Primitive Archer
Main Discussion Area => Bows => Topic started by: D. Tiller on July 23, 2007, 07:31:54 pm
-
Well, I just learned a cool thing from a friend of mine, Dave Tinsley. Turns out that if you remove the sapwood from Osage with a band saw before drying and save it and then when both peices are dry laminate them together and they will make a bow that will outshoot yew! I know, I know this is hard to believe but Dave Tinsley learned this from Don Adams in Oregon. So I believe this to be true and will try it out someday! ;D
-
why not simply chase a sapwood ring, leaving a ring or two on the back ??
-
From what I heard the sapwood will dry faster than the heartwood and cause checking. If its removed it will dry at its own rate and the heart rate at its rate and no checking should occur. Dont know if this is true or not but I think its worth a try. Anyone out there want to try it?
-
Yes, well thats a laminated bow not a selfbow, its not really the same thing so it would be hard to compare. ::)
Ive seen several osage selfbows with sapwood backs and they were nothing to brag about performance wise. It will make a bow but its not as good as the heart wood.
-
Its possible to leave sapwood on and not have checking too. You need to leave the bark on and dry slowly, and it takes a little luck. I happen to have a couple of staves with intact sapwood, I've been toying with the idea of leaving some sapwood on at least one of them. They are thick enough that I wouldn't have to, so it'd be a gamble. I do think the sapwood is probably a little lower in mass, since the heartwood does contain a good deal of extractives. And it should still retain much of its elasticity since most of this would come from the fibers.
I tend to agree with Ryan though, I have to think that if there were a real advantage then you'd already be seeing it done.
-
The leopard skin(tissue paper) backed osage bow I posted last month is about 50/50 sap/heart wood osage. I just finished an all heartwood osage bow, basically the same dimensions(60"t/t, 1 3/8" at the fades and 3/8" at the tips) and the 50/50 has more physical weight. I haven't actually weighed them but I have compared their weight. The osage self bow is 56#@26" and the 50/50 is 57#@26". The 50/50 bow does have less cast and more shock but that is probably the weight difference. I was surprised that the 50/50 would weigh more than an all heartwood bow. ??? Pat
[attachment deleted by admin]
-
The glue joint of the joined back and belly bow adds quite a bit of weight to the bow you mentioned. Pat
-
Hmmm! Has anyone tried taking off the sapwood before it cures and then glueing it back on as a laminate though? From what I was told this is the secret to getting it to work really well. From what I was told the sapwood when left on does something to the heartwood to make it a lowsy bow when finaly turned into a bow. But when laminated to gether after drying they really shine. Have no idea if this is true or not and probably wont get a chance to try it out in the future since I'm in WA State and dont have a ready source at hand. But, if someone would give it a try I would love to hear the results.
Also, the bows these guys are building are English warbow and Victorian longbow designs. That may be what is making the difference here also. ???
David T
-
This is to RynoI think you are making a armchair opinion here Ryno . Ive got 2 sapwood bows out in the shop that just has a little heartwood left on the bellys and I guarentee they will shoot faster than a all heartwood bow. For one thing Osage is osage and the sapwood is lighter than the heartwood so by design it has to shoot faster because of its lightness . and its osage regardless of whether its heartwood or sapwood. Trapper
-
Trapper, you up to doing an experiment with some fresh Osage? Maybe you or someone can try this method and let us know how it works. If it can make an exceptional longbow I am going to go for it one day when I can find a good suply of it.
David T.
-
I made a pretty good osage ELB style bow with a few sapwood rings left on the back that is an very good shooter(BOM Jan or Feb 06). If the sapwood is treated properly from the start is should be fine to use as a backing. I'd rather make self bows than lam bows(backed included). I have made a few of each and don't think its worth the trouble.IMO. My self bows shoot good enough for me.
Osage sap wood is as strong as almost any white wood so why wouldn't it work as they do. Pat
-
Trapper, it takes more lighter less dense wood to make a bow the same poundage then good heavy dense wood, thats where it loses pretty much any and all advantage the sap wood had over the heart wood.
Theres no doubt in my mind that the sap wood can make a good durable weapon, but it would need to be designed diferantly than a bow made of the more dense heart wood. Ive made bows of pretty much every white wood I can get my hands on and I havent found anything yet that will withstand the same dimensions I get away with with good dense osage heart wood. 8) Ryano
-
Ryano, have you tried a medieval Warbow design? Yew uses the sapwood and the heartwood in conjunction. It was to this type of design that I'm thinking about when making a lam. from both the heartwood and sapwood. I think it might work.
-
D.tiller, I'm sure it will work. All Im saying is it wouldnt really be any diferant than say a hickory backed osage or something like that. Yes, I have made english style yew bows with the sap wood on the back. Osage sapwood isn't as strechy as yew sap wood is though. Ryano
-
David, you are going to a lot of work to make a board bow. I don't see what the difference is in cutting the sapwood off before or after curing. Are you going to chase a ring on the sapwood or cut it ring bias? You will need a thick layer of sapwood to cut ring bias. If you are chasing a ring, make a self bow. Justin
-
Guys, I think you are missing the point. I have heard from Dave Tinsley that by cutting the sapwood from the heartwood you maintain the properties of the sapwood since the heartwood would pull the sapwood into compresion and make it worthless. By removing it and drying it seperatly you keep it from being pulled and contorted by the heartwood as it dries. Then when laminated back onto the heartwood it makes for a superior bow than just using the heartwood. Even, suposedly, better than yew wood.
This was told to me but I have no means of testing the hypothessis. But this information comes from Don Adams Vvia Dave Tinsley so I suspect there is something to it.
Yep! I would follow the sapwood under the bark just like on white woods this way but use a bandsaw to seperate the sapwood from heartwood.
David T
-
I suspect if you cut the sapwood off, reglued it after drying with a lot of induced reflex and chased a ring on the back you would have a real performer, interesting looking as well.
-
Well now David, that is completely different from what you said before. You told us we were removing the sapwood to keep it from drying uneven and checking.
I still maintain the same idea. You are talking about a glue up that will improve the bow. If the heartwood is keeping the sapwood from reflexing, it would be under tension and improve the performance. I would suggest you get sister staves to near bow dimensions and dry them. One in one piece and one in two. I suspect they will dry in nearly the same profile. I don't think you are hurting the sapwood. Then you can cut off the sapwood from the second and see if the two pieces of sapwood aren't the same profile. Justin
-
I wonder what would happen if you turned the sapwood backwards and then glued it down?
-
Then you'd have to shoot the arrows nock first :)
-
If the sapwood takes a natural relfex, I dont think I would glue it on backwards. ;D Justin
-
my point is your gaining all the performance from gluing two pieces of wood together with reflex, which holds the profile better than one solid piece of wood.