Primitive Archer
Main Discussion Area => Horn Bows => Topic started by: ecounter on August 20, 2021, 01:53:51 pm
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Tried an Egyptian composite bow and wanted to share as much as I could if it helps anyone else. Used this: <http://margo.student.utwente.nl/sagi/artikel/ancient_composites/> as my guide. Used Osage slats for all the wood and my handle is a little more Assyrian than the sharp Egyptian look but since that's where Egypt supposedly got the technology it feels better in the hand. Pulls #70 at around 26 inches which is way past my comfort zone. Will try to give all the info in the picture dumps as I'm not great at replying in the message boards but will try if I can help. I've built a dozen or so self bows and a hybrid Mongolian style but this is my first attempt at something this complex. The Sinew is made up of one layer of 3 gram 10 inch sinew bundles all around(little less on the sides as it tapers) with an additional layer on the back. I'll try to post start to finish over the course of next few days as I get the files to size.
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Osage bending and layers of horn glued on the the tapered core.
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shape and tiller adjustments made
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Slight hiccup with the side pieces as I was going to do a different harder wood as described in the link above but that was a bust so bent more Osage which wasn't exact but a little more heat after the picture got them pretty close as to not create twist once everything was glued up. Like the photo says should have bent a single wider piece of Osage and then cut into the corresponding sized strips, that is if you are going to use same wood.
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After rounding the back and tapering the sides a little got it to #30 at 20 inches which was my working goal prior to putting the second thicker layer of horn over entire width and length of the belly essentially covering up the sides slats on the belly.
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More shaping of the whole bow prior to adding sinew. The second piece of horn on the belly really turned up the poundage and I kept shaving it down until the bow was drawing about #50 at 20 inches.
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More pictures with measurements.
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No idea how the original tips were done and couldn't dig up anything on the web so decide to take this route.
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Sinew time. covered the whole back and sides with one layer of 3 gram bundles and then a second layer on just the back again with 3 gram bundles. being that the bundles naturally taper the sides were not as big a deal as I though it would be.
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Final touch ups and test before birch bark. I think the recurves were just a bit too much so I used a little heat at 150 degrees to take some of the recurve out at the tips out and adjust some very slight twist.
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I admire your work/investigation and attention to detail in all aspects.Great looking bow.Good pictures and explaining of the process also.I've always admired the shape of an Assyrian/Egyption bow.Many ways to get that shape.Splicing in the handle section etc. as I've thought about it seriously myself.
I'd think the bow should mass weigh quite a bit for it's length.I also imagine the horn used was gemsbok because of it's length but possibly water buffalo horn too.
I did a tutorial on flattening gemsbok horn for horn bows [build-a-long thread] some time ago while making horn bows.In that I stated the amount of poundage gained using horn by it's thickness.
Did you get a full draw picture of the bow and did you make some like type arrows of the era?
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(A). Wow. A lot went in to that. Well done.
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Horn was water Buffalo I had to splice the inner core pieces in three but had two lengths for the final belly. I’ll get a full length draw picture soon once I work bow in and as far as arrows I haven’t made any of my own yet but if anybody has any info on appropriate arrow style would love the info.
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Very interesting.
what is the weight of the bow?
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They kinda described them in your referral site from your investigation and were a good 30" inches long or more all with foreshafts.
Also surprisingly not all that much sinew was put on your bow,but you did a superb job.
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With all those horn layers and the reflex in the shape didn’t think I needed so much sinew but time will tell. Someone asked about weight #70 at 26 inches or did they mean actual weight of the overall bow?
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Only the belly layer of horn is doing anything. The more reflex the more strained = the more important the sinew is. Less sinew and you may have run into the core breaking.
Yes I want to know the physical weight. This is a great indicator of potential performance.
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Total weight is 1lb 8oz
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Interesting a bow of your draw weight should be around 350 - 400 grammes for best performance.
If you ever made another then use a wood like hard maple for the core and jus use one horn layer.
Horn is around 1.3s.g., osage maybe 0.8 s.g. and maple more like 0.6s.g. if you were to 'swap' the osage and the other horn layers for maple. The bow would be much lighter in physical weight whilst still storging the same energy - this would led to higher efficency. You could likely have used 60 - 70 grammes of sinew to safely back the bow. Again sinew is heavy stuff around 1.3s.g. so you want to use the least amount possible.
Just some pointers for you. I totally dig your bow and think it is something to be very happy with :)
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Thanks for the pointers! Next one I’ll try what your suggesting. This one was more of an experiment following the original cross section from the source article which admittedly seemed overly complex, especially for circa 1000bc
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Yes.Good point by bownarra.I was the one who was wondering about the mass weight.
In retrospect how mass weight can affect a bow I have a black locust self bow [no sinew] that mass weighs 14.25 ounces 63" long stiff handled that pulls 54 pounds @ 28" that is a very efficient bow.Kinda like comparing apples to oranges I know but the relativity is still there putting the mass placement where it is most needed in self bows.
Cool bow you got there though.
I've rummaged through my buffalo and gemsbok horn slat collection and have come up with a pair of gemsbok horn slats that should do the trick for me to make such a style of bow.They are 29" long apiece and 1/8" thick 1" wide midlimb which will give me around 15 to 20 pounds of draw weight.
(https://i.imgur.com/yxNcFzP.jpg)
(https://i.imgur.com/jHDtbPL.jpg)
I've made around a dozen complex bows and will do my calculations to make such an Assyrian type bow in the future using the reflex forms I have here.I have plenty of sinew also.My goal will be to get around 50#'s @ 28".
PS.....A full draw picture of yor bow would be nice.
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full draw coming promise. One thing I have no idea on, where can i source the proper maple for these composite bows. Im guessing a hardwood supply even with the proper grain running in the wood is not the place. Anybody have suggestions? Thanks in advance.
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There are other woods out there to use like ironwood [hornbeam or hop hornbeam].They are diffuse pourus also.That's what I'll use this time around.If you use maple make sure it's hard maple.
Made them from very tight ringed hickory a number of times also with very good success.
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full Draw or at least mine at this poundage
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Thanks.Looks great I think,and also looks pretty stout for you too.Some pictures of them show a more rounded full draw [out of context comparison] but that is on account of not as much reflex induced in the working limbs on theirs I'm sure.
I was looking at my Ottoman Turkish horn bow book Adam wrote and I had a sheet of paper in the book showing the preperation of an Egyption complex composite put there by me some time ago.It looks to me like an extreme version both ways of deflex and reflex.It's a copy I printed from the atarn.org/islamic/egyption composite files some time ago.Thickness taper is rather extreme in the beginning from the handle then slows down to 1/4 the rate from midlimb to tips.Paralell width to midlimb then tapering to 3/5th's width of handle.
(https://i.imgur.com/SU95zvm.jpg)
1 reason why bows such as these angular bows need to be braced fairly high to avoid inversion of the limbs after releasing.