Tillering for positive???

[snag]

I have an osage wide limb bow I'm tillering. It's limbs are 1.5" at the fades out to mid limb and then taper to 1/2" tips. I am at 55#@24" and hope to be at 55#@28". The upper limb has 1/8" positive tiller over the lower. My question is how do you tiller for positive tiller? It appears that if I were to scrape more wood off the top limb than the lower as I tiller then the top limb would have more positive tiller. But if I do this it could also mean that the top limb would bend more than the bottom....is that ok if the arch is kept even? I shoot 3 under also.

[okie64]

I get a little confused on this one too. Most people say for 3 under shooting the limbs should be closer to even tiller than for split finger shooting which doesnt really make sense to me. I shoot 3 under and I usually leave my bottom limb an 1/8" or less stiffer than the top. Has worked pretty good for me. I'm sure someone else with more knowledge on this will chime in pretty quick.

[snag]

Thanks Okie. I'm hoping I have it right. But want to make sure before I take it any further. Grown attached to this piece of wood now that it is starting to look more like a bow!

[Sixby]

Snag. I agree. that is exactly what you do. The trick is to tiller so that the limbs are timed. This means that the top limb has to play a little catch up with the bottom limb so they both stop at exactly the same time. If the center of the bow is in the center of the grip then the shelf is above center. this places the arrow and the fingers above bow center line. Also above string center line. You have to tiller postive in order not to make the limbs look exactly the same at draw but to get them to stop at the same time. This starts the arrow out on its flight leaving with all the energy the bow limbs can impart. This cuts down on lost energy , vibration, shock ect and produces a faster cleaner arrow flight.
there is a misconception that the tiller measurements are the only indicator. Not true. That is a start point only.
God bless, Steve

God bless, Steve

[George Tsoukalas]

I try to tiller the bottom limb of my selfies about 1/4" stiffer at full draw. Working with a rope and pulley helps as does digi tillering.    Jawge

[PEARL DRUMS]

I tiller all my bows even and I shoot 3 under. Course they are all junk and shoot like crap as a result!  

[John Scifres]

I don't really worry about positive tiller.  Get it bending good on the tree and final tiller in the hand, by feel and if possible using a digital camera.

[snag]

I'll take some pictures and post them soon. I have been putting together a woodworking shop. Still doing some things. One of them is drawing horizontal line grid around the tillering tree on the wall. I'm at a point that this would help me see things better too.  Thanks, David

[inksoup]

excuse me but can you explain what is positive tiller?  :(

[PEARL DRUMS]

Positive tiller is when one limb lands farther ahead or behind the other. The tips dont land on the same plane when fully drawn. One limb will work a little harder than the other.

[GREG IN MALAD]

I'm going to throw another idea into this soup pot. I set positive tiller by shooting a bare shaft. When I get perfectly flat arrow flight with the nock set 3/8"-1/2" above square, I'm done. Most of my glass bows are tillered even, and because self bows are anything but flat I dont find a tape measure to be useful at all with them.

[Swissbow]

I tiller my bows slightly positive as a starting point. But the final adjustment is done after test shooting the bow. If the bow shoots fine without handshock I leave it the way it is. If it has handshock I change the tiller a little bit and observe if the handshock is getting less or more. This way I do the final tiller until I'm happy with it. I use rather light arrows so I can feel the handshock better.

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Andy

[snag]

Andy, in what way do you "change the tiller a little bit"? Do you increase the tiller from say 1/8" positive to 1/4"?  Or lessen the stiffness of the bottom limb?

[Swissbow]

Generally I start with something around 1/8 positive tiller. If I feel that the bow has some handshock and doesn't shoot smooth, then I make the top limb a bit weaker so that the tiller goes more towards 1/4 positive. Now I shoot again with the same arrows and check if handshock has gotten worse or better. If it got better I continue this way. If it got worse then I make the bottom limb a bit weaker so that the tiller goes more towards neutral. I repeat this until I'm happy with the way the bow shoots. For a bow to shoot fine not only the tiller, but also the mass in the limbs has to be balanced. Sometimes it's very hard to make a bow shoot nice and smooth and sometimes everything just comes together all by itself.

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Andy

[snag]

Thanks Andy. This is a big help. I appreciate it. David

[okie64]

Great info on this thread!