When the tillering goal is no set

[willie]

I used the yard stick method on this build early on to get me to good clean brace. Once there i knew i was headed in a good way with this bow.  I also paid very close attention ..............  The yardstick method bassically takes overall bend of each limb independently for consistent bend and then comparing them with each other. using the straight edge of the yardstick laid accross the belly of the bow while bent to get a good view of the bend early on has helped me creep up on it. 

Hi Dave,

is this the yardstick method you mention above?  seem to recall a post where you mentioned more about your method, but cant find it now.
http://www.primitivearcher.com/smf/index.php/topic,72512.msg1016923.html#msg1016923
perhaps

[willie]

I don't get in a hurry tillering a bow, it is a week project of shooting and checking for the slightest anomaly with my gizmo, I am only using 220 grit sandpaper at the end of the tillering process.

I got a few 1/2 finished builds in the corner from being in a hurry and  gotta say that 220grit for tillering suprises me.  80 grit here.
when I take a break from tillering because my eye tell me two different things, breaking for another cup of coffee doesn't help.

[Eric Krewson]

I should have mentioned; that 220-grit paper is on an orbital sander, not hand sanding.

[superdav95]

I used the yard stick method on this build early on to get me to good clean brace. Once there i knew i was headed in a good way with this bow.  I also paid very close attention ..............  The yardstick method bassically takes overall bend of each limb independently for consistent bend and then comparing them with each other. using the straight edge of the yardstick laid accross the belly of the bow while bent to get a good view of the bend early on has helped me creep up on it. 

Hi Dave,

is this the yardstick method you mention above?  seem to recall a post where you mentioned more about your method, but cant find it now.
http://www.primitivearcher.com/smf/index.php/topic,72512.msg1016923.html#msg1016923
perhaps

Yes it is the same.  I’ll also add that I like to shoot 1/2 draw, 3/4, then full draw working my way up to full after several shots.  This helps me get a good feel for the bow and sort out many of the inconsistency and anomaly that are seen and felt.   I’ve had it that I had a perfect looking tiller balance visually going on at brace and 3/4 draw shooting only to end up with slight positive tiller because it felt smoother and shot cleaner.  This is where the 220 grit paper comes into play I think too in fine tuning.  I find this works well with my bamboo builds too not just stave wood bow builds.  I also make sure I round slightly my edges and sand with 180-220grit after each wood removal in tiller process.  Just how I do it.  It allows me a clean smooth belly to visually pick up on any early issues. 

[sleek]

Whether a bow takes set or not is often decided before it ever bends.  The bows are built either too narrow or wide enough to take the load. If your bow took set, 100% of the time it is because it was not wide enough to handle the stress. Even if the bowyer made an error in the tillering process and made a hinge, the bow is not wide enough to handle the bending load focused in that one area. While most would say, or its taken set due to the hinge, thats incorrect. The hinge is a thin spot and thickness controls bend radius, not draw weight. Draw weight, aka, set control, is 100% a factor of the bows width, ALWAYS.

So, if your bow took set, build another one thats wider. It will 100% take less set assuming the same quality of wood.

[willie]

So, if your bow took set, build another one thats wider. It will 100% take less set assuming the same quality of wood.

Hi Kevin,

we have all built another, and this type of learning gives us a better understanding,  or maybe you would call it intuition or judgement. But the next bow is not always quite the same or comes from a different stave etc....

I hope to find a more quantitative approach to detecting the working stress limits of wood before the damage is done. 

I think that somewhwere in between overbuilding with excess mass and the point where set shows you the damage done.... is a range of working stress.

 Maybe for a hunting bow that shoots sweet with heavier arrows and gets the job done, this is not such a big issue, but I am seeking a method to help build a bow that shoots a very light arrow for flight shooting and needs to get the fastest limb speed at the end of the powerstroke --  A bow that retains and can make use of the high early draw weight so often lost before set shows its ugly head.

[sleek]

Willie, for the last 7 or so years i have been looking for a way to do exactly what you are after. I think I have a formula that allows you to build a bow that takes no set. I have asked a few people to help me proof the formula and they are working on it. Once proofed Ill let the information be known, but I dont want to let bad info out, so please pardon my vagueness.

If you want to help, and you sound like a guy looking for the answers, you can tell me the wood you are going to use, the draw weight, and the bows length. Ill run the numbers and you buuld the bow. I find im right with about 5 to 10% margin for error. Im looking to tighten that up but some things are out of my control, wood quality, error in craftsmanship, etc.

[willie]

Willie, for the last 7 or so years i have been looking for a way to do exactly what you are after. I think I have a formula ......you can tell me the wood you are going to use,

If I told you birch or osage, would your formua use a book value?

While most would say, or its taken set due to the hinge,

but doesnt one have to know the correct bend versus "too much bend for the design"?

[sleek]

Willie, for the last 7 or so years i have been looking for a way to do exactly what you are after. I think I have a formula ......you can tell me the wood you are going to use,

If I told you birch or osage, would your formua use a book value?

While most would say, or its taken set due to the hinge,

but doesnt one have to know the correct bend versus "too much bend for the design"?

Yes, there are book values for each different species already available that I plug into the formula.

The idea of too much bend for the design cones from the incorrect idea tgat thickness has anything to do with draw weight. You can thin a bowout unti the bow mends into a complete circle, if it has the correct width, it will take no set.

[Selfbowman]

Kevin we will get with you on one coming up. Finalizing the design.

[willie]

The idea of too much bend for the design cones from the incorrect idea tgat thickness has anything to do with draw weight. You can thin a bowout unti the bow mends into a complete circle, if it has the correct width, it will take no set.

I agree that too thick for the bend radius will cause set.  I dont really understand what you are saying beyond that.

[sleek]

The idea of too much bend for the design cones from the incorrect idea tgat thickness has anything to do with draw weight. You can thin a bowout unti the bow mends into a complete circle, if it has the correct width, it will take no set.

I agree that too thick for the bend radius will cause set.  I dont really understand what you are saying beyond that.

I was in a hurry and had all kinds of typos. Your take away is the core of it all though.

[willie]

Willie, for the last 7 or so years i have been looking for a way to do exactly what you are after. I think I have a formula that allows you to build a bow that takes no set. I have asked a few people to help me proof the formula and they are working on it. Once proofed Ill let the information be known, but I dont want to let bad info out, so please pardon my vagueness.

If you want to help, and you sound like a guy looking for the answers, you can tell me the wood you are going to use, the draw weight, and the bows length. Ill run the numbers and you buuld the bow. I find im right with about 5 to 10% margin for error. Im looking to tighten that up but some things are out of my control, wood quality, error in craftsmanship, etc.

Kevin I have started a topic in the flight section where you can run your numbers on a bow we will build virtually.