“imo, proper balance and timing renders the notion of positive or negative tiller practically meaningless.”
I’ll give you an amen for that one Jamie!
“So how do you tiller a bow for good arrow flight while it’s on the tree?”
Roy, we discussed this at my place years ago. By tillering for good arrow flight, I mean tillering so that the arrow nock comes straight back, perpendicular to the handle/shelf, and leaves along that same line when shot. This way the arrow won’t have to recover from porpoising in flight, less energy is wasted, and the bow draws and shoots more balanced and sweet in the hand. These, and more, are natural bi-products of synchronized limbs.
Where I place the hook on the string(middle finger fulcrum point) is less than a half inch from where the actual arrow nock will be on the string, so as I draw the bow on the tree, with no tipping of the bow permitted, I watch how that hook travels down towards the floor. I have vertical lines on the wall which replicate the arrow nock’s travel in relation to the arrow shelf on the handle. When the limbs are timed equally, the hook will come straight down following the line. If one limb is stronger, the hook will be pulled toward the stronger limb. This is what I use to judge relative limb strength/timing… from the very first pull on the tree to the very last. Since I wish for this to be a pretty precise ordeal, it’s imperative that the handle is sitting level in the tree and held the way my hand will hold it. It’s important that the HANDLE is level, not necessarily the whole bow. I want the handle level and don’t care where the tips are in relation to one another. One can actually be higher than the other, and the limbs can still be perfectly timed.
If you would like the bottom limb a little stronger, as some do when it’s designed shorter for balance, you can tiller the bow so that the hook slightly fades towards the bottom limb as the bow is drawn and arrow flight and shooting quality is affected insignificantly.
“Do you tiller for even tiller, positive tiller, etc?”
No. I don’t tiller for even tiller, positive tiller, negative tiller or ANY of that jazz. That is NOT my guide. It’s a false prophet. It will lead you to tiller some bows sub-optimally. I tiller so that the arrow’s nock comes straight back, perpendicular to the handle, and leaves along the same line… straight ahead… with practically NO THOUGHT GIVEN WHATSOEVER to how the bow measures at brace.
How COULD you tiller to a predetermined measurement if you have one limb with reflex and the other with deflex… or like some of the bows I’ve made, with a big hump at the dip right where you’re ‘supposed’ to measure them? If you have a selfbow stave with one limb reflexed and the other deflexed and build the bow to say… a predetermined 1/4” positive tiller, the limbs can be far out of time. It will have more handshock that it should and you’ll have a harder, if not impossible, time tuning it. If, instead, you completely ignore any such brace height measurements, and you tiller it so that the arrow’s nock travels straight away from the handle, then straight forward upon release… the limbs will be timed REGARDLESS of what the bow looks like or measures at brace height. As such, with perfectly timed limbs, bows may end up with positive, equal, or negative tiller, but they’ll all be perfectly balanced during the draw and shoot wonderfully right out of the gate.
When I’m in bowyer mode, I like to spend my time making bows, the best bows I’m capable of making. I don’t care for messing around trying to tune a bow that doesn’t want to be tuned or ‘settling’ with arrow flight that is just passable.
“Do you tiller it to your final draw on the tree then shoot it and tiller more by feel of how the limbs react and arrows fly when shot?”
I tiller to final draw on the tree with maybe a couple extra pounds for shooting-in. If I do my job properly there on the tree, the limbs will react harmoniously, pulling the handle straight back, balanced, into the palm of my bow hand all the way through the draw, and stay that way at full draw, without me having to heel it to keep it from tipping, and the arrows will fly perfectly… every time. I’ve never had it any other way. I cannot be this precise by finishing the tillering of the bow ‘by hand’, looking in a mirror… or even taking and studying pictures of it on the computer. None of that will tell me as much as my tillering tree will tell me.
This method works equally well regardless of how a bow is designed… i.e. symmetrical or asymmetrical limb design, funky lumpy selfbows, bamboo backed bows, d/r glass bows, recurves, or whatever.
"So basicly, assuming a drawing hand placement of the tillering tree pull rope on the bow string, a bow should be tillered so both limb tips are coming down the tree to the same length? And a nice even arc in both limbs."
No. That is not the same thing. There are many reasons I can think of that would cause such a bow to still be out of time. They don't all have a perfect, symmetrical shape. They shouldn't all be tillered with nice even arcs(another pet peeve of mine). They don't all have both limb tips starting the same distance in front of the handle, etc. And if designed so that the bottom limb is shorter, it shouldn't necessarily come down the same distance since it travels in a tighter radius.
Topic: Tiller changing? (Read 791 times)
