Pyramid belly taper...

[Wooden Spring]

OK, OK, I know that a pyramid bow is SUPPOSED to have consistent thickness across the length of the limbs, BUT... Bow after bow that I build, although the tillers look good on all of them, the last 8-10 inches or so of the limbs are stiff. (see my picture for a 60# oak bow) And this is so, no matter if I'm building a 30# or a 60# all oak bow, or laminated hickory backed jatoba...

Now, my understanding is that stiff tips equal faster shooting bows, but the payoff is more set and more hand shock. (think swinging a baseball bat versus swinging a belt. The bat is stiff, and the belt flexes - and the bat moves faster)

So, what if I tapered the belly thickness, say 1/16 or so across the whole length of the bow. Would that even out the tips, and force the ends of the bow to do more work?

The other option that I thought of was to just taper the 1/16 of an inch out of the last 10" of the limb, but I thought that might create a hinge.

Any thoughts???

[BOWMAN53]

with a pyramid design most of the stress/work should be right out of the fades at the widest part, i say keep is how it is, unless your having some kind of issue.

[Wooden Spring]

Nah, no issues with it at all, I've just been cursed with an analytical mind, and I'm just trying to weed out any possible design flaws... So I quizzed folks who know a LOT more about this stuff than I do!

Actually, this bow ROCKS... I haven't chronographed anything, but this bow feels like its the fastest bow that I've made yet, and it's just a humble piece of red oak, no backing, no bells or whistles - the one problem that I DO have is that after I shoot it, it doesn't stop ViBrAtInG for about 6 seconds... Oh, well, a leather handle wrap should shut me up from complaining about it TOO much. 

[artcher1]

Man, that tiller looks great! Last thing you want is any bending in the tips. Tips are there to apply leverage, not work. More you get the tips bending the more leverage you lose. Stiffer tips will cause greater set, but you can design for that. Stiffer tips will, if anything, reduce handshock.  It really is all about trade-offs................Art

[BOWMAN53]

can we see the front profile? maybe the tips can be narrowed a bit and that will help with the vibration. also what kind of string are you using?

[Josh B]

with a pyramid design most of the stress/work should be right out of the fades at the widest part, i say keep is how it is, unless your having some kind of issue.

Well...not so much.  That is the case with a flatbow where the limbs are parallel for a bit before tapering to the tips.  With a pyramid, you want the mid limb to outers working a little more.  For the best speed on a pyramid, you want almost an arc of circle bend on each limb(not whole bow arc of circle like a warbow)  I say almost, because you want it to gradually decrease in bend from mid limb out so that  only the last few inches are stiff.  As far as the thickness taper goes, that's what tillering is about. Very seldom will it work out that the thickness will be the same from fade to tip.  It will be closer to a consistent thickness than any other design, but you still gotta fine tune it.  Josh

[artcher1]

Is the handle working any at all? What type of string?  No way those stiff tips are causing any vibrations.

Just because a pyramid design is supposedly more of an arc of a circle look, doesn't mean it can't be improved on. You can improve this design with stiffer tips just as Histanley used. There's not any gained benefits, IMO, from getting the mid-limb to tips works anymore than they are now................ Art

[BOWMAN53]

really? maybe ive been tillering my pyramids wrong lol i thought that was the whole reason for the design, to spread out the stress on the widest part of the limb.

[Wooden Spring]

These are the only other pictures I've got of the thing. I had posted them before on another topic, but I can take some more pics tonight if need be...

The handle could stand to be a bit thicker, but it SHOULDN'T be bending - my guess is that it is just a fuzz...
The string is B-50, 18 strands in 2 bundles.

[BOWMAN53]

in my experience b50 tends to vibrate way more than anything else. i love dynaflight 97 great stuff

[Josh B]

It is a subtle difference in Appearance of the full draw profile between a flatbow and a pyramid.  However, the devil is in the details as they say.  With the flatbow the parallel section of the inner limbs carries the extra bend without causing excessive set(wider and thinner for a longer section can take more bend)  the same principle a Mollagabet works on.  A pyramid doesn't have that extra width to carry the extra bend in the inner limbs.  So, you extend the bend a little further down the limb to spread out the work.  The advantage is not between the flatbow and the pyramid.  They are both very efficient designs if properly executed.  The advantage is to have the proper tiller for the design you are using to maximize the efficiency of the bow.  Just my opinion of course.  Everyone has one.  Josh

[Wooden Spring]

It is a subtle difference in Appearance of the full draw profile between a flatbow and a pyramid.  However, the devil is in the details as they say.  With the flatbow the parallel section of the inner limbs carries the extra bend without causing excessive set(wider and thinner for a longer section can take more bend)  the same principle a Mollagabet works on.  A pyramid doesn't have that extra width to carry the extra bend in the inner limbs.  So, you extend the bend a little further down the limb to spread out the work.  The advantage is not between the flatbow and the pyramid.  They are both very efficient designs if properly executed.  The advantage is to have the proper tiller for the design you are using to maximize the efficiency of the bow.  Just my opinion of course.  Everyone has one.  Josh

Then, based on that, is my pyramid tillered properly? Or should it bend a bit more in the tips?

I'd like to see what the "ideal" tiller would look like so I know exactly what to shoot for, do you have a pic of a good profile?

[Josh B]

In my opinion, you need a little more bend in the middle third of each limb.  Here's a couple examples.  The first one is a red oak pyramid that I made a while back.  You will notice that the upper limb(to the right) is a bit flat midlimb.  That's a screwup. The bottom limb however is the profile to shoot for.  The next one is a fairly short vinemaple made by pinecone.  It is an exemplary example of proper tiller and the performance reflects that.  Josh

[Wooden Spring]

Gun Doc
I appreciate the pics, that was exactly what I wanted to see.

So mine is pretty close. You've got stiff tips as well in your oak bow, I just need to "round out" the tiller just a bit further down according to that one.

[Josh B]

Yes Sir!  That's exactly what I was trying to say.  I know that i can get long winded and confusing at times so I'm always glad when I actually convey the message properly.  Lol!  Josh