Tillering and Shooting a Double Curve Bow (Not for BOM)

[JackCrafty]

Thanks Sailordad...yep, we all know what happens to sinew when it gets wet.  So far, I haven't had a sinew string break (yet) but I've seen 'em stretch quite a bit in heavy humidity.  The humidity can decrease the brace height by about an inch.

The strings wear out pretty quick but not where you might expect.  My strings always start to wear at the point where I tie them at the bottom of the bow.  Repeated adjustmets cause the string to fray badly.  A string can survive a few dozen adjustments (or so).

Here's a pic of the bottom of the bow.  (Sorry if it's a little blurry).  You can kinda see the wear on the string.

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[JackCrafty]

A lot of my time is devoted to processing sinew.  I'm currently backing a few bows with sinew....here's some pics of my setup.  Of course, no setup would be complete without an assistant....

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[JackCrafty]

Part of the process is "trimming" the sinew.  I taper the ends of the strands with a knife or scissors....this allows the strands to blend better with other stands.

The strands in the pics are thick (for bow backing) but I also trim the strands that I use for bowstrings, bow wrappings, and for hafting fletches and arrow points.

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[orcbow]

Jackcrafty- I made one of these plains style double curves back in the last winter. Mine is 42" long, and made of dogwood. This picture shows the initial set-back. I put about 6 layers of whole deer backstrap in the handle, and tapered out the layers to end up with about 2 layers at the tips.

I thought if I made one, I would understand the design better, but still I'm not sure I do.

That's a really nice bow you've made. (sorry, I hope you don't mind that I put a picture of mine on your thread)

[a finnish native]

Nice bow you got there! it looks to be tillered well and the lenght is just great. One problem though. You haven't got enough sinew on it. This may be the key reason for why it isn't performing better that you bows that have no sinew on them. In this case the sinew backing can be held as a safety precaution. To recive noticable benefits fron sinew backing in these bows one must put a lot of sinew on them. I suck at inches so I'm going to say my dimensions in centimerers. When you applied the sinew and it is still wet the layer sould be about 1.5 cm thik and tapering to the sides and tips. so the center of the bow would have the most amount of sinew.

[JackCrafty]

Orcbow, that bow you made will probably work (don't worry about posting the pic...I'm glad you did).  I think the draw will be quite short, though....maybe 19".

Is it dry?  Have you tried to brace it?  I don't see any nocks....you might want to wrap sinew (or thread...temporarily) around the tips to form shoulder nocks, then try to brace it at 1/2" (yes, very low brace).  42" is not unusual for these bows, but the wood will be strained to the max...especially a stiff wood like dogwood.

I'm going to start a build-a-long on a double curve this week.  It will be a copy of the bow in this thread.

[JackCrafty]

Finnish Native, yeah, there is very little sinew on the bow.  You're right, more sinew might increase the performance.  However, the originals have very little sinew...and since this is a reproduction, I didn't place a thick layer on the bow.  IMO, there are three main reasons for not applying a thick layer of sinew:

1. One of the characteristics of many plains bows is that they are not complicated.  (Horn bows are an exception, but these are few in number).  On the examples I've seen, they appear to be sinewed with a single layer of very long stands of sinew (probably buffalo backstrap).  A single layer of sinew is much easier to apply, not to mention faster.
2. There is the issue of weight.  NA bows are sinewed from tip to tip...without exception, as far I can tell.  Thickly sinewed bows from other cultures (like Korean bows) are sinewed only on the bending portion of the limbs.  If I wanted to apply a thick layer of sinew on a NA reproduction bow, I would have to be very careful not to weigh down the non-bending tips.  This would make the bow much more difficult and time consuming to build and, therefore, not likely to be common (see reason 1).
3. There were at least three excellent types of wood available to plains Indians (osage, hickory, juniper) that really don't need the added benefit of a thick layer of sinew.

[Papa Matt]

Jackcrafty, wasn't Ash a common bow wood of plains indians?

[YewArcher]

I have made a slew of these an prety much agree with your observations. They are a great bow. Fun to shoot and take disipline to master. I would sugest that you give your a larger draw. You can get a 24-25" draw out of the bow that you are showing there. I have been making mone 42" long and drawing them to 24" and could probably go 25". That will get your performance up a bit.

I really agree with what you are sugesting with the stack......when you pull one of these bow it really lets you know when to stop. This is how I tiller mine. You can see in this picture that I try and get my limbs bent almost 90 degrees. If I were to darw that bow to 25" they would be.



One other thing of note is unbraced profile. These bows are afully hard to shoot. One of the reasons is the balance between handel and tips.

If you take the 3 bows that are shown in the picture below. The bottom is by far the easist to shoot.



I beleive its because of the limb angles in the unbraced bow. The balance better in the hand then the top 2. I guess you could compare it to reflex vrs. a bow with some set. I have since swuitched all my new bows to that last profile. Glad to see some other bows of this sort being built.

Steve

[JackCrafty]

Papa Matt, I think ash was used by the Sioux (along with hickory).  I don't think it was common, however, because in areas where ash was available, other wood such as mulberry, mesquite, ironwood, and white oak were used instead.  Also, I think white ash is found mainly in the eastern woodlands?  Other ash varieties are not as good as white ash.

Many descriptions of the wood used for plains bows simply say "whitewood".....and I guess many assume ash was used.

[JackCrafty]

YewArcher...you are a braver man that I am!;D  I would not dare strain my bows beyond what would cause 1-1/2" of set.  I put too much effort into them...and I hate starting over when one breaks.

When I said 90^o, I meant the angle of the sting angle compared to the limb, not the limb angle compared to the handle.  (Am I reading you right?)

[a finnish native]

That is true what you said there. I have read that the plains indians used to do so that they tare the tendons into thin strips as you did and what must be done. then they would sort them out into bundles of say 20 threads according to lenght. then those bundles were one by one soaked in water and then in glue and applied on the back of the bow. this manner was done through out the bow as bricks are made into walls. of course the tips would have far more less sinew than the handle area so that the tips would not become too heavy. then an other layer was done the same way but the new bundles would be put between (still ontop) the lower bundles so that it would eventually make a crown on top ot the back of the bow.
I made one bow sinewing it like this. I had a thread about it here, but I no longer seem to find it.. It was named "a sinew backed rowan" or something like that.

[YewArcher]

lol.....i am not that brave. I really belive that the bows were meant to be drawn that way. That is when they are most efficiant and is why....(IMHO)......the bow is designed the way it is. The bow that you see on the bottom of that picture has about 1/2" of set from the original shape. Thats not overstraining the bow at all. The top 2 bows have about 3/4" set from original shape. They are well within a safe durable margin. I mean 90degress so that the limbs are alomst flat at full draw. As shown in the picture 90degrees from the handel plane. i have now made 13 of these bows in this fashion and they all shoot great and have not had a failure. The limbs can take it.

Steve

[orcbow]

Jackcrafty- Yes, I did finish my bow, here are 2 more pictures- I draw about 17", though I need to take a full draw pic. I had trouble with the sinew, as it dried it all came up separating at the wood. I glued in down again, but had to forfeit the extra inch of reflex that it gained. I used knox gelatin for my glue, but I think I made it too weak at first.
If I did one of these bows again I would use a lighter weight and more elastic wood. I had the "classic" problem making a short bow from strong wood, I couldn't get it to bend, so I kept scraping and scraping, and next thing I knew it was too much. Maybe dogwood is not very elastic (I'll have to look into that) .

[JackCrafty]

Orcbow, that bow looks awesome.    This is how I solve the problem of sinew separating itself from the wood as it dries. What you are looking at is polypropylene twine on one of my new bows under contruction (polypropylene won't stick to the glue) It leaves ridges in the sinew but at least it will be firmly attached. (The third pic shows my bow's back with the telltale ridges).

IMO, the best woods for short double-curve plains style bows are osage, juniper, elm, mulberry, and black locust.  Your dogwood bow would have worked better with less deflex and more bending in the handle...but, of course, you know that now.


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