Sharp hooks ( a how to and lots of argument as to their merits )

[PatM]

This officially belongs in around the campfire. We have PVC posted in the bow section, blasphemy. Sleek I do not have much experience in Statics but the few I've done boil or heavy steam and have your jig ready and bend them in one shot.

This is just a mechanical theory test, not a material discussion.

[joachimM]

This officially belongs in around the campfire. We have PVC posted in the bow section, blasphemy. Sleek I do not have much experience in Statics but the few I've done boil or heavy steam and have your jig ready and bend them in one shot.

Paulsemp: please read the thread before these posts. It's basically a test to see when sharp hooks are useful on a bow and when not, upon request. I don't mind continuing this thread with this specific question somewhere else, but I just want you to read the background of the reason why this is showing up here.
thanks for taking the time to do so and judge afterwards. I specifically imitated a bow design resembling the one that Sleek is intending to build. Whether or not it's made out of PVC is pretty much irrelevant right here. It's meant as a proof of principle with regards to performance.
J

[crooketarrow]

    Three things happened. As you tryed to flip your tips.

  You heated the wood to  HOT TO FAST and you did'nt use some sort of OIL GREESE, This helps by keeping the moisture in only if you go SLOW.

[bubby]

The oil or grease is unnecessary

[PatM]

 Talking full curls here, not flips.

[bubby]

Yeah i know, 6 pages worth, the post i responded to said flipped tips, plus ya don't need it with steam or boiling

[PatM]

Yeah i know, 6 pages worth, the post i responded to said flipped tips, plus ya don't need it with steam or boiling

   Sorry,  I just meant regarding the first post in response to CA.

[DC]

Where would wood quality fit in importance? If I want tight recurves is primo, straight, knot and blemish free wood right on top of the list or can you get away with some?

[bubby]

You always want the best wood possible

[joachimM]

Results on test shooting the PVC-bow. First with big hooks, then hooks shortened to smaller recurve (compare pics).
All shot with a custom-made reed arrow (163 grains; actually two broken arrows with the tip footed with chopsticks to the bottom part). Don't mind the plastic nock.

The amount of the hooks that was cut off was c. 5 cm, in total 14 grams (215 grains).

Force-draw curves were close to identical early in the draw. Late in the draw, the bow with the big hooks cleary gets the leverage, as the poundage levels off.
Average arrow speed (23 measurements) for the big hooks: 92.5 fps.
Average arrow speed (20 measurements) for the smaller recurves: 103.7 fps.
The difference was statistically highly significant, with the bow with smaller recurves shooting faster. As expected.
The draw pics show where each bow had lift-off, and how that affected string angle and the horizontal projection of the effective limb length (leverage).
Note that on the right one pic at 18" is positioned next to the one at 16", so shift that one mentally down one square...


String tension at brace didn't seem different (same tone!). The bow with the big hooks was more difficult to draw, as it sometimes wanted to shed its string. For that reason I deflexed it in the handle compared to the previous picture.

So PatM, I hope that satisfies you 
It completely follows the predictions I made with relation to excess mass and leverage.

Joachim

[Badger]

   You increased poundage by about 10% but the increse in kinetic energy went up almost 25%. Not sure if you could attribute all of that to the size of the hooks but it was the only thing you changed so worthy of looking at further.

   You nver have addressed my question to you on the baker bow you mentioned, I have asked it 3 times now.

[dragonman]

I think that is a impressive contribution to the argument  by Joachim..

Ignore my previous comments...( I think everyone did anyway )!!... i didnt read everything properly and misunderstood the discussion... i thought it was about recurves that wheren't sharp enough to lift off...not 'hooks' that where too sharp to lift off at full draw..
we all make mistakes... hahaha.....

[Marc St Louis]

Higher draw weight would account for the increased arrow speed therefore there is no advantage one way or the other

Some wood species heat bend better than others

[PatM]

There seems to be a misunderstanding of what we were mainly trying to test here. It wasn't about big hooks versus small hooks, it was about degree of hook of the same length of recurve.
   Lift off versus no lift off.
   Are you sure you didn't  also draw the shorter bow further relative to length as well? It looks like it is being bent more.

[joachimM]

   You increased poundage by about 10% but the increse in kinetic energy went up almost 25%. Not sure if you could attribute all of that to the size of the hooks but it was the only thing you changed so worthy of looking at further.

   You nver have addressed my question to you on the baker bow you mentioned, I have asked it 3 times now.

Badger, I thought I did address it? But you asked multiple questions, so let's be sure we're talking about the same thing: was it whether or not I saw that I was wrong about that pecan bow (yes I acknowledged that), or was it how you could not see a recurve not lifting off during the draw. That question was answered a few comments ago.
I'm sorry if I'm still not answering your question. Not because I don't want to, just because I'm not sure to which question you are referring.

PatM: well, then I or someone else will just have to do another test with a different bow 
Next weekend I guess.