Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on August 01, 2020, 11:04:25 am
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Just in case anyone is interested I shot a 400 grain test arrow every inch of draw weight starting at 20 inches
20"-160fps
21-163
22-169
23-174
24-179
25-184
26-187
27-192
Something I found interesting is how much scaping there was between steps. From 20 to 21 took lots of scrapes but 26 to 27 took one or two scrapes and a little exercising. I'm working on the last inch this morning. It's mostly finishing and then I'll check the draw weight and adjust it to 40#
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Interesting... must have taken a lot of work :)
Del
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I leave the bow strung for tillering, that makes it a little quicker. I make a lot more trips to the tree than you seem to do. That one vid you did when you counted trips you got to about a dozen. I'd bet I make at least 50 trips to the tree.
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Just in case anyone is interested I shot a 400 grain test arrow every inch of draw weight starting at 20 inches
20"-160fps
21-163
22-169
23-174
24-179
25-184
26-187
27-192
did you make these shots as you tillered out the bow or after the bow was finished?
doing it both ways might make of some interesting comparisons.
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As I was tillering. I had a 400 grain arrow and as the 40# came to each inch I tested it. That's why some numbers are a bit skewed. I may have overshot or undershot the 40# a bit. I was a little surprised at the evenness of the speed gain. 5# per inch even though the bow must have been taking more set in the higher draw lengths. I don't know if this means anything at all but it almost looks predictable. This bow did reach 200fps but just and that involved a bit of tip lightening. I never checked but I think it was 197-198 at 28" before i started tweaking it.
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As I was tillering. I had a 400 grain arrow and as the 40# came to each inch I tested it..... I don't know if this means anything at all...........
I think if you plotted the the speeds vs the draw lengths as you tiller, and then replotted again when you are finished, it could be a really useful tool to see how much your tillering, exercising and shooting in has affected the bow.
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If you plotted the F/D as you tillered wouldn't you get a straight line acroos the page?
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Wow! Excellent results. Jawge
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If you plotted the F/D as you tillered wouldn't you get a straight line across the page?
Don, I have made a mistake in the post above and edited it. What needs to be plotted is not the F/D but the speeds vs the draw lengths. Making three shots at each increment using a light weight arrow, a 10gpp arrow and a heavy arrow while collecting data might also get interesting.
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If you plotted the F/D as you tillered wouldn't you get a straight line across the page?
Don, I have made a mistake in the post above and edited it. What needs to be plotted is not the F/D but the speeds vs the draw lengths. Making three shots at each increment using a light weight arrow, a 10gpp arrow and a heavy arrow while collecting data might also get interesting.
You just want me to wear out my bow, don't you ;D ;D
I just may do the 10gpp though. We'll see about the rest.
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Subscribed
I thought this might pique your interest :D
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DC thanks for all of your work compiling data points. I think I learn a bit from every post.
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You just want me to wear out my bow, don't you ;D ;D
of course not, but I do think collecting data at less than full draw is useful and probably not all that much wear once the bow has been shot at the full draw a few times.
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Wow! Now those are impressive numbers!
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You just want me to wear out my bow, don't you ;D ;D
of course not, but I do think collecting data at less than full draw is useful and probably not all that much wear once the bow has been shot at the full draw a few times.
You're right, just yanking your chain ;D ;D
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Wow! Now those are impressive numbers!
Given that this is a backed bow with 5" of reflex and yours is a selfbow with not much reflex I would think your numbers are just as impressive.
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Without a proper shooting machine, it's too easy to make mistakes in measuring FPS. A while ago I was doing it while drawing almost 3 inches less than my expected 28 inch draw length. I was getting timid while shooting through the chrony. No wonder my better bows were shooting only 140 up to 150. My simplistic shooting machine at that time was also too crude to be reliable. According to it, my control group of fiberglass recurves were shooting only around 160. As I have made the machine a little better and actually simpler, they now shoot around 180. My better bows are around 160 up to 170. If I pull those a couple of inches over my usual draw length, I can probably get 180 out of some of them. But that's very dangerous. I might break them in my eagerness. The simplest way to prevent this is to use only the arrows of proper length. Now I am trying to make my machine shoot faster, instead of trying to make my bows shoot better. So silly of me.
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Without a proper shooting machine.................. Now I am trying to make my machine shoot faster, instead of trying to make my bows shoot better. So silly of me.
scp-
Don has tried a couple of release methods, and it has been demonstrated that the release matters, if not at a couple of feet to the chrono, at least to the cast of the arrow.
But what about the bow clamp? Can we assume that a bow in a rigid mount shoots the same as a bow held loosely in the hand?
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Now I am trying to make my machine shoot faster, instead of trying to make my bows shoot better. So silly of me.
All you're trying to do is make your machine more consistent, not faster. it will just take a little work to do that and then it will let you know(or at least give clues) how to make your bows faster. I've got maybe two or three days work into my machine. I consider it time well spent but only if you're a speed freak.
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Don has tried a couple of release methods, and it has been demonstrated that the release matters, if not at a couple of feet to the chrono, at least to the cast of the arrow.
But what about the bow clamp? Can we assume that a bow in a rigid mount shoots the same as a bow held loosely in the hand?
I think we're going to have to assume that they are similar. I can't think of a way to test the difference. My biggest problem with the clamp is different shaped handles. It holds a Howard Hill type very well but curved belly type sometimes fit, other times they torque.
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Try a bean bag between the handle and its clamp?
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thanks DC,, thats great info,,
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Try a bean bag between the handle and its clamp?
I have a layer of wet suit foam in there now. My machine has automatic release that depends on a pin-in-a-hole trigger so the bow has to be held in the same position every time. A bean bag may not do that. I'll keep it in mind though.
Maybe I went at this the wrong way. Maybe the moveable jaw on the clamp should be against the belly. Then the back(where DL is measured) would be constant. Sounds unsafe though. More thought required.
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thanks DC,, thats great info,,
It's interesting but is it any use?
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All you're trying to do is make your machine more consistent, not faster.
I now use a drill press clamp to hold the bow. I use a roller arrow rest, a caliper release, and a hand winch. That way I am holding the bow at full draw for several seconds. I am thinking about an automatic release mechanism. I like the way you used the medieval crossbow roller nut design, but I'm not sure how your automatic release works yet.
My shooter's machining tolerance is terrible, probably more like a quarter inch or so, as I am more of a "2x4 school" of woodworking. But I am good if the consistency margin is less than 5 FPS.
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I added a post to the Shooting Machine thread. Maybe a little clearer how it works.
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But what about the bow clamp? Can we assume that a bow in a rigid mount shoots the same as a bow held loosely in the hand?
That's a good question. A loose grip will change how a bow vibrates during the shot, especially with working recurves on R/D bows. Tough to test that, though. Has anyone tried testing using a clicker and a mechanical string release like the compound shooters use? That may be almost as good as DC's machine for consistency.
Is it more important that it is the same as shooting by hand or simply that it is consistently the same for all the bows? I say consistency is king unless we can show the clamp is significantly changing the results.
Maybe the moveable jaw on the clamp should be against the belly. Then the back(where DL is measured) would be constant. Sounds unsafe though.
Why does that sound unsafe to you? The movable jaw does need to be strong enough to not fail, but that shouldn't be an insurmountable problem. I can't criticize your perception, though. You have to stand beside it while full drawn and there is a lot of stored energy in a bow that makes it a bit of a bomb if things go wrong. Whatever feels safe to you is what you should do.
Mark
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I'm not sure why it feels unsafe, just a gut feeling. The movable jaw is held by two 5/16" bolts. It's probably stronger than the fixed jaw ;D ;D. I'm at the end of a six foot rope when I shoot it. A nice comfortable way away.
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Thanks. I saw it but didn't read it. I will check it out soon.
How fast are you pulling the string when drawing a bow in your shooting machine?
After the proper release, the speed of drawing might make all the difference. I was thinking about using a hydraulic piston, but it would be too much of a bother for an occasional hobby.
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I don't pull it really fast. It's a hard thing to describe. No where near as hard as starting a chain saw.
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I don't pull it really fast. It's a hard thing to describe. No where near as hard as starting a chain saw.
Wonderful. That means I don't need to make the pulling any faster than usual drawing. I guess the hand winch can stay and all I need is the automatic release mechanism. I got a pretty good idea from your photos. Thanks.
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DC do you think bow profile- design may have something to do with difference in draw length speeds?
Arvin
My interest is in being able to add total force draw speeds on different designs. You math guys can laugh or also be interested. If the math would help here’s you chance to do something way out of my little league . If possible I would be interested in the results. Arvin
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DC do you think bow profile- design may have something to do with difference in draw length speeds?
Arvin
I'm not sure if I'm understanding. I think there is always going to be a difference in speeds at different DL. I think DL is king for speed. For flight shooting where you're not limited by the 10 gpp thing more enters into it. Maybe the RD design accounts for the amount of speed difference. I've also found that more reflex equals more speed. I know that differs with what others have found so I have no explanation but every time I got a bow to hold more reflex it was faster. Probably I just lucked into a combination that works.
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More reflex, more speed; makes perfect sense. You have managed to avoid too much set somehow; probably by using the pre-stressed bamboo backing.
Talking about the draw length, I like to know how you make sure that your automatic release does not allow overdrawing. Thanks.
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I agree with the more reflex equals more speed as long as it doesn't take too much set.
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I think you understand. Let’s say your first arrow at 20” shot 160 FPS . If you added difference between the next shot at another inch of draw and the 160 FPS would that give you the approximate distance of the arrow??? Then add all together at say 28”. Don’t know that it matters. Real testing at full draw is more accurate. Then there is wind and such. So many variables!!!!!!! I can see why the guys just wanting to build a bow get so wore out with us guys chasing speed ! ;D. Arvin
Never mind after thinking about it that won’t work.
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I agree with the more reflex equals more speed as long as it doesn't take too much set.
That’s what I think also! The trick is getting more than 2” of tip in front of the handles back unstrung
Without it taking set. Arvin
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I agree with the more reflex equals more speed as long as it doesn't take too much set.
OK I thought you were having some problems other than set with too much reflex. I feel better now ;D
Talking about the draw length, I like to know how you make sure that your automatic release does not allow overdrawing. Thanks.
It releases at whatever DL I set it for. It can't overdraw. The trigger hits an adjusteable peg and it goes off.
I think you understand. Let’s say your first arrow at 20” shot 160 FPS . If you added difference between the next shot at another inch of draw and the 160 FPS would that give you the approximate distance of the arrow??? Then add all together at say 28”. Don’t know that it matters. Real testing at full draw is more accurate. Then there is wind and such. So many variables!!!!!!! I can see why the guys just wanting to build a bow get so wore out with us guys chasing speed ! ;D. Arvin
Never mind after thinking about it that won’t work.
I don't know how to convert speed into yards and have very little experience flight shooting. I haven't been able to find a field.
That’s what I think also! The trick is getting more than 2” of tip in front of the handles back unstrung
Without it taking set. Arvin
The one I'm just finishing is 5 3/4" reflex rested. It shot 202 the other day but I haven't tested it since because it's got wet tung oil on it most of the time.
The proof is going to be if the bow gets to Badger and he can confirm my results. That's what I'm waiting for. Tracking say Aug 11 but I'm not holding my breath.
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Well will he bring it to Wendover if it pass the test??? I want to see one of these speedy bows. No bull just interested to see some flight results. That could maybe work in flight. And possibly get close with 450 gr. broadhead. Arvin
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Arvin, the best I can figure is that 170 fps will hit 200 yards. For every 30 fps you add it goes up about 100 yards, so every 10 fps is good for about 30 yards. A 450 grain arrow will go about 7 fps faster than a 500 grain arrow. That could be good for up to about 25 yards or less.
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Ok Steve cut thru math quiz and tell me how far you can get 450gr thru a bow shooting 400 gr at 200fps ;D ;D Arvin
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275 yards?
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Thanks Sleek I better get to work. I wish my bag of tricks was bigger! :-\. Arvin
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Arvin, you still shooting your long pyramid design? How fast are you shooting it? Have you made a new one since you last destroyed the distance record?
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I think Sleek is pretty close at 275 yds maximum distance.
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239 is not 275 . Even I can do that math. ;D I think on perfect day I could get 250yds from the same bow but that’s pushing it. Haven’t tested it lately. Probably high 180s to low 190s depending on arrow weight. I think the pyramid design comes home more even yielding really good cast. It may not be the best design but very reliable. Yes Sleek I’ve built probably 10 this last winter only three were in the 50# range. I haven’t been able to improve that bow yet. Tried a bunch of times. Get close but no cigar.
Oh well got lucky once. Arvin
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Have you guys ever noticed that the bow is faster/further after about 4 or 5 shots? The last few times I've been testing bows they seem to improve a few fps. I would have thought that a fresh bow would shoot best but are they like an old man, they need to loosen up a bit.
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Exercising on a tree is different then shooting a bow . I think they have to learn to bend so to speak and learn to come to rest with an arrow. Slamming home is different. The wood has to experience the bend both ways, and wood has no brain! But it has to work the tension and compression in. Yes DC kinda like us old farts getting out of bed. This could be when the set happens also . I also think there is a point when it settles in and that’s what you get say 200-500 arrows. Seams to happen faster on a hot day. That’s why I prefer to build bows in a cooler time of the year. If 90degrees when tillering they seam to not hold reflex as well. This is just an opinion though no one way to prove such things. More of an observation. Arvin
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DC, I had a piece of yew here so decided to build one similar to what you are doing. Build when much smoother and faster than I expected. I glued in 5" reflex with no perry reflex, next time I might add 2" perry reflex. Bow holds 3" of reflex so I lost 2". Inspite of the set force draw was better than I expected at 56.8#. Going to try and flight shoot it this weekend. I should be slightly below 200 fps but I don't plan on shooting it through a crono anyway. I got lucky on the tiller. I used the belt sander to get it to floor tiller put it on the long string and it showed I was ready to brace. I braced it and took it right to 51.2# @ 28". Dropped down to exactly 50# after several pulls so no tillering at all. At 35# I think this bow would have been an absolute screamer.
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DC,, sometimes the bow shoots faster for me after a few shots,, I just thought it was my release,,
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DC, I had a piece of yew here so decided to build one similar to what you are doing. Build when much smoother and faster than I expected. I glued in 5" reflex with no perry reflex, next time I might add 2" perry reflex. Bow holds 3" of reflex so I lost 2". Inspite of the set force draw was better than I expected at 56.8#. Going to try and flight shoot it this weekend. I should be slightly below 200 fps but I don't plan on shooting it through a crono anyway. I got lucky on the tiller. I used the belt sander to get it to floor tiller put it on the long string and it showed I was ready to brace. I braced it and took it right to 51.2# @ 28". Dropped down to exactly 50# after several pulls so no tillering at all. At 35# I think this bow would have been an absolute screamer.
That's cool. I'm glad it went well. I'm living in fear here that you are going to post that you can only get 180 or something out of my bow.
I found that the Perry reflex helps retain reflex but I'm not sure if if it's just the reflex gain cancelling out the set. I could have damaged wood being held in shape by the reflex gain.
I also heat treated both sides of the belly before I glued up.
Why would dropping the DW from 50 to 35 make a big difference?
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I think at 35# it would not have taken any appreciable set.
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I think at 35# it would not have taken any appreciable set.
Gotcha :)
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DC, I had a piece of yew here so decided to build one similar to what you are doing. Build when much smoother and faster than I expected. I glued in 5" reflex with no perry reflex, next time I might add 2" perry reflex. Bow holds 3" of reflex so I lost 2". Inspite of the set force draw was better than I expected at 56.8#. Going to try and flight shoot it this weekend. I should be slightly below 200 fps but I don't plan on shooting it through a crono anyway. I got lucky on the tiller. I used the belt sander to get it to floor tiller put it on the long string and it showed I was ready to brace. I braced it and took it right to 51.2# @ 28". Dropped down to exactly 50# after several pulls so no tillering at all. At 35# I think this bow would have been an absolute screamer.
Does any reflex return after sitting awhile Badger?
When you can go straight from floor tiller to full draw, with no tillering, you have become the ultimate master bowyer. Just sayin...