cheers guys thanks again.
Springbuck - the first 6 bows in the photo you posted are the same 6 bows at the UBC museum. I posted this topic a while back
http://www.primitivearcher.com/smf/index.php?topic=52997.0I will try to address some of your questions as best as I can. I went to the museum again recently to take some close up photos and to "ballpark" some dimensions.
Side note, I spoke with a curator who said I could set up private viewing times for any of the bows they have
, so i'll for sure be doing that in the future.
"The originals are said to be made from fir or larch, but depending on location, many other woods and materials, including yew were used." THIS is where it breaks down right away for me. The middle sections look pre-deflexed of course (a good way to relieve strain on an inferior wood like fir), and seems to bend some both when braced and when bent. BUT, as near as I can figure from the photos, the wood is quite thick, fairly narrow, and doesn't seem to taper much in either thickness or width. Honestly, it LOOKS too thick to bend much at all without breaking (cable notwithstanding). It's so hard to see anything in the pictures..... the full draw pics the bow is heavily canted, for instance."
Its hard to tell even looking at them a foot away through glass, if they taper much at all in thickness. Similar to some RDs, the limbs really don't travel too far to get braced, but at least on my bow, there is plenty of early string tension. The recurved areas are the widest part of the 4 bows of this style, and they narrow at the handle. The deflexed areas I'm sure did the bulk of the bending on these bows. Why not just leave these areas a little thicker?, I figured probably because they are meant to work a little bit.
"So, in YEW, it seems like that bow can do anything it wants, bend wherever, etc....but in fir, larch, or even birch, it seems too stiff to pull and/or too thick to survive.
!!!!UNLESS!!!! those weird recurves do most of the bending and the middle bends almost not at all, either by hinging at the splice, or by a combination of bending and flexing/hinging at the angle. So, are they one piece, or spliced on?
So, which is it? In yours it seems apparent that the outer limbs taper in thickness. Do they also bend heavily at the angle? I can see the middle flexing well in yours, and it just seems like too much for fir or larch to take.
Using yew, I probably didn't need to add so much deflex, but I really wanted to stay true to the profile. They needed to add it because they were using inferior wood for the most part no doubt. Its very hard to see if the levers are spliced on the originals, but my bow is obviously one piece. Id like to get some accurate measurements of the originals, to get a better picture of how they may of bent. I tried to get mine close, then went with what I felt was right for the bow. I will share some close up pics I took of the levers on the originals.
" I used baleen for the recurve stiffeners. Such a cool material, works like horn, but has "grain"....." Are these stiffeners? Are they glued down? Or are they more of a bridge to raise the cable? OR....are they designed to stiffen the recurve angle..... but ONLY after they have flexed a certain amount? I recently patched a bow having a "previously undisclosed" bug hole on the back by making a "rocking chair" curved oval out of ipe, 1/16" thick and 2.5" long, which I clamped straight on the back and bound down with fine linen cord. So far it has held for dozens of full draw shots. It doesn't seem like it should help as much as it does.
The originals use wood stiffeners, or bridges, what ever you want to call them. Baleen was used for this purpose in other areas, and really, I just needed an excuse to try the material out. They sit on top of a piece of thin deer hide, just loose, but binded all together. The originals have some kind of hide under the stiffeners, and all the way to the tips. Are they essential? I'm not sure, I suppose I could check to see if theres any change in draw weight with and without them. All the originals use them so I did. I believe they are there to stiffen the recurve area, but still allow them to bend and hold their shape.
"The levers bend a bit, if they didn't I think it would be much worse." do the limb tips bend or the angle flex?
Its hard to tell, I think they bend just slightly.
If the tips were not deflexed, the string would contact the levers at brace, like the smallest bow of the 6.
If things are not perfectly lined up you could run into stability issues, or even the string reversing the bow when shot like some horn bows.
Thats the only real reason I can think of, it adds some stability at brace.
Or maybe it was a style thing.
I have not plotted the bow on a FD chart, but it feels much like an RD to start. Smooth out to around 22, 23", then stacks a bit near the end, but its also a pretty short bow.
I hope others try to build these bows, I'd love to get some other brains on it.
