Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on May 15, 2020, 07:03:29 pm
-
I was stumbling around the shop trying to decide what to do next. I took a bow that I'd pretty much given up on and put it in the corner of shame. While there I noticed a couple of Yew limbs from two broken bows. I've looked at them before and couldn't decide what to do with them. Then I noticed two pieces of Boo backing that I had stripped off yet another failure. A light went on. A quick look revealed that I would have to leave a little sapwood under the Boo but I've done that before. Also one limb is deflexed a bit and the other is reflexed a bit(one reason they'd sat there for so long) but the bow backing will help sort that out. Just the kind of project I like, use a bunch of junk to make something(hopefully) good.
-
Also one limb is deflexed a bit and the other is reflexed a bit(one reason they'd sat there for so long) but the bow backing will help sort that out. Just the kind of project I like
sounds challenging. How were you thinking the backing would sort it out.? Pull the deflex one into reflex before you glued the backing?
-
Yup. As it turns out one is straight and the other is reflexed so I'll make an R/D and both will be reflexed. I'll glue the reflex in. The limbs will probably be an inch or less wide.
-
lookin good,, (-S
-
the other is reflexed so I'll make an R/D and both will be reflexed. I'll glue the reflex in
if one will be prestressed and the other not, but both will look the same, how will you account for that when tillering? be prepared to monitor for set on each limb independently and posssibly have a bow that will look as uneven as the limbs look now?
you could heat bend one limb to match the other and glue up both with the same pre stress....
but I dunno what would actually be better.
-
I may steam the reflexed one straight. I'm thinking on that. It's not a lot of reflex so I'm not sure if it matters. I'll probably get them mixed up anyway :D
-
Mark one limb -A, the other limb B and hope to hell you don't forget what you are doing to which limb?! >:D (lol) :BB :BB. Sounds like a fun project! Stay safe! Have fun!
Hawkdancer
-
I may steam the reflexed one straight. I'm thinking on that. It's not a lot of reflex so I'm not sure if it matters. I'll probably get them mixed up anyway :D
How I would do it. Just like you would with a stave, but add in the extra difficulties if the limbs are off different trees. Takes a lot of patience at tiller no matter what you do if that is the case
-
Easy enough...just watch the set. Set and its location tell you everything you need to know :)
Live dangerously :)
-
Now that I've evened out the thickness and made the limbs a similar size it's just like starting with billets.
-
All glued up 64"TTT, 4 1/2" reflex. There is a chalk line on the board behind the left(bottom) and that's why it looks so fat. It has a tad more reflex so it's tentatively the bottom limb. Now if I can tiller it. These things give me fits :D
-
I vice tiller these sort of bows to brace and use a stringer on temp nocks once I'm sure it is bending good and just brace them early. Once braced to 4" or so they settle a bit.
Good luck -- it could be a screamer :)
-
Could you kinda describe your vice tillering method? If I put it in the vice and grab a tip in each hand I'm standing to close to see if it's bending evenly. Right now it's going to 40# with about 1-2" of tip movement so it's kind of hard to pull with my arms stretched out too.
-
Could you kinda describe your vice tillering method? If I put it in the vice and grab a tip in each hand I'm standing to close to see if it's bending evenly. Right now it's going to 40# with about 1-2" of tip movement so it's kind of hard to pull with my arms stretched out too.
I suspect he is talking about something like what Gordon does in his Vine Maple build thread, post #66: http://www.primitivearcher.com/smf/index.php/topic,53195.0.html
Mark
-
Gordon has a swivelling vice, that would let me out.
-
Well I'm bummed. It was going just great. I tillered it on the shortest long string I could get on. Tillered it to 14". Took a couple more scrapes and put it back on the tree. Out to 14" then it went to 15 then 16 then 17 and settled out. OK, I thought, I've gotten the surprise over with. Tiller looked great. Pulled it a few times, everything was fine. Reflex had just peaked at 5 1/4" and was now at 5". So I low braced it. Looked good. Put it on the tree, one light pull and it collapsed. A hinge in the top limb. I quickly unbraced it and took a look. There was a thin spot right at the hinge. About 1 1/2" was 10 thou thinner than either side. I could see it in the rings. No idea how or when I did that. I evened it out but I've still got this. When I unstring it and hold it up against the original tracing it looks good very little if any set. It's just very weak there. This one was feeling fast. Tons of early weight. Crap. Why can a spot that is so obviously thin lie in wait and not show itself a little earlier. Because it hasn't taken any set in that spot I might be able to salvage it but it would be very light.
-
I cheated, I glued a new belly on that limb.
-
Well that didn't go well. Turns out the belly I glued on wasn't thick enough to fix the main problem so I quit and ripped it lengthwise on the bandsaw. As I mentioned in the first post I was going to have to leave some sapwood under the boo backing. Well, I estimated wrong and by the time I got to brace height I was very close to having no heartwood left. So I had one boo heartwood limb and one boo sapwood limb. I believe as I was getting real close to the sapwood the scraper was cutting more in spots so it started hinging. Either that or the sapwood is just no good in compression and started collapsing. Or a bit of both. In hindsight if I had sanded the sapwood off that limb I probably would have had enough heartwood to complete the bow. I'm also surprised at how thick the bamboo is. The picture is mid limb and the limb is .450 thick. That puts the bamboo at around 3/16" thick. I'll have to watch that next time. Those knife edges can fool you. Anyhow I learned a couple of things and killed a few days of self isolation so It was a bit interesting even if it was disappointing. :D
The little strip of heartwood is the piece I glued on. Not much left of it.
-
Could you kinda describe your vice tillering method? If I put it in the vice and grab a tip in each hand I'm standing to close to see if it's bending evenly. Right now it's going to 40# with about 1-2" of tip movement so it's kind of hard to pull with my arms stretched out too.
I suspect he is talking about something like what Gordon does in his Vine Maple build thread, post #66: http://www.primitivearcher.com/smf/index.php/topic,53195.0.html
Mark
[/quot
Yes that's right.
Same it folded on you DC. Try adding more deflex straight out of the fades, even glue billets up into the desired shape. I think this is close tot he 'ultimate' recurve profile :)
-
I've glued about 11° of deflex in the last half dozen bows. I'm afraid that if I put much more in I'll start losing braced string tension. The limbs start to reflex almost immediately out of the fades so the deflex doesn't show much. If it doesn't show maybe it isn't there, I dunno. A quick look at my fastest 3 or 4 bows all have the reflex starting just out of the fades and that's really the only clue I've got other than more total reflex. I'm just about to glue up the next one so I'll try another degree or so of deflex. Then it it's a dog I can blame you ;D ;D ;D ;D ;D ;D