Primitive Archer
Main Discussion Area => Bows => Topic started by: superdav95 on December 14, 2022, 10:14:32 am
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Hey guys. Here a composite bow I’m working on currently while waiting on others to dry and materials for others nearing completion. It’s a bamboo horn sinew composite bow. It’ll be a somewhat Scythian style profile hopefully when done. It’s about 58”ntn. I stuck with slightly thicker bamboo core then the 1/3rd thickness on this one. It’s more like 40%. 30% horn 30% sinew. I did no pre tillering on this core as an experiment. Also testing out more crowned core prior to sinew. I did the 20tpi longitudinal grooves as I usually do but kept them shallow and clean. I did lots of size coats with very thin glue. Basically water with a little glue. Probably at least 10-12 coats or more. Just kept going till it was shiny when dry. I’d say 5% glue. I use a half and half mix of high strength hide glue and sturgeon bladder glue for sinew. For the horn I use mostly sturgeon glue. Longer gel time for horn glue up is nice.
So far I’ve got 2 layers of sinew totaling 75-80grams. I use horse leg wrap after a couple hours after laying sinew and gelled up good and firm. I let this sit for 3-4 hours then wrap in opposite direction and then leave sit over night. It’s got just the right amount of stretch and breath ability when using horse leg wrap. I use a straight stick and couple clamps to keep my tips aligned. I’ve had them dry and pull a bit wonky before. I’ll keep in creasing the reflex a little more on this one but it’s close to where I want it now. Couple of weeks for drying I imagine and will be ready for next stage. I’ll likley wrap with some thin rawhide. I suspect a peg board for this one will be needed.
Thanks for looking. Here’s some pics showing some of process in reverse order unfortunately. Hopefully it’s helps someone out there.
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The next day after removing wraps off of second layer.
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The horse leg wrap put on after an hour or 2 of gel up after second layer.
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Just after second layer
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Wraps on after first layer
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Just after first layer sinew
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The grooves. Note the shiny appearance and shallow grooves. This is the rind side of the bamboo.
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Here’s the glue I used for sizing. Apply with soft brush. Very thin about 5%. For laying sinew about 30%
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Here I decided to file down the node bumps for a smooth surface. Normally I leave them and just round them a bit prior to grooving the back.
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Very nice and very descriptive. Might have to ask Pat if he can save this thread in the archives once you complete it.
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Thanks pearl drums. I should’ve included more but I guess folks can ask for more details. Here’s a few pics of my scraper I use and blades I use.
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Figured I’d add this pic of close up of limb after wrap removed. Very little wrap marks if any at all. I find this stuff works really well.
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Looks really good Dave. Thanks for posting this.
Really good timing for me. I’ve been working on processing sinew when I get time.
Bjrogg
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That sinew looks very clean. It's obvious you're very detail oriented. The board to keep the limbs aligned is a great idea. One of the great things about this site is I'm constantly learning. Thanks for posting this, Dave.
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Great post Dave. That sinew looks really nice! Look forward to following your progress.
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I really like this post. What is the purpose of the horse leg wrap?
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Thanks guys! My pleasure to post it. As for the horse leg wrap… I like to use something that keeps sinew down on the more extreme reflex designs. I find that on milder reflex profiles it’s not absolutely necessary but still can do. Sometimes when sinew dries the top layer fibers dry faster then middle layers and can pull off the limb on some of the extreme profiles. I find also that the wraps give a nice finished look and crowned look to it that means less removal with sanding for that desired finish. I want a very smooth finish on this one so went with wraps. The difference with horse leg wraps and other bandages is that it’s a milder elastic and thinner material. Still breaths great and doesn’t leave the bandage marks nearly as bad. I could hardly see any marks on this one. The keys is not to put wraps on too soon after laying sinew. Usually couple hours is good. As far as my sinew I really wash it well with dawn soap and brush it really well with wire brush prior to that and use my thumb nail to scrape off the unwanted bits. I weight it out with good scale dry for each limb. This saves lots of headaches later.
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looking great,,, (-S
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Thanks for posting. I really learn a lot from these build alongs. Gives me a starting point to try things I would never consider doing without seeing before hand.
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Bentstick, my pleasure. I’m the same way. Seeing it done is often all I need to get started then the learning curve really begins. Visuals are great though when we can get them. A picture is worth a thousand words with this kind of stuff!
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I posted a reply on BJ post on this also but figured I’d attempt to keep it all here too for guys for ease of reference if using this post as a how to or somewhat instructional.
I’ve personally tried the process while wet and I found it does work but is sorta messy sticky stuff when wet and harder to handle I found. I did notice little less waist but not enough for me to have the benefit of working the stuff dry. To me I find the dry working this stuff better. It separates good so long as you got good quality tendons or back sinew. Some of the back sinew I use from moose and elk or Buffalo is quite thick similar to leg tendons. I pound it all with a 16” piece of muscle wood sapling about 2” diameter. I use a small maple stump to pound onto to break up. I used to use a metal hammer but found I waisted more material. Also resist the urge to speed up the drying but putting it in the oven or dehydrator. It doesn’t end well. Let it air dry. I waisted a lot of good sinew trying to rush it. Here’s a couple pics of the dog brushes I use to get the separating fibers done initially. I then use a standard wire brush from there all while dry. The other big benefit of working this sinew dry is measuring it with a good scale. Also measuring for length. It hard to fully know your weights of sinew while wet. It’s important to get as equal weights on each limb. Obviously this makes for better balance in limbs. I’ve seen guys just place it on randomly in groups of strand bundles and maybe this works out for them but I personally like the methodical approach with careful measurements dry getting consistent lengths of the strands. It just work out good for me this way. I use dawn dish soap as it’s mild but good for cutting oils out well. You’ll know it’s good when it’s almost squeaky when you get it good and wet pull it through your fingers. I had some elk sinew that was quite good but had a pronounced red look to it after being dried. I pounded it well and separated it all up well and had a pink tinge to it. After washing it all up with dawn it was white as flour. Don’t wash it with hot water either. Use Luke warm water. The finer you can get the strands now the better finish you’ll end up with in the end and less air voids in the dried sinew. More of an esthetic thing I guess but still want your sinew nice and tight fitting of the strands together. The wrap help with this a bit too.