Arrow build advice

[Trial153]

I think your a bit weak, cut out 25 grains or so.

 

[5MilesBack]

If you try to explain the physics behind your "proper spine" statements you will find yourself speechless.

Does physics determine accuracy and consistency?

 

[Zac]

Does physics determine accuracy and consistency?

It determines everything. The way people scoot around it is by the, "it works for me," theory. However if you look at why it works it is always a combination of physics properties at work. In the example of spine. Someone shoots a light spine and it works amazing. They think oh, my bow prefers a light spine. The reality is that they have a modern compound with incredible nock travel. Shepley said a few years ago that it literally doesn't matter what spine someone wants to shoot. Before you write a paragraph on that I would like you to know that he was talking to experienced archer's.

 

[5MilesBack]

The way people scoot around it is by the, "it works for me," theory.

I always take this with a grain of salt because half the time it's guys saying that that pick up their bow once a year and are shooting deer at 20 yards. However........in the end it always is about "what works best for me". I can "make" just about any spine work, but there are definitely spines that work best for me, and they aren't the stiffest.

 

[Christopher.Reed]

Gillingham, Douglas, Dorge, Snyder, T Bone, and Moss would all disagree with you. Probably many others as well. I agree that it is too stiff if the rest has to be moved way out of center, yet I have never witnessed that myself. I can shoot a 250 spine 28 inch shaft with 120 up front out of my 60 lb TRX just fine at 13/16. I can do the same with a 300 spine, makes no difference. That's with a 29.5 inch draw. The spine you can get away with only has to do with nock travel. Less nock travel translates into a lighter spine tolerance. The spine tolerance you are referencing only lives in the recurve world where risers are not cut past center. If you try to explain the physics behind your "proper spine" statements you will find yourself speechless.

Let me start by saying that I am not a physicist or engineer but, I have a modicum of understanding in both disciplines, and below is my understanding of the importance of spine. Feel free to cite a source (other than so and so says) for any information that runs contrary to this understanding as at the end of the day, we all want to get better which is why we are here.

Clearance of a riser (archers paradox) is not what necessitates proper spine in a modern compound bow but rather the combination of compression, deflection, and varying amplitudes of oscillation inflicted by the force of the bow string. In other words, going from 0-300fps in microseconds causes the arrow to do one of two things, buckle and oscillate due to compression or tail sideways (left = under-spined, right over-spined). A perfectly spined arrow will produce minor oscillations and be much more efficient.

While it is possible to “tune” a bow to a static spine which is far too stiff, your arrow will point sideways, be way out of center shot, and the result is a very unforgiving setup for most archers. Sure, the top few % of archers can pull this off but most of us aren’t hooter shooters.

Selecting the proper spine for your bow results in reduced oscillation, simplifies the tuning process, keeps you within center shot, and is a much more forgiving proposition for the majority of archers.

This is also why manufacturers create spine charts and produces arrows in different spines. As a business person myself, I can assure you that arrow manufacturers would rather sell 1,000,000 of one type of arrow than 10,000 of a hundred, and would love to produce a one size fits all solution. The reason they don’t produce “one spine to rule them all” (or zero spine according to your earlier supposition) is because of the forgiveness afforded by proper spine and they are smart enough to cater to the majority of their consumer base unlike Bud Light.

Well, I suppose Bishop Archery technically accomplished “one spine to rule them all” with their fusion rod system but the fusion rods length is simply another method for tuning optimal spine.


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[Blacknblue]

So down what path would you send someone who wants to dial in their arrows? Right now I expect I fall into the "they shoot good enough" category but I'm able to spend some time now to learn the ins and outs of finding the arrow that shoots best out of my current setup. I'm typically shooting 6 inch groups at 60 yards and would gladly spend the summer extending that even 10 yards by learning more about finding a better suited arrow than the Carbon Express my local shop pushes.

I'd welcome advice that would flatten out the learning curve. What tools of the trade would you suggest I learn to use and what setups should I consider first for my 60# V3 27.5"?

 

[Zac]

Let me start by saying that I am not a physicist or engineer but, I have a modicum of understanding in both disciplines, and below is my understanding of the importance of spine. Feel free to cite a source (other than so and so says) for any information that runs contrary to this understanding as at the end of the day, we all want to get better which is why we are here.

Clearance of a riser (archers paradox) is not what necessitates proper spine in a modern compound bow but rather the combination of compression, deflection, and varying amplitudes of oscillation inflicted by the force of the bow string. In other words, going from 0-300fps in microseconds causes the arrow to do one of two things, buckle and oscillate due to compression or tail sideways (left = under-spined, right over-spined). A perfectly spined arrow will produce minor oscillations and be much more efficient.

While it is possible to “tune” a bow to a static spine which is far too stiff, your arrow will point sideways, be way out of center shot, and the result is a very unforgiving setup for most archers. Sure, the top few % of archers can pull this off but most of us aren’t hooter shooters.

Selecting the proper spine for your bow results in reduced oscillation, simplifies the tuning process, keeps you within center shot, and is a much more forgiving proposition for the majority of archers.

This is also why manufacturers create spine charts and produces arrows in different spines. As a business person myself, I can assure you that arrow manufacturers would rather sell 1,000,000 of one type of arrow than 10,000 of a hundred, and would love to produce a one size fits all solution. The reason they don’t produce “one spine to rule them all” (or zero spine according to your earlier supposition) is because of the forgiveness afforded by proper spine and they are smart enough to cater to the majority of their consumer base unlike Bud Light.

Well, I suppose Bishop Archery technically accomplished “one spine to rule them all” with their fusion rod system but the fusion rods length is simply another method for tuning optimal spine.


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Where we disagree is that you believe a weak, or stiff spine has a tail right, or tail left reaction that correlates into a meaningful direction. If what you say is true Kyle Douglas would be walking around with an arrow that is way out of center shot. The position of the rest, and the cams dictate this. Yes you can get an exact dynamic spine reaction out of a batch of weak shafts and they react the same. You can even put a fixed blade on the front with very soft vanes and it will work. The Push did a study a few years back with a high speed camera that dispelled the too stiff theory, and that was with a recurve cut past center. Why would a compound be different? What I said was you can't go too stiff, most people if they know what they are doing can shoot a range of spines. Only time something is too stiff is if it's too heavy.

 

[Page Master]

Luckily being too stiff won't result in possible bodily harm like being too weak might. But the stiff / weak argument results in the same scenario of your tuning window. I tried to tune 300's with about 200g of point weight a few years ago and had a hell of a time keeping fixed heads in a meaningful group at different distances. I would group well at 20 and be a foot right at 50. Adjust for 50 and be left at 20. I fought that for 3 days.

I happened to have the same shaft in a 350 and sent an arrow down for curiosity and that ****** flew perfect. I switched to 350's after that and have not had any regrets. They tune easier in a broader window and seem to give me a little more space in what they like.

You can definitely tune almost any set up but it will have consequences. Just like every other argument we have with this hobby, there are give and takes.

 

[Mighty Mouse]

Clearance of a riser (archers paradox) is not what necessitates proper spine in a modern compound bow but rather the combination of compression, deflection, and varying amplitudes of oscillation inflicted by the force of the bow string. In other words, going from 0-300fps in microseconds causes the arrow to do one of two things, buckle and oscillate due to compression or tail sideways (left = under-spined, right over-spined). A perfectly spined arrow will produce minor oscillations and be much more efficient.

While it is possible to “tune” a bow to a static spine which is far too stiff, your arrow will point sideways, be way out of center shot, and the result is a very unforgiving setup for most archers. Sure, the top few % of archers can pull this off but most of us aren’t hooter shooters.

I have not observed the oft-repeated "tail left = underspined, tail right = overspined" (for a right-handed shooter) pattern in my tuning. With a compound bow cut past center (i.e., no riser in the way for the arrow to bend around) shot with a mechanical release (i.e., no influence from fingers on the string), I can't conceive of why an overspined/underspined arrow would be predisposed to leave the bow flying one direction or the other. I do think arrow spine can affect how a compound bow tunes, but it won't necessarily manifest as tail left if underspined and tail right if overspined. For a traditional bow shot with fingers, I do believe the arrow spine-to-tail orientation conventional wisdom generally holds true.

Generally speaking, I think the importance of "correct" arrow spine is far overstated in the context of modern compound archery. I've been able to get arrows significantly stiffer and weaker than what the charts/calculators recommend to group well with both field points and broadheads (with the arrow pointing straight at brace and the rest at recommended centershot). There's a plausible argument that a weaker arrow is more forgiving of flaws in shot execution because the arrow flexes more and can better "absorb" the influence of torquing the riser, punching the release, etc. without throwing the arrow off course. However, too weak can cause problems with getting broadheads to group consistently due to excessive/erratic flexing of the arrow. For a hunting arrow, I prefer to err on the stiff side, but I believe the range of workable spines is fairly broad for a compound bow.

 

[Christopher.Reed]

I have not observed the oft-repeated "tail left = underspined, tail right = overspined" (for a right-handed shooter) pattern in my tuning. With a compound bow cut past center (i.e., no riser in the way for the arrow to bend around) shot with a mechanical release (i.e., no influence from fingers on the string), I can't conceive of why an overspined/underspined arrow would be predisposed to leave the bow flying one direction or the other. I do think arrow spine can affect how a compound bow tunes, but it won't necessarily manifest as tail left if underspined and tail right if overspined. For a traditional bow shot with fingers, I do believe the arrow spine-to-tail orientation conventional wisdom generally holds true.

Generally speaking, I think the importance of "correct" arrow spine is far overstated in the context of modern compound archery. I've been able to get arrows significantly stiffer and weaker than what the charts/calculators recommend to group well with both field points and broadheads (with the arrow pointing straight at brace and the rest at recommended centershot). There's a plausible argument that a weaker arrow is more forgiving of flaws in shot execution because the arrow flexes more and can better "absorb" the influence of torquing the riser, punching the release, etc. without throwing the arrow off course. However, too weak can cause problems with getting broadheads to group consistently due to excessive/erratic flexing of the arrow. For a hunting arrow, I prefer to err on the stiff side, but I believe the range of workable spines is fairly broad for a compound bow.

That is interesting, as I have seen tail left/right pretty dramatically.

What is your draw-length? I ask because I am wondering if my observations are due to the longer power stroke of my draw-length (31.5”). 300 spines tail 3” left and 235’s tail 3” right, with consistency at center shot.

The reason I prefer a slightly weaker spine with a HIT system is based off personal observation and testing which I will explain.

Last year I shot a 70lb bow at 31” (all it had) and built some VAP 250’s which flew perfectly using a 200g broadhead and 25g Iron Will Snyder core insert/collar.

When I upgraded to a 80lb/31.5” draw bow this year, I noticed my VAP’s still shot perfectly which is contrary to any calculator I used as the arrows should have been very under-spined.

The only plausible explanation I could find was the rigidity provided on the front end by the HIT system effectively shortened the spine of the arrow from 31” C2C to 29” C2C. When plugged into archers advantage at 29”, the result is perfect which matches what I observed. Yes, I know arrow spine is calculated at 28” but that at least provides a base line.

I noticed the same deviance from calculation with 235 VAP TKO’s. What should have been a perfect spine produced a 3” tail right which I was able to partially mitigate by adding 100g to the front. The result of that experiment was a 700g arrow which isn’t optimal for an arrow I plan to use for 3D as well as hunting.

My observation was then proven (to me) when I researched Bishops arrow systems. As I understand it, he uses a single spine with various lengths of carbon “fusion rods” inserted to tailor the arrow spine which is effectively a long HIT system.

While this observation backs up the assertion that a little stiff is fine given the performance of the arrow at 70lbs/31”, there is certainly a window of optimal.

As Page mentioned, this sport is largely individual as the whole of the bow/human system is greater than the sum of its parts, and there isn’t a single solution for all systems which was my point in interjecting.

Making assertions that there is no spine too stiff is not only false, it can result in countless hours of frustration and wasted dollars to someone that is new to the sport and on this forum to learn as a lot of us are.


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[Christopher.Reed]

Where we disagree is that you believe a weak, or stiff spine has a tail right, or tail left reaction that correlates into a meaningful direction. If what you say is true Kyle Douglas would be walking around with an arrow that is way out of center shot. The position of the rest, and the cams dictate this. Yes you can get an exact dynamic spine reaction out of a batch of weak shafts and they react the same. You can even put a fixed blade on the front with very soft vanes and it will work. The Push did a study a few years back with a high speed camera that dispelled the too stiff theory, and that was with a recurve cut past center. Why would a compound be different? What I said was you can't go too stiff, most people if they know what they are doing can shoot a range of spines. Only time something is too stiff is if it's too heavy.

Do you happen to have a link to the study by “The Push”? Apparently my google skills are lacking as I can’t seem to find it and am certainly interested in seeing their results.


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[Zac]

Luckily being too stiff won't result in possible bodily harm like being too weak might. But the stiff / weak argument results in the same scenario of your tuning window. I tried to tune 300's with about 200g of point weight a few years ago and had a hell of a time keeping fixed heads in a meaningful group at different distances. I would group well at 20 and be a foot right at 50. Adjust for 50 and be left at 20. I fought that for 3 days.

I happened to have the same shaft in a 350 and sent an arrow down for curiosity and that ****** flew perfect. I switched to 350's after that and have not had any regrets. They tune easier in a broader window and seem to give me a little more space in what they like.

You can definitely tune almost any set up but it will have consequences. Just like every other argument we have with this hobby, there are give and takes.

You saw an improvement because the front and rear of your arrow were fighting each other. If you have a ton of weight in the front in the form of a fixed blade then decreasing fletching or weakening the shaft is the only solution. You can only have one master.

 

[Christopher.Reed]

So down what path would you send someone who wants to dial in their arrows? Right now I expect I fall into the "they shoot good enough" category but I'm able to spend some time now to learn the ins and outs of finding the arrow that shoots best out of my current setup. I'm typically shooting 6 inch groups at 60 yards and would gladly spend the summer extending that even 10 yards by learning more about finding a better suited arrow than the Carbon Express my local shop pushes.

I'd welcome advice that would flatten out the learning curve. What tools of the trade would you suggest I learn to use and what setups should I consider first for my 60# V3 27.5"?

Unfortunately, I am not aware of a singular authority for research as there doesn’t seem to be much of a consensus from the experts outside of the basics.

Gold Tip has a good reference with their “Super Tuning” series as do most of the other arrow manufacturers along with most reputable archery personalities.

The Ranch fairy has a lot of interesting data, even if he is the most polarizing figure in the archery world apparently. In fact, he’s so polarizing that mentioning his name will probably draw down the ire of his detractors on this post. He’s the Voldemort of archery.

Iron Will Outfitters is another great resource.

Archers Advantage is an online calculator that is fantastic for virtual tinkering and estimations. At $12 a year for membership, it’s money well spent imo.

It’s a pretty deep rabbit hole but, for those of us that enjoy that kind of thing, it provides a lot of meaningful experimentation. At the end of the day, all that matters are your results and there are numerous ways to achieve what’s optimal for you, it just takes a decent amount of digging and experimentation to find it.

It’s a great feeling to research, build, and shoot an arrow that flies perfectly for you.

It’s a bit of a paradox though as it’s also entirely possible that the reason it seems to fly perfectly is because of your confidence in the work you put into it.


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[Zac]

Do you happen to have a link to the study by “The Push”? Apparently my google skills are lacking as I can’t seem to find it and am certainly interested in seeing their results.


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It's one of the Cody Greenwood podcasts, they had the slo mo footage on their IG, you can just chat Cody on IG. However your best resource would be to call Dorge from Firenock.

 

[Christopher.Reed]

It's one of the Cody Greenwood podcasts, they had the slo mo footage on their IG, you can just chat Cody on IG. However your best resource would be to call Dorge from Firenock.

Thank you for sharing! While I haven’t found the podcast referenced yet, there is tons of great content that I will peruse as time permits.


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[Page Master]

You saw an improvement because the front and rear of your arrow were fighting each other. If you have a ton of weight in the front in the form of a fixed blade then decreasing fletching or weakening the shaft is the only solution. You can only have one master.

The opposite actually. I tried point weights from 185-225 with the 300. Went with 175g on the 340's. Same vane configuration. I could make the 300's group but it was super finnicky.

 

[Zac]

The opposite actually. I tried point weights from 185-225 with the 300. Went with 175g on the 340's. Same vane configuration. I could make the 300's group but it was super finnicky.

You can steer from the front or the back. I don't know if it makes any difference. I use to think that steering from the front was not ideal yet it seems to work well enough for some. Valkyrie seems to have a lot of success doing that. Even Dorge has given some people some FOC builds in the 22 percent range. The consensus seems to be either to use a softer vane material, or less fletching in general.

 

[Insomnia]

Where we disagree is that you believe a weak, or stiff spine has a tail right, or tail left reaction that correlates into a meaningful direction. If what you say is true Kyle Douglas would be walking around with an arrow that is way out of center shot. The position of the rest, and the cams dictate this. Yes you can get an exact dynamic spine reaction out of a batch of weak shafts and they react the same. You can even put a fixed blade on the front with very soft vanes and it will work. The Push did a study a few years back with a high speed camera that dispelled the too stiff theory, and that was with a recurve cut past center. Why would a compound be different? What I said was you can't go too stiff, most people if they know what they are doing can shoot a range of spines. Only time something is too stiff is if it's too heavy.

The push didn't disprove a too stiff arrow, they disproved that a finger-shot arrow has significant paradox past the riser.

 

[Zac]

Thank you for sharing! While I haven’t found the podcast referenced yet, there is tons of great content that I will peruse as time permits.


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The push didn't disprove a too stiff arrow, they disproved that a finger-shot arrow has significant paradox past the riser.

I'm sure they did that as well, but that's not what I was referencing.

 

[Mighty Mouse]

What is your draw-length? I ask because I am wondering if my observations are due to the longer power stroke of my draw-length (31.5”).

My draw length is 29". I tend to agree that longer DL likely makes tuning trickier and more sensitive to arrow spine (amongst other factors).

300 spines tail 3” left and 235’s tail 3” right, with consistency at center shot.

I'm surprised that a .065" change in static spine (assuming that's the only thing you changed) would cause a 6" change in tail behavior. Did you ever get either arrow tuned? If so, did you try the other arrow again afterward? Personally if I got a 300 spine arrow tuned then switched to a 235 spine (at the same length, front/rear weight distribution and same bow specs/settings), I would expect it to tear/fly the same as the 300.

Last year I shot a 70lb bow at 31” (all it had) and built some VAP 250’s which flew perfectly using a 200g broadhead and 25g Iron Will Snyder core insert/collar.

When I upgraded to a 80lb/31.5” draw bow this year, I noticed my VAP’s still shot perfectly which is contrary to any calculator I used as the arrows should have been very under-spined.

That's a good example of compound bows being able to handle a fairly wide range of spines. You added 10 lbs of draw weight and the same arrow still flew fine.

The only plausible explanation I could find was the rigidity provided on the front end by the HIT system effectively shortened the spine of the arrow from 31” C2C to 29” C2C. When plugged into archers advantage at 29”, the result is perfect which matches what I observed. Yes, I know arrow spine is calculated at 28” but that at least provides a base line.

I noticed the same deviance from calculation with 235 VAP TKO’s. What should have been a perfect spine produced a 3” tail right which I was able to partially mitigate by adding 100g to the front. The result of that experiment was a 700g arrow which isn’t optimal for an arrow I plan to use for 3D as well as hunting.

A longer insert will stiffen dynamic spine to some degree. Whether or not a 2" insert really makes an arrow "behave" a full 2" shorter, I don't know (neither does Archers Advantage or Pinwheel BTW...spine calculators just give approximations based on empirically derived rules of thumb and can't account for every variable in the bow-arrow-shooter "equation").

Making assertions that there is no spine too stiff is not only false, it can result in countless hours of frustration and wasted dollars to someone that is new to the sport and on this forum to learn as a lot of us are.

Dogmatically following the flawed "tail left = too weak, tail right = too stiff" advice can also result in compound shooters wasting time and money. "Check My Spine" threads full of posts laboring over a half inch here and 10 grains there are common on this forum and others when in reality, arrow spine isn't that critical with a compound bow. If I see a horizontal discrepancy in my arrow flight, I check my centershot then adjust cam position/lean then adjust rest windage (if necessary) before I even think about adjusting dynamic arrow spine.

As you mentioned, archery is highly personal and there are many ways to skin the cat. To each his own...if it works, it works. Good discussion.