Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on July 20, 2020, 05:36:04 pm
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After years of trying I did it. My Boo Yew 65" ntn, 1 3/8" wide at the fades. 1" wide at 22", 3/8" tips. It had 6 1/8" of reflex when I took it off the caul and has 5 1/2" reflex now. Weighs 422 grams. 40#@28". When I started testing it, it shot 202-203 @10gpp. Then I shot it every other day, I guess. About 150 shots so far. In that time I was putting on coats of tung oil and drying it in the sun. It must have liked the heat. Yesterday it shot 210 and today was 208 every time I tested it. That will probably drop back with wetter weather. But it's solidly in the 200's and that was my goal. It held the reflex better in the bottom limb so it looks a little wonky. Sorry for some of the blurry pics.
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Sweet bow and congrats on the 200+ club. What is the handle/riser wood?
Mark
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Thank you and Yew :D
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Congrats DC, that is an awesome achievement, I hope this doesn't mean we will lose your valuable input on here, your questions and the discussions they generate are an asset to this forum.
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That is a beautiful bow. I love the recurves and the full draw is awesome! Congrats on reaching your goal. Very impressive!
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Congrats DC, that is an awesome achievement, I hope this doesn't mean we will lose your valuable input on here, your questions and the discussions they generate are an asset to this forum.
+1
my guess is DC is -C- up a new project as we speak.
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The next one is about 195. I kind of messed up and had to put on a belly patch. I do that a lot :( :(
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Very nice!
What is brace height, measured from belly? And how thick the handle is? Would it be possible to get draw force measurements as a numerical table? I would like to make some calculations, for example efficiency. And, if possible, please measure the speed with light and heavy arrows too, for virtual mass calculations. How much the bow took set? What is difference in reflex with just un-braced and rested bow? Did you shoot with machine or finger release? Could you make "bow profile table", so measure reflex measured from the back of bow one or two inch intervals? And what is the mass of bow? What string, mass and strand count?
What chrono, measured in artificial or natural sun light?
I do not doubt your results, quite the opposite. You know what you do, the bow is just great and it has very good draw force curve. I just want to calculate some numerical values to support your results. As far I know, this is the first "200+ fps with 10 grain per lbs arrow and 28 inch draw" with any kind of natural material bow, so it should be documented well.
And this bow deserves better photos...
Thank you and congratulations!
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That´s really awesome! Congratulations! Did you heat treat the yew before gluing the boo backing on it?
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Congratulations! I've been following your journey for a while and it is very exciting to see you finally reach your goal. Keep at it!
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DC, thats quite impressive. A beautiful bow as well :) Congratulations!
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Beautiful bow. Would you use it as a hunting bow? Is it nice to shoot?
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Congrats DC. You put the time in, worked meticulously, and achieved your goal. Well done.
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If you have the materials and the mind to do it you should build another one identical in profile. The ONLY difference should be that instead of 6 1/8" of reflex, only put in 5 1/2" inches. This bow should take 0 set and be even faster than the one you got now.
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That is amazing speed, would you like to have that bow shot at the flight shoots in september? We could shoot it in the 35# class. Great job!
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Congrats DC for reaching your goal! 210 FPS at 10gpp is an absolutely incredible accomplishment!
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If you have the materials and the mind to do it you should build another one identical in profile. The ONLY difference should be that instead of 6 1/8" of reflex, only put in 5 1/2" inches. This bow should take 0 set and be even faster than the one you got now.
Sleek - if he did the same as a trilam ... gluing in deflex before pulling in reflex what would you feel the outcome would be?
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Very nice bow. I hope you don’t mind me asking if that speed test was done with the bow mounted in a shooting machine and with a mechanical releaser, and shot through two chronographs set up in a tandem configuration, to make sure straight arrow flight is measured. Thats how the pros is doing their testing. Shot from a shooting machine the arrow speed is higher than if fingershot.
If you had your bow tested that way and achieve 210 feet plus, it is faster than the fastest glass recurve tested until now. A Morrison Carbon with the extreme hooks. That is with 9 grains pr pound.
Anyway you sure have a smoker :)
https://www.thetradlab.com/morrison-max-6
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Very nice bow. I hope you don’t mind me asking if that speed test was done with the bow mounted in a shooting machine and with a mechanical releaser, and shot through two chronographs set up in a tandem configuration, to make sure straight arrow flight is measured. Thats how the pros is doing their testing. Shot from a shooting machine the arrow speed is higher than if fingershot.
If you had your bow tested that way and achieve 210 feet plus, it is faster than the fastest glass recurve tested until now. A Morrison Carbon with the extreme hooks. That is with 9 grains pr pound.
Anyway you sure have a smoker :)
https://www.thetradlab.com/morrison-max-6
That's the fastest glass recurve?
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I think you found the near perfect design for yew. I doubt you could have achieved that with any other wood. Yew has almost double the elasticity of other woods.
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Thank you very much for the comments, I really appreciate it.
Tuomo- I'll work on that today. You can't get the FD measurements from the graph?
Lonbow-I heat treated both sides of the belly thoroughly
Hilongbow- Thanks
Tommy- I don't hunt and I don't target shoot too much any more. My bows don't get a lot of use. Maybe I'll send it to Badger
Sleek- Thanks. I tried to do that with the one I'm working on now. I'm having difficulty getting equal and repeatable reflex in the bows. The reflex is kind of a crap shoot at the moment. I glue up one limb at a time because I use two piece backing and that doesn't give me the chance to compare the limbs. A better caul will sort that I think. That and better wood. I'm scrounging up scrap strips from all over the shop. I think this bow was the last set of decent wood I had. I've got enough Yew and Boo for 4 more I think.
Badger- I'm seriously considering that, thank you. I noticed a little change in the tiller after I did the FDC last night so I'll keep my eye on that for a bit. I only draw about 26" so I don't think I'm straining it that much shooting it. It was very muggy yesterday so maybe that affected it. I think it would like the Flats. :D
Markus- I do all my testing with the machine. I can't reliably draw 28". I do have two chronos. I bought the second one because I was doubting my results with earlier bows. I'm not sure if I have room to put them in tandem but I do like the idea. Remember that the 210 was a one off. It was backed up by a few 208's but it hasn't reached those speeds since. I think it was because the bow had been out in the sun for two days drying the tung oil. At least I hope it was. There is a very high chance the bow could start to go downhill. It's pretty stressed.
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I think you found the near perfect design for yew. I doubt you could have achieved that with any other wood. Yew has almost double the elasticity of other woods.
If I could get some good sister billets and get some luck with the glue up It might be a little more reliable. I'm getting a little worried about it at the moment. I have the feeling that nice straight edge grain is the answer. The grain runs all over on this one.
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GREAT DC!!! 😀✌️😀 congrats from switzerland too and enjoy your cigar 👍whats next? 😀
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There is one thing that is important when comparing 10ggp performance to glass bow tests in order to compare apples to apples. The glass bow tests use an AMO Standard to determine the reference point for the draw length. This reference point is 1.75” from the deepest part of the grip. So, if you are using the belly side of the bow handle as the reference point, then drawing the bow 26-1/4” from this reference point is the same as The 28” AMO Standard. Is that confusing enough?
Based on the FD curve, it looks as though the belly side of the bow handle is used as the reference point or measuring draw length. This makes the 28” draw point on the force-draw curve the equivalent to drawing the bow 29-3/4” according to the AMO Standard (Looks like 41 pounds on the force-draw curve). Let me know if I am wrong.
It looks like you may still be very close to a true 200fps at 10ggp at 26-1/4” from the deepest part of the grip using the AMO Standard. This is beyond exceptional!
Alan
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I measure from the back of the bow and the handle is 1 1/2". I've had a little indecision about how this should be set up. I sounds like nit picking but changing the draw length 1/4" could be quite noticeable. Since you use the same distance to measure the DW which affects arrow weight it can all add up. I try to use my FDC peg board when doing all these measurments but there is lots of room for indecision to creep in. The draw length on the shooting machine could be slightly different too, just to add another doubt.
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There is one thing that is important when comparing 10ggp performance to glass bow tests in order to compare apples to apples........
Alan,
If Don is fairly close to AMO standards, then one big difference between his bow and most glass bows tested is Dons 5.5" brace height.
What is your opinion about possible gains or losses a comparable glass bow would exhibit at such a low brace?
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There is one thing that is important when comparing 10ggp performance to glass bow tests in order to compare apples to apples........
Alan,
If Don is fairly close to AMO standards, then one big difference between his bow and most glass bows tested is Dons 5.5" brace height.
What is your opinion about possible gains or losses a comparable glass bow would exhibit at such a low brace?
If I understand this right, the 5.5” brace height on the force-draw curve is measured from the back of the bow? It is 4” from the belly side of the bow handle?
I would love to see this bow flight shot at the Salt Flats! The force-draw curve is amazing!
Willie,
It depends on the bow design and the properties of the string. Usually bow efficiency drops at very low brace heights. Energy storage increases, but efficiency drops and often counteracts this. A string made of very high tensile stiffness material helps the bow tolerate a lower brace height.
Alan
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I played with the brace height and the best was right around 6" on two similar bows. I didn't get too anal about it cause it's a PITA to do. Between 5 and 6 inches I gained about 4fps. There may be an arrow mismatch going on here too. I'm using 500 carbons with whatever tip makes the weight I want.
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Very nice!
What is brace height, measured from belly? And how thick the handle is? Would it be possible to get draw force measurements as a numerical table? I would like to make some calculations, for example efficiency. And, if possible, please measure the speed with light and heavy arrows too, for virtual mass calculations. How much the bow took set? What is difference in reflex with just un-braced and rested bow? Did you shoot with machine or finger release? Could you make "bow profile table", so measure reflex measured from the back of bow one or two inch intervals? And what is the mass of bow? What string, mass and strand count?
What chrono, measured in artificial or natural sun light?
I do not doubt your results, quite the opposite. You know what you do, the bow is just great and it has very good draw force curve. I just want to calculate some numerical values to support your results. As far I know, this is the first "200+ fps with 10 grain per lbs arrow and 28 inch draw" with any kind of natural material bow, so it should be documented well.
And this bow deserves better photos...
Thank you and congratulations!
BH-6"
Handle-1 1/2"
Speed 320 grain-224fps and 450 grain-196-198. I'm getting different readings from the two chronos.
Reflex rested 5 7/8". Just unbraced 5 3/8"-5 7/16 depending on how fast measured. It recovers full reflex in less than 15 minutes.
I made a profile table but I measured to the belly. I'll redo it. There is a marked difference between the limbs.
Bow weighs 422 grams no string
String is 6 strand D-97 Flemish 42 grains
Caldwell and Chrony artificial light
I just checked the DW and it was 41 today. I shot a 409 grain arrow and got 204fps. It's never the same. Up and down by 4-5 fps from one day to the next.
It will have to wait for a better photographer ;D ;D
Thank you.
I'll get back to you with more info.
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No I didn't, I measured to the back. Here ya go
Bottom Top
2 5 7/8 5 13/16
4 6 1/16 5 7/8
6 6 1/4 5 13/16
8 6 3/8 6
10 6 1/2 6
12 6 9/16 6
14 6 5/8 5 7/8
16 6 9/16 5 3/4
18 6 7/16 5 5/8
20 6 1/4 5 7/16
22 6 4 7/8
24 5 5/8 4 11/16
26 4 7/8 4
28 3 3/4 3 1/4
Hope this is of some use. Let me know what you discover. I've got the numbers written down so if any of these don't make sense I can check them. I've been concerned that the top limb is weakening but I'm hopefully thinking that what I'm seeing is that the bottom limb has so much more reflex to start. The speed hasn't plummeted so maybe it's OK. I'm probably pulling it weird on the tree.
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If you have the materials and the mind to do it you should build another one identical in profile. The ONLY difference should be that instead of 6 1/8" of reflex, only put in 5 1/2" inches. This bow should take 0 set and be even faster than the one you got now.
Sleek - if he did the same as a trilam ... gluing in deflex before pulling in reflex what would you feel the outcome would be?
The short answer is, anything you change about the build will negate those exact reflex numbers given
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Thank you for the additional information! I really appreciate it.
I would prefer numerical force-draw table, it is more accurate. If possible, please measure draw force one inch increments. And, please see this, my tiny test:
https://www.tapatalk.com/groups/paleoplanet69529/one-bow-two-draw-force-curves-t66460.html
So, there is a difference between maximum value and rested value in draw force. It is important to know, how you measure the draw force in force-draw measurements. Stored energy should be calculate as accurately as possible, because with it the efficiency can be calculated accurately also.
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There is one thing that is important when comparing 10ggp performance to glass bow tests in order to compare apples to apples........
Alan,
If Don is fairly close to AMO standards, then one big difference between his bow and most glass bows tested is Dons 5.5" brace height.
What is your opinion about possible gains or losses a comparable glass bow would exhibit at such a low brace?
If I understand this right, the 5.5” brace height on the force-draw curve is measured from the back of the bow? It is 4” from the belly side of the bow handle?
I would love to see this bow flight shot at the Salt Flats! The force-draw curve is amazing!
Willie,
It depends on the bow design and the properties of the string. Usually bow efficiency drops at very low brace heights. Energy storage increases, but efficiency drops and often counteracts this. A string made of very high tensile stiffness material helps the bow tolerate a lower brace height.
Alan
Alan, thanks for taking a look. I really appreciate your input. The bow seems to have risen to 41#. I'll have to remember to do a draw weight every time I do a test. I'm finding it difficult to make accurate measurements. It would be nice to see how it's really done. Do you have any links that might show me something? When you say the FDC is amazing what exactly are you looking at? I don't see a bunch of difference between this and my other bows. Does a small difference make a big difference? The one think that stands out to me with this one is how heavy it is to brace. If I had to guess(because I don't have a lot of heavier bow experience) I would say it's like bracing a 50-60# bow.
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Thank you for the additional information! I really appreciate it.
I would prefer numerical force-draw table, it is more accurate. If possible, please measure draw force one inch increments. And, please see this, my tiny test:
https://www.tapatalk.com/groups/paleoplanet69529/one-bow-two-draw-force-curves-t66460.html
So, there is a difference between maximum value and rested value in draw force. It is important to know, how you measure the draw force in force-draw measurements. Stored energy should be calculate as accurately as possible, because with it the efficiency can be calculated accurately also.
Here's the numbers. You'll notice that it goes to 42.65# this morning. I tested it with a 421 grain arrow and only got 199 and 200 fps on the two chronos. This seems to change daily. I'm starting to doubt myself here
6=0
7=4.73
8=8.26
9=10.91
10=13.33
11=15.32
12=17.19
13=19.06
14=20.72
15=22.37
16=23.91
17=25.57
18=27.11
19=28.54
20=30.20
21=31.74
22=33.25
23=34.94
24=36.37
25=38.02
26=39.46
27=41.80
28=42.65
Badger, I have to amend that 35@24 to 35@23. Not looking so good now. Could it gain draw weight and lose speed?
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DC, I wouldn't even worry about those small losses, you are still way up there.
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congratulations DC,, I knew you could do it,, just enjoy and proceed with having fun,,we are all proud of you and your bow,,have the best bow making day ever,, :)
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Could it gain draw weight and lose speed?
sometimes a weight measured on the way up is not the same as if it is measured on the way down.
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Maybe not related but I think one of the things that's messing with me is parallax. From where I stand to pull the tree brace height is right on but once the string gets down to 28" the angle I'm looking at makes 27 1/2" look like 28". Not a problem when just tillering but when one measurement affects the next one it starts to add up. If I pull the bow to what looks like 28" and is actually 27 1/2 it can make the bow look lighter by 2-3 pounds. So now I choose an arrow based on the lighter weight. So now the arrow may be 9 gpp instead if 10. Then I shoot it though the machine which is actually a 28" draw. So now I've got a 42#(instead of the 40#) shooting a 9 gpp arrow. Presto, the chrono shows 8-10 fps faster than the bow is. It's this kind of crap I've got to sort out before I go much further.
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Wood fluctuates. That's just how it is.
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Wood fluctuates. That's just how it is.
Yeah, it's kind of frustrating to put your pride and joy out for the world to see and then two days later you're back tracking. Oh well, ain't the first time I've looked foolish, won't be the last ;D ;D ;D
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Wood fluctuates. That's just how it is.
Yeah, it's kind of frustrating to put your pride and joy out for the world to see and then two days later you're back tracking. Oh well, ain't the first time I've looked foolish, won't be the last ;D ;D ;D
Its in the eye of the beholder. If you look foolish to anyone on here, the fool is the observer. Not many on here can get within 30 fps of you. You are making bows that inspire people.
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Thanks Sleek, I remember a few years back you posted a bow that shot 200fps. I think that's where it started. Don't know whether t thank you or not ;D ;D ;D
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Yeah, that was a good time. I dont remember what the exact arrow weight was, but I do recall the arrows were close but not quite 10gpp. It was like 8 I believe. So you got me beat by miles.
Edit to add: But, that was also with a 26 inch draw. And, for a long time now, I have been arguing that 10gpp is not accurate for anything other than 28 inches. You must drop grains as you drop draw length.
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I made some calculations according to the draw force table (42,65#@28") and with these chrono numbers: "Speed 320 grain-224fps and 450 grain-196-198".
Stored energy: 62,60 J
efficiency (10 gn/# -arrow): 82,3 %
virtual mass: 6,78 g
calculated 10 gn/# -arrow speed: 200,4 fps
The only problem is tht hysteresis seems to be a bit negative. If that 450 grain arrow speed would be 195 fps, then hysteresis would be about 2 %, but then 10 gn/# -arrow speed drops just below 200 fps.
So, every measurements should be made perfectly and with precise routine. For example, shoot 20 times, measure speed at least with three different weight arrow, then let the bow rest an hour or so. Shoot 20 times and take draw force measurements with precise system.
But, as a conclusion I would say, that the secret of this bow is very low hysteresis. The same is with my fastest bows, they have low hysteresis. But I think that meaning of low hysteresis is already well known fact.
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That 450 grain arrow actually weighs 451 if that makes any difference. I would redo the test but it would be different today. I don't know if it's humidity or my ineptness but nothing has ever been exactly repeatable. When I was just using one chrono I was happy with the results but now with two the results are always contradictory.
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I think the chronies should be moved further apart.
To check if both are correct, how about firing a 22 caliber over the chronies. That bullet will go in a straight line and the reading should be the same if both chronies are right.
Probably have a small hole in the wall, but what a heck.
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Don't have a .22 any more but I do have a pellet rifle. The bag will stop that. Good idea.
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Tuomo, my calculations were very close to yours. I came out with a virtual mass of 90 and efficiency of about 82%. Extremely good numbers. Speaks a lot for low set designs.
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It took a bit but the pellet rifle worked. I had to change out the LED lights like Willie said. I suspected that but they seemed to work as well as incandescents with the arrows. Wouldn't even trigger with the rifle. What kind of lights are on your chronos Markus?
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Tuomo, my calculations were very close to yours. I came out with a virtual mass of 90 and efficiency of about 82%. Extremely good numbers. Speaks a lot for low set designs.
Thanks Badger
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I bought two sets of these. They have light for Caldwell https://www.lancasterarchery.com/competition-electronics-prochrono-pal-chronograph.html
Scroll down a bit to see the lights
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Its in the eye of the beholder. If you look foolish to anyone on here, the fool is the observer. Not many on here can get within 30 fps of you. You are making bows that inspire people.
+1, DC's bows are top notch and super fast (regardless of what number the chronograph says today).
When I was just using one chrono I was happy with the results but now with two the results are always contradictory.
;D
As the old proverb says - A man with one watch knows what time it is, a man with two is never quite certain.
Mark
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Referring back to your force-draw curve, it looks like you hit the inflection point right at 24 inches.
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Referring back to your force-draw curve, it looks like you hit the inflection point right at 24 inches.
Sounds like a good thing Eric, could you elaborate why its good @24"?
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And what is it? :D