Broadhead Tuning Question

[MattB]

Interesting thread. I get the notion in theory of the rest is giving the nock end a direction of travel. It's just contrary to how almost every bow I have ever tuned has acted in practice. The exceptions have been where there was vane contact which did what you are referring to by causing the back end of the arrow to move off the rest roughly opposite the direction of contact.

 

[Gumbo]

I find it interesting that there are a bunch of people throwing out analogies to try to prove their point. You can make a lot of things sound good in theory, but it doesn't mean they are right. Honestly, I'd trust Gillingham not to matter-of-factly stake his reputation on something he wasn't pretty damn sure of. I also trust Dudley, and don't know jack about the superman guy, but if you watch those videos they don't really fix anything, they just explain the theory (as in most online tuning segments), which to my muddled knowledge was based on old tune charts relating more to fingers, stickbows, and old-school rests. What I do think I know is that grip and pulling angle can screw up bareshafts and broadheads way worse than fletched field points. Unless you are already well-tuned and are super consistent you probably are putting banadages on nosebleeds with broadhead or bareshaft tuning, or in other words getting a couple seemingly good results that were essentially based on an inconsistent foundation (tune or form) and having faith that all is well. I mean we all hate to admit we don't know it all and aren't professional caliber in what we are passionate about. I do know that what ontarget7 says has worked for me in terms of bareshaft flight, but only up to the point that I can replicate my grip and pull. I also can't say I've been skilled enough in tuning or shooting to really ever definitively correct broadhead flight. The last couple years I've had a perfect bullet at about 2-3 yards which has resulted in Ramcats with fieldpoints at 70 yards when I do my part. Luck? Definitely at least a little, as well as dogged determintaion in tuning fundamentals and good shooting form. If I wasn't hitting field tips with broadheads I'd definitely have torn into my setup. As I learn more about fine tuning my bow I realize there is so much more to learn in fine tuning myself, my shot, and my consistency that I need to master before the rest of the tuning process can be mastered.

 

[madkaw284]

That’s very true what you’re saying. You can only tune to your shooting ability. The same applies to sighting in too


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[Shearingthehunt]

Need some advice from those with more experience on this. So from my understanding from everything I've read or watched, if my broadhead is hitting in one direction from my field points I move the rest in the opposite direction, correct? If broadheads hit right if fieldpoints, move rest left?

What I was seeing today has me a little messed up. I am going to shoot a little more at these distances to verify but it seemed consistent through several strings today.

I am shooting 125gr Iron Wills with a 27" BE Rampage, HIT insert and 4 fletch Heat vanes.

So when I first got these arrows made we tweaked the rest to get the vertical good at 20 yards..the broadheads were hitting a little high.

Today as I got out to 40 and 50 yards I noticed my Iron Wills were hitting high and right of my field points. Maybe 3-4" in each direction. At 20-30 they were hitting good with field points. So I started moving my rest(integrated QAD) to the left. At one point i got up to 8 clicks on the microtune which to me seemed like a lot at 50 yards and didn't seem to be noticing them coming together.

This had me kinda baffled so I adjusted the rest back to where I started and figured I'd come back to it fresh on another day. Curious if anyone has seen anything like this?

I was also a little confused on not seeing the variance until 40 yards. I know any little mistake or adjustment will be amplified with the broadheads at distance but from being on at 30 to the same amount off at both 40 and 50 had me scratching my head a bit. I would have though if I was off at 40 a certain amount it would be more at 50.

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[jmez]

Tail left tear, your nock travel is like this / .

It is coming from a point to the left of centerline of the bow and moving to the right. This gives a tail left tear when the arrow is in line with the powerstroke. When you move the rest you are not altering the powestroke of the bow, it is still going left to right. If you push the rest to the right this will move the tail of the arrow farther to the left. Since the powerstroke is unchanged, still going left to right on a line, the string will push the tail end of the arrow to the right moving POI to the left.

You move the rest to the left you are now moving the tail end of the arrow to the right. Powerstroke is unchanged, still going left to right. The string is now going to the pull the tail end of the arrow to the left and make things worse.

 

[5MilesBack]

What happens is, the arrow wants to fly in the direction of the string’s travel. So if your rest is too far to the left, the point will kick to the right as it leaves the rest to follow the string path, and your paper hole will show a nock-left tear. Move the rest right to solve the problem.

The bolded underlined part seems to be the kicker.......literally. Hard to imagine that the string path pushing on the nock end (away from the point) somehow kicks the point end in that same direction. In an extreme example: Point pointed 45 degrees right of the string travel, with the string pushing the nock end in the direction of the shelf, and somehow the point and nock ends suddenly flip sides. Just hard to grasp that mentally.......visually.......or logically.

Anyone know of any high speed frame by frame videos showing that happening?

Also, how do you measure or determine the path of your bow's powerstroke without allowing tear or impact indicators to influence that determination?

 

[ontarget7]

The tip weight is the controlling factor and will want to get behind the powerstroke so you are chasing that tip impact point with the rest so rest and powerstroke are in line.

No difference when twisting the yokes or shimming cams, you are just making opposite end adjustments so powerstroke is in line with a particular centershot.




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[Btaylor]

The tip weight is the controlling factor and will want to get behind the powerstroke so you are chasing that tip impact point with the rest so rest and powerstroke are in line.

No difference when twisting the yokes or shimming cams, you are just making opposite end adjustments so powerstroke is in line with a particular centershot.




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For my simple mind this is the best explanation yet. Adjusting based on tip and not tail makes a whole lot more sense to me. Then all horizontal adjustments for sights or rest are always chasing.

 

[Brendan]

The bolded underlined part seems to be the kicker.......literally. Hard to imagine that the string path pushing on the nock end (away from the point) somehow kicks the point end in that same direction. In an extreme example: Point pointed 45 degrees right of the string travel, with the string pushing the nock end in the direction of the shelf, and somehow the point and nock ends suddenly flip sides. Just hard to grasp that mentally.......visually.......or logically.

Anyone know of any high speed frame by frame videos showing that happening?

Also, how do you measure or determine the path of your bow's powerstroke without allowing tear or impact indicators to influence that determination?

I have to be honest with you - I agree with your sentiment. I've proved that it works for me, but I still don't like the explanation of "Well, the tip just wants to be in line with the power stroke". The physics don't seem to line up in my head yet but What I think may be happening is that rest is acting like a fulcrum - giving the rear of the arrow lateral travel and lateral momentum stronger than the front of the arrow causing the rear to "kick". As the rest drops, the rear of the arrow still has that momentum. If this is true - rest timing would play a big component in this - does rest drop early or late? Ideal video would be high speed camera from above at release.

In terms of power stroke - you've got vertical and horizontal nock travel. There are some videos about people trying to measure it. Vertical nock travel determined by top and bottom cam take-up, which you could probably estimate by measuring from where the string leaves the cam (top and bottom) to center of nocking point. Measure at brace and full draw, then compare. Horizontal nock travel - you can visualize it by comparing cam lean at brace and then full draw using an arrow on the side of the cams. If the cams tilt in one direction, and by how much, that tells you direction of nock travel during the power stroke. What's causing it is the cable guard - more tension at brace than full draw I think because it needs to flex the cables out of the way of the arrow / vanes.

 

[5MilesBack]

What I think may be happening is that rest is acting like a fulcrum - giving the rear of the arrow lateral travel and lateral momentum stronger than the front of the arrow causing the rear to "kick". As the rest drops, the rear of the arrow still has that momentum.

Ya, except there are all kinds of rests out there. Can't imagine a lizard tongue rest impacting any fulcrum effects on the arrow. And most drop aways are dropping so fast into the release that I doubt they have that much effect.........and yet I have absolutely had to adjust the opposite way to get BH tuned with some bow/rest combos. And even if a funky grip was involved in that, if the initial indication was a left tear, then the opposite adjustment should make that worse......not better........and certainly not perfect. But if the grip is centered down the slot between your thumb and index finger and across the meat of your thumb, things should be very consistent. And if the grip is inconsistent, then BH's are going to be flying all over the place. I've never experienced that.........even at 100 yards.

That whole arrow tip changing course brings all kinds of things into the equation.....including dynamic spine, grip, rest type, draw length, brace height, arrow length.........all could have an effect on the timing and the distance of that arrow kick. And what could possibly change that kick in the other direction?????? If it's possible that the point and nock end flip directions at or during the shot, then it could be equally possible that something could either negate that flip, or influence it the other direction.??????

 

[Wrench]

Do yourself a favor and set up some paper and shoot 20-30 arrows through it. Don't aim for anything, just try to use your best form possible for every shot.

*IF* you end up with 95-100% of the arrows showing the same tears, begin tuning. If *NOT* you have form issues and need to stop driving yourself nuts and get to the bottom of this.

This all assuming that you have your bow in reasonable tune and the correct draw length.

Start right at the start and it'll come together.

 

[Brendan]

Ya, except there are all kinds of rests out there. Can't imagine a lizard tongue rest impacting any fulcrum effects on the arrow. And most drop aways are dropping so fast into the release that I doubt they have that much effect.........and yet I have absolutely had to adjust the opposite way to get BH tuned with some bow/rest combos. And even if a funky grip was involved in that, if the initial indication was a left tear, then the opposite adjustment should make that worse......not better........and certainly not perfect. But if the grip is centered down the slot between your thumb and index finger and across the meat of your thumb, things should be very consistent. And if the grip is inconsistent, then BH's are going to be flying all over the place. I've never experienced that.........even at 100 yards.

That whole arrow tip changing course brings all kinds of things into the equation.....including dynamic spine, grip, rest type, draw length, brace height, arrow length.........all could have an effect on the timing and the distance of that arrow kick. And what could possibly change that kick in the other direction?????? If it's possible that the point and nock end flip directions at or during the shot, then it could be equally possible that something could either negate that flip, or influence it the other direction.??????

I think that any rest will impact an arrow, as long as it is in contact with the arrow during the powerstroke. How much it will impact it is a different story, so I think you're right - a whole lot of factors impact what's happening. Tip weight, arrow diameter, dynamic spine, rest timing, rest blade/launcher spring pressure, grip, facial pressure, torque tune, lateral nock travel, vertical nock travel, etc, etc. And, you're a lefty, with a long draw length, long arrows if I remember? So - lateral nock travel for you is probably reverse that of a righty, so the back of the arrow is moving in the opposite direction during the powerstroke.

Some of Gillingham's videos are pretty good. Go watch the left tear one. He starts talking about rest adjustments not working very well in certain scenarios and needing to rely on other methods (Cam shimming, Cable Guard, Yokes) and if you read between the lines in his videos, and the Dudley one I linked, I think they're alluding to stuff like this.

 

[5MilesBack]

Do yourself a favor and set up some paper and shoot 20-30 arrows through it. Don't aim for anything, just try to use your best form possible for every shot.

*IF* you end up with 95-100% of the arrows showing the same tears, begin tuning. If *NOT* you have form issues and need to stop driving yourself nuts and get to the bottom of this.

This all assuming that you have your bow in reasonable tune and the correct draw length.

Start right at the start and it'll come together.

I've never had any problems tuning........except after a bow blew up after a yoke loop broke, and the limb pocket was twisted. That was an exercise in frustration and untunable.

I shoot fixed BH's year round out to at least 90 without any issues.

 

[5MilesBack]

Some of Gillingham's videos are pretty good. Go watch the left tear one. He starts talking about rest adjustments not working very well in certain scenarios and needing to rely on other methods (Cam shimming, Cable Guard, Yokes) and if you read between the lines in his videos, and the Dudley one I linked, I think they're alluding to stuff like this.

I've watched his videos, and I totally agree that with some bows, rest adjustments will only get you so far. That's the beauty of a yoke bow.......easy to adjust and tune........along with adjusting your cable guard as well if it has that feature.

But here are a couple other thoughts..........IF the front of the arrow always wants to get inline with the powerstroke, and that's what is causing the point and the nock to basically switch directions from static position.......at what point in that powerstroke has that kick taken place? The millisecond that it takes place, now the tip is already on the other side of the powerstroke, and the point should then be trying to get behind the powerstroke the other way. These reactions should happen the entire time the arrow is attached to the string and being propelled by the powerstroke. So........is that different for a bow with a 26" draw versus a 32" draw........6 more or less inches of powerstroke to impart those reactions????? Or does it happen slow enough that only one reaction can take place during the powerstroke?

And........if the powerstroke can impact the weighted tip of the arrow enough to make it want to get in front of the powerstroke, then can the weighted tip impact the direction of the string travel to any degree?

And finally.........as the powerstroke pushes the arrow, it has no idea what's on either end of the arrow at that point (i.e. FP, BH, fletching, no fletching).......it's just pushing. So I would assume that all arrows are reacting the same way until they are released from the string. Then at that point, the only directional changes will be from the fletching........unless of course the BH arrow has insufficient fletching to stabilize the arrow. So I would also then assume that the fletched FP arrow would come out with a right tear just like a BH or bare shaft arrow would, but then as soon as the fletching catches so to speak, that's going to kick that arrow's fletched end left, straightening out that arrow that would then impact right of the BS or BH arrow.

That high speed video would really come in handy.

 

[Wrench]

You have to think in terms of center of gravity for your point. If you have a 100 gr weighted insert with a 100 grain field point, will it spine the same as a long 200 gr point with a light insert?

As you move the center of mass it will make a difference. Is it enough to matter in your rig? Maybe....maybe not.

Paradox, rest/fletch influence, string travel, form....they're all a variable to be sorted out.

 

[5MilesBack]

You have to think in terms of center of gravity for your point. If you have a 100 gr weighted insert with a 100 grain field point, will it spine the same as a long 200 gr point with a light insert?

As you move the center of mass it will make a difference. Is it enough to matter in your rig? Maybe....maybe not.

Paradox, rest/fletch influence, string travel, form....they're all a variable to be sorted out.

Ya, I already mentioned those earlier. Getting the final tuning sorted out isn't the problem....or even the question. Getting BH's and FP's together isn't all that difficult. It's the path taken and the "why's" of this apparent "kicking" that started all this.

 

[madkaw284]

Ya, I already mentioned those earlier. Getting the final tuning sorted out isn't the problem....or even the question. Getting BH's and FP's together isn't all that difficult. It's the path taken and the "why's" of this apparent "kicking" that started all this.

Read through post 52, there’s a rough analogy in there that might help make more sense of this.
Take a 10’ piece of 1” pvc (shaft), hold it by one end and try pushing a 10lb bowling ball (point weight) around with the other end, especially applying a fast sudden force, both ends will stay in line with each other while the middle buckles outward. This is what your arrows are doing.


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[Boxerboxer]

Read through post 52, there’s a rough analogy in there that might help make more sense of this.
Take a 10’ piece of 1” pvc (shaft), hold it by one end and try pushing a 10lb bowling ball (point weight) around with the other end, especially applying a fast sudden force, both ends will stay in line with each other while the middle buckles outward. This is what your arrows are doing.


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I don't follow how that explains anything other than oscillation of the arrow in flight. What's that got to do with poi, especially since that oscillation is all but dead by the time the arrow hits the target?

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[Beendare]

Some good info here.

In my style of paper tuning FP's first....then BH tuning; I find that I sometimes have MOVED MY REST EITHER WAY to get it to work. I suppose the reason why on this ....is due to the flaws in Paper tuning itself.

It appears that the times I have to move my rest in the wrong direction...its because I overshot on the paper tune!

The good news is its never more than a 1/6"....if I start moving it a lot then I know I'm doing something wrong.



I think we all know by now, Paper tune is really just getting it close. There is a fairly wide trough of what works....not so with bare shafting or BH tuning.

..

 

[madkaw284]

I don't follow how that explains anything other than oscillation of the arrow in flight. What's that got to do with poi, especially since that oscillation is all but dead by the time the arrow hits the target?

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That oscillation is what is causing the initial reaction. It’s what’s happening to the arrow after it leaves the bow that affects POI. Again, perfectly tuned bow, bareshafts hitting with fletched, now you bump the rest to the right (right hand shooter) and it’s now out of tune.
This is going to cause a nock right condition, meaning;
•Bareshafts hit left of fletched
•Broadheads hit left of fletched
•Right paper tear

So with this situation, when you release the arrow the force of the bow string is applied to your nock (pvc bowling ball analogy), point wants to stay in line with the string. So when your fletched shaft leaves the bow the rear is being guided to the right by the offset rest and is going to kick out to the right when it leaves the string. The fletchings are then going to takeover and pull the front of the shaft in line with the rear.
Fire a bareshaft from that same bow and it will do the same thing, except when it leaves the string there are no fletchings to correct the rear so it will fly tail right all the way down range, the point will guide it’s POI.
Fire a broadhead from that same bow and it will hit left of your fletched, broadheads are basically fletchings for the front of your shaft. When released from the string you’ll get that same nock right and the fletchings will attempt to take control but the broadhead doesn’t want to cooperate as easily as a field point so its leaving the bow nock right and the broadhead wants to plane off to the left of your fletched.



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