circular and eliptial tiller

[mullet]

This is real interesting, thanks for the pictures, Adam.

arachnid; I sent you a PM.

[PatM]

Whip tiller IS probably the best example of elliptical tiller that there is...
 People in the bow world hate to modify terms to make them more accurate once they are set in defining something a certain way, even if incorrect.
 Hence the Mollie/Holmegaard confusion to this day.

[adb]

I think there is a big difference between whip tillered (which in my mind is an incorrect tiller) and elliptical tiller. Whip tillered infers the bow is bending no where but at the tips, which makes for a less than ideal bow... one which will take excess set. To me, a whip tillered bow is just a short bow with a very long handle.

[PatM]

Really? I would just say it bends excessively, not "only" at the tips. It would be virtually impossible to make a bow that only bends at the tips and has any sort of  normal profile to the inner limb.
 Take an image of an ellipse and put a string across half of it. Bingo, whip tiller.

[adb]

I think you're missing the point, but carry on.

[WillS]

I'm a total beginner so bear with me, but isn't "whip tillered" just short for "whip-ended tiller"?

As in, the bow is tillered just fine, but the very tips (say the last 6" or so) suddenly both bend more than the rest of the bow, almost like two equal, smooth hinges?

[PatM]

Which is exactly like half of an ellipse....

[mikekeswick]

In a nutshell the thickness of the limb dictates how far it can bend. As the thickness changes so should the amount of bend.
I think it''s essential to understand this (or if not understand at least adhere to!) if you are after any kind of performance.
As Badger says - tiller logic.
Getting hung up on the minutiae of descriptions doesn't really help! The problem is we have a whole variety of different bends to describe with a couple of words so of course some of the descriptions aren't wholly technically accurate....

[nathan elliot]

I may start out with a tiller profile, draw weight etc. in mind - but nearly every time I do the wood tells a different story. A knot here a kink there and before I know it the wood is telling me what to do not the other way round. 

[Del the cat]

This is all well and good, but there are a couple of problems with the concept.
1. Eliptical is so vague as to be virtually meaningless! After all a circle is an elipse that just happens to have its two focii at the same point!
A straight stick when strung and drawn will look eliptical (with stiff tips)... but the long axis of the elipse will be in the direction of the string rather than along that of the bow!
2. Any bow with a stiff non bending grip section will tend to look eliptical. E.G If you take an arc of circle tillered ELB and stick 8" of stiff riser in the centre, it will fit an elipse better than a circle.
3. How much of the ellipse do you take? If you take a complete half an elipse, that would be whip tillered! You may notice, I usually say 'arc of a circle' tillered rather than 'circular' as the bow doesn't form a circle nor even a semi circle. It can get fairly close to a semi circle, but would probably be stacking badly by then.
4. I think if you try too hard for 'eliptical' it's easy to over do it and end up with the outers working too hard, or whip tillered. I actually go for a very fat elipse or slightly flattened circle when drawing curves onto pics of my bows.

I think it's a useful term to describe what Mike has explained, but it shouldn't be taken too literally.
After all, eliptical with stiff tips and a stiff centre section isn't a section on an ellispe any more!
Del