Primitive Archer
Main Discussion Area => Bows => Topic started by: Azmdted on June 26, 2020, 08:05:52 am
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Hi all,
I just completed a hickory fire hardened bow IAW the Shannon video. I enjoyed doing it this way, next time I will bring a hotdog and cook it over the coals while I'm watching the bow. But my question here is about how to measure set. Hopefully this won't turn into a set v string follow discussion, but if I'm using the wrong terms please correct me. Here are the basic stats:
Off the caul after hardening but before serious tillering: 5" reflex
After tillering but before shooting: 3" reflex
After putting almost 400 arrows down range with 12 hours of rest: 2.25" reflex
After unstringing after 30 shots: 1.25" reflex
I just read in TBB1 that set should be measured immediately after unstringing. I'm thinking that my set is 1" (2.25-1.25) or, would it be 1.75" as measured from the original tillering reflex?
It's 67" NTN, 29" DL, 49# after tillering, but 46# after getting shot in and finished. After 30 shots the weight bottoms out at 42#, but then goes back to 46# after a rest. After a few days of shooting it I found a great deal on a Ballistic Precision Chronograph on Amazon and I'm now playing with arrow speed, which is very interesting. My first five shots of a session will average 163 fps, but after 30 shots my fps is down to 155. I think that all makes sense considering the set and decrease in draw weight as I shoot.
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I like to be brutally honest with myself. If in fact I bother to measure it, I count all set that it took from the beginning... that is, measured before any flexing begins, to freshly unstrung after shooting(within the first minute or so). So in this case, (off the caul 5" of reflex) to (after shooting 1.25" of reflex) = 3.75" of set.
Others will figure it other ways, ignoring some of the set it took to make themselves feel better... but like I said, I like to be brutally honest with myself... which sometimes stings at first, but ultimately works out better for me and my bows.
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Thanks, no problem with brutal honesty here. I figured that was likely the answer. I think in this case I followed the thin clues in the Shannon video too literally. They said to fire it when it 'was barely bending', so that's what I did. Which I think caused some over stressing as I tested the floor bend after that. Next time I'll wait till it's about done with floor tiller and be more gentle on stressing the bends.
Live and learn. Thanks again.
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I measure set by pretending someone gifted the bow to me and didn't tall me anything about its original profile or manipulation.
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How I measure set is rested reflex minus just unbraced reflex on a finished bow.. I don’t worry too much about loosing reflex while building heavily reflexed bows, some lose is to be expected when you are stressing wood like that.
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Next time I'll wait till it's about done with floor tiller and be more gentle on stressing the bends.
if the stave was a bit green or the fire hardening was not all that deep or a lot of belly got removed while tillering after the fire hardening, then maybe a follow-up heat treat could be beneficial.
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I do like DWS
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I like to be brutally honest with myself. If in fact I bother to measure it, I count all set that it took from the beginning... that is, measured before any flexing begins, to freshly unstrung after shooting(within the first minute or so). So in this case, (off the caul 5" of reflex) to (after shooting 1.25" of reflex) = 3.75" of set.
So you're not in the Badger camp that considers heated in reflex that pulls out during tillering to be different than set that comes out after unstringing the bow?
Mark
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I like to be brutally honest with myself. If in fact I bother to measure it, I count all set that it took from the beginning... that is, measured before any flexing begins, to freshly unstrung after shooting(within the first minute or so). So in this case, (off the caul 5" of reflex) to (after shooting 1.25" of reflex) = 3.75" of set.
So you're not in the Badger camp that considers heated in reflex that pulls out during tillering to be different than set that comes out after unstringing the bow?
Mark
I think it "may" be different. I haven't figured a way to prove it one way or another. I think the set that slowly comes out is an indication that the wood is damaged/has high hysteresis. The shock absorber analogy fits here. The reason I kinda exclude "pullout" is that you can heat a bunch of reflex into a bow, measure it, and then give the bow a little bit of a bend. One that would in no way cause set. Then recheck the reflex and a lot of the time you will find you have less reflex. The bend has relaxed/pulled out but I have a hard time calling that set.
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I’m with Marc and DWS. If the tips touch the wall first off the caul. Measure handle to wall off the caul. Any less than that is set. Some times there is pull out . Wood just dont want to accept the heat. You will just have to experience it to know it. Arvin
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(-P
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I’m with Marc and DWS. If the tips touch the wall first off the caul. Measure handle to wall off the caul. Any less than that is set. Some times there is pull out . Wood just dont want to accept the heat. You will just have to experience it to know it. Arvin
And me. That is the only logical way to call it. Otherwise how do you establish a definite baseline to measure from?
Then there is 'rested reflex' and 'just unstrung' reflex. The difference between these two is interesting....but that figure is definately not total set.
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Thanks all. Follow on question. For sake of discussion let’s say set is measured from straight off the caul to immediately after unstringing. In my case this bow would measure 3.75” of set. So, what would be considered good, average and poor set for a heat treated hickory bow?
I’ve seen several references suggesting that 1” of set is good for performance and accuracy. Should my goal be 4” of reflex if it comes off the caul initially with 5? I’m just trying to figure out what a realistic goal is as I improve my skills. Thanks again..
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It might be worth addressing how much you are changing the wood from its natural profile in the tree before calling things set.
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Btw, this piece of hickory was from a large diameter tree as it had a fairly flat back. It was cut about a year before I started working on it and I had it in my house for the last six months. It was flat with just a hair of propellor twist. The bow has a 4” handle, 3” fades, cut in shelf, limbs are 1 5/8” wide till the last 12” and then tapers to 1/2” tips.
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I agree with DWS. Jawge
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If your finished unbraced profile comes out 1 inch of reflex for an example, and you string the bow ,and shoot it a bunch, and then when you unstring the bow, and it springs back to it's original profile right now then you have built an excellent bow, and in my opinion that is what you are looking for. Some of mine do ,and some don't. Some of my bows will take 20 minutes to a half hour to come back to original unbraced profile. If you lay the bow on a table you can watch the limbs slowly come back to it's original shape.
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PatM,,,, good point
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Another thing which people new to bow making seem to get stuck on is trying to make wooden bows with loads of reflex....there is absolutely no need to heat bows in excessive reflex, thinking that you are going to increase performance.
A bow that had say 5 inches of reflex initially, tillered out it sits at 1" reflex = 4" of set
Another bow that was straight to begin with and only took say 3/4" set
Which bow do you think will perform better?
The 2nd bows belly wood hasn't been over strained and is therefore in better shape to take compression and more importantly its return speed after being compressed will be higher. After all set is permanent deformation of the woods cells on the belly. IF you can keep this damage to a minimum you WILL have a better bow.
So my advice is to begin with do not heat in more than say 2" maximum of reflex. 1" would be better. Aim to have a straight bow after tillering. The bow will be easier to tiller, will be less strained overall and you save all the headaches that lots of reflex can cause!
KISS is a great motto when it comes to learning bow making :)
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shooting a bow through a chronograph,, takes out alot of the speculatioin,,
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I agree with several of the posts above about starting with less reflex. Set carries hysteresis with it. It may be impossible to accurately measure set because I also believe there may be some pull out involved that is not really set. I tend to ignore early set on a heat treated bow. Best indicator of how much set your bow is taking that I have found is to see how much it comes back after unstringing. The less the better. I have had bows that will comeback as much as 3" if thy were highly rel-flexed, none of them I would consider fast shooters. I usually start with about 4" heated in just off the cawl before bending it might be about 3 1/2, after shooting the bow in if I can get 2" reflex as soon as I unbrace I am pretty happy as long as it doesn't gain back more than about 1/2" after sitting.
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Azmdted I can not even begin to answer the question about what would be the proper way to measure set. I figure there are lots of opinions on this and lots of variables also. I do enjoy reading everyone elses opinions though. I have made a few hickory fire hardened bows using the same process as you. I now try to take it as close to a finished profile as I can thus creating a lot less stress on the wood during tillering and have been very pleased with the amount of reflex I was able to retain. I have also pushed it too far and came in under weight on bows by doing this. When it does work out the tillering process is very short compared to my past bow tillering. I love being able to keep as much reflex as I can in a bow, that is one of my main goals besides good tiller. I just made a new caul for a bow I'm working on now, I just like to see how much I can keep and how the bows shootability reacts. Its all part of the process for me.
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ok if you have two bows roughed out from same stave...they are the same mass weight at this point, and straight0
you make the first one, no heat,, and it comes in 50#@26 and has one inch follow,, or set or what ever you want to call it,, the tips are 1 inche behing the back when unstrung,,
now the second stave you heat reflex into the whole bow,, bout 3 inches,,
you tiller it out and its holding one inch reflex in unstrung profile,, and the mass weight less than the first bow,,
so you have a bow 50#@ 26 with the tips one inch in front of back of bow that has mass weight less than the first one,,
my experience tells me the second bow gonna shoot harder,,
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ok if you have two bows roughed out from same stave...they are the same mass weight at this point, and straight0
you make the first one, no heat,, and it comes in 50#@26 and has one inch follow,, or set or what ever you want to call it,, the tips are 1 inche behing the back when unstrung,,
now the second stave you heat reflex into the whole bow,, bout 3 inches,,
you tiller it out and its holding one inch reflex in unstrung profile,, and the mass weight less than the first bow,,
so you have a bow 50#@ 26 with the tips one inch in front of back of bow that has mass weight less than the first one,,
my experience tells me the second bow gonna shoot harder,,
Good luck but my experience tells me that you can't make the two bows you just mentioned. The one that held the reflex would have to be thinner and or wider. Being thinner and wider it will have less return speed. Rarely do we see wooden bow makers mentioning that thicker is quicker anymore. Think of tuning forks does the thicker one have a higher note?
Bow making is rarely as simple as it may initially seem :)
Another problem with your experiment is that you would be comparing apples to oranges if one is heat treated and one not. What I was talking about is how much set the excessively reflexed bow will take getting to full draw. That set isd killer to performance. Whereas if a bow was heat treated BUT NOT given an induced reflex and takes less set getting to full draw, thus keeping a straight profile AND not having the belly fibers getting crushed I know for a fact that the 2nd bow will be in much better shape as a long lasting durable bow.
I gave up on excessive reflex in wooden bows about 6 years ago after chasing it for years and have made better bows since. I've made a few real screamers (chronoy tested!) over the years and none of them where heated into excessive reflex.
Now if we use different materials that have the elasticity to take the extra bending eg horn/wood/sinew composites then yes chase the reflex! However it is only a part of the picture :)
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I gave up on excessive reflex in wooden bows about 6 years ago after chasing it for years and have made better bows since.
So you stick to your suggested 1"-2" yourself?
Has anybody ever chronographed a flat bow, then heated some reflex in and chronographed it after? Results?
Mark
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a straight stave bow with one inch string follow is pretty basic,,moderate design,,
a straight stave bow,, holding 1 inch reflex is pretty basic too,,,,
if you take a straight stave bow,, and test it,,
then heat treat it,, with some reflex,not excessive as suggest, the weight will usually go up,, and require retiller to get back to original draw weight, the performance can be inhanced,, the bow having less mass,, and some reflex,, at the same draw weight,,
its pretty easy to test it as suggested,, ,, the increased draw weight will add to the original arrow speed as well,,, if not re tillered,,,
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The bow that launched a broadhead for me the the furthest was the same bow I had at mojam, It was a straight bow not heat treated per say but heat straightened. I think I shot 231 at mojam and have hit as far as 238 yds in practice sessions. The only thing unique about the bow is that it took no measurable set and when measured immediately after unbracing it will still measure the same the next day, it has maybe 1/2" reflex. I think keeping set to a minimum is the most important aspect of bow building. Adding tones of reflex hoping to keep a little is very damaging to a bow.
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I don't think the theoretical bow Brad mentions would react quite like Mike says. That seemed like a more moderate scenario not actually requiring wider thinner limbs.
The two bows could still be relatively narrower and thicker.
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The bow that launched a broadhead for me the the furthest was the same bow I had at mojam, It was a straight bow not heat treated per say but heat straightened. I think I shot 231 at mojam and have hit as far as 238 yds in practice sessions. The only thing unique about the bow is that it took no measurable set and when measured immediately after unbracing it will still measure the same the next day, it has maybe 1/2" reflex. I think keeping set to a minimum is the most important aspect of bow building.
I usually start with about 4" heated in just off the cawl before bending it might be about 3 1/2, after shooting the bow in if I can get 2" reflex as soon as I unbrace I am pretty happy as long as it doesn't gain back more than about 1/2" after sitting.
Steve, are the bows you mention above both built for the same purpose?
Adding tones of reflex hoping to keep a little is very damaging to a bow.
I suppose one always hopes to keep every bit of reflex , and at best, can only be disappointed to lesser degree when tillering ;D.
But, this begs the question of how often do you get a bow that starts with 4" off the caul and doesn't gain back more than 1/2" after sitting?
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The bow that launched a broadhead for me the the furthest was the same bow I had at mojam, It was a straight bow not heat treated per say but heat straightened. I think I shot 231 at mojam and have hit as far as 238 yds in practice sessions. The only thing unique about the bow is that it took no measurable set and when measured immediately after unbracing it will still measure the same the next day, it has maybe 1/2" reflex. I think keeping set to a minimum is the most important aspect of bow building. Adding tones of reflex hoping to keep a little is very damaging to a bow.
I agree in principle and it all makes sense but with my boo backed yew it seems that the more reflex I can get it to keep the faster it goes. If I lay out the last ten or so bows in order of speed the one thing that sticks out is the increase in reflex. It's not a lot of increase, maybe a foot or so per bow. It could be improved tillering but I don't think so since I've had to put new bellies on a lot of them to correct where I've gone too far :-[ :-[ :-[
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If I lay out the last ten or so bows in order of speed the one thing that sticks out is the increase in reflex. It's not a lot of increase, maybe a foot or so per bow.
just curious how much the reflex has ranged in those 10 bows for that 10 FPS or so?
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Probably from 1" to 3" maybe 4". I don't keep records, I might be past 200 if I did. :-\ :-\
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Thanks to all for your replies, a lot of information to digest. I've picked up a new hickory stave that is two months from cutting. Yesterday it had 3/4" natural reflex and then I cut it down to rough bow dimensions plus about 3/8" to help it dry. By the evening the reflex was gone and one limb is perfectly flat and the other has about 3/4" deflex from about mid limb out. I'm thinking that moisture loss and strength from the belly side of the stave was holding the reflex and with the loss of wood and some moisture loss it changed.
I'll be building a new caul for heat treating. Consensus seems to be that my current 5" reflect caul is way too much. BTW, it's a gentle curve from handle to near tips of about 2" and then 3" more in the tips getting me to 5" overall. My goal is to end up with a 50#, 29" DL, 67" NTN bow with little set and good efficiency. Based on all I've heard, what should I do?
Straight flatbow?
Flat out to the tips and then 2-3" reflex tips?
Gentle curve for an inch or so and then 2" reflexed tips?
Also, since I never knowingly exceeded my desired draw weight on my last bow and the wood was a year from cutting, did my set come from me being too aggressive in flexing it during floor tilling, attempting to short string it before it was ready and exceeding my design weight there, breaking fibers during too aggressive bending on the caul? On the last bow I steamed it before putting it on the caul, let it rest for 3 days and then put it over the coals. I didn't want to try to bend a not even floor tilled stave without steam first thinking that I would be too aggressive.
Any ideas and suggestions are helpful and appreciated. Thanks.
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Your stave has moved because it was growing on an angle. Wood can 'store' the forces it felt whilst growing. As you remove wood these hidden forces reveal themselves. It can be quite surprising how much wood can move once you cut a bit off, even stuff that has been drying for years. Of course it could also be from regular moisture loss but my guess is the former.
Don't worry too muc about it. The problems start when your stave goes sideways :)
Personally I would get it to a nice limber floor tiller to speed drying. Strap it to a board to stop any further warping as it dries.
Once nice and dry. I would heat it into a gentle 2 " reflex. Least (none!) near the handle, gradually increasing as you progress along the limb.
Then gently tiller to 20" or as soon as you see any set. You can trace your pre-bending profile on a wall or something to use as a reference as you continue.
Then do the fire hardening process. Keeping the 2" reflex as a max.
Tiller out using Badgers no set method.
Then let us know how it turned out :)
Good luck :)
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........ I think in this case I followed the thin clues in the Shannon video too literally. They said to fire it when it 'was barely bending', so that's what I did. Which I think caused some over stressing as I tested the floor bend after that. Next time I'll wait till it's about done with floor tiller and be more gentle on stressing the bends........
thin clues are not too helpful sometimes. I have never seen the video, but I understand it is an involved process, and would hope the the video shows more about the tillering required before the heat treating session is begun. It suppose it is possible to cook the stave too hard, and conversely, to get the proper amount of treatment on the belly, only to remove the treated wood if the stave is not close enough to dimension after cooking. Steaming the stave to get it on the caul before the heat treat seems to suggest you are being too cautious or still had it too thick.
Bracing too early is an easy enough way to over stress a bow. I think every bowyer can remember one like that.
Learning floor tillering can be a bit of a subjective exercise as it's an acquired skill. The long string and a tillertree can help with developing the feel for how much and where when it comes judging bends.
Without seeing some pics of your stave, its hard to tell. If you are going to build a caul and do another heat treat? why not draw up your new proposed shape on another 2x6 and post some pics also? There are some new guys here recently that I think would also be interested in a thread seeing some simple deflex reflex curves.
Bowmarra's suggestion to get the bow built before fire hardening has merit, so maybe propose a curve, then build to it as close as feasable, then cut your caul, possibly adding some final recurve?
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I just put an osage bow on the cawl, the cawl was 3 1/2" came out of the caul at 2 1/4" Just unstrung profile is 1 1/2" reflex and goes to 2" after sitting for an hour.
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I've started my next Pignut Hickory bow. This started as a stave with 3/4" natural reflex. I've floor tillered it being very gentle in my bending. It's bending nicely, but it's already at 1.5" backset on the upper limb (left) and 1.25" on the lower limb. It started bending this way as soon as I took off some wood, well before I ever got around to bending it myself. I clamp it on the edge of a 2x4 when not I'm not working it. I've only flexed it about 4-5 times and backed off before the pressure got to be more than where it should be for a 50# bow.
The weight is stable so I think it's most of it's drying. Length is 68.5 TTP. My goal is a finished bow at 50#, 29 DL, 67" NTN that will keep most of that weight as I shoot it. I've left the last 6" on the ends near 1/2" thick because I'm still looking to get 2" or so reflex fire hardened in and thought I'd need the extra support to hold the flex in.
Thoughts?
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Depending on how humid it is where you live hickory can take a long time to drop those last few points of moisture. About 8% is the minimum I like to work hickory at. I would put it in a drying box unless you have a very dry climate.
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Thanks Badger, I'll get one made up. Maryland is not known for it's dryness.
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I would put it in a drying box unless you have a very dry climate.
Can you define 'very dry'? It's been a stupid wet June here, with the outside RH into the 90's many days. Indoor seldom gets more than 45-50%, even in a wet month like this one has been. Is 45-50% dry enough to keep hickory workable?
Mark