Optical illusion

[Louie]

Hi Guys

So the bowyer bug has bitten and I'm on my second bow. I'm busy with a hickory backed ipe 68" ntn 35mm wide at the fades and tapered to just under 1/2" at the tips. I'm looking to reel in 40# @ 27".

So here is my dilemma, when I look at the bow at 22" draw the right limb seems to be stiffer. No problem. Then I flip the bow around and, well, now the right limb seems stiffer (obviously I'm now looking at the previous left limb). Do you guys suffer from this optical illusion sometimes? I know the bottom limb needs to be slightly stronger than the top and at full (fist melee) brace the positive tiller measures in at 1/4".
I'm close, its really just a slither away and I really don't want to miss my target draw weight by removing shave after shave and this illusion just wont go away.

What would you do?

[PatM]

Why do you call it an optical illusion?  Is the limb actually stiffer in the flipped position? Why are you flipping it if it's how you want it?

[Louie]

PatM, when I look at the bow the limb on the right seems slightly stiffer (not having the same arc as the limb on the left). Then I rotate the bow, now the limb that was to my left is now to my right seems to be the stiffer of the 2. This cannot be, if one limb is stiff (lets make it the bottom limb), then it should remain that way no matter which way I look at the bow.

[PatM]

No, that is also dependent on how the bow is stressed when bent.   The bow should not be mounted on the tiller like a crossbow.

 Also you haven't said why you are flipping it is you're happy with it the first way.

[JWMALONE]

Loui, I had the same problem, drove me crazy and caused me to make a few kiddie bows.. I' only have about 5 successful bows to my credit so I'm no expert. Pat M is correct if youre looking at it strapped to a  tiller tree it could stress one limb differently, it will drive you crazy. Use a mirror and grip the bow in different positions and the tiller will change slightly. Also check out Dons thread on Balance in tillering. Pictures will also mess with you're head as well.

[Marc St Louis]

Never mind what it looks like.  You should focus on how it feels when it is being drawn

[Louie]

This is what she looks like. But on the tree she freaks me out.

[PatM]

We shoot bows by hand, not off the tree.

[High-Desert]

Nothing wrong with that tiller. Don't let the tree fool you. It's great for making sure things are even for getting to brace. The best thing to check tiller is to use your phone and take a photo of you drawing the bow. It allows you to really study the tiller. 

[Weylin]

You need to forget the tree at this point and gauge the tiller purely by hand. Like these guys said. The tiller in the hand is what is important. The tree isn't always the same but it's not ultimately important.

[Jim Davis]

And, the sooner you get confident enough to not ask for opinions here, the better off you will be. 

[ohma2]

Looks good to me too,nice bend.

[aaron]

Never mind what it looks like.  You should focus on how it feels when it is being drawn

Mark, what do you mean by this?

[aaron]

And, the sooner you get confident enough to not ask for opinions here, the better off you will be. 

This may be true, but the way you gain confidence is to ask questions- keep asking. I have been building bows for 20 years and I wstill ask about tiller.

[aaron]

If your'e having trouble deciding on tiller, here are some options to help:
Ask someone else (you did!)
Use a measuring tool such as a tillering gizmo.
Take a photo and superimpose a circle or oval onto it.( look at photo while holding a CD up to it)
At brace height, look to see if the handle is parallel to the string.
Compare the angle between the string and limb tip.
Just cal it good as it is.
Looks pretty good to me. A little stiff towards the tips perhaps.