Primitive Archer
Main Discussion Area => Bows => Topic started by: Badly Bent on July 08, 2014, 10:52:36 pm
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Thought I'd put this one up for discussion after reading the thread Sidewinder started, maybe you'll feel better about your work after seeing this one Danny. :)
This is a Tupelo stave that Gun Doc gifted me at the classic this year. Thanks Josh. I liked this wood and it just seemed to want to bend and become a bow, always fun to try new wood species and this almost finished bow shoots nice and I am very happy with it. Gonna put some nice skins on it and a finish as soon as I have time.
Now if you'll all look at the unbraced profile you'll see it's a little less than attractive but mimics the natural shape that I started with in the stave. I first tried to heat the deflex out of the top limb to match the bottom and tempered the whole bow real good with the heat gun. This was after floor tiller and three weeks in the hot box until it quit losing weight. It lost all of the reflex that I had added after I got it braced and bending evenly out to about 12"-14" of draw. Tempered again adding the same amount of reflex as before. Didn't hold again after getting it drawing evenly out to 18"-20".
So to be clear I added 2" reflex and tempered, lost it and then added the same 2" back and tempered again and lost it. From there I just tillered it on out to a finished 25" draw where it took an additional 1" set. So now it is apprx. 1" of set from the staves original side profile. Is that 1" of set or 3" of set? ???
The picture of the side profile below was taken just after shooting it in and the limbs crept back up about 1/2" or more after resting an hour. It's around 55" ntn and somewhere in the mid forties for draw at 25". I'llpost the specs after I get a finish on it. Would like to hear your opinions on the set and any discussion on what may have been done differently. Could be something to learn from this. Thanks, Greg
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The way I understand it, if you started with 2" reflex and ended with what looked like 1" of set, then its actually 3" total set and 1" string follow. Anyone please, feel free to correct me. :)
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Excellent tiller. It could have been a little wet?
1+2+2=5" of set which happens to include an inch of follow.
Don't worry about it.
Jawge
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I don't have anything to comment about the set but I really like that simple bendy bow Greg
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could it be the argument of dry vs seasoned? regardless is a very nice-looking bend!
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Could be it was still wet Jawge and thats kinda what I was thinking as I worked it initially. I did have it in the hot box
for three weeks after floor tiller and started working on it a couple days after it stopped losing mass weight on the scale. Another thing is that it was really humid here for some of the days in the time I spent working it on and off and a few of those days I had it at home and not back at the shop in the box. I did notice that it gained some physical weight on those days when I weighed it. Could be one of those woods that absorbs moisture rapidly.
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Second the tiller Greg ! Challenging piece of wood. I'm not into the numbers, except deer harvested with the bow :D. I really thought the second tempering would have stayed put. Looks like another great bow!
Tracy
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Tiller looks excellent, classic example of just getting all you can get out of a bow. Do you know how much mass the bow has? The mass principle tends to run a bit light on shorter bows but I would think you need a minimum of about 12 oz, if you have considerably more than that I would suspect moisture or high humidity in your area.
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Very nice work Greg. I'm saving this post for future reference ;)
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Excellent tiller. It could have been a little wet?
1+2+2=5" of set which happens to include an inch of follow.
Don't worry about it.
Jawge
Bear with me a second on this...
I understand (I think) the definition of set and string follow that you're using here. And this is something I'v mulled over for years as well as read and participated in more than a few discussions on the subject.
We always talk about set in inches (e.g. total number of inches deformed from the original profile, irrespective of induced reflex). The problem that I struggle with is that I don't really believe set can be truly measured in inches. String follow is of course measured in inches because string follow IS how much the bow bends towards or away from the string when all is said and done. Therefore string follow is a 'length.'
But I would like to argue that set isn't really a 'length.' Because set is really about damage to the structure of the wood. So, I would pose the question, does two inches of set in, say Osage, and two inches of set in, say Oak, cause the same loss energy to transferred to the arrow. Or to put it another way, does the amount of set in different woods produce the same increase in hysteresis and/or limb vibration (ultimately energy that is not going into the arrow). My feeling is that it does not, although at this point that is just a conjecture.
Maybe this is fodder for just another "set," "string follow," energy in wood type discussions... but I figured I'd add it here.
Whats interesting about this case (given what I just wrote) is this question: if you induce reflex, lose it in tillering, re-induce it, and than lose it again, have you done an equal amount of damage to the wood in both tillering sessions? Perhaps, but perhaps not. Again my feeling is probably not (I'd guess that most of the damage to the wood was done in the initial tillering session, because the strcutre of the wood is fundamentally different after heat treating it....)
Thoughts? Should I start another thread? Should I go to bed ;)
BTW, Sweet bend on that puppy Greg, that's a great looking bow.
Gabe
p.s. definitely not trying to start and argument with you Jawge, just wondering if we can expand on what "set" really is.
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That bow looks like a dandy to me Greg. Set or no set. Great looking scalloped job behind you as well :)
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Gabe, those are good questions. I know it does vary with different woods, I don't know how much. I have seen red oak board bows that were almost unaffected by heat treating and reflexing, they just go right back to where they started like this bow did. I don't know the wood he used here, but possibly it doesn't take heat treating and may be no more affected by the set than it would have if not reflexed. I can tell you that osage is greatly affected by set. 10 fps difference in two bows with the same finished profile but one having taken less set is not uncommon.
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Sweet bow Greg,tiller is very nice,looks like a shooter to me. ;) Man I am going
to get to see all kinds of cool new stuff up close at ElmHall. :)
Pappy
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To answer your question Badger the finished mass is right at 15 oz. when I weighed it yesterday out of the hotbox where I'm keeping it until I have time to put the skins on it. It was at 15.25 oz. when I put it back in there three days ago and lost that .27 oz. overnight then has remained stable for the following two days which makes me think the 1/4 oz. was from humidity. Is the 3 oz. above ideal mass a big factor in the finished bow in your opinion? Seems like a lot of extra mass to me if this is the case. I think it would be helpful if I paid attention to side tillering when working my bows and seeing set as it is happening.
One thing I forgot to mention is that it was from a small diameter tree of about 4" at the base so it has a pretty good crown on the back if that matters.
I still don't understand how to determine total set/string follow. Seems to me if the bow finished at 1" below roughed out profile and 3" below heated in reflex that would be a max. of 3" set. And the sting follow would be about 1/2" since that is the difference between where it lays when unstringing after shooting from where it sat prior to stringing.
As far as performance goes it does seem a little sluggish for the draw weight but not overly so compared to some of my other similar bows but then again I don't consider any of my bows to be screamers. A chrono would be helpful but that might cause some disappointment from the readings. ;)
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Thats a nice bendy 8) I love the shape of a natural unbraced look.
So far as set goes I can only pose more questions. Is natural shape as good at resisting compression as a heated in shape? No idea.
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Looks great Greg, you sure know how to tiller them ;)!
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Greg, you knocked that tiller shape out of the park man...Very small amount of set and I'm sure it wasn't anything to do with your skills, I've seen to many excellent bows from you... ;)
Don
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I remember that one Greg. Nice tiller, as usual.
Yes, the tips moved back 3" from the original starting point. We can pretend it doesn't matter, that's just not true. You know that as well as anybody. Its not about how much reflex you hold, its about how much you lost. That's why string follow isn't a bad thing. If your losing 3-4" on each bow then something needs to be wider or longer.
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I used to carve duck decoys out of Tupelo. The butt cut was as soft as balsa wood but the log cut was like iron. I always thought lumber from the log would make great hardwood arrow shafting, straight, hard and dense. Never doweled any up as it had much more value as carving wood.
Good to see you can make a bow from the stuff.
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Yes,set is damage to wood cells and it cuts down on cast, Ross.
I believe you will get that damage even if their is no visible follow and you have started with a reflex.
Comstock talks about the benefits of over building in his book, The Bent Stick.
There is little to be gained by pushing limits and a lot to be gained by striking a happy medium.
But you use what you have. :)
Jawge
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Greg, I don't think a little extra mass in the inner limbs will hurt anything at all. A little extra mass to get a target draw weight really does indicate high moisture most of the time because moist wood is weaker, it can also indicate a lot of crushed wood which I doubt in your case.
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First, really sweet tiller on this one. Very nice. Second, I have no answer to the question. Some just seemingly refuse to take the set that others do and visa versa. Not fully dry, not seasoned, design issues, problems with the tiller, problems with the construction. I think all of these things can have an impact for sure. But sometimes one comes along for me that just outperforms the average. Sometimes the reverse. Not sure why at all???
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That is a great tiller Greg! Is tupelo the same as blackgum? Ive heard some people call blackgum trees black tupelo around here.
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OK, I miss quoted the mass weight numbers in my post this morning, I actually have been keeping notes on this one and two other builds as well and quoted the numbers from one of the others. Soooo, as it stands now the mass weight is at 14.55 oz, down from 14.85 when I put it in the box 3 1/2 days ago. Seems to have stopped losing weight, I'll see what happens in the next couple days. Lesson learned, make sure the wood is done drying and don't leave it out for a couple days of tillering and exercising when humidity is hovering around 75 to 99%. ;) Also think I likely caused some damage during the tillering trying to balance tiller on two limbs with near exactly different side profiles, (one with reflex and the other with deflex in the same area). Just the same though I do like the bow and I am anxious to get
the finishing done when time allows. Thanks for the input guys, appreciate all the comments. :)
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Sorry Okie almost forgot to answer your question. I think Gun Doc also referred to this wood as black gum as well as tupelo. If I remember correctly he said he had cut it just north of Atlanta. He also gave me a yew stave from Oregon and a choke cherry stave from Montana. The man is a road warrior, coast to coast, border to border, catch him if ya can. ;D
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Shouldn't your tiller match that of when your bow is unstrung? If one limb has a natural reflex, and the other has a natural deflex, shouldn't your tiller mimic this in order to get both limbs bending the exact same amount? If you tiller them to both bend to the same imaginary vertical line, the limb with the natural reflex would be bending more than the limb with the natural deflex. Therefore making one limb travel at a different speed than the weaker one, creating hand shock, correct? Please correct me if I am wrong.
Badly Bent-don't get me wrong, it is a beautiful bow, and the one in the background with the scallops is sweet! I am just trying to get a better understanding of how I should tiller my uneven bows.
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I don't honestly know the answer to that Aaron, is does have some kick in the bow hand so you are quite possibly correct. If you look at the braced profile closely you'll see how it still shows the bottom limb which has the reflex in
the outer portion looking stiffer at brace. Even/equally bending limbs at full draw then may not be right, anybody have any thoughts on this?
Thanks for posing this question Aaron, there is quite a bit about tillering and bend distribution that I'm still not sure
I understand myself. :)
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I don't have any exact thoughts on it as I try to work with ballanced limbs from the start but bow limbs have one thing in common with all springs. Springs are rated in how fast they build tension when compressed, or stretched. Bow limbs are the same. You could only test them by pusing on them individualy with a scale. I think they should be somewhere around a pound per inch. If a bow is reflexed in one limb and deflexed in the other limb the deflexed limb would likley be a stronger spring if it were to be ballanced at brace height because it had less bending to do to get to brace. As you pulled it back the deflexed limb would build weight faster than the reflexed limb.
This would cause the nock of the arrow to go up or down toward the stronger limb as you drew the bow most likely causing porpoising in the arrow. I don't know about shock. I find any bow tillered evenly as you might do with a gizmo produces some kick.
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there is a difference between thump or bump...and handshock...one is a pleasant little arrival...the other...can jolt the bow outta your hand...most of all my bows have had the former...one was dangerously close to the latter...but was still shootable.
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excellent work Greg,
interesting seeing the profiles unsymmetrical in braced to balanced in the fd. a beauty of a bow.
IMO string follow/set is to be measured after the last heat treating by laying the bow on a even surface and measure to the deepest point of the grip (when reflexed). measure again when the bow is tillered and shot in. The difference is the amount of set.