zuccolo, su Flickr
M2A:
I'd try to keep that area working just as much as the rest of the limb. Its tricky and better a bit too stiff than creating a hinge by accident. I think your tiller looks good so far. Are you going to heat treat and add some reflex? or leave as is? I think your dimensions are good for 45+ lbs easy. You could trap the back later in tillering, to take some stress off the belly wood. I do that at about 20" when tillering out to 28".
Mike
George Tsoukalas:
The belly should reflect what the back does. So if there is a hill on the back the belly should follow it with the wood doing an equal amount of work. It looks like you've done that perhaps inadvertently?
The only leaving extra wood is needed is if there is a knot involved. Then leave extra wood on the width letting the knot swirl.
The tiller loks lood.
Watch mid limb and on to the nocks it does need to come around later on in the tillering.
Jawge
Zugul:
--- Quote from: M2A on October 15, 2022, 08:04:19 am ---Are you going to heat treat and add some reflex? or leave as is? I think your dimensions are good for 45+ lbs easy. You could trap the back later in tillering, to take some stress off the belly wood. I do that at about 20" when tillering out to 28".
Mike
--- End quote ---
I was thinking not to heat treat the bow because heating it again could make the parts I've bent return to their original shape, changing the string alignement. If I'll do it anyway I won't put in reflex but heat treat it straight, a section at a time with a heatgun, having 2 or 3 C clamps per side to ensure it won't chage shape... Could this be a good idea? I've never trapped a bow, but in theory I know how it's done. The only information I'm missing is what's the correct angle at wich you should srape material from the corners of the back of the bow. I'd say about 45° shoud be allright, correct?
--- Quote from: George Tsoukalas on October 15, 2022, 10:43:29 am ---The belly should reflect what the back does. So if there is a hill on the back the belly should follow it with the wood doing an equal amount of work. It looks like you've done that perhaps inadvertently?
--- End quote ---
I did it simply laying out on the sides of the bow a line with a caliper, 13 mm thick from the corner of the back so I would have a reference and avoid getting one side thicker then the other. Then I scraped the belly very close to those lines, leaving it a bit round in the areas where I was not sure how to proceed.
--- Quote from: George Tsoukalas on October 15, 2022, 10:43:29 am ---The only leaving extra wood is needed is if there is a knot involved. Then leave extra wood on the width letting the knot swirl.
--- End quote ---
there's only a very small pin knot right at mid bottom limb, I left 1/8" extra width there to be sure.
--- Quote from: George Tsoukalas on October 15, 2022, 10:43:29 am ---The tiller loks lood.
Watch mid limb and on to the nocks it does need to come around later on in the tillering.
Jawge
--- End quote ---
so should I leave those parts a bit stiff for now and work them later or should I make them come around a bit more?
anyway, thanks guys for your imput, I'm really glad I'm going in the right direction :BB
George Tsoukalas:
I was talking about the belly in relation to the back. What the back does the belly does also to make the thickness constant. Jawge
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