Main Discussion Area > HowTo's and Build-a-longs
Sinew Backed, Double Curve Bow
JackCrafty:
This is my first build-a-long.....and my hope is that it will spark a discussion on how to produce a replica plains bow with the best possible performance.
The wood I will be using is juniper....not because juniper is awesome.....but because it is what I have available right now. The wood has already been chosen, cut down, shaped, and seasoned. What's left is the application of sinew, making a bowstring, final tillering, painting, finishing, and shooting to test performance.
Many of you guys have already built double curve bows and it seems a lot of people have one. The one thing missing, though, is how to get one to perform well without turning it into a wide-limbed, narrow tipped, long, non-bendy handle, laminated monstrosity with an arrow shelf cut in the side (yuck) and fast-flight string. I've looked high and low and there are few references on how to build a reproduction of one of these.....far fewer than the databases on how to build a traditional ELB, for example.
Ok, enough introduction, the first step is choosing the right wood. The wood must, first and foremost, be very flexible. The MOE and Work to Maximum Load (WML) must be higher than average....with ash wood being the average. It must be easy to bend with heat and or steam. It must have been available to NA's. And the wood has to be able to withstand the strain imposed by the dimensions of the originals.
Since I am using juniper, I will discuss how I choose a juniper stave. The pictures show that not all juniper is created equal. The ratio of sapwood to heartwood varies quite a bit between trees and between branches and trunks of the same tree. As a general rule, tension wood (the upper side of limbs or leaning trunks) has a very high percentage of heartwood...and is the best choice for bows...if you can get a long enough piece without twist or branches. However, juniper trees growing close to water seem to have a lot of heartwood in their trunks (which are usually straighter than limbs) and this is the wood I try to harvest. I have made bows with all heartwood and all sapwood and they both work well.....but the heartwood is better at not absorbing moisture and taking set. The bow in this build-a-long is almost 100% heartwood.
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JackCrafty:
The measurements for this bow will be very closely matched to a bow I've already built out of juniper (with the same amount of heartwood).
The older bow's mass is 10.9 oz. The accompanying string is .4 oz. The new bow's mass is 12.9 oz.
The width of the older bow is 1-1/16" and the new one is 1-5/16' wide (I plan on making it stronger than the older bow).
The thickness of the older bow is 1-3/16" (including sinew) and the new bow is 13/16".
The limbs of both bows are tapered gradually to the tips in both width and thickness (just like the originals).
The new bow will have slightly recurved tips.
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benjamin:
is that the normal brace height on the older bow? does it slap your thumb? Very nice. Can't wait to see the rest of the build along.
sailordad:
i was curious too, however if you look at the left limb you can see the string is off the nock, atleat i hope it is cause thas gonna hurt other wise
JackCrafty:
The overall length of the older bow is 47-1/2" and the new bow is 49-1/4" long. The extra length is for the "tassel pin" at the top of the bow.
I'm also posting a couple pics of how I measure the "curves". The shape was mainly done by eye and then fine tuned with a tape measure. The general shape is something that I learned with practice (with juniper in this case). Other wood types will have slightly different curves depending on how much set I expect to have in the final bow.
The central curve is 1-1/8" from from the edge of the board to the back of the bow. The distance between mid-limb curves is 24". The distance from the edge of the board to the back of the bow @ tips is 1" (not shown).
(That's it for now...I'll post more soon).
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