English Longbow Help (with image)

[DC]

I would shoot it a bunch, couple of hundred shots, before doing anything else. You may find that after shooting it in that it will be 70#@32.

[markc324]

I was speaking to the fact that your tillering stands at 70#@ 30", leaving some small reductions undone to make weight at your design pull of 32".

Haha, sorry Willie. don't know why I misunderstood it

I light sanded the limbs a bit this morning and then re-check the tiller; it was still fine, so I took her out to the local range. All the archers were thrilled to see the handcrafted bow! I was a bit embarrassed because things could still go wrong with it as it needs to be shot in, to be trained to shoot.

I put 50 arrows through her and she managed to handle that pretty well; no chryshal or splinter raised. My goal was to put 100 arrows through her, but being she is a 70lb'er and with a whole day of tillering workout yesterday, my limbs are much weaker than hers today......

there were two archers I met when I was on my way out of the range. We chatted a bit and became friends. They were generous enough to help me train the bow some more!!

here is a pick showing the tiller after 50 arrows, and surprisingly the set/string follow reduced to just 1" end of today?? it was at 1.5". I've always heard of set increasing but not reducing is this normal?

[Badger]

  If you weren't drawing the bow as far as on the tiller tree it could easily show less set after shooting.

[markc324]

  If you weren't drawing the bow as far as on the tiller tree it could easily show less set after shooting.

i'll look into that. I'm not sure about the two archers who shot some arrows, but for the first 50 arrows shot by myself were pulled to full 30", and I used the 30" arrows so I know if I've drawn it far enough and not over.

[Del the cat]

There are two things, set and string follow.
Set is permanent, string follow recovers after a few hours.
So after a full days shooting you may easily have 1.5" next morning it will be back to 1".
There is a lot of hysteresis in the wood.
Del

[loon]

nice work!

[mikekeswick]

I'm surprised nobody has said but next time forget this 'true arc of a circle' tiller for elbs'  Your tiller should be more elliptical. Elb's taper in thickness. Wood at any given thickness can only bend so far. As wood gets thinner it can bend further. If thicker it can only bend less. Put all that together and apply that thinking to an elb and you have an elliptical tiller. I still think the handle is bending a little too much and mid limb out should be bending more.
The wood will have told you! If you look at where on your bow the set is you get a definitive answer on tiller that is never wrong!
Anyway well done on making a working bow

[willie]

I hope nobody construes "a true arc of a circle at full draw might be a good place to start" as being a given for all elb's. I make no claims to being an authority on elbs, and gladly defer to those with more experience across the pond. The uniform bend idea was suggested as a possible way to hone tillering skills.

[WillS]

FWIW some of the best bowyers in the world specialising in "true" English warbows/longbows and responsible for numerous records tiller their bows to a perfect circle.

[mikekeswick]

FWIW some of the best bowyers in the world specialising in "true" English warbows/longbows and responsible for numerous records tiller their bows to a perfect circle.

Good for them.
As wood gets thinner it can bend further before taking set. There are ways to prove this scientifically but simply watching set will tell you that an elliptical tiller is correct for any elb 30# or 130#. If you think about it it is quite obvious really   I guess where a lot of people get hung up is on the amount of progressive bend needed - it isn't a huge amount. I suppose it is easy to think in back and white when actually we are talking about shades of grey.

[willie]

mike
does this progressive bend add anything to the performance or handling of the bow? could you point to a photo that exemplifies this nuance of tillering?
thanks
willie

[Ian.]

Bend a small piece of wood and it will return to shape. Bend a massive piece of wood and it will break long before it bends much at all.

[Wooden Spring]

We talk a lot about bows bending in an "arc of a circle" but the only true way to do that without the bow suffering undo fiber stress (exploding) is to taper a bow's width with a constant thickness. Whenever the bow's thickness is tapered, it will always bend into an ellipse provided that the fiber stress is even along its length.

Remember: R/T = E/2S
Where:
R = radius of curvature
T = Thickness
E = Modulus of Elasticity
S = Modulus of rupture

Your bow looks fantastic to my eyes.

[willie]

Wooden Spring

"it will always bend into an ellipse....." seems like a bit of an absolute. I was under the impression that if the thickness taper is too litttle, then the bend happens more at the handle, and if too much, then more bending happens towards the tips. Isn't there a thickness taper that gives the circular bend? Of course we often taper both the thickness and the width, and I am sort of partial to a constant thickness taper, where the tips are 1/2 the thickness of the handle, combined with some width narrowing in the outer third of each limb,at least for a bow that is 2.3 longer than the draw length, as over drawing and under drawing seem to change the relative shape.

willie

[Wooden Spring]

Wooden Spring

"it will always bend into an ellipse....." seems like a bit of an absolute. I was under the impression that if the thickness taper is too litttle, then the bend happens more at the handle, and if too much, then more bending happens towards the tips. Isn't there a thickness taper that gives the circular bend? Of course we often taper both the thickness and the width, and I am sort of partial to a constant thickness taper, where the tips are 1/2 the thickness of the handle, combined with some width narrowing in the outer third of each limb,at least for a bow that is 2.3 longer than the draw length, as over drawing and under drawing seem to change the relative shape.

willie

Well, we live in a universe governed by laws, whereby everything that moves, moves according to universal and absolute principles established at creation, and mathematics is one of the tools that we have of making sense of those laws - the structure and motion of an archery bow are just as absolute as the laws of thermodynamics.

One may well get a thickness tapered bow to bend in the arc of a circle, but the inevitable result will be that it will suffer uneven fiber stress. It is the reason of uneven fiber stress that is why a Welsh Long Bow is not the most efficient of bow shapes. This is not to say that it isn't a "good bow," it's just not very efficient.

A bow's thickness may be obtained by
T = [(2S))]/E
Where:
T = Thickness
S = Modulus of Rupture
E = Modulus of Elasticity
R = Radius of curvature at a particular point along the limb

It's width may be defined by
W = (6PD)/(S)(T)(T)
Where:
W = Width
P = Tension in string (about 12% more than draw weight)
D = Distance in inches from the fade to the string measured perpendicularly to the string at full draw
S = Modulus of Rupture
T = Thickness