Tiller Help Please!

[ajbruggink]

Hey guys, I'm working on my fourth bow and I'm kind of stuck at this stage of tillering. The stave is a red oak board, no backing, it is 70" ttt right now, it is a rigid handle flatbow and the limbs are parallel, 1 3/4" wide until it tapers 10" from the limb tips. The goal is 50#@28. I've got it to full brace and tillered to 24" but I'm stuck on where I should remove wood next. To me the right limb seems 'off'. The left limb seems like its the right shape for this style of bow but the right limb starts bending out of the inner limb too early and the whole limb looks like it has less bend than the other limb even though its bending further. I've tried to remove wood where I feel it is stiff to try to get it to bend at mid-limb like the left limb but its not working. What do you think I should do? Your replies are greatly appreciated.

Thank you,

Aaron

[sleek]

Your tiller isnt bad. It isnt perfect but it will work.

But off course we all chase perfection. So, right limb is great, left is a little more bendy tlon the inside of center. Your tips are very long and stiff. I dont know what your front profile looks like. I need that pic to tell you anything further.  There is a temptation to chase perfect ballence between limbs until you reach full draw. But often enough, both limbs get to a point where they match and just need wood removed evenly from both. Common spot to get stuck on.

[Josh B]

The main concern I see right now is that you have the beginning of a hinge right before midlimb on the left limb.  You need to relieve that by removing wood between it and the fade before any thing else.  The next issue is by your description, you carried the parallel section of limbs out a bit far by "normal" standards.  I would go to midlimb on each limb and start removing wood from the sides to start your taper to the tips.  That should get your outer limbs doing their fare share.  Go slow with it though.  If you hog the wood off, you could end up with a whip tiller.  Josh

[Eric Krewson]

Left limb, kinda' hingy at mid limb, right limb, kinda' stiff from the mid limb out.

[Selfbowman]

What is said above. What is the washer for ? Looking pretty good though. Arvin

[mikekeswick]

With that width taper you should have an elliptical tiller. Eg. the side profile of the limbs should look like part of an ellipse.
So your outer limbs are very stiff. Make yourself a tillering gizmo. As you run it along the limb the bend so be increasing as you move along towards the tips.
Pyramid width taper = arc of a circle tiller. Parallel width for most of the limb = elliptical tiller. This concept is the real key to making good bows.

[Pappy]

What Eric said.
 Pappy

[ajbruggink]

Your tiller isnt bad. It isnt perfect but it will work.

But off course we all chase perfection. So, right limb is great, left is a little more bendy tlon the inside of center. Your tips are very long and stiff. I dont know what your front profile looks like. I need that pic to tell you anything further.  There is a temptation to chase perfect ballence between limbs until you reach full draw. But often enough, both limbs get to a point where they match and just need wood removed evenly from both. Common spot to get stuck on.

This is what the front profile looks like. The original stave was 74" long and I decided to try to simplify things by just starting to taper 12" from the limb tips instead of figuring out what half of 37 is for my mid-limb length measurement. I roughed out the bow at this length but before floor tillering I decided that having it 74" long ttt for 28" draw length, when my goal is to cut it down to 66-67" ttt eventually, was ridiculous, so I cut off two inches off each limb tip, leaving me with now less of a taper. At the time I didn't think it would matter much, the Meare Heathe has little limb taper, but now I'm having second thoughts about my earlier decisions.

The main concern I see right now is that you have the beginning of a hinge right before midlimb on the left limb.  You need to relieve that by removing wood between it and the fade before any thing else.  The next issue is by your description, you carried the parallel section of limbs out a bit far by "normal" standards.  I would go to midlimb on each limb and start removing wood from the sides to start your taper to the tips.  That should get your outer limbs doing their fare share.  Go slow with it though.  If you hog the wood off, you could end up with a whip tiller.  Josh

I was going to ask about that. As I already stated, I thought the little limb taper wouldn't matter much but now I think that was a mistake. Should I increase the limb taper with a few strokes with a rasp at a time, check tiller, rasp some more, check tiller, rasp some more, until I get the taper from mid-limb without affecting tiller?
[quote author=Selfbowman link=topic=54093.msg734438#msg734438 date=1442282481
What is said above. What is the washer for ? Looking pretty good though. Arvin
The washer is part of my tillering string. Instead of using a flemish twist string with a timberhitch for a tillering string, I made a really long endless string and use the washer to shorten the string to whatever length I want. I stole this idea from Del the Cat. I was having problems using a timberhitch, so I tried this and I like it much, much better, its just so much easier for me. 

[Josh B]

If you want a more common flatbow profile and tiller, that would be the way to do it.  If you want to keep the front profile you have, then an elliptical tiller like Mike suggested would be the way to go.  You have enough length that an elliptical tiller shouldn't give you any string angle issues(stack)  so really it's completely up to you on how to proceed.   Josh

[PEARL DRUMS]

If you mark each limbs half way point and straight narrow it from there to the tips, it will be bending pretty dang close to how it should. You width is carried out much too far now and will make the bow doggy and jumpy.

[sleek]

If you mark each limbs half way point and straight narrow it from there to the tips, it will be bending pretty dang close to how it should. You width is carried out much too far now and will make the bow doggy and jumpy.

Its gonna be a weird day.... I agree with you.

[PEARL DRUMS]

Its easier that way sleek

[Josh B]

With the proper tiller, in this case an elliptical tiller, this bow would be no more doggy or prone to hand shock than any other design.  But therein lies the rub.  Getting the proper tiller to make the most of the front profile layout.  This is especially so with designs that require a more complex tiller that includes gradually increasing/diminishing bends to achieve maximum efficiency.  Personally I would recommend that folks just starting out stick to pyramids or full circle bendy handle bows until they get a better understanding of how the subtleties of tiller correlate to the various designs.  Tillering and bowmaking in general is a balancing act.  To get it right, one must understand all the variables involved and know each affects the other.  The more variables one has to deal with when just learning the ropes, the tougher it is to succeed.  There is of course blind luck, which admittedly I rely on all too often, but blind luck is not a repeatable skill.   My best advice for the new builder, keep it simple until the basics are hard wired in your head.  Then and only then, start increasing the complexity and difficulty of your builds a bit at a time.  In long run, I think you'll find this craft much more rewarding.  I apologize for getting off on a tangent, but it's something I felt the need to say for a long time.  Josh

[JRMakowski]

I thought the washer was a stab at a peep sight......  J/K

[PEARL DRUMS]

My guess is that washer takes up and lets out string as he wraps it round.