Finished composite hickory bow/ pics

[BowEd]

DC....Yes I see what you mean there.My mistake.This is new to me....lol.Sorry.Then that extra 1 pound would make it 53#'s then as it says at the top of the curve.I did'nt even notice that.Thanks for seeing that.Here's a pic with the right poundage where it's supposed to be and the upgraded average of poundage the first 6" of draw.I really don't know why it progressed the way it did there totally,and wish I could answer your question.As I said this is the first time I've measured a bow's fdc.What I did on my digital poundage scale was pull it an inch at a time.Held it there a 1/2 second at most and released slowly back to brace.The same for every inch measured.Maybe giving 5 seconds of time between draws I guess.

[DC]

I've been thinking more about the oil can thing and I think there may be something in it. I've seen reflexed bows kind of do a pop when they are on the long string and are approaching brace height. I think it's usually just one limb but I never paid a lot of attention. Anyway with your's having so much reflex maybe that pop is somehow delayed to six inches of draw. It would account for the steep rise and then the levelling off. Dunno, just a thought.

[BowEd]

DC.....Only thing I can figure why that fdc line is the way it is in the beginning like that is from looking at the bow at rest.The tips themselves each had been bent 2.5" back above handle before sinewing the bow.The string does not touch the belly really at brace much.Maybe a tad.Makes it a lot easier for me to string up with just a primitive stringer with leather booties too.I really don't call this bow a recurve because of that.It's just a reflexed Ed bow I guess....lol.Anyway these figures on these bows are known to have a small % of error by the way it is done.

[BowEd]

DC....There is no noticeable feel of a pop as you say when drawing on the bow that I feel.It's really smooth and steady as she goes.I can't say I've seen that on any really reflexed sinewed bows I've tillered either.They are stout no doubt to get pulled around 16" of travel to brace though.I can remember this one actually took 54#'s to get there.Honest to God.Very elastic type pull to it.

[DC]

I doubt there would be a noticeable change as the draw weight would only change by a small amount. Maybe I'm out to lunch but I can't think of another solution at the moment. Something in the shape of that limb is changing the tension right at that spot. Are the limbs stiff from the horn out or do the tips work a bit? They look stiff in the full draw picture.

[BowEd]

The horn was tapered before I glued it to the core.The core was tapered too before glueing.The tips do work a bit but the horn on the inner 1/3 is fairly thick.Wish I could explain it too.All I know is I got it into good tiller and I'm leaving it.I should just do another fdc on it maybe.I'm bumbled by your question too.I guess the bow does what it does.
I don't know if you got Adam Karpowicz's book to be on the same page with me but I'm trying to figure out something.How well to measure a bows' capabilities of putting energy to an arrow. On page 171 he talks about a useful coefficient[Ce] to compare stored energy of different bows is the ratio of the measured energy to the energy of a bow with the force-draw curve exactly straight at the same draw length and weight.In modern bows,a ratio of stored energy to the peak draw weight[SE/PDF] is another common indicator.The higher the Ce or SE/PDF the more energy a bow is capable of storing.I don't know if he's talking here about how well a bow is capable of putting energy out to what it has stored or what.He says good modern bows have the SE/PDF in the range of 0.85-0.96 for 28" draw and 0.92-1.04 for 30" draw.Does this just all mean a bow gets more efficient shooting heavier arrows or what?I'm confused.

[DC]

No, I don't have the book. I'm not sure that I fully understand what you're saying but it sounds like,"If the FD(force/draw) curve is humped, it's good, if it's sagging, not so good." If Adam's coefficient is comparing his FD curve with a linear one then we're thinking along the same lines. I'm going to do some googleing along the lines of "understanding an FD curve"

[BowEd]

Yes I was thinking so too.That it means a straight line fdc is not as efficient as a humped fdc showing stored energy.

[mikekeswick]

The initial 'hump' is there because of the unbraced reflex the bow has. The more reflex - the more force required to get it to brace. The tighter the string at brace the more of a 'hump' you will have because you simply have to pull harder due to the 'preloading' of the limbs making the string tighter. An average  wooden bow simply cannot have the same amount of unbraced reflex therefore the string isn't as taut at brace requiring less force to start it moving.
A big hump is good!
When you have actual recurves you will also get a point in the f/d curve where the string lifts off the recurves this will make the bow longer and thus more leverage to work against bending the limb making the last few inches of the f/d curve level off.

[BowEd]

Yes the bow should have more set back in the tips.That might increase fdc hump too.It's still a blast to shoot.
Here's 3 short videos of shooting the bow,including shooting through the chronograph[I reweighed the arrow after shooting and it was a 630 grain arrow @ 11.8 gpp] from a 53# bow @ 28" @ around 175 fps which puts the efficiency of the bow a little over 79% and the kenetic energy of the arrow to 42.8#'s.Crappy short drawed form and all target shooting.....lol.At twenty yards though even at that draw the cast is pretty decent.Without the more extreme set back bends of the tips it braces much easier.Video of that too.Very stable easy to work with bow.I've shown about as much about this bow as is necessary.More than most I've made.Mostly because it is that enjoyable to shoot for me.Thanks for looking.
http://youtu.be/tzI_SemADvc
http://youtu.be/6K5--yTZ5T4
http://youtu.be/dYYro-hmpD8
http://youtu.be/eOCt26XTOKQ
Well I could'nt resist knowing exactly what a 500 grain arrow would do through this bow.I had Robin video it.I shot the bow a couple of times before testing then through the chronograph.After seeing the results I reweighed the bow at full draw.It is pulling not quite 55#'s @ 28" now almost 3 months later.Around a 1.5# increase from last testing.Sinew curing the reason I'm sure and it being winter time here in Iowa too.I don't think I come to complete full draw yet though testing.Maybe 27.5".Results were 210 fps @ 48.95#'s kenetic energy @ 89% efficiency with a 500 grain 9gpp arrow.Somewhat comparable to your turkish horn bows yet from my investigating.Here's the video:
https://youtu.be/gmrye1L5_Ks

[sieddy]

Man that is absolutely flipping brilliant in every respect! 

[BowEd]

Thanks sieddy...Through all the testing done shooting and hunting this bow has not gotten very many days' off from the month of June till present.Because of sinew curing more as time went on from the time of intial tillering chronograph results have been updated.Very pleased with every aspect of it.

[BowEd]

Did a little more testing....Placed the test onto reply number 69 with the rest of the testing and videos.At the very end of reply there is 1 more video shooting a 500 grain arrow.It's important to mention these test shots were made with a 2gpp 9 strand string  made of fast flight.Around 110 grains.Using B50 would not produce as much speed but still very respectable.

Update without reposting the topic here.A modification so to speak.Not wanting to put this done bow to the forefront again.
A crack developed lengthwise off the corner of the fade at the deeply carved out arrow pass.Too much carving too deep not into the depth of the handle far enough back the cause along with the back not being rounded enough.Fixed it with sinew wrap and covered it with like type copperhead skins.Retillered the bow down to 48#'s now too with horn removal never pulling it past 48#'s.It reduced mass weight down to 16.55 ounces.Still kept all 8" of reflex and degree of performance.Shooting a 550 grain 11.5 gpp hunting arrow into the mid 170's.A 10 gpp arrow of 480 grains into the mid to upper 180's.I actually like the look even better now myself.Some pics.Sure am glad I updated the pics of this bow with imgur as photobucket has struck again.It's good they can only delete the pics and not the info about the bow.
The problem.


The crack actually did'nt migrate onto the back any....Just the side length wise as shown.Sinew job on back prevented that I suspect.

The fix.No reason it won't work here as well as it does reenforcing lap splice handles on sheep horn bows.Not the thickness of sinew that all horn bow handles get but still around a good 3 layers of wrapping thick.


The finish.Veg tanned beavertail handle grip & copperhead skins over sinew wraps.




Thought I'd take a few more proper pics of the bow in better surroundings on a hollow hickory stump that I made a nice drum out of.




I'm actually aiming right at about where Robin found the latest deer shot with this bow.Here's the deer harvested with it.
http://www.primitivearcher.com/smf/index.php/topic,62008.0.html

[willie]

That is quite a project, Ed.  Beautiful bow and workmanship.

[bjrogg]

Ed, not sure why but I hardly ever come here. That is probably stupid on my part. I had to come here to see you primitive stringer video. Sure glad you sent me here Wow, that is one awesome bow you made there really beautiful bend. I really like the profile kind of a combination long bow recurve horn bow really sweet. I bet most wheelie bow guys would think your stringing it backwards. lol. Sure wish you could have got a buck this year with her but I'm sure she'll be shooting for many years yet. Thanks for the stringer tip looks like it works real slick
bjrogg