Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: monterey on January 22, 2015, 01:51:00 PM
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Not by me! I'm one who thinks I could benefit from it.
I got thinking about this while reading the wood or glass topic and Bowjunkie mentioned how much he enjoys the tillering and timing aspect of bow building.
It's the limb timing aspect that intrigues and evades me. Maybe someone with developed skill in this area could do an explanation? (hint thrown at Bowjunkie :) )
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Ya Bowjunkie, how about it?
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:campfire:
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Originally posted by Roy from Pa:
Ya Bowjunkie, how about it?
X2 :thumbsup:
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+1
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Ill watch :thumbsup: :campfire:
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HA! Listen to you guys. I could write a book on this subject trying to cover everything and yinz want it in a message board thread. Geeze, you guys are tough.
I have full intentions of doing a pictorial... even have a few bows started explicitly for it, but I'm still putting the shop together after our move. I don't even have a tillering tree up yet... let alone completely redesigned... but I'm working on it. Gonna work in there for the next three days, so if things go well.. well, we'll see.
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I got a tree, come on down Saturday for the bownanza... I got a camera too..
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Thanks but I really want to get work done on the shop.
Besides, working in someone else's shop just isn't the same... and all I get done at your place is b.s.'n drinkin and eatin'... which is fine :^), but if I'm gonna do this thing right, I need access to all my tools, bows, wood, not just a few rasps and scrapers in a duffle bag :^)
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I understand.. :)
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You're stronger than me. If forced to choose between either working or drinking, eating, and bsing. Well, let's just say that it wouldn't really be a choice.
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Well it was last spring when I packed up all my bowmaking stuff. Doing without it for this long is a pretty good motivator. Yep, in this instance, I'd rather work.
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Originally posted by ColonelSandersLite:
You're stronger than me. If forced to choose between either working or drinking, eating, and bsing. Well, let's just say that it wouldn't really be a choice.
X2
But since I know so little I'm really looking forward to this. :campfire:
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Good things come to those that wait. I will wait I guess. :goldtooth:
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Originally posted by mwosborn:
Good things come to those that wait.
That's a dirty lie perpetrated by those who don't wait ;) .
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In my tri lam build, you can see limb timing on the tree. Jeff and I have been friends for about 12 years at least. He has been my mentor all those years. He is the master bowyer in my opinion. His bows, wood and glass are always top shelf because he is so meticulous. Jeff has been building his new shop for a few months now, I promise when he gets around to starting the new timing thread, it will be just like sitting in a classroom, and you guys will gain a huge amount of information.
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Easy with the namecalling there Roy, I'm just a regular guy trying to figure this out like everyone else.
You hittin the hooch again buddy?
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nOt mE... :)
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This is the final video in my tri lam build thread from a couple months ago. I assume a 3/8th high arrow nocking point on my bow string, so I laid out the tiller tree cradle and vertical lines to replicate where the center of my middle finger will be when pulling the bow string to shoot. On the floor where my bottom pulley is anchored, I have it designed so I can slide the pulley left or right to align it with either black line. Equal limb timing is achieved when the tiller tree pull rope travels straight down the black vertical line on the wall. There are 2 black lines, the line on the right is where I would connect the pull rope when tillering for a split finger shooter, the line on the left is for tillering for a three under shooter. From the very first pull on the tree, I am seeking to get the pull rope traveling straight down the line. The pull rope will always drift towards the stronger limb. So wood is removed from which ever limb needs weakened to get the pull rope traveling straight down the line. You don't worry about a positive or negative tiller, it will be what ever it's going to be when the limbs are timed. I'm sure Jeff's thread will be much more precise, but then again he has WAY more B.S. than I do.. :)
https://www.youtube.com/watch?v=QTU0h5LDNwU&list=UUBMjR2l-xfFufcLpkUpYYBQ
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One question, you say that "the rope will always drift towards the stronger limb". That seems backwards on the face of it and it's an easy thing to get backwards in conversation, so are you sure? I'll take your word on it, just want to make sure.
Regardless, that is actually a very well thought out point imho. Making the tillering rope pull the string at the same point that the archer pulls the string just makes so much sense. I had thought of something similar, but the bows I've seen on tillering trees around the net are usually just arbitrarily pulled at the center, so I figured that was just the right way to go.
It really explains a lot. My last bows tiller was pretty close to perfectly the way I designed it on the tree but when looking at a photo of it being pulled by hand, the bottom limb is a bit wrong. There is also some hand shock and I can't seem to get the nock point low enough without hand contact on the bare shaft test.
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Absolutely sure. Think of it as the weaker limb bends more, allowing the tree pull rope to drift towards the stronger limb that isn't bending as much.
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Yeah, in my head, it seems that the hook connecting the pull string to the bow string would want to slide downhill towards the weaker limb. I'm probably just thinking of it wrong and it would be more evident when looking at an actual bow on an actual tillering tree.
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Roy gave a good basic view of it. This 'enhanced version' might help those who wish to dig deeper...
First let’s understand that “Timing the limbs” means “balancing the limbs’ strength at full draw relative to the archer’s holds on the bow and string”… or perhaps better defined as ‘full draw dynamic balance’.
It can be achieved in a couple of ways.
The method I use most often is accomplished by mimicking the archer’s holds on bow and string as closely as possible(very important) on the rope and pulley type tillering tree, and then adjusting the strength of the limbs so the string fulcrum comes straight back(or down as drawn on the tree). This means NOT pulling the string from directly behind the center of the handle in any instance… as nobody shoots a bow this way, but rather, we hold and draw the bow on the tree the way we do so in ‘real life’.
Dynamic balance means, if the limbs are of equal strength relative to the archer’s holds, at full draw the string hand fulcrum(hook on the string) will follow a line projected perpendicular from the bow… a line drawn on the wall to indicate perfect string fulcrum travel. The pulley down by the floor is placed precisely on, or plumb to, this line as well so that it attempts to pull straight back/down, not toward one limb or the other. Additionally, the bow’s handle area should be level in the tree to start, regardless of whether one limb tip is farther ahead of the handle than the other, etc.
To note: Bows that aren’t dynamically balanced reveal themselves as they tip forward or back in the archer’s hands at full draw… more obvious of course if they’re ‘off’ enough.
Each person must figure out the exact location of the indicator line(and where to hook onto the bowstring to draw the bow) for themselves, as it will vary depending on how they hold the string and where they prefer to nock the arrow. I have taken provisions to make my cradle and lower pulleys adjustable to account for the various idioms of the archer’s I intend to make bows for, but building it to suit YOU specifically, is a good start.
The ‘indicator line’ drawn on the wall, our main reference, is our beacon, and could also be drawn to indicate perfect perpendicular travel of the arrow nock, instead of the string hand fulcrum. I have done it both ways and either will give satisfactory and practically the same results.
Once it’s set up and the bow is drawn, if one limb is stronger than the other in the ‘dynamic sense’, it will flex less and its tip will travel less distance as its drawn than its weaker counterpart. If the bow handle doesn’t tip in the tree’s cradle, the effects of this imbalance will cause the string fulcrum and/or nock point to drift toward the stronger limb as the bow is drawn. Adjustments can then be made with confidence as we deem fit.
This is true whether we’re using a “long tillering string”, a string that allows for a very low brace height, or a proper length string for the bow… so this method can be applied very early in the process. There are a few caveats we can discuss later.
Sometimes folks prefer to leave the bottom limb a bit stronger than the top, as in the case of asymmetrical bows, and that can be done by allowing the fulcrum and/or nock to drift to that side of the line a little bit. If I do that, I allow 1/8” or so of drift toward the bottom limb at full draw. “Relativity” is the name of the game here. 1/8” drift at full draw is relative to the archer’s holds and has virtually nothing in common with a 1/8” positive tiller at brace. Think about it. How could it? What if one heel’s the grip? What if one limb has deflex and the other has reflex? Don’t let it be confusing. What it tells us is what it is. Set up to mimic your particulars, and trust what your tree tells you.
The popular brace height measurement differences… i.e. 1/4” positive tiller and such, what many folks use arbitrarily for limb strength reference, can be completely misleading in regards to relative limb strength and are not used at all to help judge a bow’s ‘dynamic balance’ at full draw with the above method. Read that again… it’s fundamental.
The only thing I do with those measurements is mentally record them after the bow is complete and use them to judge whether the tiller has shifted as the bow is shot in. By the way, balancing bows with the above method, tiller is MUCH less likely to shift as it’s shot-in. There will be no reason to ‘flip the bow’ end for end to mask shifting tiller. I have NEVER had to do that.
This method can reveal truths to the discerning bowyer about design relative to shooting idioms, bow performance, feel, arrow performance, tuning, and such that he may have never entertained without it. It will also allow for a more straightforward tillering practice with no backtracking, missing weight due to said backtracking, losing weight or acquiring set due to shooting it differently than it was tillered/timed for, and will result in a bow that is inherently tuned(one of my favorite by-products) and soooo sweet to shoot. Since the arrow nocking point was ‘ground zero’ from the get-go and the bow was timed around it,(inherent tuning) there will be no need to move the nocking point up and down trying to make the bow behave or mask inadequacies, while seeking good arrow flight. You set it where it was designed for and tiller to/timed for. Good arrow flight and limb harmony was built into the bow from the beginning. Tuning is an afterthought. Any discernable handshock is due entirely some other place… and in fact, even if it was created some other place… as-in due to an overbuilt limb design… it won’t be magnified by poor limb timing.
With proper dynamic balance, efficiency can be epitomized, handshock minimized, the arrow is sent straight away and recovers faster… the bow is doing what it is meant to do as well as it can do it.
Oh, there’s more…. Like I said, I could write a book :^)
I respect your wherewithall if you've stuck with me so far.
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Roy, since Jeff is busy, coulld you post a picture of how. Your pulls is anchored and adjustable?
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I'm looking forward to this, too!
:bigsmyl:
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Jeff, great stuff!! Just what I was hoping for.
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This is already very informative. I'm pretty excited to build my next bow and apply what I've already learned here.
Hmm... I wonder if I should build an artificial drawing hand.
I shall call it "THE CLAW." MWA HA HA HA.
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Wow that's great stuff...Thanks for the great conversation guys!
So how do you mimick the archer’s holds on bow at the top of the tiltering tree? I just built one on the garage wall and the top where the bow is to sit is a flat 4x4... now my mind is wondering...
And how do you mimick finger string hold using a pulley and rope? Maybe a patch of leather?
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Oh, btw, after some thought, I think I get why the pull line goes to the stronger side now. In my head, I was picturing the hook sliding on the string towards the weaker side. But it doesn't actually slide does it? It just stays in place because of friction so the line ends up veering towards whichever side has less give.
Is that correct?
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Correct.
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I warned ya all that Jeff has more bull crap than me... But he knows his crap on this tillering for limb synchronization / limb timing. Mac I'm in the bow shop now, but will put pictures on here of the bottom pulleys in a bit.
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Soooo looking forward to page 3 of this thread!!
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Here are my lower pulleys.
They are all adjustable by loosening allen head set screws, so actually, one pulley would be enough. I just use four of them so I don't have to mess around moving them as often.
The two on the left are for when the top limb of the bow faces left. The two on the right are for when the top limb faces right.
The outermost pulleys are for split finger holds on the string, and the two innermost pulleys are for three under holds on the string.
The two outer verticle lines are those referenced in the earlier post... lines indicating string fulcrum travel perpendicular to the bow. (the middle verticle line is just a seperation between two pieces of plywood).
(http://img.photobucket.com/albums/v312/Jeff_Durnell/TilleringTreePulleys_zps54234bef.jpg)
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Here's a bow at full draw, balanced so that the string fulcrum is towing the line. Asymmetrical design, top limb is on the right.
(http://img.photobucket.com/albums/v312/Jeff_Durnell/Raven/BYO80_zps8e4b1ae1.jpg)
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Nice, Jeff
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I'm looking forward to the book! Lol. Great info and pics. Thanks for taking the time to share your knowledge.
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The outermost pulleys (for split finger holds on the string) that utilize for reference the two outter vertical lines are how far from center? 1.5"?
Thank you for the pictures Jeff... worth many words for me!
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Yes, string drifts towards the strong side. Took me 10 years to realize that. Jawge
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Mac, I only use one pulley that I slide left or right.
(http://i47.photobucket.com/albums/f165/ROY-CHRIS/pulley1.png) (http://s47.photobucket.com/user/ROY-CHRIS/media/pulley1.png.html)
Picture below is setup for three under tillering.
(http://i47.photobucket.com/albums/f165/ROY-CHRIS/pulley2.png) (http://s47.photobucket.com/user/ROY-CHRIS/media/pulley2.png.html)
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Thanks Jeff and Roy. Now have to pick up the saddle bearing and pulleys.
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Sockrsblur, for me the line is at 1 5/8"... that's the middle of my middle finger. The line's precise location will depend on where each of us elects to set the nocking point, how wide our fingers are, etc. Just lay everything out on the wall or a piece of paper and it will be apparent where the line and hook should go.
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Ok, thank you sir!
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Up to this point I have not made my shelfs a fixed distance from center. Usually just fisted the handle and drew a spot for the arrow pass.
I'll have to measure and see how they came out.
Jeff, Roy if you use a number like the 1 5/8" is,that close for most folks that use the same draw.
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Mac, yes, should be close. Although I used the width of my own fingers to come up with that number.
I got there by measuring up from the shelf location to the bottom of the nock point(3/8"), down 1/4" for the width of the nock, and down another 1/8" to allow the arrow a little clearance over the shelf. That puts us right back at shelf height. And then my middle finger is 3/4" wide so half of that is 3/8".
Since I feel my middle finger is where the center of the pressure on my string hand is, my string fulcrum is 3/8" below the shelf... or 1 5/8" above a 4" handle's center... so that is where I hook onto the string to pull it on the tree.
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Jeff it appears that at the top of the tree your bows is held stationary so the bow won't tip either way when pulling the string. Is that correct or is the bow free to pivot? Currently my setup lets the bow pivot and I work the limbs so the bow stays level as the string is pulled down.
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His bow just sits in the cradle like mine does in my picture. They are free to pivot if one limb is stronger than the other.
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Ben, in the above picture it is supported more towards the left and right ends of the handle, so is less prone to tip, but WILL if the limbs are unbalanced by much. It will tip in that cradle before the hook drifts more than about a half inch or so from the reference line.
I also have inserts I made that drop into the cradle to change its shape so that the bow will tip much more easily, and/or to mimic different pressure points.
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Well, I just bit the bullet and am basically set to try this information out.
This time, I wanna try out a hickory backing, heat treating, and back setting as well. I'm pretty excited about the project. Damn you both for reinfecting my with the bow building bug.
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WELL? Pictures? :)
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Sadly, the weather here is suck right now and my "workshop" is my backyard.
I should be able to get it roughed out and heat treated and bent to shape on tuesday I hope.
Also, I'll start a new thread for the build. No need to clutter here.
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Hey guys.
So what ever happened to that tillering/timing tutorial BowJunkie? Is it posted somewhere else on the forum and I just haven't found it yet?
The bit you did explaining the dynamic balance point is very much appreciated, It goes well with what Dean's article talks about.
I'm working on my first bow, and every little bit helps. thanks for the knowledge you do share, I'm sure your life is busy like the rest of ours, so the time you take for others says a lot about you.
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I just haven't done it yet. I aplologize. And yep, been busy. Haven't worked on a bow in quite some time. Don't even have my tillering tree installed yet. Bow season is fast approaching and I want to make a new one to hunt with this year, but I dont know if that's going to happen. Yesterday I moved big rocks, and today, when I get off the heating pad, I'm installing chain link fence. I need to clone myself :)
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Awesome information. I finished the basic tillering yesterday on a Bamboo/Osage/Osage that I tried to mimic Roy's builds with. Happy I'm early enough to use this method to get it finished up. Thanks a lot for the tips. Gonna go home and draw a line on my tree now.
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I should really stop reading this forum. I have a good bow that I love. Plus I just won a store bought bow in a raffle.I just want to work on my form, shoot 100,000 arrows and get ready for october. Now all of sudden I'm redesigning my tree, making a hardware parts list, thinking about the staves I have on deck, and wondering how long I need to dry that last piece I cut. Thanks alot guys. This is all really good stuff, but I think I might need a twelve step program.
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Come on Bowjunkie, get off your butt and get er done.. :)
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As long as someone brought this thread up again (I can't believe I missed it the first time...), thanks again Bowjunkie for sharing your insight on tillering. I read and re-read your posts on this thread and it totally makes sense to me as far as where to pull on the tillering string. I do have a little question, though:
While I understand why you'd want to pull more in line with where the archer is going to pull on the string, would there be a difference pulling the tillering string with your fingers instead of a pulley?
I only ask because if you're trying to reproduce how the archer is pulling on the string (even having different spots for split finger and 3 under), then wouldn't the pulley drawing on a single point be more akin to someone using a mechanical release vs using their fingers? Also, I've read many posts and seen pictures of how bows look different in the hand at full draw vs on the tillering tree at full draw. Whether or not this is because of the bowyer pulling the tillering string in the middle, I can't say. It seemed like in most of the pictures the bow's tiller looked better in the hand. So I just wonder if you were to tiller with the bow in hand if the tillering process would go better or not.
Just so you know, I will be using your method of tillering as soon as I get a tillering tree set up, but I was curious if you had given it a thought. Thanks again!
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I don't think any difference is enough to matter, but others feel it is and make provisions for it with leather or strapping to spread out the area of pressure applied to the string. Try it both ways and see for yourself.
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As soon as I get enough free time, I certainly will... that is, if I ever do get some time!
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I recently changed to this method of tillering and must say that the last two bow made using this method have been the sweetest shooting bows that I have ever made, not perfect, but much better than anything I've been able to build so far. Both are selfbows, one a 64" osage and the other a 68" Honey Locust from billets.
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Yupper, Dan. They sure do shoot sweet and quiet.