Here is a project I have been working on for a little bit on the sidelines while working on my 2 other horn bows. It’s a modified Korean horn bow. Its core is bamboo and horn is It’s little longer than traditional Korean horn bows. It’s going to be around 54-56” depending on how things go with poundage estimates. I’m aiming for 50-60lb bow at 28”. So at 30” may be in the range I’m aiming for for full draw. If I feel like it can do more and isn’t stacking too bad I’ll go further then 30”. I’ve never made a Korean style bow before so some experimenting going on here. It sits around 33mm widest part out of handle then very slightly narrows to 25mm at the tips. I have some wiggle room for length at the tips. The thickness now is just around 9mm on main part of bending limb section with core wood and horn. The horn tapers towards the tips and thickness increases overall to about 10.5mm. I’m planning to sinew this with approx 65-70 grams of sinew. I’m estimating that sinew thickness after both layers will be around 2-3mm thick giving me an overall thickness around 12-13mm. Should be interesting where I end up with my poundage and how close I’ll get to my goal here. The tips of the core were soaked and steam bent the recurves. The limbs were then heat treated/belly toasted and rebound flat and grooved for horn. The nodes placement was a key consideration for me as well. So I used a pair of matching limbs from same section of moso pole bamboo that was prepped. The main bending portion of each limb is identical and have no nodes in that section. Over the last 3 days I have been preparing the backside of this little bow for sinew. I used 28tpi groover blade to score the surface after removing all of the rind. I then sized the back with sturgeon glue 5% for 12 coats until shiny. I know this is likely overkill but figured deep penetration of thin glue may save my bacon on this bamboo. After three days of sizing it looks good and clean and saturated. It’s ready for its first layer of sinew! I’ll be using 25% sturgeon glue for the sinew layers. I like to do premeasured bundle/strips for each limb. I’ve tried sinew many different ways and for me this is the smoothest/cleanest look. I pre soak and clean and comb out each bundle on a board just slightly wider then my limb. I let it just rest long enough to gel a little then apply fresh glue with little radiant heat to adhere well. I then smooth it out with my fingers. Can’t remember where I first saw this method or who to give credit to but whoever you are… thankyou! lol. I do like this method. Here are a few pics
You forgot a side profile picture. 
Surface for sinew seems perfect. I like that way of laying sinew also - i don’t see a better way either. Lets you align the fibers perfectly.
Your bow length is absolutely enough for 30" draw, even 32" or 34" would be doable. The original korean bows were really highly sinewed and therefore took a lot of “torture”, when pulled to 30" in many instances. The drawing style looks a bit ridiculous even to my understanding…
But long draw needs a good tip angle.
Sinew amount seems low? Have you had success with this low sinew before? In my bows, this would lead to core break. I wonder if you could get more out of the bow by increasing sinew amount to 100g.
Hmm interesting. You may be right. I’m shooting for an estimate of a 2-3 sinew thickness when dried up so it may actually require me to add more layers to get there. I’ve got the sinew for 100gr prepped and ready but wasn’t thinking I’d need it. I may though if I don’t get the thickness I am hoping for. I’ve had luck with less sinew on my longer horn bows where the bending portion was about 12-16” only. These bows are non traditional asiatic bows. This may be the reason I got away with it. I had read somewhere that some Korean bows had as little as 60grams. I’m basically gonna go till I get the 12-13 mm overall thickness after sinew dried. It should amount to about 2-3 mm sinew when I’m done. I do appreciate your input as I’ve not made a Korean horn bow before. We shall see how it goes.
The sinew prep I believe is necessary for good adherence to the bamboo. I don’t go this nuts for sizing on my other white wood cores for sinew. Horn yes but sinew is pretty good for sticking well with a few good size coats. Again thanks for your suggestion
You should reach your draw weight and draw length with those thickness’s probably before 30".Excellent prep.Like the looks of that bow.
Alignment can always be an issue.At least with me.Makes the tillering so much easier.I’ve been going as far as prebracing it before applying the horn.It gets very close to being in tiller at brace then also.
It does’nt hurt to prepare it to be bomb proof.How much reflex you gong for?
I will not be forcing this into a complete c shape with the tips touching. I may attempt with another one later on in different build. For this one I’m gonna keep it mild I think. I started with about 8” reflex after glue up on the horn. I’m hoping to get around 13-15” reflex. This bow was pre tillered to a point of being balanced at brace prior to horn glue up. The horn was tapered as I normally do to get the thicknesses I want in the places I want. Alignment was good then so we shall see. I did do a little mild bending after the horn glue up to see if anything changed drastically which it hadn’t. I was carefull not to do too much bending with the horn on as I want to reserve those stresses to work in tandem with the sinew later. I wanted the bend concentrated more on inner and mid limbs. So far it looks to be on track. Still so much is up in the air till I get the bow done but that’s the fun and gratifying part.
That’s a plenty of reflex IMO.Usually I lose 2" after tillering and shooting in.I try to taper my thickness to where I want my set taken.The area my limbs do the majority of work is midlimb.That’s where the set is taken.None on inner limbs and none on outer limbs.Yours has more reflex on the inner limbs though,but that is’nt a problem.
Checking points along the way insure an easy tiller.
I’ve braced after horn glue up also with no reduction in reflex.That’s where a good tension strong core used is best.I figure if the glue line and horn can’t take that the outcome after tillering won’t be good…ha ha.
Most times it’s a little tenuous even a great day when it comes to getting it to brace.Then the process speeds up.
Your on solid ground with this one.
The first layer After a couple days it’s looking pretty good. Here’s a few pics. It currently back strung to about 12” reflex from the 8” I started with. I have these side inclusions or delam section out towards the outer third of the limbs. I’m not overly concerned but thought I’d ask here. I plan to wrap sinew around onto the belly a bit anyway. Will this be sufficient to protect against delam here. I did soak this area of the larger inclusion with thin sturgeon glue and clamped it. I’m hoping with this and the wrap around of sinew it will be enough to protect it.
That’s a good jump from 8 to 12 inches.It’s looking pretty good.
Not sure what you mean inclusions…Is there a crack on the edge revealing seperation?or just a lighter shade of color there.I don’t see any crack.Was this grooved core and horn joinery?
You did about the best you could flooding the edge with hot thin glue.
I don’t see water buffalo horn much with any blonde or white in them.Looks nice.
Is that red cedar in the handle or probably bloodwood.
Ya it’s on the other limb that’s more black in color. Here’s a close up of it. I did soak some glue in there so we shall see. The handle wood is paduak. I’m did groove the horn prior to glue up. I’m hoping that a little wrap around with some sinew to help too.
A crack in the horn itself.Not on the edge exposing horn to bamboo joinery.I see.
Like self bows if the crack does not run out to the edge it’s safe.Otherwise it’s a cosmetic thing.
The horn should be rather thin there.Your fix sounds like all that can be done.
Thanks Ed. We shall see. The crack is in the horn itself and has been filled with glue. Time will tell when I get it bending.
Personally I’d bet $100.00 it’ll be ok.
Here’s a few pics with about 60-65 grams of sinew applied. Drying up nice. Thicknesses will still go down as it dries more but I suspect I will need yet more sinew then the 70-80 grams I originally thought. Another 30-40 should do it I suspect. I’ve saved more last layer as my longest strands which will add the thickness I will need.
Sweet looking sinew job.
After a few weeks to a month the thickness does not go down much.Hardly measurable in 1000’s.
That one will be a stout one to uncoil.
Do you induce bending area with some sort of form or tepeliks?
Thanks Ed! Ya I imagine i will have to make a new set though. Maybe not. We shall see. The bend on this one will be little different then my others and suspect a new set are in order to match the bend I’m after for this one. Yes it will be nerve wracking to string this one up! All part of the fun.
Something else I’m noticing is that one limb is reflexing a smidge more then other other mid limb. I was quite carefull to measure my horn thickness prior to glue up and even tillered the bare boo limbs for an even looking brace. I also remeasured after the horn glue up to match the limbs. My suspicion is that the colouration figured horn on the one limb is stiffer than the other. They were pretty darn close when I glued them and also after in overall thickness once glued. This is the only thing I can think is going on. I’ve heard of this before but never noticed it much. I may need to do some horn scraping to even this thing out I guess or apply a little heat perhaps.
Sometimes no matter how perfect you think you got things something will be slightly off.A smidge is’nt much as long as it is’nt too dramatic.
I’ve had one limb have more reflex than the other more than once before.I usually put that limb on the bottom to be stronger yet.Even though a little horn removal sometimes was necessary like 4 to 5 /1000’s to even the tiller up.Horn and sinew is so versatile that I’ve never seen any repercussions ever come from it down the road.You may have your own solutions yourself from the like.
I can only speak from experience putting bows through hunting and 3D seasons of shooting.
I mostly even tiller my bows or slightly positive.It all depends how one shoots.Where the handle pressure is and where the arrow pass is above center.
My arrow pass’s are usually like my self bows around 1.5" above center of the bow.
If I changed those things I’m sure the limbs would let me know…ha ha.
I’m sure you have your own observations of breaking in a bow also,balancing bow limbs the way you like to shoot.
These type bows take a bit longer to completely reveal the way they want to look or settle in.No less than 500 shots and multiple hours of shooting brace height time far as I’m concerned.
At least 7" brace to the back of the limb on the arrow pass for good arrow flight.
