When tillering a bow what is the difference between tillering for 3 under versus split finger.Just trying to get answers in advance of starting to build.
1/8 positive is a good starting point.
I think it varies somewhat from person to person depending on how you grip and hold the bow. I do best very close to even with a medium style grip.
Most will tell you even for three under. I try to keep mine 1/8th to even and a person can play with nocking point placement to tune. How a person grips the bow does have affect on things.
Brace height 'tiller measurements' should be the RESULT after timing the limbs related to the archer's holds on bow and string... not something predetermined.
The resultant profile will also be affected by bow center relative to handle fulcrum.
So, it's not possible or proper to give you an exact answer. But generally, bows tillered for three under will be weaker in the bottom limb than bows tillered for split-finger shooters. I know... not much help is it? ;)
Bowjunkie,give me a step by step on timing the limbs and how do you know it's correct?
I plan to do a build to show my process, and have the bow started, but I have a few bows in front of that one.
Basically, I use a rope and pulley type tillering tree, the cradle of which mimics my grip on the bow, and the hook is placed on the string at my fulcrum point, I.e. center of my middle finger. A verticle line is drawn on the wall to replicate perfect string fulcrum and arrow nock travel perpendicular to the bow handle... that is, with the nock point set 3/8" above the shelf. This is also where the pulley is set directly below. Then I time the limbs so that the nock follows the line down to full draw and back.
How do I know it works? The resultant bows' nocks are preset, never need nock point adjustment, bows don't shift tiller, don't tilt in the hand at all during the draw or at full draw, shoot an arrow perfectly straight away without porpoising, don't shock the hand, etc.
With this method, I begin timing very early in the draw, the first few tugs on the string actually... with asymmetrical bows anyhow. The osage bow I'm tillering now looks like it will probably end up with an even tiller, or possibly slightly negative. We'll see.
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With this method, I begin timing very early in the draw, the first few tugs on the string actually... with asymmetrical bows anyhow.
What would be the difference between asymmetrical and symmetrical bows with your method, Jeff?
Same method, Roy, but in the symmetrical bow there is a greater shift from the static balance point to the dynamic, so the bow needs to be allowed to make that shift. If ya don't understand what it's trying to do, and fight it by trying to time it too early in the draw and tillering process, the bottom limb can be made too weak... then you'll be playing catch-up later and possibly induce unnecessary set, shifting tiller during shooting in, etc.
Asymmetrical bows, with the smaller shift needing made, can be timed earlier in the draw.
Looking forward to the build along...
Jeff, if tillering a symmetrical bow for shooting 3 under, then wouldn't the shift from the static balance point to the dynamic, be less than tillering a symmetrical bow for shooting split?
No Roy, it would/could be exactly the same... at least it is the way I most often offset my bows.... but it depends on how far the bowyer shifts the bow center away from handle center.
The big difference, among the most common approaches, the big shift in balances, happens when a symmetrical bow is shot split-fingered.
Ya want virtually no shift? Shoot an asymmetrical bow three under. I would, but I like the split finger release, like my bows balanced in the hand while carrying and don't have a problem with the tiny shift at the beginning of the draw.
Jeff I look forward to the show. I have lost the lower limb more times than I can count. My tiller looks great and then some where along the first 100 shots or so I loose it. Thanks
The big difference, among the most common approaches, the big shift in balances, happens when a symmetrical bow is shot split-fingered.
Well that's what I just asked, first you said no, then you say that?
I confused. :)
So lets say a bowyer who shoots with a medium grip, finds the center of the bow, measures up 1 inch for the top of the handle " arrow shelf ", and down 4 inches for the bottom of the handle. He accounts for a 3/8th high nocking point on the string. He shoots split, so the middle finger of the drawing hand will be at the arrow shelf, which is 1 inch above the bows static center. But if he shoots 3 under, then the middle finger will be 5/8th above bows static center.. That sound correct? :)
You asked about shooting a symmetrical bow three under, then quoted my reference to a symmetrical bow shot split. You SHOULD be confused :)
In regards to your last queston, no, the center of my middle finger is below the shelf when shooting split-finger. I figure for a 3/8" high nock point, subtract 1/4" for the thickness of the arrow nock, subtract half the width of the middle finger, about 3/8"... that puts the center of my middle finger 1/4" below the shelf. That's where I put the hook on the string.
Switching from split to three under moves my string hand down 3/4"... because that's the width of my pointer finger. So if I shot three under, we'd add the 3/4" to the 1/4" and the center of my middle finger would be 1" below the shelf... the bow center in your example..... no shift.
No, I said if tillering a symmetrical bow for shooting three under. Compared to tillering a symmetrical bow for shooting split. Wouldn't the difference between static and dynamic be less for three under tillering.
You said:
So if I shot three under, we'd add the 3/4" to the 1/4" and the center of my middle finger would be 1" below the shelf... the bow center in your example..... no shift.
That is what I ask about the tillering difference being less than split. :) Are you confused now? :)
However, I see now that your 3/8 is the top nocking point and you place the arrow under it, I was assuming the 3/8th was the bottom of the arrow nock... Hain't this fun? :)
Yep. I like it.
Yes to your question.... in a symmetrical bow, three under would require less of a shift than split finger.
3/8" is to the bottom of the nocking point. With a 1/4" thick arrow nock, and an arrow shaft slightly thicker than that, it sets the arrow just barely above perpendicular. .. which provides excellent arrow flight. You won't see a bow of mine with a jacked up nock point.
I understand now, Son. :)
No doubt I'm going to need pictures. And a drink
I didn't think I was confused till I figured I was confused and I confirmed I was definitely confused now I want that drink too and I may have to go back to buying bows. :confused:
Jeff, so at that point your gonna work towards perfect nock travel? I would think if you had perfect nock travel and no bow rocking in hand your limbs would be in time, starting and stopping at the same time. Is my thinking correct.
When you were talking static and dynamic earlier in the thread would static refer to bow at brace and dynamic refer to bow being drawn adding energy to the bow.
Sorry for the dumb questions, I'm just trying to learn as much as I can.
Cory
Static is the true center of the bow, measured tip to tip. Dynamic is where the bow balances in your hand according to how you grip it and where your draw hand is on the string.
I might go out and buy a compound tomorrow. :) LOL, not....
Blasphemy Roy!!! Lol.
This is very interesting stuff. Gonna be hard to incorporate on my next glass build. Might have to build the shelf and grip around the tiller(timing) of the limbs. Boy, I might need a couple drinks while thinking about this one.
Well, not exactly Roy.
The static point of balance is where the undrawn bow balances with no drawing pressure at all exerted. It is USUALLY very near the measured center of the bow, but depends also on mass orientation.
Dynamic balance is where the bow balances at full draw relative to limb timing, and the bow and string holds of the archer.
The dynamic balance point of a bow at full draw will change when gripped differently... or timed differently.
The shift between static and dynamic balance points happens as the bow is drawn. The farther they're seperated prior to the draw, the greater the shift needing made. I suspect, even if limbs are balanced at full draw, that the more shift being made, the greater the affects on smoothness of draw, felt recoil, arrow flight, etc... but I haven't dug around in that dirt too much yet.
Well, not exactly Roy
I thought about that last night after I went to bed and knew you was gonna say that. :) But it's going to be very close like you said.
LOL.
With the mass thing, I'm sure many here, especially those who build balanced bows, can tell long before a stave hits the tree, whether one limb is likely to be too strong, simply by where the static balance point is in the hand.
Bowjunkie, I definitely need to see your build along. Look forward to that.
Does your process work the same for self bows or laminated bows?
How do you define the static balance point and the dynamic balance point?
This is good info. I need to learn about it.
Thanks for your help.
Drewster, look three or four posts above yours for the descriptions.
Yes, regardless of what the bow is made of.
I was hoping to figure out the answer to this question ,but when they handled out stupid I got my fair share.I may have even got a little greedy.
But what's the definition of a asymmetrical bow and a symmetrical bow????? Or what is the difference?????
Sorry for whats probably a dumb question. :dunno:
Symmetrical bow, both limbs are the same length.
Asymmetrical bow, bottom limb is shorter than the top limb. Normally about 1 to 1 1/4 inches shorter. This is done to keep the static and dynamic center closer to the center of the grip area.
Bowjunkie does the cradle on your tree allow the bow to rock freely? if so how do you get around the bow wanting to rock off the cradle at the beginning of the draw... when tillering for split?
Symmetrical design - A type of bow whose limbs are of equal length and whose longitudinal center is at the center of the handle.
Asymmetrical design - A type of bow whose limbs are of unequal length... and hence, whose longitudinal center is offset from the center of its handle.
Rockkiller, for future info, these and other definitions can be found near the top of the list of threads in a 'sticky thread' when you open the Bowyer's Bench forum.
No such thing as a dumb question, bud... especially questions about bowyerin' :)
A Bowyer's Glossary thread
http://tradgang.com/noncgi/ultimatebb.php?ubb=get_topic;f=125;t=006396
Eric, my cradle 'base' doesn't allow the bow to tip unless it's moderately out of time, but I have variously shaped inserts that drop into it, some for various grips on the bow, some of which allow it to pivot.
I mostly time the limbs by referencing how the string fulcrum pulls down... how it drifts from or follows the line on the wall indicating movement perpendicular to the shelf... so I don't want it to pivot.
I have plans to redesign my tillering tree, for the umpteenth time,
very soon. I don't yet want to devulge my super secret idea until it's up and running. It's gonna be the friggin bomb THIS time. BREWHAHAHAHAHAHA :bigsmyl:
cool. ive been trying to meet the intent by allowing the bow to pivot freely, and sync the limbs by keeping the bow from rocking. thats proving to be difficult. i think im going to put on a more stationary cradle for now and snap a vertical line and do it your way as i finish up this trade bow.
Why don't cha just hold the bow up with your hand and have the wife pull the pull rope? :)
A girl could pull your bow, Roy, but ain't no way a girl's pulling mine :laughing:
Ah, took yer smarty pants pill this morning I see.. :)
bowjunkie id like to see your cradle with swappable inserts. sounds like it would beat the hell out of screwing and unscrewing different things to my wall. :laughing:
Roy and Jeff, thanks for pulling my head out.
Bill are you confused yet?
Give me a call when you get building I will try to help you out.
Terry
I'm thinking about building my first bow(a red oak board bow) at first I was worried about tillering.... Then I read this thread! Lol ! Seriously thanks for all the information you guys post . I want to make a couple of kids bows for my grandsons and hopefully one day make one good enough to hunt with.