A line of diff. tiller shapes

[4dog]

overrated Dragonman...overrated...lol

[simson]

Haven't thought this post gets so much interest ...

Many thanks to all of you guys!

Some of you asked for more pics. I will do so, but it will take some time.
I think it is the best to post the pics in extra threads. I have pics from bow No. 5 which I post now. The others came in a few days (I'm not at home this weekend).

Thanks again!

[burchett.donald]

Simson, Those are all beauties and I can't find a flaw in your tiller as usual...Wonderful work, and I think this would be an excellent "Sticky note" at the top of the page for reference to tiller...Enjoyed looking
                                                                                                     Don

[Del the cat]

If front profile has no bearing on tiller profile, does that mean you tiller a Mollie the same as a pyramid? 

Of course you don't...
BUT...
The different tillering is because the outer limb is is left thick and unbending... not because it is narrow.
The curve tiller shape isn't because of the front profile.
If it was because of the front profile a Molly would have a horrible hinge at the start of the lever and be hugely whip tillered.
Thickness is self evidently 8 times more important than front profile as stiffness is proportional to the cube of thickess.
Thus you could make a bow with any front profile and still achieve any shape of curve you wanted by tillering thickness.
The Mollys and paddle bows actually prove my point rather than showing the opposite.
I could make a bow 1" wide in center tapering out to 2" wide at the nocks tillered full compass , if I could be bothered!
Del

[4dog]

The Cat must build it...The Cat must build it!!!!!   

[Josh B]

We are discussing two different things Del.  I misunderstood what you were saying.  Of course you can tiller it to what ever side profile you want regardless of front profile.  I completely agree on that.  My point was to maximize the efficiency of the bow, you need to adjust the tiller profile to match the front profile.   That's why I used the comparison of the Mollie and the pyramid.  They both perform great if the tiller matches the design.  If you were to tiller a pyramid bow with a Mollie tiller or vice versa, they probably wouldn't work so well.  Josh

[Del the cat]

Anyhows, I've done it...
Here:-
http://www.primitivearcher.com/smf/index.php/topic,45989.0.html

@Gundoc, I wasn't having a go at you, it's just I've heard the 'front profile' thing so many times and I think it causes huge confusion and missunderstanding.
Del

[PatM]

There is a bow with that profile in the Western Indian bows of TTBB.

[simson]

Some of you brought an interesting discussion:
Should the front profile match with the side profile?

IMO yes, but it is no dogma.
Here are my thoughts:
When we build a bow, we make it only that long as necessary to save limb mass. To make it as short as possible we should get all parts of the limb working (= bending). Bending wood means getting stress on belly and back. Of course it is the best to spread the stress all over the limb from tip to handle and also sideways from one edge to the other. The best design is to get equal stress on each wood cell, but the farther you come away from the neutral plane, the stress you get (increasing exponentially). In other words: the goal is to minimize set/stringfollow.

Of course you can make a bow with parallel limbs, or even with an inverse side taper as Del (http://www.primitivearcher.com/smf/index.php/topic,45989.0.html) made. You can get bending these experiments quite fine, but ….

you will get bows with very narrow parts near the handle
narrow limb causes thicker limb
thicker limb = more stress
more stress = more set in these parts
To get set here near the handle is the worst thing, because the effect on the whole bow is the strongest.

Hope I could explain that with my crude English.

Thanks all for your input!

[Josh B]

@Gundoc, I wasn't having a go at you, it's just I've heard the 'front profile' thing so many times and I think it causes huge confusion and missunderstanding.
Del

I never took it as such Del.  If I post up something that is questionable, I welcome those questions.  If I'm wrong, by all means correct me.  This not only helps the beginners, but helps the community as a whole IMO.  I'm here to accomplish two things, help others where I can and improve my own craft as well.  I knew there was some confusion on the front profile/tiller subject.  What I didn't understand is where that confusion came into play.  Now I understand.  Some were under the impression that the front profile created the tiller, when in actuality the tiller should be adjusted to get the most from the front profile design.  Josh

[Del the cat]

Some were under the impression that the front profile created the tiller, when in actuality the tiller should be adjusted to get the most from the front profile design
Very well put, clear and concise
Del

[simson]

Uooops, now I see what you have meant, Del.
Excuse my silly words. If I have read it closely ...

Thanks for clarifying this