Primitive Archer
Main Discussion Area => Bows => Topic started by: MattZA on May 19, 2019, 03:01:36 pm
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Hi all,
I was hoping you could give some tillering input here before I go any further. I've never tried this shape before, nor have I ever used sinew. This has both.
Any thoughts on where to remove wood? I'll definitely provide more pictures when I've got a second opinion, and cleaned it up some. It still has gross bits of linen everywhere that I'm scared the sinew might raise.
*Edit* As you can see, the sinewing job is clearly my first attempt.
Thanks!
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your left limb is significantly stiffer than the right
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Thanks Jeff.
I didn't realise it was so significantly stiffer. To my inexperienced eye it was a tiny bit stiffer, but that's all. I haven't really drawn it too much. I'm nervous the tiller is far too out and it snaps.
I'll definitely adjust it.
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your left limb is significantly stiffer than the right
Have to see it drawn with the arrow nocked correctly to really get the whole picture.
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+1 PatM, If the right limb in the picture is the upper it may be near perfect drawn in hand with the string angle changing...
Don
Yank that bow back and lets see a full or partial draw with proper hand and nock placement...
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You can only tell proper tiller at full draw. Draw it slowly and take pics at different draw lengths so you(we) can see how she opens up.
So far it looks good.
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I'll give it a (eyes closed, heart in mouth) draw as soon as I get home and can take a photo.
It makes me feel good that you all at least don't think the overall shape at least isn't entirely wrong. I've found it quite tough to tiller with all the curves. At 46" and just over an inch wide it doesn't leave much room for error.
How does one keep the sinew down on the tips? Should I wrap them with silk/more sinew/linen where the sinew feathers out?
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Yes Matt, you can do a sinew wrap at the tips for more insurance...
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either silk or sinew will work. If the glue job is right, you shouldn't need much of anything. by the way , you should have seen my first attempt. this actually looks pretty good. what is the draw weight?
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I'm all out of processed sinew, and I don't want to go to the effort of stripping a whole new one for an optional extra wrap, haha. Silk it is, then. The sinew hasn't lifted, but I had to build underlays onto the tips to keep them static and stable (they're 3/16" wide). So I'd just like to wrap them to 100% keep the whole lot intact.
Jeff, the draw weight is quite tough to tell, since I haven't drawn it yet. My educated estimate is 45# at 24'. That's based on what it drew prior to sinewing, and the amount I've taken off the belly since. My aim is +- 50# at 26". I built it to share with a lady who does horseback archery. She draws 40# at 23", which suggests it's exactly where I want it.
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that looks very good matt! just don't just remove wood now unless its obvious. you have to exercise the sinew first with patience. the sinew will become less stiff and tiller will change. i'd exersise it a while at the tiller wall and shoot heavy arrows at short draw (SH) then remove wood...
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Hey Simon, thanks mate!
Yea I am definitely going to give it a bit of an exercise.
I'd promised everyone a drawn picture, but I braced it and gave it a few pulls yesterday and the tiller kept shuffling around the place. It never went out horribly, but it drifted a bit here and there. So it was impossible to get a reliable photo. I did manage to draw it to around 20" after much exercising though. No drama.
I'm going to shoot it a bit at that short draw and then take a photo again when it settles down.
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what was the weight at 20 inches,, then you can tell where it would be at 23,,
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*Sad Update*
Unfortunately I experienced my first bow explosion last night.
I was shooting the bow fine, with the draw length slowly increasing, while checking my tiller every few arrows. All was fine. Bow was shooting like lightning. Very little (if any) set.
Turns out there was a 1/4" hairline fracture in the back (over the side edge). I knew about it, but I covered it with extra sinew to protect it. Clearly I didn't protect it enough.
Nonetheless, thanks for all your help throughout. Back to the drawing board. You live and learn.
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Save the sinew. What kind of wood was it?
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Yup, I will save the sinew. Should I just soak it in water to release it from the glue?
It was a local hardwood called Leadwood. Combretum Imberbe. Extremely dense (considerably more than Ipe). It does seem like it has great potential though - since it was pulling 46# at 25". Effectively zero set, and 1 1/8" wide and 46" long before steaming the bends in.
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Sincere condolences. Just soak it in water for a while - maybe takes several days to solve the glue...
46# at 25" and 46" long, stiff handle sure demands a lot from the wood. Can't be so bad - probably worth another try :BB
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Thanks Simon,
As you say, I was asking an awful lot from the wood. The handle was stiff, and the recurves were too, so I had approximately 17" of working limb per limb. But then again, with an SG of 1.22 and a Janka Hardness of 15880N, I don't know if I'll be able to work a bigger piece without breaking both wrists!
You suggest I just soak it in plain water? Goodness me that's going to be a nightmare to then put all the sinew back in bundles (A)
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Would it be possible to soak the sinew just enough it off as a single piece? Store it like that and then rehydrate it just enough to be flexible and glue it on the next bow?
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Besides where it obviously snapped, yes I think it should be. The sinew is in one single piece, just with a neat snap.
I think I'll do that.
By the way, I made myself a draw knife out of a cheap old backsaw blade yesterday. I'll post about it in Globalmark's topic in the How-To section.