Tillering question

[DC]

If I have a bow bow that is 40#@28, 72" NTN and has taken no set(this is a hypothetical question) and I pike it 2" and retiller it to 40# will it be faster? Can I carry on piking and tillering like this and gain speed each time until it starts to take some(too much) set? Would this be a reasonable way to sneak up on peak performance

[willie]

I have wondered the same thing DC. It seems like a lot of work for a one off bow, but if you were trying out something with a new material or a new design, with the intent of improving a design, then the extra work might worthwhile.

Would you want to measure the speed of arrows with various a range of GPP, in order to define "peak performance, at each piking?

[Del the cat]

That's fine in theory, assuming it will take set before it explodes...
All my hypothetical bows perform superbly... it's only the real ones that explode.
http://bowyersdiary.blogspot.co.uk/2016/11/damn-it-exploded.html
Del

[DC]

Willie, the only extra work is temp nocks, I've got lots of various length string from practising making strings. The "peak performance" was just words. At the moment my target is 180FPS with a 40# bow.

Del, Yeah reality sucks. That bow was coming along nicely until it didn't. Oh, well like you said you've got a bunch of nice staves for next year.

[willie]

DC

hope I do not seem like  am trying to discourage, not my intent at all.  In fact, retillering  a bow after a piking is seems a whole lot easier than building a second bow (or third, or fourth). Hope you post your results.

You might find that at some point in the piking/retilering process, that you will cease to gain speed. That might tell you something that you could not see by looking at set. 

[DC]

DC

hope I do not seem like  am trying to discourage, not my intent at all.  In fact, retillering  a bow after a piking is seems a whole lot easier than building a second bow (or third, or fourth). Hope you post your results.

You might find that at some point in the piking/retilering process, that you will cease to gain speed. That might tell you something that you could not see by looking at set.

No I'm not discouraged, takes abject failure to discourage me. The tough part is for me to come up with a bow with no set

That's why I mentioned excess set. I think that would be the limiting factor. Otherwise we would have 24" selfbows that were faster than compounds.

[SLIMBOB]

That, and other factors I believe.  As the bow gets shorter your leverage is less, so more stack at 40 lbs means diminishing returns as well.  Interesting test though.

[Badger]

  Why do you think shorter bows are faster? With a medium weight wood 72" might very well be optimal. I like my osage bows about 66", I used to make them 62" but get better performance at 66".

[DC]

Mostly less limb weight is what I was thinking. With the same draw length the force/draw would be the same I would think.

[mikekeswick]

Mostly less limb weight is what I was thinking. With the same draw length the force/draw would be the same I would think.

No it wouldn't longer bows have better string angle and therefore leverage on the limb. A longer lever lifts a heavier weight right? Short bows store less. Recurves store more energy because of the reduced string angle.

[George Tsoukalas]

No, I think piking "confuses" the bow and makes it "wonder" where the neutral plane is.

I also believe that piking introduces additional set that counteracts  any speed gains that could be possible.

I agree with Badger that a shorter bow, from the outset, doesn't automatically make it faster.

I also agree with Mike about string angles.

I am so agreeable today.

I also think piking  is  a crutch that keeps the neophyte bowyer from learning how to tiller a bow to make weight.

Jawge

[simson]

All what Jawge said!
I'm also so agreeable today 

[Jim Davis]

There's been al lot of experimenting with this. In my wide reading of published material (not forums), the consensus all else being equal, shorter limbs return faster. The difficulty is getting all else to be equal.

I think we would all agree that a 40# bow that is 10 feet long is not going to be as fast as a 66" 40# bow. Predicting the best length is where the difficulty lies.

Jim Davis

[DC]

I was reading TBB1 last night and Tim Baker brought up pretty much all the points that you guys have. There are so many things going on at one time it's tough to keep them all in mind when I'm trying to think about this stuff. It seemed a little simple to be true so that's why I asked the question. That's what you guys are for. To smack me upside the head and get me thinking straight again. There was one thing that Tim said though. In one comparison of different length bows he had a 94" Maple that he cut down to 88" and gained 6FPS so there is something to my idea but that was a rather extreme example.

[gfugal]

I think you should try it and record your findings and let us know. Theoretical talk is great and all but nothing can beat hard evidence.