Primitive Archer
Main Discussion Area => Bows => Topic started by: Don W on July 17, 2021, 09:10:26 pm
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I've been playing around with draw weights, arrow speeds etc. For the last couple days I will take a bow and check the draw weight. Then shoot 12 arrows through. The arrows are around 640gr. Each shot is through the chronograph and the hi, low and Ave recorded. I then check the draw weight again, shoot the 12 arrows, check the weight.
Each set I loose a little draw weight. The first time might be right around a pound. Maybe a little less for lighter bows. Each set looses a little less each time. After about 4 or 5 sets the weight loss stops. Cast drops slightly as would be expected. Total loss is never 4#, can come close for a 55# bow, and may only be a pound or 2 on a 40# bow. My osage board bow actually gained 4# the first time before going into the loss routine.
The next day I start over, all weight has been regained and a very similar routine starts. The end weight is close to yesterdays end weight but usually not the same (although this could be inconsistencies in weighing and my scale)
I've searched but could not find any references as to the draw weight going down, so if it normal that seems odd I couldn't find anyone noting it or asking, if it's not normal how did I manage it on absolutely every bow I've made.
Edit to add images:
(https://www.diy.timetestedtools.net/wp-content/uploads/2021/07/HHB-7-21-stave-1-FPS-b.jpg)
Day 2
(https://www.diy.timetestedtools.net/wp-content/uploads/2021/07/HHB-7-21-stave-1-FPS-a.jpg)
Day 3 added
(https://www.diy.timetestedtools.net/wp-content/uploads/2021/07/HHB-7-21-stave-1-FPS-day-3.jpg)
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Sounds to me like soft set and then the bow returns to its initial profile overnight and the cycle repeats.
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What Airkah said...
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Sounds to me like soft set and then the bow returns to its initial profile overnight and the cycle repeats.
I agree it's soft set, but is it typical? Is it a problem? Is it bad tillering?
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Very typical, every selfbow I ever made did the same and that is 158 of them so far. My first 5 or 6 arrows out of a bow are noticeably faster, then it settles into a consistent speed.
My current bow steps down one more time about the middle of a 25 target 3D round and I start shooting a little left as my arrows become a slightly overspined. I have already shot a few dozen warm up shots on the practice butts before I hit the course so my last stepdown is at about 50 shots. My last bow, which became to stout for me to shoot as I got older, had only a very slight loss after the first few shots and settled in to be stable for as long as I kept it strung, even if that was 8 hours. All my bows are osage.
I have also had bows that seemed out of tiller for those first 5 or 6 shots then settled in to be a tack driver for the rest of the day. When I hunted with one such bow I would fire off a half dozen arrows at my archery target before I headed to the woods to settle it in. I won a lot of tournaments with that bow but knew it had to warm up a little before I got into any serious shooting.
I have been making selfbows for 28 years so this is not a selfbow trait I just pulled out of the air, I noticed it long ago.
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Thank you Eric. It seems like a somewhat important aspect of a self bow that nobody seems to ever mention. I've built up quit a library over the last year or so and I've heard and read about set, soft set and string follow (still a little fuzzy on that) but nothing about draw weigh changing like this. I know in a hunting situation it's not as much of a concern, but practice all day would be.
I've been concerned about using hickory which I have easy access to because I hear a lot of folks talk about how their hickory bow will loose weight even in a day of humid shooting. It didn't make sense to me. Others say that as long as a bow is kept indoors a day or two of hunting in the rain will not matter if the bow is well protected, which makes perfect sense.
Now I believe what those folk who see the weight drop have is this "soft set" condition (which should have it's own name I think) and has nothing to do with moisture content.
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I've added the HHB log to the original post
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It’s possible most bowyers have an intuitive sense of this and exercise their bow a bit before measuring draw weight. Unless I was flight shooting I wouldn’t consider the fresh/right after stringing draw weight to be representative of performance over time.
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It’s possible most bowyers have an intuitive sense of this and exercise their bow a bit before measuring draw weight. Unless I was flight shooting I wouldn’t consider the fresh/right after stringing draw weight to be representative of performance over time.
But for a hunting bow, it's that first arrow that counts most of the time. For a target bow it's required to know the bows change over time. It's not as simple as a single draw weight. Based on Eric's response, a few warm up shots isn't close to sufficient and my test show a need for up to 60 arrows to get to a flat line.
It's certainly good information to know, and at my age, if it takes me 10 years to make "bowyer" status, it'll probably be to late.
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60 arrows seems like a lot. I could be wrong but that seems abnormal if conditions aren’t extreme like humidity or hold time at full draw. What is the behavior of the set of these bows after unbracing and when allowed to return fully?
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The behavior is different. Some of the bows I tested I made before I started researching"how" to make a self bow, and the have excessive set and string follow. The last few show almost no set. The last reflex deflect has no noticable set, so it's small.
I would assume wood type and design will have some effect.
I have an white oak, backed with ash and a bloodwood power lam and handle. Its 43#@28 (@1st draw) 56" ntn. It only takes about 36 arrows to level out. It's also been hanging in my shop forever so MC is likely high. It's also one of my first, so set is higher than others.
A maple bow takes about 36 arrows.
I also assume arrow weight would play a role. I would think a lighter arrow would take longer, but that's just me using logic, which seems to bite me sometimes.
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What I’m wondering is how much set does the bow have immediately after unbracing versus over several hours. For example, a bow may have 1.5” of set right after shooting but may relax to 1” over several hours. I would guess even bows with no set might lose a small amount of weight but bows that have more unbraced set and lose some over time lose more weight. I wonder if the poundage loss is proportional to the change in set during that relaxation period.
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What I’m wondering is how much set does the bow have immediately after unbracing versus over several hours. For example, a bow may have 1.5” of set right after shooting but may relax to 1” over several hours. I would guess even bows with no set might lose a small amount of weight but bows that have more unbraced set and lose some over time lose more weight. I wonder if the poundage loss is proportional to the change in set during that relaxation period.
I'll add that to the log
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Day 3 added for the HHB bow
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seeing similar.
My sinew bows pull back out of set after some arrows or lots of pulling on string.
I see as much as 3# loss after a lot of arrows, but I can not recall exactly because these are wood bows and arrows and I am tired of using decimal points.
I like to shoot a stumper or two before getting into the hunt properly.
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Every bow stave is different and every bow will react a little differently to initial poundage loss after shooting, lots of factors, the skill of the bowyer, the type of wood, the bow design, the relative humidity and host of others.
I know my bows well and tweak the tiller endlessly if they need it while I own them. I only shoot one bow, I have a bunch but find I am the best shot if I shoot one bow exclusively so I know its personality. I hunt and shoot tournaments with the same bow, I know when it is good to go after a brief warm up, it doesn't take 60 shots for me to figure this out.
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you may have found a way to evaluate bow wood for it's viscoelastic properties.
The last reflex deflect has no noticable set, so it's small.
there is also the what has been called hidden set. A belly might ordinarily become compacted and cause the entire bow to exhibit some set. A belly could also suffer from compaction, but a strong back can pull the bow straight giving the appearance of no damage.
I also assume arrow weight would play a role. I would think a lighter arrow would take longer,
Please clarify what you mean by longer. Testing with lighter arrows might be more revealing when searching for efficiency.
PS. one statical method when evaluating a series of fps is to throw out the high and the low and average the remaining ten.
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white woods especially tend to take the humidity and soak it up.. is this bow finished and sealed ? if not this is not uncommon.. gut
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white woods especially tend to take the humidity and soak it up.. is this bow finished and sealed ? if not this is not uncommon.. gut
Yes, all the bows are finished. It's not 1 bow, it's a dozen or so.
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If you want to see how it does for hunting, why not give it a few warmup pulls, then let it sit in the shade for a few hours, then shoot it. Just don't forget about it!
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If you want to see how it does for hunting, why not give it a few warmup pulls, then let it sit in the shade for a few hours, then shoot it. Just don't forget about it!
The max was 4# difference, which will make very little difference in hunting situations. I was just looking for information. It seems it's normal, but it seems there is a lot of confusion. Lots of opinions but no firm reasoning.
I just thought it odd it's never been mentioned anywhere in all the design and how-to books and articles I've read.
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what type of sealer are you using. ? any idea what MC was before they were sealed ?..
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what type of sealer are you using. ? any idea what MC was before they were sealed ?..
Most were tru-oil, the last 2 or 3 are several coats a spar varnish. Last several around 7%MC (i built a better hot box) . First several between 8-11%
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Took my bow scale and inch-marked stick into the mtns to shoot and hunt yesterday.
While out in MO, the humidity in S. AZ rose quite a bit, 60% common.
One sinew bow recently posted came in at first stringing with a DW of 51.6#, 25". It had sat for two weeks inside.
Shot it 25 times, and it came in at 50.4#.
Hunted rabbits, high humidity outside and strung a good 8 hours. The DW measured 49.84#, so about 50#...lost about 1.5 #. I am peering down at the scale and the bow string and the marks, so these are approximate measures.
I can live with that. Like Eric K said, the variable are numerous.
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Took my bow scale and inch-marked stick into the mtns to shoot and hunt yesterday.
While out in MO, the humidity in S. AZ rose quite a bit, 60% common.
One sinew bow recently posted came in at first stringing with a DW of 51.6#, 25". It had sat for two weeks inside.
Shot it 25 times, and it came in at 50.4#.
Hunted rabbits, high humidity outside and strung a good 8 hours. The DW measured 49.84#, so about 50#...lost about 1.5 #. I am peering down at the scale and the bow string and the marks, so these are approximate measures.
I can live with that. Like Eric K said, the variable are numerous.
The question is, is it moisture, or just the nature of a wood bow. I don't believe any reasonably sealed piece of wood will change MC in the matter of minutes or even a few hours.
The same thing happens to my bows that are hung (stored) in my shop, the shot in my shop. No MC change whatsoever. That has been my last few test.
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The question is, is it moisture, or just the nature of a wood bow.
both, or rather the nature of some woods, (some more, some less)
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don those numbers are pretty dry.. anything under 8% is too dry IMO.. and over 12% is too wet... if you really stuck the wood and got those numbers it certainly isn't too wet.. spar varathene is what I use and good success.. I've never used tru oil on a bow.because it is too shiny to me.. but as for a sealant it should be fine.. a bow can also lose a few pounds during break in... and if taken to a much drier climate gain significant poundage... gut
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don those numbers are pretty dry.. anything under 8% is too dry IMO.. and over 12% is too wet... if you really stuck the wood and got those numbers it certainly isn't too wet.. spar varathene is what I use and good success.. I've never used tru oil on a bow.because it is too shiny to me.. but as for a sealant it should be fine.. a bow can also lose a few pounds during break in... and if taken to a much drier climate gain significant poundage... gut
As I keep saying, I don't believe this is moisture related. Some of the bow have been in my shop for months and since it's been raining sometimes, several of the test scenarios never left the shop and even going outside, moisture isn't going to affect wood in the few minutes it take to shoot a dozen or a few dozen arrows.
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This is normal. Wood compacts a little and then expands when rested.
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As I keep saying, I don't believe this is moisture related. Some of the bow have been in my shop for months and since it's been raining sometimes, several of the test scenarios never left the shop and even going outside, moisture isn't going to affect wood in the few minutes it take to shoot a dozen or a few dozen arrows.
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Tell that to hickory down south and it will prove you wrong..gut
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This is why I'd like to figure it out. If a hickory bow can loose 4# without a moisture issue, what would it be with a moisture issue, or is it still just a wood issue.
As I keep saying, I don't believe this is moisture related. Some of the bow have been in my shop for months and since it's been raining sometimes, several of the test scenarios never left the shop and even going outside, moisture isn't going to affect wood in the few minutes it take to shoot a dozen or a few dozen arrows.
Tell that to hickory down south and it will prove you wrong..gut
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You can find opinions that say a days shooting in higher humidity will affect it and opinions that say you can hunt a week in the rain and not have an affect.