Tiller changing?

[Roy from Pa]

Mitch, I think what Jeff is saying here is. His stationary pulley mounted on the floor is directly vertically in line with where his center finger on the bow string will be. He can move his pulley one way or the other to compensate for split finger or three under tillering. Therefore with the pulley being mounted rigid, he wants the pull rope to come straight down the vertical line on the tree, and there will be a couple lines on the tree corresponding to where the pulley is positioned. Yes the pull rope will "always" move towards the stronger limb, so if the pull rope drifts off to one side or the other from the vertical line, that means one limb is stronger than the other. So wood will have to be removed from the stronger limb to keep the pull rope coming straight down the vertical line. Jeff, post a picture of your tree setup.
I think I got that right.. LOL

[4est trekker]

As a general rule, the way you grip the bow also has a lot to do with how the bottom limb responds in proportion to the top.  The lower the heel of your palm rests on the riser, the more the bottom limb has to work (i.e. the further the tip has to travel to achieve full draw).  I prefer an Asbell-influenced grip in where the heel is completely off the riser.  On most bows, this creates a more even tiller/timing/limb recovery scenario.  

However, I'm NOT suggesting you change your form just to save a bow     It was just some food for thought...or, more like the crumbs from dessert after the above posts!    

[Roy from Pa]

Well good morning 4est, yer up late:)

I believe it's also true that shooting three fingers under puts less stress on the lower limb than shooting split fingers:)

[Bowjunkie]

4est, that's why it's important we set the tree up to hold the bow the way we do.

Roy, I told you that because we were building bows with shorter bottom limbs. A shorter bottom limb is under more stress per inch than a longer one, so leaving it a little stronger MAY help in some instances.

Also, if you think about it, since the limb is shorter, it travels in a tighter radius, so it will never come down just like the top limb. Imagine if you pulled them all the way down to the 6 o'clock position, the bottom limb tip would be above the top limb tip by the amount you offset the limb length. This helps you envision the fact that it will never travel in the same radius, and shouldn't be tillered to come down the tree the same distance as the top limb. Shorter limb = tighter radius = less distance down the tree.

When you, or anyone, was just starting out making bows up here Roy, I tried not to give you too much info. Until you gain some understanding of this stuff, too much information can get in the way.

[Tom Leemans]

Read this article   Torges on tillering  It's Dean, so read it several times over. I believe you'll get English Lit credit for it.  

[Steve B.]

I try to duplicate hand placement on my tiller tree too.  I also use an arrow puller to help simulate the effects of three fingers on the string, to radius the string at the pull point.  I have a rounded chunk of wood for D-bows that allows me to slide the bow to different pressure points on the handle in order to compare tiller and I have a rectangle chunk for stiff handle bows.  Its offset so that I can pull the bow as though I'm hand-drawing it, 2 or 3 fingers under, etc.  It seems to work.  

Here I'm actually trying to break a stick of vine maple that had 6" of reflex.  It was too twisted to make a bow so I decided to test its flexibility.  I could not break it.  I went from floor tiller to 20+ inches repeatedly.  It lost 2" of reflex...in case you're interested.


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[Bowjunkie]

Tom, yes, Dean describes things well in that article. I've read it several times and picked up on, and affirmed in my mind, more each time. That's what happens when you read Dean's writings. There's more quality, helpful info packed into his careful selection of words than their sheer quantity would lead you to believe.

That article and discussions I had with Dean are what prompted me to step back and be more objective and critical of my tillering methods and goals... which I continue to do... always trying to learn, always trying to improve.

Dean is my mentor and inspiration... whether he knows it or not  

[Bowjunkie]

mwosborn, the stationary pulley can have an effect on how much the hook pulls to one side... how much depends on how far out of sync the limbs are... the harder the stronger limb pulls to the side, the more the stationary pulley will try to hold it back... but, it's not a real problem. It will never hold it back to the point that you can't see the discrepency. You can still see that it's being pulled sharply to the side and which limb needs weakened. And, if one limb is CONSIDERABLY stronger, you won't have to watch the hook because the whole bow will tip in the tree.

This is why it's also a good idea to have a bow cradle on the tree set up like Dean's and Steve's(picured above), convex shaped, which will permit the bow to tip with the slightest discrepency in limb timing.

I plan to rework my tree, yet again, so that I can change out my cradles at a moments notice. Using the stationary version to get it close by watching the hook, then the convex version to fine tune by how the bow tips, or doesn't, as it's drawn.

Both methods reveal the same thing. Relative limb strength and timing.

[macbow]

Wow, lots to digest and I'm working on it. I see where this all works.
The original problem was the first time I'd had such a drastic  change.
I shortened the bottom limb a little and reduced the top limb a little, not looking bad right now. I'm only 2 pounds lighter on weight.

[mwosborn]

Thanks guys - appreciate you answering my questions.  Can't wait to get some time to work on some bows!

Mitch