Stress and performance

[Selfbowman]

Yes Willie I do believe I need some tillering lessons from a few of the guys on the forum. There are guys better at it than me for sure. I’m good at making them bend even but they end up with more set than I like.

[willie]

I think most could learn from you, Arvin.  tillering can be an art.
Do you find the set happening in the same places when it ocurs? perhaps if you could write a little about how you monitor set as you tiller out. where you measure. when you measure etc, detail your procedures a bit more for the reader

maybe the set gets worse as you shoot the bow more?

[Selfbowman]

I think most could learn from you, Arvin.  tillering can be an art.
Do you find the set happening in the same places when it ocurs? perhaps if you could write a little about how you monitor set as you tiller out. where you measure. when you measure etc, detail your procedures a bit more for the reader

maybe the set gets worse as you shoot the bow more?

Willie set never happens til I reach 20 inches of draw . Yes some times the more I shoot in a bow more set creeps in. Usually not more tan than 1-1/2” . On flight arrows maybe I should design a 20” draw. But the arrows have to be 22” long. So you might as well go for at least a 24” draw. I floor tiller to about 20 pounds over desired draw weight then go to the long string never going over desired draw weight.at about twenty inches of draw on long string I brace the bow.then go from there.

[superdav95]

I think most could learn from you, Arvin.  tillering can be an art.
Do you find the set happening in the same places when it ocurs? perhaps if you could write a little about how you monitor set as you tiller out. where you measure. when you measure etc, detail your procedures a bit more for the reader

maybe the set gets worse as you shoot the bow more?

Willie set never happens til I reach 20 inches of draw . Yes some times the more I shoot in a bow more set creeps in. Usually not more tan than 1-1/2” . On flight arrows maybe I should design a 20” draw. But the arrows have to be 22” long. So you might as well go for at least a 24” draw. I floor tiller to about 20 pounds over desired draw weight then go to the long string never going over desired draw weight.at about twenty inches of draw on long string I brace the bow.then go from there.

What Arvin said.  I pretty much do the same thing.  I may vary a little depending on type of bow build but pretty well what Arvin says here for alb or pyramid style and recurve long bows. 

[mmattockx]

I’m good at making them bend even but they end up with more set than I like.

Make one 1/2" wider at the fades than your usual. You pay almost zero limb weight penalty with your pyramid design and the extra width makes a huge difference in the strain on the wood.

tillering can be an art.

Not just 'can be', I'd say it really is in almost all cases.


Mark

[willie]

I think most could learn from you, Arvin.  tillering can be an art.
Do you find the set happening in the same places when it ocurs? perhaps if you could write a little about how you monitor set as you tiller out. where you measure. when you measure etc, detail your procedures a bit more for the reader

maybe the set gets worse as you shoot the bow more?

Willie set never happens til I reach 20 inches of draw . Yes some times the more I shoot in a bow more set creeps in. Usually not more tan than 1-1/2” . On flight arrows maybe I should design a 20” draw. But the arrows have to be 22” long. So you might as well go for at least a 24” draw. I floor tiller to about 20 pounds over desired draw weight then go to the long string never going over desired draw weight.at about twenty inches of draw on long string I brace the bow.then go from there.

Hoping you can clarify about the "not more than 1-1/2""
would that be an additional 1-1/2" from shooting in over whatever set  happened when you finished tillering?

going back to the general question about monitoring set as you tiller:

earlier in the discussion the idea was presented that different limb back profiles should result in different bend profiles (eliptical vs circular etc.) this principle is based on the assumption that all parts of the limb are (or should be) stressed equally.

when the stress is equal throughout the limbs the set should also be equally distributed.

when I started tillering bows I made the typical newby mistakes and overstressd different parts of the limbs creating set in various places. its not hard to pick up one of these bows today and see where the oops occured.

If I were visually inspecting one of your well tillered bows with not much set, I would have a very difficult if not impossible job determining where in the limb set might be more or less than set in another part of the limb, and hence, where one might try to stay a touch wider or thicker next time.

When tillering?
Do you have a predetermined idea or a pattern for what the bend profile should look like?

when you get to 20" and start noticing set.......
are you looking for where the set is occuring and changeing your plan for how the limb bend profile should change?

[Selfbowman]

Willie I very seldom have over 1-1/2” total set. If so it’s a hunting bow that has been strung for hours on end. Still a great bow just has more Set. As far as following a certain bend profile on my tiller tree no. My tiller tree has my record bow traced out strung. When I get it to match that profile at brace  it usually makes a good bow. No matter what the draw weight is. Hundred pounders of the same length take more set. That being said I have only built 100 pounds for flight. They broke records but I think there is room for improvement. As far as where set shows up . I’ve had it thru out the limbs. Fade to mid limbs. My last 9” that has most all of the reflex in it does work out to about 3” from the tips. So I probably over build this area some. You take to much off in this area it will pull out if your not careful in tiller process. I will post a pick of my tiller board but Its posted before. That’s why I am sure some of you guys are better at tiller than me. I’ve tried different methods . One being tiller the bow and take the last couple pounds off at the fades making the working  limbs longer at the fade.ive moved the mass around in 67” for some years.

[Selfbowman]

Pic. I think that was a snake bow . See the shadow in n the left limb about mid limb. If so Bob has that one.

[Selfbowman]

The second pic is unstrung. The tracing above the braced tracing is of my record bow unstrung. So I would say that the bow unstrung took set fade to mid limb.

[Selfbowman]

Three record bows . The selfbow in the middle took no set. The one on the right simple composite boo backed Osage took set thru out the limb. Different design though. The one on the left a complex composite boo back boo laminate gemsbok horn belly took set fade to mid limb. All three 67” long

[Selfbowman]

Simple composite.

[Selfbowman]

Complex composite

[superdav95]

Sweet lookin bows there Arvin. 

[mmattockx]

Sweet lookin bows there Arvin.

+1 on that.


Mark

[willie]

the  record self bow with no set, that design  seems hard to improve on....
perhaps it was an exceptional piece of wood that could take more stress
Marks advice to go 1/2"wider at the fades (and therefore a touch thinner when using wood not up to that quality) to reach the same weight goal, sound like a plan that might be fruitful. that is , if you are still replicating the design.

Didnt you do a bow to some perdetermined specs for someone? Alan maybe? how did that experiment go?


I have rambled on hoping others might share how they evaluate or measure set while tilling.
maybe things are slowing down on the forum...............