REALLY tiller on the edges?

[Del the cat]

Sorry Del, I kept saying "we" as if I had something to do with this experiment. 

No no not at all... I want it be "WE" I'm cocky enough to think I know the answer, but it would be fun to get some pics... heck I could edge light the bows with disco lighting...
No point me doing something and then others saying' yeah but you diddn't do this or that.
Anyhow I should apologise for taking over the thread.
Should I put it up as a fresh topic?
Del

[DC]

If you shine a torch (note the correct term) on one of the cut edges it will illuminate all other cut edges won't it?

[bubby]

If you shine a torch (note the correct term) on one of the cut edges it will illuminate all other cut edges won't it?

a fiber optic arc

[Del the cat]

Could be all the rage in Christmas decorations...
I expect I'd need to polish the edges... we'll see. Maybe it will become an after Christmas project.
Del

[scp]

Actually Knoll who started the thread can do the test for us, if he is willing to draw the curvatures meticulously on a sheet of paper by following it on a tillering tree after narrowing the triangle enough to be discernable. I would like to know what kind wood he has and how long is the stave. Once he reached his target draw strength but not his draw length, he can draw the line following the curvature of the limbs. After that he would be pulling less and less in poundage but same in draw length to matched the drawn line and see if the curvature stays the same even though the poundage is less and limbs are narrowed. He has to remember that the start and ending points of the lines should be same for all lines. I expect to see just one thick line.

[Jim Davis]

If one wades through all my posts on this topic, I THINK it will be found that I reported Klopsteg et al as describing a limb that tapers to a point, modified to run parallel from where the lines reach the width that the nock needs to be.

So for your test, the taper should run right to the point, or aim for the point and stop narrowing when the sides are the width the nock should be.

BTW, just by  way of disclosure, I have done this experiment with thin hickory slats with the results I expected. Your experiment should be even better because the material you plan to use is more uniform than wood. I look forward to seeing the results.

Jim Davis

[Knoll]

My bow is hard maple.  It's a Christmas gift and, being that we're well into Dec., there's no way I'm gonna commit it to an experiment.     Hopefully, it'll be "harvesting" forest rats next year.

It'll be interesting to see Del's results!!

[mikekeswick]

To be honest Del I don't think it's worth bothering. We all know the answers! It really is quite simple as I stated earlier - thickness determines bend. As a material thins it can bend further. It's just common sense really. 
The theoretical pyramid bow with no thickness taper goes to a point.
I've pretty much always made my bows following the 'thickness rule' and the set that the bow takes is as much of an indicator as is needed.

[Del the cat]

If one wades through all my posts on this topic, I THINK it will be found that I reported Klopsteg et al as describing a limb that tapers to a point, modified to run parallel from where the lines reach the width that the nock needs to be.

So for your test, the taper should run right to the point, or aim for the point and stop narrowing when the sides are the width the nock should be.

BTW, just by  way of disclosure, I have done this experiment with thin hickory slats with the results I expected. Your experiment should be even better because the material you plan to use is more uniform than wood. I look forward to seeing the results.

Jim Davis

Yes I can mark the taper to a point at the nock, but obviously it will have to be thickened locally and extended a tad to allow stringing.
Ah, I can see the caveat "tapers to a point" makes a big difference rather than just "narrowing the triangle doesn't effect the curve" The latter statement allows wider tips and was the subject of a discussion about thickness vs width taper of the working limb in a molly.

Maybe I can simplify the test to two extreme cases 4" tapering to zero and 1" tapering to zero.
Del

[PEARL DRUMS]

After reading threads like these I wonder how my dumb a$$ ever gets a bow to stay together.

[PatM]

Luck Pearlie, dumb luck.

[Badger]

After reading threads like these I wonder how my dumb a$$ ever gets a bow to stay together.

    Pearlie, you are proably one of the best examples of why these discussions exist. I don't think anyone is consiously thinking about all these things when building a bow but if they have been doing it for a while they know the principles behind building one and the techniques they need to use. Your bpws pretty much conform to sound principles, you most likley picked up your style of building through experience and looking at other bows you liked.

    When you are stepping way outside your comfort zone with either a style of draw weight this is where having some knowledge can come in handy. If you are new everything is outside your comfort zone. Luckily you will have plenty of examples of successful bows you can refer to and use as a refference.

    Not all the rules we use have to do with stressing the wood, a lot of the rules relate to efficiency. Example s light stiff tips will usually outshoot heavy wide bending tips.

     Most of the mantras that folks actually think about are because they make good sense.
 " thickness determines how nuch wood can bend" "Width determines how far it will bend". 

   "tiller shape should match front profile"  is saying the exact same thing as above.  These mantras help to achieve even stress in the wood as best as possible. 

    Some of the interesting arguements come in about best possible performance when it comes to tillering and stress on the wood. I feel like too even of stress over too much a limb makes it easier for the limb to occilate and vibrate costing some efficiency. I can't prove it because I don't know how. Some of my fastest bows have not been good example of proper tillering.

    I am building one right now for a lady, same demensions that I would normally use for a 70# osage except ths one is only 35#@28. The overall mass is comming out at about what I would normally expect from a 35# bow contradicting a lot of things I have said in the past. Bow is not taking any set and hopefully will be a good shooter.

[bradsmith2010]

Badger, is it because the mass of the piece of osage is more like hickory?

[PEARL DRUMS]

Luck Pearlie, dumb luck.

Guilty as charged Pat. Im just a hard-headed German guy that never stops trudging ahead until I get/see what I want. 

[scp]

My bow is hard maple.  It's a Christmas gift and, being that we're well into Dec., there's no way I'm gonna commit it to an experiment.     Hopefully, it'll be "harvesting" forest rats next year.

It'll be interesting to see Del's results!!

Knoll, what I have described is just another way to do "no set tillering". Doing the "experiment" will help you make a better bow and it's the safer way to tiller than just trying to make the curvature look good.

But, we need to clarify one thing first. It appears that Del is assuming that we are going to reduce the width of sides evenly, thereby changing the proportions of the widths at fades and at tips. If we do that, of course, the curvature would change. We are assuming that we are going to keep the proportion intact when we say "narrowing the triangle doesn't effect the curve". If we also assume that wood is practically uniform, there is almost no need to do the experiment.