Tillering Tree Question

[Roy from Pa]

LOL, why did you buy a 1 inch shaft anyways?

[onetone]

Hehe. Thanks. I missed that …

[Stagmitis]

Same price as 1/2 “ and got it same day:) even the pillow blocks were the same.

[Kidder]

I’m a little late to the party but might as well throw in my 2 cents. My current rack has a slightly curved rest for the bow to sit on and I usually pull from wherever the balance point is. My previous rack had a strap rest similar to Mocoon’s. The nice thing with that is that you get instant feedback on which limb is stronger.
However, I’m a big believer in finishing tillering (the last couple inches) by drawing in hand and photographing it. There are aspects that you can’t see necessarily but you can feel and I find that helpful.

[Bowjunkie]

I have that too. I made inserts that fit down in the cradle of the tillering tree that are shaped flat and others of various curves. I also have a short piece of a half-round file that I can place anywhere on the cradle to reveal the balance point, or allow the bow limbs to be balanced relative to that fulcrum point... to an extent, i.e. there's only so much we can do when it comes to moving the fulcrum under the bow hand because of bow design and geometry.

BUT, I've found those inserts almost entirely unnecessary. When I balance bows as described earlier, they balance perfectly during and up to full draw, and shoot an arrow dead straight away from the nock point location on the string that I originally intended, from the very first arrow.

When the bow is done on the tree, it's dynamically balanced, it feels finely balanced in the hand each and every time, no additional adjustment/tuning/corrections needed. The pictures I've taken at full draw revealed that balance. All I have to concern myself with after the bow is done is arrow spine. Work moves straightforward toward that first arrow launched, no backtracking, no guesswork, bows are inherently tuned. Nothing to fix, no discrepancies to try to overcome by moving nock point location, etc. This is the main benefit to tillering with focus on dynamic balance... it's the quickest & easiest, consistently reliable way to a balanced bow that I've found.

[Stagmitis]

Bowjunkie Ive seen you post the nock height that you tiller at before...... 1/8" above 90Deg and nock  above? This has always puzzled me since my knock point is higher 

[Kirkll]

Bowjunkie Ive seen you post the nock height that you tiller at before...... 1/8" above 90Deg and nock  above? This has always puzzled me since my knock point is higher 

Your exact arrow knock location will vary from one archer to the next depending on where the pressure is applied to the grip, and your finger placement on the string. Balancing the limbs has a huge effect on hand shock and overall performance of the bow, but string knock location and arrow flight is dependent on set up.

With that being said…. There is a huge difference between tillering a self bow, and tillering a composite backed bow.

[Bowjunkie]

Stag, just to be clear, when I say that, I mean the back end of the arrow is raised 1/8" above perpendicular, and that would be measuring from the shelf to the bottom of the arrow nock(not the nocking point on the string). Assuming the arrow nock is 1/4" thick, which mine are, the bottom edge of the actual nocking point on the string is then 3/8" above perpendicular to the shelf.

Ultimately the arrow may be a wee bit less than 1/8 above perpendicular when everything is considered... arrow taper, arrow diameter vs arrow nock thickness, etc, but I'm fine with that.

Kirk, I balance limb strength in glass bows the same way I do with wooden bows. Due to the materials used, there's a difference between selfbows and glass bows in construction methods when it comes to 'tillering' the limbs for even flex or the curve wanted, but the physics is the same, and my practice in achieving dynamic balance is the same. I balance glass bows the same way as selfbows, boo backed, sinew backed, all of em. All nock points are set at the same place, then I balance the limbs as closely as I can relative to the archer. I mostly make bows for myself, but when I've made them for others, I collect as much pertinent info about their shooting idioms as possible and design and build the bow accordingly, and they've remarked on the shooting characteristics that come with such balance and appreciated not having to make adjustments to nock point height. There should be no need for that if we collaborated well and I do my part.

[Kirkll]

Stag, just to be clear, when I say that, I mean the back end of the arrow is raised 1/8" above perpendicular, and that would be measuring from the shelf to the bottom of the arrow nock(not the nocking point on the string). Assuming the arrow nock is 1/4" thick, which mine are, the bottom edge of the actual nocking point on the string is then 3/8" above perpendicular to the shelf.

Ultimately the arrow may be a wee bit less than 1/8 above perpendicular when everything is considered... arrow taper, arrow diameter vs arrow nock thickness, etc, but I'm fine with that.

Kirk, I balance limb strength in glass bows the same way I do with wooden bows. Due to the materials used, there's a difference between selfbows and glass bows in construction methods when it comes to 'tillering' the limbs for even flex or the curve wanted, but the physics is the same, and my practice in achieving dynamic balance is the same. I balance glass bows the same way as selfbows, boo backed, sinew backed, all of em. All nock points are set at the same place, then I balance the limbs as closely as I can relative to the archer. I mostly make bows for myself, but when I've made them for others, I collect as much pertinent info about their shooting idioms as possible and design and build the bow accordingly, and they've remarked on the shooting characteristics that come with such balance and appreciated not having to make adjustments to nock point height. There should be no need for that if we collaborated well and I do my part.

You are absolutely right about limb balance and the "tiller" being the same with self bows and glass bows. Only the tillering process is dramatically different. Most of your bow tiller adjustments in a composite bow is determined by your taper rates and wedge configurations in the limbs, and controlled by consistency in mill work and laying them up the same without anything shifting in the core.  If everything is accurate, and your limb width profiles are the same, it's just a matter of sanding glass to balance things out, and maybe a little limb trapping.......

But.... i'd be willing to bet that 90% of the bowyers out there don't actually "tiller" a composite bow at all... they sand the glass to an even "Tiller Measurement" or 1/8" positive for 3 under, and just call it good.... There is a difference between adjusting the limbs to a set tiller measurement, and actually tillering the bow and balancing the limbs.

Now if something shifts slightly during lay up, things can get a bit more interesting trying to get things balanced and have the limbs bending the same.     Kirk

[Roy from Pa]

But.... i'd be willing to bet that 90% of the bowyers out there don't actually "tiller" a composite bow at all... they sand the glass to an even "Tiller Measurement" or 1/8" positive for 3 under, and just call it good.... There is a difference between adjusting the limbs to a set tiller measurement, and actually tillering the bow and balancing the limbs.

Exactly, Kirk...

[Bowjunkie]

I agree that's what many do, set the brace height according to conventional 'wisdom', like 1/4" positive for split finger is a common practice... with many selfbow makers too unfortunately. It makes it quicker and easier for the bowyer... but doesn't result in the best bow.

[Kirkll]

I agree that's what many do, set the brace height according to conventional 'wisdom', like 1/4" positive for split finger is a common practice... with many selfbow makers too unfortunately. It makes it quicker and easier for the bowyer... but doesn't result in the best bow.

I’m curious where you came up with 1/4” positive tiller measurements is common practice for a split finger shooting application?   You called that “conventional wisdom” ? Or was that tongue in cheek?   

Btw…. There is a big difference between a seasoned bowyer, and someone that has just built a lot of bows. The season self bowyers that learn to manipulate natural materials and get longevity from their creations are what I would consider the masters in this trade. They understand how these things work a lot better than most glass bowyers do…..  But…. It’s just too much heart break for me to indulge that much time and energy into myself. My hat is off to you masters out there.   

 Kirk

[Bowjunkie]

Yes, tongue in cheek. I call it conventional wisdom not because it's correct, it's not, no single predetermined tiller measurement is, but rather because it's indeed what many folks advocate. Bottom limb 1/8 to 1/4 stronger than the top at brace for split finger, with no other qualifiers or considerations. It's really crappy advice.

[Kirkll]

That's what i thought... Judging from your posts on other topics it seems to me like you have a pretty good feel for this stuff. its a real shame there is so much speculation, philosophy, and down right bogus info being spread on the internet.

But ......there are a lot of bowyers that truely want to build a better product out there. But how many of them that are willing to take the time and effort to actually do it are few and far between. It takes experience to get there. The knowledge i've accumulated has taken many years building a lot of different limb designs and documenting test results, materials used, and detailed lay up data in my log book.  If i can share a few tips here and there to get the new bowyers off on the right track, i'm all in...    Kirk

[Honest Jon]

Still learning from this thread. This morning I put a selfbow on the rack and was concerned about funky horizontal torque. So, I cut an 11/16” arrow shaft to length, flattened on one side and stuck it over the “saddle”.  Really free floating.

[Kirkll]

Wrap that baby with duct tape or leather and you wont scratch finished bows   A 1 1/4" closet poll rod works well too with a flat spot.

[Honest Jon]

That baby’s wrapped in oil tan leather.

[Kirkll]

 

That baby’s wrapped in oil tan leather.

 

[Stagmitis]

Bowjunkie thanks for responding. I guess with your tillering method you can choose the location of the nock point in advance of tillering- typically mine are 3/8 from center and I nock above- once I finish my tiller tree I might try a lower nock point. Btw you were right a 1” rod is too big and doesn’t fit the 1” blocks or pulley. I have to get it milled or find one a few thousands smaller 

[Roy from Pa]

There are a ton of 1/2" rods on the market..