Primitive Archer
Main Discussion Area => Bows => Topic started by: hedgeapple on July 17, 2013, 03:36:38 pm
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I'd never really thought about this until last night working on a bow. But, I've never made a bow with this much of a flip on tips. I got the tips pulling 7" on a long sting @ 50#. So a strung it with a short string. It was then I realize how strong the bow was just pulling the string over the bracket on my tillering tree. It was probably 40-ish #. Of course, the scales aren't reading this weight because there is no pressure on them. Then I started working the bow. The thought came to mind, if there's 40# stored/unmeasured weight with just stringing the bow and I'm pulling it 40#, the limps are actually being pulled 80#. ???
With that being said, getting a good tiller from the floor tillering stage to brace can be more critical than I initially thought as a way to reduce set.
And, maybe gradually working/tillering a low braced bow at 35# to start with until the tiller is perfect with the goal of being at my target weight of 50# at full brace is a good idea.
Your guys thoughts?????????
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Lol "the limps"
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So you are saying you pull it #40 to brace it, then draw it another #40... so #80? it makes perfect sense.
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I've posted about this before. If you mark the tip deflection at brace onto the wall and then put a long string and measure the pull to get there. It shows the advantage you get from the tight braced string. You can repeat this at other draw lengths by going by tip deflection not draw length.
That's why my warbow exploded at 100# despite having been drawn to 110# several times on the longer string.
So basically if you want to make a 50# bow, pulling it to 50# on a long string early in the prcess isn't going to over stress it. And that's why it's important to get to a low brace early to avoid coming in under weight.
Can't remember off the top of my head but I think longstring measures about 20% higher than braced string at the same tip deflection.
By 'long' I mean just long enoght to get on the bow.
Del
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I've posted about this before. If you mark the tip deflection at brace onto the wall and then put a long string and measure the pull to get there. It shows the advantage you get from the tight braced string. You can repeat this at other draw lengths by going by tip deflection not draw length.
That's why my warbow exploded at 100# despite having been drawn to 110# several times on the longer string.
So basically if you want to make a 50# bow, pulling it to 50# on a long string early in the prcess isn't going to over stress it. And that's why it's important to get to a low brace early to avoid coming in under weight.
Can't remember off the top of my head but I think longstring measures about 20% higher than braced string at the same tip deflection.
By 'long' I mean just long enoght to get on the bow.
Del
So about the length of the bow?
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I've posted about this before. If you mark the tip deflection at brace onto the wall and then put a long string and measure the pull to get there. It shows the advantage you get from the tight braced string. You can repeat this at other draw lengths by going by tip deflection not draw length.
That's why my warbow exploded at 100# despite having been drawn to 110# several times on the longer string.
So basically if you want to make a 50# bow, pulling it to 50# on a long string early in the prcess isn't going to over stress it. And that's why it's important to get to a low brace early to avoid coming in under weight.
Can't remember off the top of my head but I think longstring measures about 20% higher than braced string at the same tip deflection.
By 'long' I mean just long enoght to get on the bow.
Del
So about the length of the bow?
Eh? What about it?????
With any bow a log sting will give a flase reading of draw weight... end of.
Del
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Hm... that might explain some stuff- why a floor tiller bow feels sooo stiff but winds up #20 on the tiller.
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Thanks Del.
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Ha, I trawled through all my posts and found it...
http://www.primitivearcher.com/smf/index.php/topic,25438.msg341928.html#msg341928 (http://www.primitivearcher.com/smf/index.php/topic,25438.msg341928.html#msg341928)
The figure isn't as dramatic as I recalled but it does show the difference.
Del
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Boy Dave.......... I'm go'n to have to get me another beer and read this again :) ...............Went right over my head the first time :o
DBar
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Less thinking more bow making is what I say...
Please take with sarcasm :)
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Duck, haha My philosophy is anything worth engineering is worth over engineering. haha
I can make a pretty good, bow. I'm just wanting to learn to make great bows ;)
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Duck, haha My philosophy is anything worth engineering is worth over engineering. haha
I can make a pretty good, bow. I'm just wanting to learn to make great bows ;)
Hehe :) I know. I just let the wood tell me what its wants to do :)
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Dave,
Read it the second time with a couple of more beers.
quoting you......
"With that being said, getting a good tiller from the floor tillering stage to brace can be more critical than I initially thought as a way to reduce set."
This is what I think Chris (Blackhawk)means when he doesn't use a long string and floor tillers only. I have also heard it said, don't tiller past any flaws until the flaw is fixed.
The light just can on for me too, if my thinking is OK. The bow I'm working on now, I'm doing more floor tillering than I usually do and paying real attention to the bend. I may end up with less # than what I looking for on this bow, but my tiller may be better and the bow may last longer. Which has been an issue with me in the past. I can always catch up on the weight on the next bow.
I enjoy posts like yours........... despite what Duck says ;)
DBar
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despite what Duck says ;)
I know I know.... I just swear my mind goes blank when I am tillering a bow, I just "listen" to the wood and trust my judgment. When I see people worrying so much about technical details I just always think K.I.S.S. No harm meant by my comments, just how I feel :)
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Hey Duck,
Understand where your coming from.........I've been working in an Engineering field for 35 yrs. And appreciate more than you know the KISS method. ;D
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despite what Duck says ;)
I just "listen" to the wood and trust my judgment.
Duck, no harm. "listening" to the wood is very important. But, one must know what to listen for, otherwise it just you staring/listening to a log staring/listening to you. haha I'm working on being a better listener. Most all of my bows take 1/2" to 3/4" set. That's not bad but I want zero set or better yet reflex. Granted I only start with a couple inches of reflex.
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Cardboard Duck certainly makes a good point.
I'm all for avoiding loads of complicated maths and overthink.
BUT.
You mustn't loose sight of the fact that it's all about observation.
Most of the public wander about in a daze never actually looking at something. You have to observe, and if it doesn't look right fix it or question it.
That's why I did a simple meaurement to see if what I felt and observed really was true.
Basic scientific method.
Observation,
theory (or a few strokes of the rsp/scraper)
test.... and back to the Observe.
If you can't explain your observation, it becomes random dabbling or attributed to witchcraft. It's how us humans learn from cradle to grave.
Never try to work past a flaw... indeed! Once it's to brace it is very late to be trying to catch up with poor work early on.
Del
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Starting from your point of saying that the limbs are really pulling 80lbs.
Think laterally about what this is doing to the wood.
What state do you want the wood in when the bow is finished and shot in?
Fresh is the short answer.
People always think that a reflexed bow is the best but that isn't necessarily the best way to go.... think about what deflexing the inner limbs will do.......look at virtually all modern recurves, look at a lot of the old bows that show up from time to time....what design feature do they all (mostly) have?
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Hedge if you started with 2 in. of reflex and end up with 1/2 to 3/4 string follow
that is 2 1/2 inches of set. :) Not sure on the poundage thing,never thought about it but I do try and get one on the short string at low brace as soon as I can. Long string [Just long enought to fit]on a tiller stick till it ready to brace,never check the weight,when it goes on the tree it is braced. More reflex the easier it is to miss weight because of the early draw that will trick you very bad on the real weight the bow actually is.. ;) :) What was said about never tiller passed a problem is a very good rule also, fix it then move on. :)
Pappy
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+1 Pappy. Short string low brace as soon as I can manage it. I Don't check the weight then because it's way heavy. I stand on the shoulders of those who have done all the measuring and testing. Not my thing personally, but hard to ignore the importance of it.
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Hedge if you started with 2 in. of reflex and end up with 1/2 to 3/4 string follow
that is 2 1/2 inches of set. :) Pappy
exactly, Pappy, so there's room for improvement. ;)
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;) ;D ;D ;D I hear ya Hedge. :) :)
Pappy
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Del and Pappy,
I have just understood exactly what your saying on my last bow, and Blackhawk has made some posts in the past that has help me understand the tillering process. It was like a light came on. It has been about three years and 15 bows later, slow learner, but once there it stays. One other thing I've learned with getting a good tiller and less string follow is PATIENCES, don't get into a hurry. stay within your comfort level. I was not a very patience person in my younger days. But I'm no where perfect or where I want to be, I just now understanding the concept.
Hedge, Dave good post, it never hurts to reiterate the process. Reiterate wow is that a word.......I guess I mean discuss.
O well...later
DBar
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Once I get. A little bend on the floor it goes straight to the long string on the tree. Flexing and exercising the wood, rasping and checking till the long string deflexs the tips to brace hieght. At this point normally it's about final weight. Short string and tiller on out to final draw. Never went back and checked the brace weight. Or the poundage to deflex the tips to brace hieght . Humm :o
Knapper
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One other thing I've learned with getting a good tiller and less string follow is PATIENCES, don't get into a hurry. stay within your comfort level.
Yep! Right there, sometimes putting it in the corner is the best thing to do :)
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I tillered one this week from start to finish, I told Will and Jon I would have it ready for their pretty work by this weekend,Will said, never seen you do that before,I usually tiller in 4 or 5 stages. Get it bending on the floor evenly,then to the form if it needs ant tweaking,then to the tiller stick on a long string,again just long enough to go from nock to nock,I use that until I am ready for a low brace,then to the tiller tree out to 10 or 12 inches of draw ,then full brace,back on the tree to 20 or so and then to full draw,letting it rest in between all of these.
So it takes a week or 2 on most bows. :) My wife says I have no patience's except for bow building and deer hunting, ;) she is about right on that. :) :) Slow and easy is the way to go for me,fixing any problem that can be fixed as you move along before they become bigger problems. :)
Pappy