chrysal season

[sleek]

Making a classical American flatbow, you are scraping and guessing all the way.

Jim Davis

  Hardly. No matter what type of selfbow you make you're not cutting it out with a cnc machine.

As a cnc machinist, challenge accepted.

Now, where is some perfect osage?

[bradsmith2010]

i like the idea of making the belly slightly rounded for the high crown,, I need to keep that in mind,,

[Jim Davis]

Making a classical American flatbow, you are scraping and guessing all the way.

Jim Davis

  Hardly. No matter what type of selfbow you make you're not cutting it out with a cnc machine.

No, but you could cut out a pyramid bow that way and it would be ready for the short string right off the machine. I work mine down to about 9/16" thick and they are usually very close to finish tiller. Usually just a matter of smoothing them up and fine tuning. The straight side taper and uniform thickness involve arithmetic ratios. A thickness taper involves exponential ratios--exponentially more skill and care required.

[PEARL DRUMS]

It all depends on who you are, what you know and your personality type. Its just who we are and how we see things. Different brains approach tasks differently. I consider my tiller-eye quite accurate and guessing isn't a part of any equation. I've never made a pyramid bow and probably never will. Tillering is one of my favorite aspects of self bows. Nothing I like more than helping or teaching tillering.

[willie]

slightly rounded seems work for me, as I also find it a little easier to take the belly down that last little bit when it is rounded some.  Has anyone experienced any demonstrable benefit to keeping it super flat?

btw, Thanks Mark for describing possion effect in plain english.

Frodolf, even though the summer humidity change is not all that drastic, could the edge of the bow be most affected by humidity, due to its thinness?

Jim- I have found that wood free from obvious defects can be remarkably uniform, and agree that consistent thickness (tapered or straight), is the most critical aspect of tiller longevity.

[PatM]

Making a classical American flatbow, you are scraping and guessing all the way.

Jim Davis

  Hardly. No matter what type of selfbow you make you're not cutting it out with a cnc machine.

No, but you could cut out a pyramid bow that way and it would be ready for the short string right off the machine. I work mine down to about 9/16" thick and they are usually very close to finish tiller. Usually just a matter of smoothing them up and fine tuning. The straight side taper and uniform thickness involve arithmetic ratios. A thickness taper involves exponential ratios--exponentially more skill and care required.

    You could  also do it with an American flatbow. A CNC machine has no trouble with math after it's programmed.
 But I can tell you really love the process of bowmaking.

[Jim Davis]

Actually, though I  have probably made 200 bows since 1997, I like shooting much better!

[SLIMBOB]

I'm with PEARL.  Most of mine are closer to parallel than pyramid.  I have no problem with either, but there is very little guessing on the thickness taper beyond roughing it out.  The rest is a pretty methodical process. 

[Frodolf]

I know, George. That's what I mean by perfect tiller – each part of bow doing its part of the work, no matter if it's parallel or pyramid, wavy, snaky, knotty, etc. I'm pretty used to character staves and their challenges. My experience as a bow maker – which I would hardly call extensive, but thorough enough – has led me to start questioning the common explanations as to why bows fail in compression. Simply because the failures I've had do not often fit the common explanations. It's like the data that I've gathered over the years don't quite fit the theory, which makes me want to rewrite the theory. I don't know in what ways yet, though... Was sort of hoping I wasn't the only one with odd examples of compression failures that seem to deviate from the rules...

Willie, that's a good point! I've never thought about that but it makes sense.

I too agree that that there isn't much guessing involved in tillering. I always make sure to look at the bow in many different angles before removing wood. I often use pencil lines drawn with a ruler on the side of the limb to help my eyes see past too much character. But maybe "guessing" was just a poor choice of words? It's still not math based but based in one's ability to see shapes. That can appear to be guess work. I think the more experience you have the less guessing it becomes.

[Jim Davis]

The guessing I'm thinking of is in how much to scrape to correct what can be seen in the curvature of the limbs. It's a guess that becomes less uncertain with experience. But it's not a matter of making straight lines and even thickness. The latter takes less skill. That's all I was trying to say.

Those of you who make American flat bows and other bows with parallel limbs have to be more skilled than what is required to make a bow with uniform thickness.

Really hard for some of you to take a compliment, isn't it!   

Jim

[Frodolf]

Hahaha! Point taken, Jim!