Primitive Archer
Main Discussion Area => Horn Bows => Topic started by: BowEd on June 01, 2016, 12:45:39 am
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Hello.Here's a bow I sinewed the first week of April I've been waiting to tiller.A 60" pignut hickory with a horn belly on it.As a few of you may know you've seen me make this type of bow before.This one is different in the way I constructed it.I pre measured,tapered and estimated the components to come out when glued and cured so that it would be in tiller and be very close to my draw weight.Sorta like a glue up of a BBO right off the form.Reason being I did'nt want to remove hardly any material tillering especially the horn.I'm pleased to say it worked.Core is 50%,Sinew is 25%,Horn is 25% of thickness.
Tillering time took less than a half hour.Draw weight initially was 55# @ 28".I tillered off 2.5 pounds which to me is very minimal.Close enough.Just a few sanding strokes from a sanding disk pad on each limb.It now is 52.5#@ 28" just what I wanted.Been shooting it in at this time.
The bow started out before with 10" of reflex.After tillering/bracing and shooting the last couple of days it holds 8" reflex @ rest in 2 hours and 8.25" over night.It held over 80% of it's reflex for me.It is far from finished for close up pics of it yet but would like to show a few pics of it anyway at this stage.Been thinking birch bark or copperheads over the back and staining the hickory with some sort of stain.Nothing really that special.Thanks for looking.
From a pretty much flat core to just after horn is applied.
(https://i.imgur.com/FeEposs.jpg)
(https://i.imgur.com/HnTVtkV.jpg)
Starting profile and sinew job smooth as glass before tillering.
(https://i.imgur.com/7E8heVC.jpg)
(https://i.imgur.com/iAzo6g7.jpg)
(https://i.imgur.com/EkDD1tw.jpg)
After tillering and 2 hours after shooting all afternoon @ rest
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1268_zpshzzaa7gr.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1268_zpshzzaa7gr.jpg.html)
Brace
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1264_zpsqvo5xjrf.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1264_zpsqvo5xjrf.jpg.html)
Full draw
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1265_zps5fsoge54.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1265_zps5fsoge54.jpg.html)
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Cool :)
It would interesting to see what it does through the chrono.
How long is it and how wide are the limbs?
It looks like it needs more strain!
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Wow, that's a work of art there, that thing must be a beast to brace! What kind of horn?
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I'm really impressed with the profile. Looking forward to seeing that bow finished up.
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Very cool ed
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Mike.....I realize you are a student of these horn bows and Karpo's book,and a credit here.I've had his book too for a number of years.Me a student probably not to the extent you are in that you have a couple of beautiful horn bows to your credit that you displayed on here and although I have one cured I have not tillered it yet and one ready for sinew also.I did go through the work of grooving core to horn though on both and finishing out these horn bows can get you a more in depth view point.
You are right from what I can gather from Karpos' book that this bow @ 28" is definitely understrained.It is 58.25" long NTN 60" TTT and 1.25" wide at fades.Approximately an 8" handle.At least 8" stiff levers on the tips.Taper on width and thickness app.1/16" every 5 and 3/8" length along limbs from the fades.Slow and evenly.It probably should be pulled up to at least 30" anyway.Then I believe the draw weight would be around 57#.Mass on it is 17.40 ounces.Which according to Karpos' book is a pretty high mass to draw weight ratio.A little over 9,but in the ball park or under a bit of Steve Gardners mass weight formula for self bows which says it should be around 22 ounces because of induced reflex or 18 ounces normally.Hav'nt shot it through the chrono.According to what I've stated here what do you think it will shoot?
Construction was usual like horn bows are.Core prepared and tapered flat side view profile.Horn tapered too and glued onto belly of core but heated into a bit of a curvature before applying it.No grooving.Then sinew applied using a reverse stringing of 3 courses over a weeks time tapered and crowned slightly too.
Peacebow_Coos......Yes it's always an adventure to string these up especially the first time.After that not so much.The tips are not too sharply bent to static so a normal type primitive stringer can be used to string it.Pretty safe actually and not too strenuous.Too dangerously set back to string these using the push pull method though.A different type stringer is used when the statics are sharply bent.Actually getting the tips to 6" past the handle only required around 54 pounds.16" of tip travel.Gemsbok was the horn that was used.
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Thanks fellas.I'm still shooting it and have a #D shoot this saturday to go to to help that along and then the finish work will begin.
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@BeadMan , please allow me to ask you a question:
I've always been fascinated by horn bows , technically what I understood about your bow is that you made a hickory selfbow to start off, backed it with sinew and added horn to the belly for compression purposes?
Thanks in advance for your answer, you did an amazing job!
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Knotty....In a nut shell yes but in a different order.The width/length/and thickness will determine your draw weight.The core of this one might have been barely a 20 pound bow @ 28".I did not test this one on the tree.In the past I did.I did'nt want or need to this time.After making enough of these you get a better insight as to how much poundage you will get from your composites that are added.
The horn is applied first to the core then the sinewing begins.Reverse stringing it as the courses are applied.Reasons for this is that I want to put the horn into tension and the sinew into compression gradually as it drys between courses.This is hard to understand unless you have Karpos' book but what happens then after it is cured when the bow is drawn during tillering and shooting the composites press themselves into the core to eliminate delamination if glue lines are properly done.I'm sure there is someone else on here that maybe can explain it better but that's my understanding of it.I hope you can picture what I said.
These bows can be really magical in a way compared to making self bows.Flexing/tillering/and seeing them come around to tiller.Shooting them is a little like pulling on a rubber band.I'm sure the all horn bow makers know this feeling but if you put enough horn and sinew thickness on a wood core the feeling will be the same.Your outside third of limbs towards the tips needs to be set back and stiff enough to eliminate any stack at the end of the draw while being light enough to eliminate hand shock.Sounds like a tall order ehhhhh?It is'nt once you do a few.
This one I got to working a bit more on the outer limbs than ones in the past without it stacking and not quite as much on the inner limbs.To me one reason why besides being overbuilt for the draw weight that it did'nt take much set.The length on this one is another reason too.
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That's a cool bow. I know a bowyer in Washington state who makes similar modern style composites.
I agree with that length you could get a little more draw length, but I bet it shoots great at 28"
Unstrung profile is awesome
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Looks great ed, get a horn ring and yank it back and see what ya get
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That's a beautiful bow. Love the braced and full draw pics.
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@BeadMan don't worry I totally understood, thank you for taking your time to answer my question 😊
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Thanks DC.
bubby....Pulling back to 30" will make my form even more screwed up then it is.I'd have to start all over again.I like coming close at least to what I'm shooting at......lol.and then a horn ring too yet....that's too much change....lol.The bow should probably get pulled back to 32" to get the right amount of efficiency from it.That means a kiper and new arrow shafts just for a specific bow.Ahhhhhhh too much.....lol.Then to top it off I'd lose a bunch of my wonderful set back too yet.Guess that's the test these bows should get put through though.
wizardgoat.....I guess it's a modern composite.Really Knotty hit it on the head to me.It's just a self bow with composites on it.Only I've refined my self bows to work a bit better than I did 7 years ago.....lol.
There is no sinew on the last 8 or 9 inches before the tip.I always do that for easier no nervous tip alignment to be done with the heat gun.
I'm gonna open a subject up about heat adjustment to horn applied to a wood core with smooth on with sinew on the back of wood core.I've done this in the past with no problems occuring.Waving the heat gun on the low setting of 500 degrees[mines' a Wagner high-1100 degrees/low-500 degrees] back and forth and then checking with a laser thermometer to not go over 150 degrees slowly twist/reflex/and deflex can be done a limb.Everything has to be cured well though first to do this.Smooth is supposed to be able to handle up to 280 degrees before delamination.I've never needed to go that high.Sinew should'nt go over 120 degrees but if cured well you can push that too and creep back then won't be much either.
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Beadman - thanks for taking the time to reply properly ;) I would guess at 28 inch draw 10gpp arrows = 170fps. Increase that drawlength and it will obviously be better.I look forward to seeing your two Turkish? hornbows as well.
I've been learning to shoot with the thumbring....it takes some dedication....it's taken me two months to start to get any where near my 'normal' accuracy back. I just went to our 3D National champs.....only managed 500 points normally I'd be closer to 700. Once you get down to about 50 inches I think the thumbring is the only logical choice.
Again congratulations on your new bow. It will look a million dollars when you do the finish work.
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Thanks Mike.....Kuddos to ya for exploring and perfecting the art of making and shooting these horn bows.What sense is there in making them really without seeing what they can do.A thumb ring I suppose relieves any finger pinch that may happen.I've never tried it yet.I'll have to get after my Turkish prospects in the future here.It's as long a dedicated road to this bow making that a person wants to be on for sure.That's the beauty of it though.Always room for improvement.I always remember a saying I read Jim Hamm write when I started.You got to be more persistent than smart sometimes making these bows or rather you can't be afraid to fail is what I get from it.
I figure to shoot this bow in quite a bit then take a fps reading on it.Breaking it in.By my naked eye shooting I'd say you were'nt too far off there.I'll see once.The old unmerciful extractor of truth reveals all.I know I won't put in the time and perfection in finishing that you did on your horn bows.
As with my coondogs I believe in calling a spade a spade in ability no matter if it's my dog or bow or someone else's as well as giving credit to where it is deserved.Trying to hide behind excuses for set or terminology to describe a design does not improve a person's construction or tillering ability to make these bows.It's very hard to hide set on an all reflexed bow.It can't be done.I realized hunting coondogs in these competition hunts that a man with excuses about his dog will never improve.A sorry man handles a sorry dog.
I notice shooting this bow like the static bow I shot that the arrow flight is not as clean consistently as less reflexed bows.Pisses me off really.Could be my crappy form a bit too.Also a person needs to check these arrow knocks occasionally too.Chances are a knock can get blown apart for a potential dry fire.That can end the fun quickly too.I'm shooting heavier arrows to drain energy using fast flight and will never go below 10gpp arrows.Suits me fine right now since I'm lucky enough here to be in a good hunting area for game and that's really my main concern anyway.
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Yeah, thumb ring really helps with finger pinch and it also gives you a few inches more draw length.
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I see.I can see the advantage of it there.Especially too in that it will lower the drag and friction factor on the release compared to a finger release.All up sides I quess but still way different.
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Very cool bow, Ed. I have one similar in my future...if that time ever comes. ;D
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This bow is really different here compared to the others I've done in the past in that besides coming very close to my draw weight in construction it takes more what I call soft set after shooting.That turned out to be that the sinew was not fully cured yet.I started with a flat core and glued the reflexed horn onto the core which was different than the ones in the past which was a flat horn with no reflex in it onto a flat core.A pic of core after horn glued on this one.Hope I explained that properly.
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1193_zpsiaq1czar.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1193_zpsiaq1czar.jpg.html)
I can see that one limb got more reflex after horn glue up.That was really the only adjustment I needed to make on this one losing 2.5 pounds.I put that limb as my top limb also.After bracing most times I still need to press the string on the weaker limb onto belly to strain the stronger limb for maybe 5 seconds for it to come into tiller.Then throughout the shooting the tiller stays.This extra horn thickness on here must have something to do with that.Suppose that's normal too.I fixed that retillering.
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Thanks Pat.You'll do it.I've seen your work and you'd have no problem getting what you want.
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I should mention here after glueing horn on reflex was 5 and 3/8" from a flat core.Then the sinew and reverse bracing put it to 10"+.
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I should of took pics of this bow just before tillering it but it slipped my mind.Sorry.
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Beautiful bow, Ed. I'm looking forward to seeing it finished.
If you feel like you are slighting that bow on the Draw length, you can send it to me and I'll work it out, my draw is a tad over 30" with,or without a thumb ring.;-)
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OK I'll remember that mullet.Did'nt realize your draw length was that long.Mine really should be longer I'd say though too.
These composites seem to take a bit more shooting than a self bow before finishing.
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Thats a beautifull & fasanating bow Ed , you got me going just bought Karpo's book Great bow !
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Great Ritch.....It's quite a book and an immense amount of information and testing to digest.Making a bunch of self bows first gives a person a lot better insight and understanding of info to get the best out of natural materials.
I think I'm finally through shooting this bow in and giving it the needed bracing time to see what it's going to be.I guess it's just a nice set of copperheads is about all I'm going to put on it.Too many decisions again......lol.
This bow is not even close to what a Turkish horn bow is or like although I've never actually shot an actual Turkish horn bow.This one is just my own version and theory of a lot of reflex and reduced outer limb mass weight to get a faster bow without all of the extra work that a Turkish horn bow requires.Having it hold together profile for years or even decades with proper care is definitely the goal too.
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These composite bows are different.With having a little more reflex I mean.Just the little extra this one has recovery time from shooting can continue for days.An intial bunch the first 2 hours then a little at a time from then on.Guess that's the revealing quality of sinew being able to stretch 8 or 10 times more or so than wood.I was thinking about doing an efficiency test[like in the TBB 4 book] but that might have different readings depending on bracing and shooting time too.
Got the skins ready.Just need the titebond 3 to come in the mail.
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Well it's been another 3 weeks and finally finished this bow up with the skins,stain & finish.Pulling almost 53#'s now @ 28".Finished mass weight is 17.65 ounces.Shoots pretty decent.Comfortable for me to shoot.Starting at about a 5.75" brace from the belly it has a high poundage gain the first 8" of draw of around an average of 3#'s per inch then the next 8" at around 2#'s per inch then the remaining 6" at 2.5# per inch.Releases with a kind of whispery snap.No hand shock I can detect.Gave it some copperheads I had.Cow horn overlays.Left it a bare bones handle.The stain on it ended up a light brown trying to get a coppery reddish type look to it.Hickory is kinda a hard for me to stain nice and evenly on the edge grain.Some finished pics of it.Kinda fuzzy though.Thanks for looking.
Rest
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1299_zps2m1iphc5.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1299_zps2m1iphc5.jpg.html)
Brace
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1283_zpssowdxyqm.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1283_zpssowdxyqm.jpg.html)
Full draw
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1282_zpsjtcqrdxh.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1282_zpsjtcqrdxh.jpg.html)
Back
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1298_zpsqa9egbz6.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1298_zpsqa9egbz6.jpg.html)
Belly
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1296_zpsdhwnvr6o.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1296_zpsdhwnvr6o.jpg.html)
Handle
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1295_zpsihupko5h.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1295_zpsihupko5h.jpg.html)
Tip
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1289_zpssnfzr5rq.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1289_zpssnfzr5rq.jpg.html)
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Very cool!
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Hands down Ed thats my favorite bow of yours I have seen especialy after starting to read Karpos book & starting to see the technoligy & craftsmanship it took to make it ,if I where you I would be real proud of it , congradulations she's a bute!! I like the fact that it turned out as you planed with only 1/2 hour tiller time. Ler us know how you do with it at the end of the month ?
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Thanks fellas...it's a quicky compared to the time consuming masterpieces in Adams' book.Not completely in love with the full draw profile really.Should be working yet more on the outers but it's done in my book for now.A favorite for a bit of time anyway.I'll shoot it throughout the summer.Maybe try to poke a deer or two with it later.0 issues of any kind throughout with it so should last quite a while.
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Very cool Ed
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That is one outstanding looking bow! I love how you stained the belly. That is some reflex on that baby!!
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OK.....Thanks fellas.
Been shooting it most days yet.Took a slight more material off of the top limb for positive tiller.Top limb had a little more reflex than the bottom limb.It's back t 52#'s@ 28" again.Still gives the arrow 6" of set back after 6 hours of shooting.Well pleased with it.
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That looks like a fast bow. The skins look good on it.
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Thanks Clint.As you know yourself with recurves they load up right off the bat drawing,but not overly much.This one is no different.My style of shooting is that through the aiming process I come to partial draw then pause then to anchor and release in one motion without pausing.Pausing at the end gets me in trouble.
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You kicked that things butt, Ed. That tiller is dead nutz.
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Well hey thanks a lot.....Thought I was the only one thinking that......ha ha ha ha.Don't worry though my perfect made bow has not been made yet.........lol.At least by me anyways.......lol.
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They cant get much better than this one, better put the "perfect" label on it ;)
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Nahhhhhh not me now but thanks.I'll leave that to someone with tighter fittin underwear.ha ha ha ha ha.
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glad to finally see the lipstick on this beauty Ed, tiller is nails and i hope ya stick a buck with her thus year
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Ed, ya forgot the arra shelf ... again! ;D
Stunning bow ... look forward to seeing it in less than couple weeks!
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Bub .....Thanks.I'll be happy just to shoot a yearling or a doe but I suppose I'll hold out a bit for something with horns too.Should have you tiller this one for me......lol.Not enough set back on siyahs but will still make some kind of bow.Close to 50 pounds I think.
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN0089_zpsomzafh59.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN0089_zpsomzafh59.jpg.html)
Knoll.....Thanks.I can never remember that.......lol.You shoot it too.I'll have a glove to be sure you don't knit yourself a feather quill in your knuckle.Personally it's never happened to me yet.Sometime I guess it will.
You bet Mojam.
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Ed I'll tiller it for you but you might not get it back😈😜
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Bub....Beware of what you wish for my friend.......lol.I tell ya that backwards C has to be cured I'm sure of that anyway.
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The one you said with the siyas not set back enough will be a slick bow when you get it done ,it should be easier to string for sure , is that maple core ?
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Hickory I think.The other is ironwood and needs to be sinewed yet.
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I like your style ;)
That perfect one may be right around the corner....
Seriously though that is a real beauty and i'm interested in how your next ones turn out.
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Yes I should be finishing the one horn bow.It's been curing for over 3 years now.Ought to be cured heh....lol.Some limb tapering outward needs to be done on that one for good tiller.Horn and core got interlocking grooves with hide glue.It's 50.75" NTN and 368 grams.
Seems these sinewed bows need updating.The hickory/horn/sinew bow gained a few pounds.Even though I waited 8 weeks for it to cure before tillering.Tillered it back down to 52.5#'s @ 27.5".Did'nt lose much reflex.Still holding 8" @ rest yet.A 625 grain arrow @ 27.5"gets me in the lower 40's in KE#'s @ 175 fps or a little better while learning to try to get the best out of my release through the machine.Seems to be the best I can get out of it.
Still shoots smooth,quiet,and dead in the hand.Been shooting it most every day for 2.5 months.Put a brain tan leather handle on it now.Going to use it for deer soon.
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1332_zpspoj7qyt8.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1332_zpspoj7qyt8.jpg.html)
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1333_zpswupsdtsf.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1333_zpswupsdtsf.jpg.html)
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Like the brain tanned handle nice touch , just curious Ed how much reflex was in that bow prior to putting on the horn & sinew ? Also how much weight did it pick up before retiller ? Hope you can skewer a dear with that sweet bow ! Good luck huntings right around the corner !
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Stick Bender....I'm assuming about the reflex you mean the wood core itself prior to composites going on.None.No reflex at all.No heat treatment either.I took my horn laminatons and heated a curvature into them before glueing them on.Showing back on page 2 I think.After the horn was glued on the bow had 5 and 3/8" reflex.After the sinew cured it had 10" reflex with reverse bracing inducing more reflex.
The bow was finished sinewing April 6th.I tillered it around the 3rd week in June if I remember right.A good 8 weeks for sure.Now being September 12 a good 2.5 months later it gained 2 to 3 pounds in that 2.5 months.I keep things around 50% humidity where it's stored.As I did while the sinew cured and while I tillered it.I feel if truth be told on bows with around 3/16" thick cured sinew on it a good 12 weeks or more is needed to completely cure.Conditions can vary for that number to be a bit different but I'm not too far off.I had to retiller it and I put it to a positive tiller of about 1/8".Weakening the top limb some.I don't need to push the string against the weak limb at all now just after brace for a short bit to get it to that tiller.It is that way right from first bracing now.I think the bow was right on the cusp of the tiller I wanted.
I'll say it on here too that it's been in damp conditions[misting and very foggy] for 6 to 8 hours strung with absolutely no ill affects.Not an absolute strenuous length of time test but for hunting here in my situation it's good enough for me.I really like this bow.Here's some more pics.
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1336_zpsrfqmkef1.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1336_zpsrfqmkef1.jpg.html)
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1335_zps7m58nc7g.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1335_zps7m58nc7g.jpg.html)
I guess I could increase the KE#'s and fps speed to in the 50's and around 190 with that 625 grain arrow by drawing to 30" but I feel satisfied with it and drawing to 30" feels too uncomfortable and different to me for accuracy.
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I've got that wrong I tillered it in the end of May.So in an extra 3 months it gained 2 to 3 pounds.
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Ok thanks Ed just dreaming about someday making one of those that is one tuff durable looking bow bet you that one will last a life time of hunting That's some real talent you have there to get that one built I know your to humble to say that but realy should be proud of that.
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Thanks Ritch but you've got all the skills you need to do this type bow.You already are finding out what thickness of sinew will give what poundage to a bow.The horn poundage info is in the build-a-long.
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Stick Bender....The mass weight of a bow like this compared to it's draw weight is way too high compared to a turkish horn bow.It would be way overbuilt.In self and backed bow comparisons it is comparably normal 17.40 ounces before leather handle.Especially holding the reflex it does which in self and backed bow comparisons it should weigh 22.00 ounces.The fps readings are all true and accurate.The only thing that accounts for this is the reflex it holds.After 6 hours of bracing it does not show an over amount of soft set when unbraced.Less than 1.5" which tells me it is not over stressed.I believe it has cured more to account for that also.
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Got ahold of some graph paper & had pre measured this bow by each inch earlier just as it was tillered and made up this fdc paper.It's a 60" TTT & 58.25" NTN bow.It should say 52.5# @ 27.5".It was measured to 28" @ 53.3# at that time.Close enough for me.I should measure it again.I see I forgot to show the 27" line.No biggie the end result is the same at 28".I corrected it farther along this posting showing efficiency and kenetic energy etc.It's been 2.5 months since these figures were took.It has cured a bit more and is performing a little better because of that.
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1340_zpsdxcnq3fd.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1340_zpsdxcnq3fd.jpg.html)
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I love your bows Ed, they are beautiful. I have a question about the F/D drawing. Do you know what causes the hump in the F/D graph?
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DC...Because of the reflex the bow is holding the draw weight starts higher per inch then it levels off[I imagine then the composites go to work and length of limbs too] then it begins to go up again as string angle and strain gets higher.The hump is stored energy the bow has.A self bows' fdc line would be more straight line maybe even concave a bit the way I understand it because they do not store as much energy.
I should of done this earlier to find out myself here but after crunching all of the figures this is what I come up with for bow efficiency and the kenetic energy of this arrow.These figures may be skewed a few percentage points one way or the other too but overall pretty close.
Shooting lighter arrows of course reduces this bow's efficiency as with most bows.Looking at Adam Karpowicz's efficiency ratings of his horn bows as a goal to look at this bow hangs in there close to most of them shooting heavier arrows[12/gpp].Hard to believe I know but there it is.Arrows shot below [10/gpp] the shorter horn bows out shoot and take over in efficiency and speed.The slightest difference in figures transfers to a lot in the field.Now pulling this bow to 30" would make up a lot of difference and by the looks of the graph line it is not strained so much it could'nt do that.Really did'nt take all that long to figure out and kinda fun too.Even for this old farmer.First time actually doing this.In the future making more types of bows when I want to check a bow out thoroughly I can with confidence know exactly what I've got.Just another tool in the bow making tool box the way I see it.
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I made a recurve sometime back and did an F/D curve on it. It had a hump like that but the hump coincided with string lift off. I could understand that, but your bow is past string lift off at brace. I can't understand why the reflex would cause a hump like that. I can understand it causing higher early draw weight but I would have expected an even curve. It's almost like there is an "oil can" in the limb(if you know what I mean?) and it's kind of popping through at that point. I'm buffaloed and I'm rambling, sorry.
I'm taking a closer look and I'm confused. You say 17.6 at 6" of draw which should be 12" on the drawing but the drawing says 18.7. Am I missing something?
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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.
(http://i920.photobucket.com/albums/ad41/Beadman1/DSCN1405_zpskowr95zk.jpg) (http://s920.photobucket.com/user/Beadman1/media/DSCN1405_zpskowr95zk.jpg.html)
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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.
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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.
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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.
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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.
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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.
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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"
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Yes I was thinking so too.That it means a straight line fdc is not as efficient as a humped fdc showing stored energy.
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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.
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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
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Man that is absolutely flipping brilliant in every respect! :)
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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.
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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.
(https://i.imgur.com/pCC0FJW.jpg)
(https://i.imgur.com/6s8iuUZ.jpg)
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.
(https://i.imgur.com/eQqVPPJ.jpg)
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.
(https://i.imgur.com/ZHlKnF9.jpg)
(https://i.imgur.com/AVVoZmK.jpg)
The finish.Veg tanned beavertail handle grip & copperhead skins over sinew wraps.
(https://i.imgur.com/kgQQdcx.jpg)
(https://i.imgur.com/PkxOjGf.jpg)
(https://i.imgur.com/SjzYlAI.jpg)
(https://i.imgur.com/P7IZoUl.jpg)
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.
(https://i.imgur.com/MitdEkv.jpg)
(https://i.imgur.com/K4SJ7Yu.jpg)
(https://i.imgur.com/1NzGP9k.jpg)
(https://i.imgur.com/e26AIQJ.jpg)
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
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That is quite a project, Ed. Beautiful bow and workmanship.
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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
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Bead! (A) I never come here either but it occurred to me you might have a bow posted here and low and behold... (-S It looks awesome brother. One of these days I'll get the courage to try one of these but I'm sure I'll consult you first. Way to go man! :OK