The physics of paper tuning

[TheCougar]

Can someone explain the physics and dynamics of paper tuning? I have a persistent nock left tear. I can’t get rid of it by moving the rest to the right. Been there, and I had to move to rest comically right. I can understand how moving the rest can be used to get a bullet hole. I’m trying to understand how the force and direction of the string affects the arrow. For example, if you were to have a string travel that was not parallel with the riser, how does that change the nock travel?

This is difficult to explain with words, but here’s my best shot. If you were to look vertically from the top of the riser to the bottom (looking straight down from the top of the bow), with the rest at center shot, the arrow would be pointing at the 12 o clock position. If you went to full draw and the string travel was perfectly from the 6 o’clock to 12 o’clock position, you would get a bullet hole. Or for that matter, any time the rest is perfectly aligned with the path of string travel, you would get a perfect bullet hole. If the string travel is not perfectly aligned, perhaps traveling from 6:30 to 00:30, but the rest was at the 12 o’clock position, what would be the corresponding result? I drew a janky picture below.

I’m trying to understand how shimming with top hats and changing my grip torque affects my paper tuning so I can make proper adjustments instead of just guessing. It helps if I conceptually understand what is happening with the dynamics of the shot.

I know the picture sucks… but the crayons made a great snack when I was done…

 

[wildwilderness]

Not sure on your exact question but I do know the cams need to be timed and no lean in them. With a Hoyt the tears can be fixed with yoke tuning.

 

[TheCougar]

Not sure on your exact question but I do know the cams need to be timed and no lean in them. With a Hoyt the tears can be fixed with yoke tuning.

Yeah, it’s difficult to articulate the concept I’m trying to understand. It’s a Mathews, so yoke tuning is done via top hat shims.

What effect do yoke tuning and shimming have on the string and arrow?

At full draw, how I hold my bow changes the riser angle relative to the string. Therefore, the string travel (and force) may not be in a perfect line parallel to the riser.

 

[ResearchinStuff]

Bowshop bible app has some good videos that show the arrow flexing as the string pushes it. And step by step tuning directions.

 

[Turkeygetpwnd38]

The rabbit hole goes deeper…. Some bows shoot better with slight tears, some need more cam lean, it’s all black magic!
I bareshaft at 10 then 20 and then broadhead tune. I used to paper tune, whenever I really got to chasing a tear, it was usually in the grip.

 

[HuntWyld]

You chase the tear with your cams using the top hats so tail left tear try shimming your top cam to the left a little by putting the thicker top hat on the right side and the thinner on the left. If you need more then move your bottom cam to the left as well with the same method. If the top hats you have installed already have your cams pushed to the left with the thicker top hats being on the right then you need to buy a top hat kit or the next size up so you can shim a little more to the left. I like to set center shot and tune with top hats to almost perfect then slightly adjust rest for a bullet hole.

 

[Billy Goat]

The cams need to be aligned so when the arrow is released, it goes straight. If they fight the string left or right it can push the shaft on release. Riser flex can come into play as well.


Think of it as when the string is racing to braceheight, it might not be going dead straight at it. It can get pulled a little to the left or right of dead center, and the arrow takes that reaction on as it leaves the bow.

 

[wapitibob]

Nothing more than lateral nock travel, in every bow with a cable guard since Tom Jennings put the first one on a 2 wheeler.
When you're done chasing your tail, throw the paper in the trash, bare shaft and group tune, and go shoot. You'll have a more forgiving and more accurate bow than one that shoots a bullet hole in paper.

 

[tdoublev]

I certainly give you exact advice as I don’t shoot a Matthew’s, but this gohunt article might be helpful (forgive me if it’s behind the paywall). https://www.gohunt.com/content/skills/bowhunting/what-does-it-really-mean-to--tune--your-bow-

In short, it says move the cams left to correct left tear

 

[TheCougar]

The rabbit hole goes deeper…. Some bows shoot better with slight tears, some need more cam lean, it’s all black magic!
I bareshaft at 10 then 20 and then broadhead tune. I used to paper tune, whenever I really got to chasing a tear, it was usually in the grip.

Yeah, I think it is in the grip. I am trying to understand how the riser torque may be affecting the paper tune. I may be chasing my tail. I typically walk back tune because I have never had much luck with paper. This is why!

 

[TheCougar]

Nothing more than lateral nock travel, in every bow with a cable guard since Tom Jennings put the first one on a 2 wheeler.
When you're done chasing your tail, throw the paper in the trash, bare shaft and group tune, and go shoot. You'll have a more forgiving and more accurate bow than one that shoots a bullet hole in paper.

This is probably what I’m going to do…

 

[TheCougar]

You chase the tear with your cams using the top hats so tail left tear try shimming your top cam to the left a little by putting the thicker top hat on the right side and the thinner on the left. If you need more then move your bottom cam to the left as well with the same method. If the top hats you have installed already have your cams pushed to the left with the thicker top hats being on the right then you need to buy a top hat kit or the next size up so you can shim a little more to the left. I like to set center shot and tune with top hats to almost perfect then slightly adjust rest for a bullet hole.

Yup, I know what to do, but I’m trying to understand the “why” behind it. I’m not clear why moving the cams to the left is supposed to fix a left tear.

 

[sneaky]

What bow are you shooting? Is it a V3X by chance? Paper tuning is more aggravation than it's worth. Solid advice has already been given.

Sent from my SM-G955U using Tapatalk

 

[olkuma]

Correct spine is an important factor as well.

 

[Mighty Mouse]

You are correct that you want the rest in line with the path traveled by the nocking point from full draw to brace. The manifestation of left/right misalignment between the rest and string path and the adjustments needed to correct it seemed counterintuitive to me until I watched a video in the Bow Shop Bible app that shows what's going on in slow motion. I attempted to explain what the video shows in the sketch below, but the video itself is worth a million words (and the price of the app).


The conditions shown in the sketch would produce a nock left paper tear, bareshaft right of fletched shaft, and broadhead right of field point, which would all be fixed by moving the rest to the right (or by moving the cams to the left via shimming or yoke tuning). The seemingly counterintuitive left/right tuning adjustments now make perfect sense to me after seeing what's actually happening in slow motion.

Dynamic bending of the arrow shaft also plays a role, which I didn't attempt to include in my illustration. Rest type is also a factor: the longer the arrow and rest are in contact, the more pronounced the effect of misalignment between the rest and string path.

 

[Miflatlander91]

I'll have to check out this bow shop Bible sounds kinda neat. I'm far from an expert but I also skip the paper for me it's more convenient to shoot bareshafts at a target if I can get bareshafts shooting at 40 I have very little work to do when I put a broadhead on and shoot it out past 60. Many ways to do it just sharing what I have found works the best for me

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[5MilesBack]

View attachment 540213

This explains it.........but.......it's still hard to see how the arrow tip can be pushed left (and nock end pushed right) and then suddenly completely changes to the opposite as soon as the arrow releases from the string. Especially when let's say a drop away rest is completely out of the picture very closely to the release of the arrow so there's no more directional impact from the rest at that point.

I've seen bows with capture type rests that have arrow contact until the arrow completely clears the rest needing opposite tuning adjustments to tune them. So that continuous rest contact and forced directionality until after the arrow completely clears the string and rest does make a difference on the arrow flight.....or perhaps how much the arrow goes to the opposite direction shown above.

 

[TheCougar]

What bow are you shooting? Is it a V3X by chance? Paper tuning is more aggravation than it's worth. Solid advice has already been given.

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Yes

 

[Wrench]

Super slow mo video is your friend. Paper tuning is essentially a time machine. It catches the arrow for one moment in time and space which you can extrapolate that data.

 

[sacklunch]

Nothing more than lateral nock travel, in every bow with a cable guard since Tom Jennings put the first one on a 2 wheeler.
When you're done chasing your tail, throw the paper in the trash, bare shaft and group tune, and go shoot. You'll have a more forgiving and more accurate bow than one that shoots a bullet hole in paper.

Do you have a favorite article on group tuning basics? I understand bare shaft tuning with nock position, at least I think I do. Interested in group tuning vs paper tuning again, but too many "experts" these days with a YouTube to ID the true experts.

So jot to hijack, a PM would be great