Tiller shape vs front profile

[BowEd]

Yep you can put all the figures and dimensions to a bow you want but when it comes to bending and tillering it that goes out the window for final dimensions when tillered.Then it's by eye and feel and there is always a bit of majic to it then.

[RyanY]

How do you tiller a heavily  scalloped bow?

This is a great question. I think there’s two ways I would go about it.

The simple version would be approximating the bow based off of the narrow sections of the limb to avoid set or breakage in those areas and tiller to a shape based off of that.

The more complex version would split the bow up based on a couple approximations. The limitations of the inner limb are the narrow parts of the scallop given that moving mass doesn’t matter as much here. The opposite is true in the outer limb where the wide portions of the scallop are more detrimental to efficiency due to excessive mass. Even though the wider portions of the inner limb could bend to a tighter radius with low set by being thinner, this would increase the movement of the outer limb robbing efficiency. The narrow portions of the outer limb are more similar to an average bow and as a result can bend to a fair degree. To make outer limb mass movement more efficient it might be possible to squeeze more bend out of the wider outer limb sections to result in a more elliptical shape assuming relatively parallel or mildly tapered limbs similar to existing scalloped bows.

I don’t know what a “Heavily scalloped bow” is to you but I think in general these ideas could guide the tillering thought process. No doubt any tillering of specific sections of the limb would be technically extremely difficult due to the small margins of thickness and varying tapers along the limb. Given that there’s not a perceivable performance advantage that I can tell due to the nature of having areas of excessive and nearly unusable width, I’d always go for the first method.

Speaking of unusable width, mollegabet bows with sharp transitions from a wide working limb to a narrow stiff outer limb likely have inefficient use of the wood in that area for either low set or mass movement.

[BowEd]

I'm not into quessing.I'm into testing.

[RyanY]

I'm not into quessing.I'm into testing.

I look forward to seeing your multiple tests of PatM’s heavily scalloped bow. Does an n=10 seem reasonable? 

[Kidder]

Willie - I’m still here. Just mentally processing these things. I started out in engineering and made it about 3 weeks until my calc professor told the class to “forget everything we’ve covered so far - it was supposed to be for a different class.” It was that point that I went in a different direction that led me to the law. So needless to say, I don’t have the background that makes studying these things easy. For me it is about art - from seeing the bend, to shaping, inlays, overlays etc. But that doesn’t mean that I don’t want to understand it on a mechanical level, just that that aspect doesn’t come as natural. I’ve also learned a ton from this thread. I’m not looking to “build bows by number”, just looking for any way to enhance what I find an incredibly enjoyable craft and “craft” bows that are more durable, faster, lighter or whatever the goal is. Having that knowledge will help me utilize understand the path to the goal. So thanks to all for contributing, even if a good portion is at the edge of my comprehension, and frankly disputed. As a side note, I find it interesting that there are those who can function on such an advanced mathematical level and still be drawn to wooden bows opposed to glass. We are an interesting group for sure...

[bownarra]

This is amusing to read, going down all sorts of rabbit holes.......these threads show the problems with not talking face to face.....
The 'answer' to all this is really very simple.  Follow the set mantra and listen to the wood. It will always show you whats going on - it can't do anything else!

[willie]

Willie - I’m still here. 
I went in a different direction that led me to the law. 
I find it interesting that there are those who can function on such an advanced mathematical level and still be drawn to wooden bows opposed to glass.

I find natures composites more intriguing than glass or metal.  What makes it fun for myself is it is not often one gets to design something right to the limit of breaking, with no harm done if it blows.

[scp]

Speaking of unusable width, mollegabet bows with sharp transitions from a wide working limb to a narrow stiff outer limb likely have inefficient use of the wood in that area for either low set or mass movement.

I also find that transition interesting. It's rather appealing to senses, but problematic in execution. The width narrows rather sharply when the thickness increases gradually. Way too complex for me to begin to understand how those curves would look in mathematical formulas. For that matter, I even have no idea how to describe mathematically the simple but graceful bend of bow limbs in full draw. Either forgotten or more likely never learned.

It would be much simpler if the width can be narrowed gradually as the thickness increases gradually, according to the need. But the change in thickness matters much more than the change in width.

See, https://www.primitivearcher.com/smf/index.php?topic=65396.0

Intuitively, I see the efficiency of the Eiffel tower transition, not inefficiency.

[Don W]

Last night I decided to join Clay Haye's patriot site. I'll just cut my beer intake in half to cover it.

So how is this relevant? He has a new video on using calipers to help tiller. He calls it "micro tillering". As with most of his stuff, he doesn't have great detail.

I started college in a civil engineering track, and took classes on truss design, so I don't necessarily agree that wood is to unpredictable to formulate or calculate a predictable design given some assumptions. I barely made it through those classes, I could always (well, maybe not always) come up with the answers but could never show how, and the professors didn't like that. Along with really not being experienced enough making bows, I am not sure where to start, but I really think some old school commenters are really missing an opportunity to help further the craft. There is nothing wrong (imo anyhow) with bringing modern ideas into and old craft. One can choose to use them or not, just like we choose modern broad heads or stone.

[Del the cat]

... but I really think some old school commenters are really missing an opportunity to help further the craft...

I really think you are making assumptions about how some old school commentators practice their craft!
Del (an old school commentator who does know the value of a cube root and can use a set of vernier calipers!)

[Don W]

... but I really think some old school commenters are really missing an opportunity to help further the craft...

I really think you are making assumptions about how some old school commentators practice their craft!
Del (an old school commentator who does know the value of a cube root and can use a set of vernier calipers!)

It wasn't a comment on how they practice their craft ( see the comment on "One can choose to use them or not") it was a comment on how they advance said craft. It's ok to want to stick to the old ways. There really real really is nothing wrong with that. The problem arises when they insist that everyone do the same.

[PatM]

  The work of Hickman et al covered a lot of this decades ago in Archery The Technical side.

 In fact when Torges and Baker started sniping at each other the comment was made  by Torges that Baker was lucky that the  copyright had expired or he could have been caught with plagiarizing.

[scp]

... but I really think some old school commenters are really missing an opportunity to help further the craft...

I really think you are making assumptions about how some old school commentators practice their craft!
Del (an old school commentator who does know the value of a cube root and can use a set of vernier calipers!)

It wasn't a comment on how they practice their craft ( see the comment on "One can choose to use them or not") it was a comment on how they advance said craft. It's ok to want to stick to the old ways. There really real really is nothing wrong with that. The problem arises when they insist that everyone do the same.

Actually it's the other way around. Most people here, including old timers, are rather well acquainted with mechanics, basically using ordinary language terms. Things get murky when some people tries to use higher math and physics to answer questions that are basically about skills, craftsmanship, or at most mechanics.

In my view, their math and physics are not quite mature enough to answer questions in bow making with natural materials. Otherwise we would have robots making character bows. But the money is not there. There are much more effective ways to kill people than using wooden self-bows.

[Del the cat]

@ DonW
No one (AFIK) is insisting that everyone do the same.
A lot of us others spend a lot of time trying to not only help newbies advance their craft, but also advancing their own.
I'm always careful to point out that how I do things is NOT the only way, and I'm only too happy to learn from others.
I do however try to keep it simple and based on practical demonstrable theory and experiment.
Del

[scp]

  The work of Hickman et al covered a lot of this decades ago in Archery The Technical side.

 In fact when Torges and Baker started sniping at each other the comment was made  by Torges that Baker was lucky that the  copyright had expired or he could have been caught with plagiarizing.

No need to worry about that. Tim Baker is basically using ordinary language words to explain some technical stuff in his own way.

But as his bow making skill is improved, it's the scientists who need to explain what he is doing correctly in technical terms, preferably after producing bows of his caliber first. If the ordinary language terms work for him, most bow makers simply need to learn that language, no matter how vague or ambiguous it might be. There is no need for them to translate the language into scientific terms that might be still too immature to work on natural materials used in artistic ways.