Primitive Archer
Main Discussion Area => Bows => Topic started by: bownarra on December 16, 2020, 01:08:59 pm
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After seeing Marc's White Lightening 1 and 2 bows being talked about in a recent thread I decided I would have a go at trying to copy one. 190 fps would be nice but we will see......Not an easy task!
I've pulled out some nice 10 year old billets and have recrved and spliced them. I am going to reduce the blank down to floor tiller tonight. The billets were an inch or 2 too short and it is 63" now it is spliced up.
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I've also been a bit inspired by those threads and may try something similar soon. I was looking through the catalogue of Marc's bows on here and the three factors that stand out to me are 1) the high amount of retained reflex, 2) tips are relatively stiff compared to more circular or elliptical tiller in some bows (even in the recurves), and 3) perfect tiller. I have a feeling, even if I could nail the tiller shape, that I would have a hard time retaining as much reflex as Marc does in his bows.
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My thoughts exactly :)
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Following along looking forward to this developing.
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Following along looking forward to this developing.
Me too
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Nice
The Recurve Shootout.
I will Ante
HH~
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Just remember.
Keep it flexible
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Should be interesting.
Just so you know. When I was going strong making this type of bow I made pretty well all of them with about 10" of reflex and they would end up keeping around 6" after tillering and shooting
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10 inches! Struth.....
I'll put a picture of it up when I get back from my morning run and swim. I guess i'll be adding some reflex then :) At the moment its got about 4" and has been to 60# with good tiller. No set yet. Going to make this one around 60#.
So Marc should I induce the reflex now that i've got a good floor tiller? I've never had a wooden bow so reflexed....it should be fun!
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Stringing them are definitely fun...
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10 inches! Struth.....
I'll put a picture of it up when I get back from my morning run and swim. I guess i'll be adding some reflex then :) At the moment its got about 4" and has been to 60# with good tiller. No set yet. Going to make this one around 60#.
So Marc should I induce the reflex now that i've got a good floor tiller? I've never had a wooden bow so reflexed....it should be fun!
Absolutely and give it a solid heat-treating. I've found that when reflexing that much with dry-heat you need to do it before applying any heat to the limb. If you try to reflex after giving it some heat then you stand the chance of a tension failure ( big crack open on belly :o )
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Marc, don't you use some sort of bench mounted bow stringer for those? This will be fun to watch... :OK
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Why not just glue in a bunch of reflex in the finger joint. Wont that take care of half the reflex issue you all seen to be concerned with. Think my quickest most accurate static sits about flat unbraced.
HH~
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Subscribed
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Why not just glue in a bunch of reflex in the finger joint. Wont that take care of half the reflex issue you all seen to be concerned with. Think my quickest most accurate static sits about flat unbraced.
HH~
No, because setback is not the same as limb reflex.
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True but it moves tip forward. Some wood will hold reflex very well some will no at all and that in same wood species. I would think any way the tip starts and finishes lengthens the stoke until string hits the recurved limb. One of reasons why i like my big hook with a fairly low brace. Shoots very well like this.
Shawn~
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Ok not sure I understand but I’m watching and probably will make a go at it along with some knife blade attempts. Arvin
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Just so you know. When I was going strong making this type of bow I made pretty well all of them with about 10" of reflex and they would end up keeping around 6" after tillering and shooting
What shape was the caul you used to heat the reflex in? Elliptical, circular, something else? 10" of reflex is a stupendous amount for an all wood bow.
Mark
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True but it moves tip forward. Some wood will hold reflex very well some will no at all and that in same wood species. I would think any way the tip starts and finishes lengthens the stoke until string hits the recurved limb. One of reasons why i like my big hook with a fairly low brace. Shoots very well like this.
Shawn~
The overall reflex being the same would likely result in similar amounts of energy storage but the stress on the limbs would be totally different. Substantially more so with just reflex at the handle due to the tighter bend radius that would result in the limbs.
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Just setting back the handle will inevitably cause the working limbs to slump a bit from the strain. Actually reflexing the limbs with heat mitigates this problem.
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And it forces the limb to bend more mid to outer thus lowering energy storage...
photos coming...only manged to get one limb heat treated and reflexed today so can't say how much total reflex yet but...it's a lot :)
Tillering this thing will be interesting.
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nice work so far, Im sure it will shoot great,,
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Really
I have see them set forward then reflexed with good heat and seen no ill effects to "working limb " what so ever. In fact we just did one like this. Real dense orange, hard, close ring piece and it held every single bit we put to it. Its a killah Bart says. One the finest we've made in some time. Hard to remember I make a chit ton of bows and forget most of em. I do remember Gary Davis telling me "he liked billet bows" and that was one reason why. The other is rather obvious.
Get up with the Recurve shoot out. Ante be getting on the hard reflex caul soon. Not going to burn the bejesus out of it like i seen guys do though.
HH~
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My caul was somewhat elliptical but I would adjust the reflex by using small shims between the back and the caul to add more reflex in specific areas of the limb if that was what I was looking for ( that's where being flexible comes in handy :) ). I also used clamps to restrain certain areas that I had already heat-treated since adding more pressure further down the limb would change what I had already treated and I didn't want that. Probably having a specific caul for each bow would have made things simpler but I was experimenting and quite often changed things around and that would have left me with a lot of cauls, still wound up with 1/2 a dozen of them.
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Really
I have see them set forward then reflexed with good heat and seen no ill effects to "working limb " what so ever. In fact we just did one like this. Real dense orange, hard, close ring piece and it held every single bit we put to it. Its a killah Bart says. One the finest we've made in some time. Hard to remember I make a chit ton of bows and forget most of em. I do remember Gary Davis telling me "he liked billet bows" and that was one reason why. The other is rather obvious.
Get up with the Recurve shoot out. Ante be getting on the hard reflex caul soon. Not going to burn the bejesus out of it like i seen guys do though.
HH~
You said setback and didn't mention heat initially. Many of Marc's bows being mentioned were just one piece.
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Watching (with safety glasses and hard hat ;) )
Del ;D
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Watching (with safety glasses and hard hat ;) )
Del ;D
Me to Del. I have always been amazed at Marcs highly reflexed bows. How much reflex he’s able to keep in them. I’m just not that confident I could pull off trying to tiller one myself or I would have tried it by now.
I know one thing for sure. When I do I’m not going to post the build live.lol.
Good Luck Id love to see another bowyer develop the tillering skills of Marc. The man just really seems to have the eye and patience to find what’s a bow and what isn’t.
Bjrogg
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Trying with elm is a good idea. You can tie limbs in pretzel shapes and not have a catastrophic with it for most part. Fast bow and accurate bows are usually two animals with different spots.
Love to see some more on this elm super reflex.
HH~
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Pics!!
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Finally manged to find some time. So i,ve got it reflexed, heat treated and ready to tiller further. It's 19 oz. Reflex is around 7 inches. One very faint belly crack that should be removed with a pass or two of the rasp...fingers crossed. I've made bows with them in and they seem to hold up but of course not ideal in this case...time will tell?
Here are a few pictures of the progress.
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Couple more.
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looks great,, :)
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Here's a couple old pictures of bows I used to make back then just after being heat-treated and reflexed just to give you an idea of how much reflex I put into the bow and the general shape I started with, these 2 are Elm. The pictures are poor quality but you still get the idea
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You guys are making me want to get my football and go home!😁😁😁Arvin
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The pictures are poor quality but you still get the idea
Boy, just looking at them make me squirm at the idea of trying to string them. Still I would like to try that side profile with a thin bamboo slat at 20 pound draw weight.
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Many thanks for those pictures Marc. They are very helpful.
I should get around to tillering this bow in the next day or to. I'm just making sure it's m.c. is stable now.
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Still watching!!!
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Me two (-P
Bjrogg
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Well she hasn't lost any weight for a few days = tillering time :) Definately going to get on with it today, i've got all my jobs done so I can concentrate fully on this bow now.
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The fun begins.
Shawn~
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I’m guessing that one is going to feel extremely heavy at beginning draw, but not gain as quickly as the string comes off.
Be interesting to watch.
Bjrogg
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I’m guessing that one is going to feel extremely heavy at beginning draw, but not gain as quickly as the string comes off.
Be interesting to watch.
Bjrogg
x2
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I'm watching! (-P (-P :BB :OK I think I need to gain more skill before I try it, though - a lot more!
Hawkdancer
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Got it to 60#@20 and still holding 5 of it's starting 7 inches. It's starting to get pretty sensitive to wood removal. One of the outers is bending a shade too much but not bad and i've just got room to sort it out.
The 80% r.h. and temperature of 2 degs in the workshop isn't helping matters but that is what it is :)
I'll get some photos taken.
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Bownara this is where it starts happening to me. Set that is. Do you think some just doesn’t hold? Then when I get to 23” is where I think the set starts really happening. Arvin
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I would look really closely to the fades to see if I could get a little more bend in that area, it doesn't take much to get another 6" of draw, even if you might have to shorten the handle just a tad. I would also consider dropping the weight to 50# at this point.
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Bownara this is where it starts happening to me. Set that is. Do you think some just doesn’t hold? Then when I get to 23” is where I think the set starts really happening. Arvin
Ain't that the truth! Haha...easy to get to this point but the fun starts now. We will see what happpens, I'm definately out of practise with wood recurves.
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I would look really closely to the fades to see if I could get a little more bend in that area, it doesn't take much to get another 6" of draw, even if you might have to shorten the handle just a tad. I would also consider dropping the weight to 50# at this point.
Thanks for the advise. I will consider what you've said and have a look when I get back to it tonight. I feel you are right about the weight.
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this is where it starts happening to me. Set that is.
(-P (-P (-P
dumb question from the comfty couch: why not heat treat again at this point...or a bit later, when the set really has kicked in?
(I myself have done this again and again to keep a desired profile with some bows,... but finally also had some bows broken exaggerating it...)
What are your guidelines?
Merrx Xmas everybody
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Oh, I thought you couldn't heat out set as it is permanent compression damage? The once or twice I tried heating out an inch or so of set, it came back as soon as I strung the bow
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I think it depends on how far gone the wood integrity is and how good the tempering is.
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Yes I will be heat treating it again today. I'm getting close to a finished bw now, only a little wood to come off the limbs. Yes I should heat treat before much set turns up. Waiting until you have set and trying to heat it out isn't ideal. It is possible but the belly cells can't be tourtured too much :) If you were trying to do that Stuckin the mud I'd make sure the treatment was to dark brown/black.
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That explains it then, I usually treat a bow until I can feel the heat on the back but with no real colour change on the belly.
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Isn't black too much? I think brown is when the air is forced out of the cells (hence hardening), but black is when they start to break down and burn.
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Brown is good black is bad, unless you have enough material to tiller that black away
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We definitely need input from wood scientists or material engineers.
Anyhow, according to my "primitive" speculation,
it appears that deep heat treatment should be
around 175°C (347°F) at the minimum and
about 230°C (446°F) at the maximum.
But charring the wood will damaged the stave.
Cf. https://bioresources.cnr.ncsu.edu/wp-content/uploads/2019/02/1965.1.555.pdf
Synopsis - The thermal softening of isolated samples of lignin, hemicellulose
and cellulose has been investigated by observation of the thermally induced
collapse of a column of powder under constant gravitational load. Softening
temperatures of lignins ranged from 127-193 °C. Birch xylan and pine glucoman-
nan softened at 167 ° and 181'C, respectively . Sorption of water by lignin and
hemicellulose caused pronounced decrease of the softening temperature-in
some cases, to as low as 54°C. Softening points of both dry and moist lignins or
hemicelluloses have been shown to correlate with the temperature at which the
sample develops adhesive properties. The softening and adhesive behaviour has
been explained in terms of the concept of the glass transition for amorphous
polymers. Sorbed water is considered to act as a low molecular weight diluent
in plasticising the polymer chains and lowering the glass transition temperature .
Celluloses were found to soften at temperatures greater than 230 °C. In contrast
to lignin and hemicellulose, sorption of water by the cellulose had negligible
effect on the softening temperature . This difference was probably due to the
crystalline nature of cellulose and indicated that water did not plasticise individual
cellulose chains at the molecular level .
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in my limited experience: a little charring isn't so bad. off course it's got to be removed. the heat treating will always give room to tiller down...and if only the surface is charred a little, its no problem; very little scraping will leave the perfectly hardened wood.
our friend druid as well likes the belly slightly dark
https://www.youtube.com/watch?v=aeDnw0-moDs (https://www.youtube.com/watch?v=aeDnw0-moDs)
https://www.youtube.com/watch?v=cmqFuhw6-LE (https://www.youtube.com/watch?v=cmqFuhw6-LE)
(-S
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one limb bow wonder why the other blew up, Heavy crown flat belly?
HH~
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We definitely need input from wood scientists or material engineers.
Anyhow, according to my "primitive" speculation,
it appears that deep heat treatment should be
around 175°C (347°F) at the minimum and
about 230°C (446°F) at the maximum.
But charring the wood will damaged the stave.
Cf. https://bioresources.cnr.ncsu.edu/wp-content/uploads/2019/02/1965.1.555.pdf
Synopsis - The thermal softening of isolated samples of lignin, hemicellulose
and cellulose has been investigated by observation of the thermally induced
collapse of a column of powder under constant gravitational load. Softening
temperatures of lignins ranged from 127-193 °C. Birch xylan and pine glucoman-
nan softened at 167 ° and 181'C, respectively . Sorption of water by lignin and
hemicellulose caused pronounced decrease of the softening temperature-in
some cases, to as low as 54°C. Softening points of both dry and moist lignins or
hemicelluloses have been shown to correlate with the temperature at which the
sample develops adhesive properties. The softening and adhesive behaviour has
been explained in terms of the concept of the glass transition for amorphous
polymers. Sorbed water is considered to act as a low molecular weight diluent
in plasticising the polymer chains and lowering the glass transition temperature .
Celluloses were found to soften at temperatures greater than 230 °C. In contrast
to lignin and hemicellulose, sorption of water by the cellulose had negligible
effect on the softening temperature . This difference was probably due to the
crystalline nature of cellulose and indicated that water did not plasticise individual
cellulose chains at the molecular level .
If this paper relates to heat treating, is it that the heat changes the properties of lignin and hemicellulose to cause them to be more advantageous to compression or possibly reduce how much moisture the wood holds? And to not heat so high as to damage the cellulose that does the majority of the work in compression anyways? Interesting stuff for sure.
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in my limited experience: a little charring isn't so bad. Of course it's got to be removed. the heat treating will always give room to tiller down...and if only the surface is charred a little, its no problem; very little scraping will leave the perfectly hardened wood.
I read wood can be charred even at lower than 175°C, if it gets dry enough. What matters is how deep it is charred. Blackened surface is not a big deal, if you don't let it smoke too long. I doubt anyone here would let it smoke knowingly. But I did it once unknowingly and broke the bow eventually. The thermostat was set at 175°C, but I left the silicon heating pad on for over an hour and the bow was smoking. Luckily the pad still works.
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exactly: it's a function of time and temp. and white woods are different than non whites... e.g. I would never charcoal osage. but we are coming near off topic ;D
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is it that the heat changes the properties of lignin and hemicellulose to cause them to be more advantageous to compression or possibly reduce how much moisture the wood holds?
maybe some of both. It has been demonstrated that heat treated wood is less able to reuptake moisture. Hetatreated wood is marketed in europe widely as a preservative treatment alternative to cca (anti fungal).
it seems properly heatreated wood cannot get wet enough to support rot. I don't know if it can be used below grade in wet locations or is a substitute for what we call "above ground" applications.
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Just to clarify I wasn't meaning charcoal black....;) or smoke...;) Dark brown is proabably more correct. I was really meaning on the well done side of dark brown to make sure corrections/set removals hold.
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Hopefully I should get some time to myself to get this bow finished today, I'm interested to see what the chrono says. The string tension so far is unreal, like a hornbow :) Obviously it will lose some of that but lets hope not too much.
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Yes string tension on these types of bows is pretty high
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Well you win some you lose some....got her to full draw and heard the dreaded 'tick'. Inspected it throughly and finally found a little tension break on the back. It has only just gone on the surface fibers so I could rasp some off the back then sinew it. It is probably worth doing as the few shots I had at 24" or so were smokin'.....It held 4 1/2" inches of the 7" I put in it so not bad. At least sinew would make it completely tension safe.
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Well you win some you lose some....got her to full draw and heard the dreaded 'tick'. Inspected it throughly and finally found a little tension break on the back. It has only just gone on the surface fibers so I could rasp some off the back then sinew it. It is probably worth doing as the few shots I had at 24" or so were smokin'.....It held 4 1/2" inches of the 7" I put in it so not bad. At least sinew would make it completely tension safe.
That’s a shame. Hopefully it can be saved.
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Wow
Never had tension back problem with Elm. Never worked 10yr old billets either. I bet with elm it’ll sinew very well. Wonder if to much heat on old elm or the reflex contributed to this?
Shawn
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Yes i'm fairly certain the heat/reflexing contributed. It was at a spot where the heat had crept onto the side of the limb....
Nevermind I will find some more wood and give her another crack :)
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Got a picture for review??
Shawn~
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If your wood has thin rings then that can be problematic for the back.
All of the best Elm I ever cut had uniform rings, although this did not necessarily hold true throughout. Some trees that I cut had rings that varied from thin at one point to thick further down the tree. This was usually still good wood just not as good as trees with uniform rings. I never knew if the wood I cut was very good wood or just good until I made a bow with it, sometime it would even turn out to be crap wood. The conclusion I came to years ago is that not all Elm are equal and the good ones are few and far between, unlike HHB where it is rare for a tree to be poor bow-wood
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I find this interesting because right now I am working on an elm bow with limbs that taper from about .8" to .75" and it is already underweight. It is 69" ntn with a 10" riser and is 1 5/8" wide for the first 6". It is more bendy than a 55# HHB bow I have. 2 other staves I've worked from this tree where also quite whippy. I am having a really hard time getting the mass down because of such thick limbs.
I hope this isn't to far off topic. :D
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Here are a few photos just before the break.
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Looks like your left hook was working a bit (small). Had tip overlays on it. Flattened out like most unbraced recurves will but that depends on the quality or the piece of wood. Was looking good too. Never had an Elm stave have a back fail even after crazy heat and putting rather big sweeping static hooks in them. They were beefy bows however and I was never chasing speed.
Shawn~
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Did most of the reflex pull out?
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That last picture is after being to 28" a good few times as it sits now.
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Definitely worth a scraping down the back and sinew strip down the crown.
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Pity. Tiller looked pretty darn good
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I scraped the outer ring off and luckily the damge is only in the outer ring. The wood underneath is sound, guess I may as well sinew her now I know it is worth it. The outer ring did feel a little suspect when scraping? The ring underneath is hard. I'd be happy to string it up and use that ring as the back BUT it wouldn't have much draw weight :)
Anybody want to trade some sinew? :)
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I have plenty you can have. Deer backstrap, not prolly wnough for entire back of bow however.
Shawn
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I’m still watching (-P
Might have to get another bag of popcorn. This one looks like a to be continued.
Bjrogg
PS I have sinew to