Primitive Archer
Main Discussion Area => Bows => Topic started by: stuckinthemud on July 01, 2021, 02:59:17 pm
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This is a bit of a prototype. Its Scotch Broom. Please don't comment on the splice, I haven't cleaned off the excess glue or pen marks. Currently 20lb @ 20 inches 64 inch ttt, no set yet, stiff tips. I counted 18 significant knots with a slight weak point out of the lower fade
My feeling is the outer thirds need to move more but I'm really not sure
(https://stuckinthemudsite.files.wordpress.com/2021/07/20210701_1840489114324088622139695.jpg)
I posted a left and a right side view as the swoops distort the curve a little bit
(https://stuckinthemudsite.files.wordpress.com/2021/07/20210701_1830311748592669663706077.jpg)
(https://stuckinthemudsite.files.wordpress.com/2021/07/20210701_1829594825842219399054513.jpg)
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Both fades look like they’re bending too much for that width profile. The outer half-2/3rds needs to come around more as it looks like it’s hardly bending. Difficult to do with the knots though
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Yup... outer thirds need to move more...
What is the front profile like??!!! ::) ::) >:D :o
Stop me someone, I'm only kidding. I don't care a rat's nether regions!
Del
PS Del's had too much white vino with his pasta! (Damn lightweight ;D )
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Me and the wood had an argument, I wanted parallel sides, the wood insisted on constant taper from fade to tip. The wood won.
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Steady, steady....don't pull it so far! It's only bending in the fades both limbs.
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Me and the wood had an argument, I wanted parallel sides, the wood insisted on constant taper from fade to tip. The wood won.
Haha! That's hilarious. I know exactly what you mean. For me personally, I don't take up an argument with wood unless we're sitting around the camp fire.. >:D
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And... In the top picture you have a hinge starting in my favorite spot, right out of the top fade. It's out of the bottom fade in the bottom picture.
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There is a hinge. Tape it up and scrape all other places. The mid-limbs need to bend the most. At that length, tips do not need to be stiff.
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The wood should almost always win.
I agree scrape pff some wood from mid limb on.
Exercise the stave 0-20 times at short pulls between removal sessions.
Jawge
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We need a picture of it unbraced. That's the baseline that should be used to judge how the limbs are flexing, or not. Without it, we have no way of gauging it accurately. Without it we're pretty much clueless. Do you want tillering advice from a bunch of clueless fellas? I know I don't. ;)
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+1 dws. The hinge could be just a kink.
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If there is a kink, it should be thicker there. It also should have been corrected. It's unreasonable for a spliced bow to have a kink there by design.
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Who said anything about by design? You simply can’t judge the tiller of a bow without seeing it unbraced. Now you can make guesses. But until you know what the unbraced bow looks like, any judgement on the tiller is just a guess. Are you arguing the contrary?
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It's always nice to have an unbraced photo. I would love to ask for one. But as a person who never bother to provide photos, mainly for privacy reasons, I usually don't.
It would be reasonable to expect a person who ask for a tillering advise to mention such a kink even before asked. He even asked us to ignore the sloppy splice job, when it looks good enough for me. When I said by design, I just meant "knowingly". Most people who bother to splice limbs would not knowingly use a limb with a kink. Just my common sense expectation.
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That comment from you was argumentative, as most of your posts seem to be. But hey, maybe you know a few things about tillering bows that I don’t. And I am eager to learn from you if so. Is a bow, with a perfectly circular drawn profile, perfectly tillered? I’m interested to know your take on this.
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That comment from you was argumentative, as most of your posts seem to be. But hey, maybe you know a few things about tillering bows that I don’t. And I am eager to learn from you if so. Is a bow, with a perfectly circular drawn profile, perfectly tillered? I’m interested to know your take on this.
;D (-P
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I would love to improve on Tim Baker's mantra. But I have no interest in learning and using higher math and physics, almost from scratch, at my age. I also have no time and energy to make hundreds of bows. I would love to have the ability to do thought experiments on mechanics of natural material, especially using ordinary language.
IMHO most hobbyists can only rely on their sense of "beautiful curves" and arrow speed or flight distance. But I have faith in our common sense. If we think hard enough, we might be able to come up with an ordinary language paradigm for making decent bows without too much trial and error. Therefore I spend more time thinking about the "best process" to follow in making good natural material bows, than actually making bows.
The only thing that's actually going for me for now is that I have no vested interest in any dogma. I don't have to commit to any of dogmas. They are usually too vague and ambiguous or way too specific, to be useful anyway. Common sense does not have to be simplistic. If you are cock sure about something in this life, you are probably clueless about it.
With humility but also with sincere faith in our capability, we need to tackle whatever that is worthwhile. If lawyers can decide life and death issues using mostly ordinary language reasoning, we can probably come up with an improved mantra useful for making good bows. As I said earlier, I think it would be useful to combine Tim's mantra with the mass principle. We are pursuing more efficiency here. Searching for perfection would be silly and counter-productive.
My current guiding principle is "the evil of banality". What is our most common mistake in making wooden self-bows? Most beginners are too eager to bend the staves when those are not ready. To many people, this kind of reasoning process might look silly. But this common sense reasoning is what actually prevails even in this forum. By and by, I will do my best, if my schedule permits, to flesh out how we can actually make our bows more efficient, by just talking about them using ordinary language. No technical jargon, no higher math or physics required. It has been that way for thousands of years and bow making did evolve.
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Woah, steady on guys, I asked for tiller advice because I don't like to work on my own. This "project" in effect is a bend test. I did in fact glue in a weak spot as I thought the splice would re-enforce the weak point. I was wrong. Lesson learned. I am also testing new (to me) glue. It is brilliant, definitely going to use it again. Also a new type of timber. It is amazing, going to harvest as much as I can get. Also suitable front profiles and thickness needed for desired draw-length/weight . I have that info now. The mistake I made at glue-up has forced me to halve my draw weight but its been a very useful project. I'll post another picture soon. This is the unbraced profile
(https://stuckinthemudsite.files.wordpress.com/2021/06/20210618_1914115452368163166023428.jpg)
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Hey stuck. My thoughts, that pic shows several things. The bow has already taken set near the top fade or, as I mentioned, that is the natural resting shape of the stave. Secondly, the outters show the same, and yet the drawn pic doesn't show them bending much at all. If it is a hinge, you need to get the limbs bending mid limb and out. Really, even if it is a kink, the the outters still need to bend more.
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Hey stuck. My thoughts, that pic shows several things. The bow has already taken set near the top fade or, as I mentioned, that is the natural resting shape of the stave. Secondly, the outters show the same, and yet the drawn pic doesn't show them bending much at all. If it is a hinge, you need to get the limbs bending mid limb and out. Really, even if it is a kink, the the outters still need to bend more.
If I may ask a related question in a question, how would you tell (or can you) the difference between set or natural string follow unless you have the original picture of the stave before construction begins (which I really need to remember from now on)
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Thanks. The lower fade does show a slight deflex. It might have been that way or it can be the effect of set. Did you say how well seasoned the stave is?
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Don, I can't from a pic. The maker knows what the original prestressed profile was and the rest of us only make assumptions. The same goes for set. The bowmaker knows the bow started with 1.5" of reflex and ended with 1". Or, started with 6" of reflex and ended with 1". They both look the same to us, but they can be different bows in performance.
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The only set the bow took at the point shown in the picture was a little straightening of the reflex the billet took while drying. What deflex there is below the fade is the weak spot around a knot that caused me a lot of trouble. Anyway, having failed to cause any set, I did manage to create a big hinge reducing the tips so I piked 4 inches off both limbs and cut straight through the edge knots just to see how much abuse the stuff can take. Still got no set and it doesnt seem to care what you do with the knots, looks like they can mostly be ignored
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It currently looks like this, drawn to 16 inches on a short brace height of 3 inches. No permanent set as such, 1/4 inch of "soft set" that disapears soon after unstringing so need to go slowly now but top limb centre looks stiff at the moment. Heading toward 30lb at 20 inches. I'm thinking a 44 inch bow ttt with a 4 inch handle plus 6 inch of fades would pretty much max out at 20 inches draw length?
(https://stuckinthemudsite.files.wordpress.com/2021/07/20210704_2045555694488990038277951.jpg)
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Stil at 16 inch draw, figure I need a couple of scrapes on both outers and just a bit off the inner right, centres are working too hard.
(https://stuckinthemudsite.files.wordpress.com/2021/07/20210706_1915413658323100279608723.jpg)
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Its a bit better balanced now, this is at 14 inches, any thoughts on how I gain 4 more inches of draw length?
(https://stuckinthemudsite.files.wordpress.com/2021/07/20210707_2102158235811414855707679.jpg)
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It looks to me as though you are not using the straight edge. It will dramatically help your tiller. This one appears to be headed out of balance. Not too late, just check it and see what it says. It is better in the last pic, but it can be improved upon.
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Umm, no , I am using a 4 inch straight edge, not gone full gizmo yet but will attach a pencil to the edge for final shaping. Theoretically, the limit for this bow (43 inch ntn) is 17inch draw, its pulling happily to 15, showing a little soft set which disapears within 5 minutes of unstringing when drawn tp 16. It looks to me like the tips could soften a little. Would you shorten the fades at all or be happy as things are?
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I would simply v-splice at least 6 inch long new tips and reinforce them with underlays and possibly even overlays. With modern epoxy, you don't have to to wrap them with sinew or other fibers. Even 12 inch glued on tips are not out of the question. They just need to be stiff. You have choices.
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Ordinarily that would be a good way to go but the extra length will push it too far under weight. Its lighter than I would like as it is and going to be lighter by the time I'm all done, unless I sinew it of course
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Sorry, I forgot about the low draw weight. I don't like to work with sinew. Even though I don't do laminated bows, I occasionally backed bows. I don't know why you cannot "back" the belly, instead of just doing partial underlays. I am not sure I have ever done that myself. I might have just thought about doing that. Nowadays my memory and wishful thinking keep on blurring their boundaries, mainly because I post here as a distraction from work. All depends on what we want from our bows. Good luck.
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I have a set of different length gizmos that are really help full for tillering purposes right from the start for me any how stick.
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Now drawn to 18, there is mid-limb set, the tips are not quite touching a flat surface an hour after unstringing, I suspect it will have all pulled out by the morning. I'm not happy with it, its still unbalanced, tips still too stiff
(https://stuckinthemudsite.files.wordpress.com/2021/07/20210708_1758016909597147863206237.jpg)
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Unless you make a gizmo you will keep chasing tiller, it is not a disgrace to use one.
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Not a disgrace, and I do use them, in fact, I find them invaluable, but, although this bow will be arc of circle, my preferred shape is elipse, where a gizmo is much less useful , so, I am trying to train my eye to operate without relying on it
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(https://stuckinthemudsite.files.wordpress.com/2021/07/20210727_1912323556595802585457816.jpg)I'm moving on to my next project but I still tinker with this occasionally. Just given it a light heat treat which raised draw weight to 30@22. The limb centres are working too hard and the tips need softening some. Any thoughts?
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Bottom looks decent. Top is out of wack. The gizmo is a good tool as is the straight edge. Nearly 30 years and I use one, every build. You can always use a little “figerin’”. If the inners will stay stiffish, just use these tools from some point past the fades. Your tillering eye will love you for it.
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Use your gizmo all the way to the tip on the top limb. You could also get the handle itself bending to share some of the load. God Bless