Primitive Archer
Main Discussion Area => Bows => Topic started by: Badger on June 21, 2012, 12:05:45 am
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I was tillering out a bow today, a short osage with a stiff handle and fade area. Target weight was 75#@24".
I did my usual floor tillering then braced the bow at a low brace height about 4". I used Erics tillering gizmo to even it up at brace as much as possible pulling it about 10" after every wood removal. Once I got the bow evened out at brace height I moved it to the tillering tree and decided to check the weight and see where the bow would begain breaking down the wood. I pulled it to 6" then 7" then 8" etc carefully recording the weight at each increment. I also would go back and check the 8" mark to see if it had shown any signs of loosing weight just from drawing it. This will let me know when set is just begaining to happen at it's earliest stages. By the time I got to 14" I noticed I had lost about .2 of a pound at the 10" mark from where it was at the begaining. Logic tells me with each new inch I pull it I will loose more weight. I continued up to 19" each time checking to see how much additional weight the bow had lost. By the time I got to 19" I had allready lost 2.3# and the bow was only pulling 50#. With each each further I drew it past the 14" mark it would loose an increasingly large amount. If I would have continued up to 24" I would probably have lost close to 10#. Performance of the bow goes ut the window when more than a couple of pounds is lost. Tomorrow I will finish the bow out, making careful corrections with each additional 1" past 14". I doubt I will get more than 50# out of the bow but it will hopefully be a good shooter.
I really would recomend trying the scale as you progress your pull from the very begaining, it is really an eye opener.
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Good info, thanks badger!!!
Tattoo Dave
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So why do you think you may end up twenty or so pounds under? Density or lack thereof? M.C. ? I am curious as to your answers cause this happened to me once and I couldn't for the life of me understand why. I never come in light . My wood was Osage as well and I use my scale all the way through tillering. Really bumfuzzled me ???
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So, what are you left with?
I bet your bow can still hit 60#, but not much more. Will it lose more weight, ya think?
Michael
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Very informative post, I've never tried doing that.
I'll have to try it on an ELB and see how it looks.
Thanks for posting Badger.
Del
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Ver good point, Steve. I've recently been applying this technique as well. Basically the "no set tillering technique". Draw to a certain drawlength and record drawweight. Pull a few inches further to excersize the limbs, and return to the same drawlength as before. Have you lost drawweight? Then the bow must be taking set.
A friend and I were tillering a black locust bow. The bow had already taken some set (maybe 2 inches) early on in the tillering process. Yet the design appeared in accordance with the drawweight he wanted and the tiller was spot on. He could not tell me where the set came from, but he was worried he would end up with 4 inches of set by the time he reached full drawlength. We put the bow on the tillertree and pulled it to the maximum drawlength he had pulled it to thus far, which was 22" maybe. We accurately recorded weight at the drawlength, using a digital scale. Since the tiller was good, we decided to pull it further, so we excersized the limbs several times up to 24". We returned to the same 22" again (without removing wood) and measured the drawweight again. We lost maybe 0.2 pound. Nothing to worry about, so we pulled it to 26" several times. Again, we measured the drawweight at the inital 22" and we lost about 0.4 pounds. This was a clear indication that the bow was hardly taking more set. So we continued tillering (which was not much) and came at 2" or maybe 2½" of set at a very acceptable drawweight.
We still don't know what caused the initial set up to the 22" mark, but the "no set tillering method" clearly indicated we had nothing to worry about from that point onwards.
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Jon, in this particular case I have more outer limb I can get bending and still come out with a good shooting bow. I built the bow 2" wide which for a short 70# bow should have been enough but in this case wasn't. Might be a bit more moisture in the wood than I thought also. I could probably finish the bow out at 60# but I don't think it would be as crisp as I am looking for so will go ahead and just finish it out at 50#.
A lot of us including myself go by the rule of never pulling a bow further than what it takes to expose an area that needs work. Using the scale tecnique I don't really have to make any adjustments until the bow shows signs of breaking down, in this case I should have started adjusting tiller at 14" but wanted to measure how fast weight would drop.
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I went ahead and finished her off at 62#@24" 50" nock to nock. I lost a total of 5# just from drawing the bow which may not be too bad for a short bow, 1st time I have ever measured this on a short bow. My goal was 70#@24" and I was hoping not to loose more than about 3# so I didn't quite hit the target but did a bit better than I was expecting yesterday. Now I will just pretty her up, refine the tips and go shoot some light arrows to see how she does.
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profile
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Thats looking pretty dang sweet to me...nice curve steve. No wonder you were losing the weight and taken a lil more set than you wanted due to the short high stressed design. And those stats are perfect for me ;) 8) this makes me wanna go walk downstairs n go make a short osage curve ....two inches wide you said yours was? ;) think ill go 2 1/4" n monitor my weight n set n go from there.... ;D
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62# @ 24" I'll bet she's pretty punchy. Probably jars the old tennis elbow a bit too? (compared with a looooong ELB)
Del
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Del, no handshock at all, shot some light 300 grain arrows through it and she behaves very well. I may draw it out to 26" for the flight shoot.
Here is one I am tillering out right now, 5" reflex hope to finish with 3 1/2", will do the no set tiller process as I go, looking for 50# at 28, but may stop at 27" This is bamboo backed ipe, 66" long
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2 nice ones, Badger. I love those sweeping curves on the bbi!
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I applaud your effort at tackling a 5" reflexed BBI! I would be certain that would give me horrible limb twisting issues. I hope you get those sorted out and turn it into a screamer.
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Dark, I have a fairly high failure rate on this type with the long levers and a lot of reflex. Making it for the flight shoots so if it holds up for a dozen shots thats good enough.
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With the high reflex bows(especially the reflexed lever bows)i find it best to floor tiller/long string tiller till theres only an estimated 5-10 pounds left to remove before i first brace. And i make sure its as close to dead nuts as i can get it. Because low bracing does not work most of the time. They just want to flip. So the first brace usually has to be at least 4"+,and thats why i wont brace em till theres only 5-10 pounds left to go. And this helps to keep n retain some of that lofty reflex.
Whats your take on tillering high reflex badger? Your the man if you can retain 3 1/2" of that. At best i would retain 3" of 5" starting reflex.
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Chris, just like you said, I floor tiller till they look about right and feel equal, then I put on a long string and double check tiller then go for a minimum 4" or 5" brace height. From that point the scale come in handy, I start going down 1" at a time several pulls at each increment as soon as I detect the slightest drop in weight I start adjusting tiller and don't go past that point till I feel tiller is about perfect. The last few inches it is really hard not to loose a little bit but 3# of weight is equal to about 1" reflex or less.
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Thats looking sweet Steve,love them curves,that's got to spit and arrow. :) :)
Pappy
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I find the same...that an inch of lost reflex is losing 3 pounds,so earlier on when im estimating weight i need to put that into the equation that ill lose aprrox 6 pound to lost reflex(pending on how much i start with).
That BBI is pushing it,but you know that ;) with the high reflex kicking out half way in the limb it can be a fine balancing and juggling act keeping it all together. I havent tried kicking out high reflex further in closer to the handle,but id imagine it wood be even tougher to keep it from flipping. I think string tracking is super critical with high reflex like that...i find that if the string is dead center thru the handle,and dead center thru each lever or high reflexed tip,that the better stability you have.
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Well that reflexed bow was a bit of a disaster. Haven't done one like that for a few years and forgot how stiff they feel when floor tillering. I floor tillered braced the bow and had no room to work as I was right at 50#, brace needed some adjustment so I went ahead and straightened up the tiller at brace now am at 45#, shot a few arrows through it and noticed a hinge developing right at the turn for the reflexs, same place I always hinge them. Now I am reverse tillering glueing wood back on the hinges, LOL. The patch seemed to have worked but I never feel the same about a patched bow. Really like how it shoots so plan to do another next week but round out the relfexed area a bit more.