"which tiller is better for what?"

[mikekeswick]

Tiller profile is dictated by the width profile of the limbs. What I said above about set is really all there is to making nicely strained bows.
The wood will always tell you if you have done a good job of tillering a bow. You just have to watch set as it starts to show up. I like to trace the profile of a bow before bending it at all so that I have a definite reference of where exactly along the limbs the set is. Also when I say set I'm talking about the first hints of set not 2 inches! Only tiny amounts but they tell you with no second guessing where the strain is highest.
Elb's and heavy arrows go hand in hand not because of tiller profile per se but because the limbs are long and therefore heavier and slower moving than a shorter bows limbs and need a long heavy arrow for decent efficiency.
Badger I know what you mean. Although my fastest bow yet seems to be doing well with the light arrows (split cane). 75# ish and 200 - 240 grain arrows are going around 350 - 400yds. It is doing 250fps with 5gpp.

[Badger]

   A few weeks ago I built an elb for Josef to flight shoot. He got one world record in the simple comp broadhead class but missed the ELB flight record. He told me that he was hitting over 440 yards regularly durring his practice session but only scored 380 something yards in the official shoot. This bow is 90# @26"  and is 66" long.

   Mike your bow is doing very well and would be a cood candidate fo a world record. Especially in the new 70 class.

[BowEd]

Yes I've noticed too the standards have definitely been raised from the first Mojam.Monitoring set makes the difference.Many very good bow makers on here.
To me now though a 500 grain arrow is not that heavy really.I'm sure it's because I don't flight shoot at all and am not familiar with the rules  etc. account for that.What weight arrow did the 90# bow shoot?

[George Tsoukalas]

willie,  bows with parallel limbs or pyramid limbs will shoot just as well provided they are tillered well.

What does tillered well mean?

I and others have outlined that in the previous thread so that ship, seemingly, has sailed? But read on.

After 35 years of teaching and answering questions I sense that there is another underlying question that's bothering you.

I just can't get a handle on what it is.

If you start out with parallel limbs tiller elliptically. If you start  out with pyramid limbs go for a circular tiller. Its personal preference. This is so set is kept to a minimum.

I prefer parallel limbs; with pyramids I have  a hard time getting the circular tiller that is needed.

Like Steve I often tiller both from the belly and the sides even on parallel limbed bows..

For example, if I start out too wide for the strength of the wood the stave stops responding to belly wood removal. So to keep the stave from getting to thin I begin to narrow it. My parallel limbed bow ends up slightly pyramid.

We are creating an artificial dichotomy for teaching purposes.

Just make bows and let the wood dictate how it wants to be.

Jawge

[Badger]

Beadman, all broadhead bows shoot 500 grains regardless of weight. I shoot in the 50# class so for me I am shooting 10 grains per pound. A 100# bow is only shooting 5 grains per pound. In regular flight you can shoot any weight arrow you want.

[SLIMBOB]

This has been a good post and I have enjoyed reading all the opinions.  I think most everybody has touched on an important idea or 2.  For me, set tells the story.  Keeping that to a minimum starts with the proper design for the bow you want.  Part of that is wrapped up in front profile.  I personally like the bow Ed mentioned.  Semi parallel to mid limb, so elliptical tiller (low set inner limbs), then a nice taper to the lever like reflexed tips.  Monitor set as Mike mentioned all through out the build and keep it to a minimum while keeping the mid (pyramid) to outer limbs (lever) as light as possible.  Finesse the tiller from start to finish and get it as close to ideal as possible from step one, all the way to the finish line.

[bradsmith2010]

about the first Mojam standards,, well,, most the bows were shooting b 50,, and thick hunting strings,,
the bows werent really set up for speed,,
I think the bows would have shot quite a bit faster with just a bit of fine tuning
I know the bow I shot had a 16 strand string and silencers,, well anyway,,
 I think if with Badgers release and some fast flight or more linen,( I think Tim shot the only linen string) the results would have been closer to what we see today,, just my thoughts,,

[Badger]

  Brad, I think you are probably right. Tim gave me a list of all the results and I was really surprised at how low most of them were. B 50 and linen are actuall pretty close in speed even though linen is non stretch, string weight seems to be the biggest factor. I found with fast flight for every 1 strands I remove I pick up about 3/4 of a ft per second in speed. One big factor in performance was the older bows tended to be wide and flatter and bend all through the limb. Thse loose quite a bit to vibration. If you go back about 70 years the bows being made then would be on a par with the bows being made now. Those guys were making some really nice osage and yew bows ithe 1940's and 50's.  Thin outer stiff limbs, a little reflex. Great shooters.

[bradsmith2010]

wow thats cool, that the older bows shot that well,, nice to know,,I guess when the figerglass came out ,,some of the wood making got a little lost,,

[willie]

I sense that there is another underlying question

 yes George, there is something that I am trying to understand better. I will try to explain.
 with all due respect to Mike, whom I quote below, I think that some of the "dictations" need qualification.
 
 

Tiller profile is dictated by the width profile of the limbs.

 This is certainly true if a constant thickness taper is assumed. It is the physics or beam theory that he mentioned earlier.
 
  Let's for the sake of a thought experiment, consider a pyramid bow that is almost tillered out. It has the desired circular profile that is considered correct for the width shape, and the assumed constant thickness. If I then thin the thickness of the mid to outer limbs, they will come around more into an elliptical shape considered "proper" for the straight limbed bow. Have I created set anywhere by doing this?

  Or consider the opposite width profile, a straight limbed bow with the preferred stiffer inner limb. Will thinning that inner limb to make the overall appearance more circular create set? Only if I go too far and create a hinge. For the sake of examining tiller profiles, Lets assume that we can tiller either limb to any profile we want
 
  The purpose of this "experiment" is to try to separate the out the reasons or (at least, suspicions), of whether one kind of tiller profile might outperform the other.  There are two things that come to mind. The first being the mass distribution of the limb.
 
 

not because of tiller profile per se but because the limbs are long and therefore heavier and slower moving

 Mike states the case for heavy arrows well, and others have mentioned  similar logic. Heavy arrows are a joy to shoot, taming the vibrations of the limbs, and extracting efficiency from the bow. They can also be uninteresting.
 
  Considering the case for light G.P.P arrows seems a bit trickier. Ignoring the weight distribution "dictated" by the back shape. (I know, that's a co-premise to what Mike actually said), Is there anything inherent in tiller shape it'self, or the way the limb "unwinds" and returns it's energy to the arrow, that can be ascertained? Performance of light arrows is not just raw speed, as Steve frequently points out, and creating a "sweet shooting" bow while shooting light arrows is of interest. Steves observations about simpler limb designs often out shooting more complex designs are keenly noted.
 
 I do not actually expect that anyone can answer these questions definitively with facts and numbers, but we all have our intuitive ideas formed from experience, and I appreciate all the comments, ideas and even speculations of all.

[SLIMBOB]

Willie.  I see a small problem with your question in the first question you posed, the pyramid that was retillered to give it an elliptical shape.  It might not take set because you have lowered the draw weight.  If however the first bow was 50 lbs at 28 inches, circular, and you built the identical bow elliptical in shape also 50 lbs at 28 inches, then yes, I believe it would take more set mid limb.  If you instead kept the mid limbs wider, they would not take set.  Getting them wider would be a function of lessening the width taper to some degree, perhaps as much as parallel.

[SLIMBOB]

As to the second theoretical bow, parallel retillered to a circular shape.  Your mid limbs are heavier than ideal as they are wider than needed.

[willie]

Slim
yes, of course both hypothetical bows have excess mass that could be eliminated with the "proper" tiller, but as I hoped to point out in my last paragraph, raw speed, does not always indicate down range performance. The arrow has to leave the bow as best as it can. A sweet shooting bow, to to me, anyways, is one that seems to plunk the arrows in the same spot consistently, and I have found that arrow tuning and string/nockpoint tuning can only go so far.

[George Tsoukalas]

"  Let's for the sake of a thought experiment, consider a pyramid bow that is almost tillered out. It has the desired circular profile that is considered correct for the width shape, and the assumed constant thickness. If I then thin the thickness of the mid to outer limbs, they will come around more into an elliptical shape considered "proper" for the straight limbed bow. Have I created set anywhere by doing this?"

Yes, you more than likely will get too much bending mid limb on where the limb is at its narrowest.

Jawge

[Badger]

  George you are exactly right, you have not created more set. Most everyone I know slightly tapers pyramid bows.