# What is the physics behind left and right bare shaft tuning?



## jim p (Oct 29, 2003)

Lets beat some more hair off a dead horse and see if we can understand what is happening with the bare shaft and the fletched shaft. I realize that this is probably not going to go any where because some will have the opposite experience with how to correct for the left and right hits of bare shafts and fletched shafts.

My experience is that the fletched arrow needs to be moved toward the bare shaft. What is your experience?

Lets just start here and see how it goes. Now if anyone wants to give the complete explanation of what is happening I am all ears.


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## nuts&bolts (Mar 25, 2005)

jim p said:


> Lets beat some more hair off a dead horse and see if we can understand what is happening with the bare shaft and the fletched shaft. I realize that this is probably not going to go any where because some will have the opposite experience with how to correct for the left and right hits of bare shafts and fletched shafts.
> 
> My experience is that the fletched arrow needs to be moved toward the bare shaft. What is your experience?
> 
> Lets just start here and see how it goes. Now if anyone wants to give the complete explanation of what is happening I am all ears.


Correct. The FLETCHED arrow has STEERING correction. The BARESHAFT has ZERO steering correction, so the BARESHAFT shows you WHAT direction the bowstring is pushing the UNGUIDED missile, the BARESHAFT. So, WHY does a shooter PULL a bowstring sideways? WHAT? HUH? THIS is what is happening, when a bareshaft flys to the RIGHT, but your stab is pointed dead at the x-ring. WHAT do ya mean, pull a bowstring SIDEWAYS? WHY would a RIGHT handed shooter pull a bowstring SIDEWAYS?



So, look at this picture, and can you see that this shooter has the draw length STUPID too long? The right elbow is SEVERELY ELBOW left. So, when THIS shooter fires a fixed blade broadhead, even with the stabilizer pointed DUE NORTH...the FIXED blade broadhead is going to miss SEVERELY to the RIGHT of the fletched arrows. So, THIS shooter is pulling the bowstring SIDEWAYS LEFT...rather obviously. So, THIS shooter, the PHYSICS of THIS shooter is that BARESHAFTs will also fly SEVERELY to the RIGHT of fletched arrows....arrows with STEERING correction, namely vanes, the VANES will TRY to course correct the arrow and PUSH the arrow point CLOSER to the vitals of the 3D deer, of the bullseye for the paper target. Sooo MOST folks will say the BARESHAFT missed to the RIGHT of the fletched arrow group. 

I say, the FLETCHED Arrows are grouping to the LEFT of the TRUE arrow flight, the FLETCHED arrows are missing to the LEFT of the BOWSTRING PUSH direction, the FLETCHED arrows are missing LEFT of the bareshaft point of impact. WHY are my BARESHAFTS NOCK LEFT in the target? Well, cuz the shooter is SEVERELY ELBOW LEFT in the overhead photo. SOOOO, WHICH direction do I push the arrow rest to FIX my BARESHAFT nock LEFT?

WELL, for THIS shooter...



Cuz the draw length is about 3-INCHES too long



THIS shooter tried moving the arrow rest MAX LEFT, and got the SAME results.....FIXED blade broadheads are missing 24-inches to the RIGHT of the field points at 20 yards. THIS shooter tried moving the arrow rest MAX RIGHT, and got the SAME Results....bareshafts are missing 30-inches to the RIGHT of the field points. BARESHAFT and fixed blade broadheads miss in the SAME direction, for rather OBVIOUS reasons. BUT BUT BUT, the shooter moved the arrow rest MAX left and MAX to the right. So, what is the CORRECT FIX for THIS shooter?



See the RED dashed line? The physics are that the BOWSTRING is swinging to the RIGHT, cuz the shooter is SEVERELY pulling the bowstring HARD LEFT. So, if you put a Hamskea OVER-DRAW on his arrow rest...and then jig a fixture that will allow THIS shooter to move the arrow rest about 6-INCHES to the RIGHT,
cuz that is where the bowstring is pushing the BARESHAFT...then, mAYBE THIS shooter who is OVER-DRAW nearly 3-inches too LONG, cuz he KNOWS his draw length is CORRECT, cuz it FEELS GOOD....the FLETCHED arrows will be STEERED MORE to the RIGHT, and the FLETCHED arrows will hit with the BARESHAFTS.

THE ARROW REST is just a ski jump ramp, for the FLETCHED arrows. YOUR job for arrow rest centershot is to BLOCK the bowstring flight path. IF you pull the bowstring SIDEWAYS HARD RIGHT, the bARESHAFTS point of impact tell you WHAT direction to move the arrow rest. IF you move the arrow rest SIDEWAYS ENOUGH, to put the FLETCHED arrow LINE OF SIGHT, to MATCH the bowstring flight path direction (compass direction of where the bowstring is flying)...then, the vanes will have LESS and LESS steering correction work to do. WHEN you put the arrow rest in the CORRECT sideways position, when you move the arrow rest SIDEWAYS ENOUGH...then, the VANES have ZERO steering correction work to do, and you get THIS result.



That's schuler26.

BUT BUT BUT, no arrow rest in the WORLD can move the arrow rest 6-INCHES to the RIGHT. Yup. OBVIOUSLY. So, if your arrow rest cannot MOVE 6-inches to the RIGHT...maybe, just MAYBE...this fella should DROP the draw length a bit SHORTER, eh?

MAYBE from 3-inches TOO LONG on the DRAW LENGTH, to only say 1-inch TOO LONG on the draw length?



So, this is what 1-inch or maybe 1/2-inch TOO LONG on draw length looks like.



See the pattern here? ELBOW LEFT. Again. Different shooter. Right forearm is NOT in line behind the arrow. So, same physics. RIGHT elbow is pulling the bowstring SIDEWAYS LEFT just a LITTLE. So, you can GUESS what direction the bareshaft is going to FLY. PULL the bowstring SIDEWAYS LEFT. Nock of the bareshaft is pulled SIDEWAYS LEFT. Bareshaft skids through the air SIDEWAYS LEFT. WHAT do we get? POINTY end of the bareshaft flys SIDEWAYS RIGHT,
and hits to the RIGHT of fletched arrows. BUT BUT BUT, Easton Tuning Guide says a BARESHAFT missing SIDEWAYS RIGHT is a WEAK arrow SPLINE? No, only for a FINGERS compound shooter, ONLY for a FINGERS recurve shooter. FIX the form, FIX the draw length, for an INLINE release forearm.


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## nuts&bolts (Mar 25, 2005)

Bow hand grip position also has an effect on BARESHAFT point of impact.



Bow hand position, and WHERE you point your bow hand thumb, has a HUGE impact on bareshaft point of impact.



MASKING Tape has a vertical line for a reference line. GRIP your bow normally and mark the back of your hand. FOR STARTERS. NOW, make a plumb bob, with some dental floss and put a weight on the end.



Duct tape shooting line, just 2 yards. TRY with a fletched arrow first. YOur job is to SPLIT the dental floss. Should take you no more than 5 minutes. NO adjustments to the arrow rest, no adjustments to the bow. ONLY work the bow hand thumb pointing direction.



EXCELLENT. NOW, graduate to BARESHAFT grip training school.



See. YOUR USUAL bow hand thumb pointing direction is CLOSE, but NOT good enough.



So, what now? Well, you MOVE your bow hand thumb and point in a new direction, say 1/128th of an inch sideways LEFT or RIGHT. MOVE the mark on the back of your hand offset to one side of the masking tape reference line.



MOVE The mark on your hand ONE pen line width left, MOVE the mark on your hand ONE pen line width RIGHT...or a half pen line width. YOU get the idea.



EXCELLENT. FIRST time. I had Adam929 do this exercise and it took him just 5 minutes for the FIRST time. ONE time is just beginners LUCK. I told him gotta do it TWICE. TOOK him an HOUR to do the 2nd time. AFTER 2 weeks of practice, Adam929 could split the dental floss TWICE inside of 15 minutes. NOW, that's progress. Bow hand grip technique. YOU try.

WHY spend so much time TRAINING how you position your BOW hand? CUZ, your FLETCHED groups will tighten up, once you learn bow hand GRIP technique.


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## Fury90flier (Jun 27, 2012)

Alan, I wish you'd stop posting all this confusing/misleading information here on AT...lol. Sorry, couldn't resist.

There is also the issue of dynamic spine of the shaft...though it doesn't apply as much to compounds as it does recurves. Bet Alan can give a great synopsis of the need for proper spine so L/R Bare shaft misses don't occur.


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## jim p (Oct 29, 2003)

It is looking like the correct draw length is critical to getting a good left and right tune.

The last bare shaft tune that I did came together when I shortened the draw length.


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## jim p (Oct 29, 2003)

So the bare shaft gets no correction and the bare shaft goes in the direction that the draw forearm is pointing.

So for bare shaft tuning would it be good to set the center shot of the rest per manufacturers specs and then adjust the draw length until the left and right come together? Maybe the rest and yoke should only be adjusted to do the final tiny alignments and should never be used to make major corrections to arrow flight. Tiny adjustments to the rest might be reserved for walk back tuning.


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## nuts&bolts (Mar 25, 2005)

jim p said:


> So the bare shaft gets no correction and the bare shaft goes in the direction that the draw forearm is pointing.
> 
> So for bare shaft tuning would it be good to set the center shot of the rest per manufacturers specs and then adjust the draw length until the left and right come together? Maybe the rest and yoke should only be adjusted to do the final tiny alignments and should never be used to make major corrections to arrow flight. Tiny adjustments to the rest might be reserved for walk back tuning.


Yup, agree 100%. Set the arrow rest to a "reasonable" centershot position. I tell folks set the arrow rest sideways position for DEAD straight ahead, and skip the laser. Riser is not twisted. We can all agree on that. So, pinch a second arrow against the riser, and move the arrow rest sideways, until both arrows look pointed in the same direction.





Now, set your sight pin windage UP CLOSE, like 2 yards. SPLIT a dental floss plumb bob, with NO moving the arrow rest. THIS is just for STARTERS.





SHOOTING and trying to SPLIT a length of dental floss UP CLOSE, like 2 yards, will dial in your sight pin windage down to SUPER DUPER TINY amounts. THERE is no excuse to MISS a length of dental floss, from only 2 yards away. SPLIT the dental floss, by moving your sight pins a little left or right.

NOW, go LONG, 20 yards or 40 yards...whatever floats your boat. THE LONGER, the BETTER. WORK the draw length. NOT arrow spine. NOT arrow spline. Not point weight. WORK the cables to grow or shrink draw length, to get TIGHT groups, and to get your BARESHAFT hitting inside the FLETCHED arrow group. IF you change draw length, either by 1/2-inch DL module sizes, or by only 1/4-inch shorter/longer...KEEP the same form, the SAME bow arm elbow bend. WHY? CUZ the goal is to move your anchor point. TO move the nock MORE FORwARDS on your face, or to move the nock more BACKWARDS on your head. NEW anchor point, nock landing more FORWARDS or REARWARDS on your face, changes the DRAW forearm compass pointing direction.



Draw elbow is too far LEFT...ELBOW LEFT means bareshafts will hit NOCK LEFT, means bareshafts will miss RIGHT of fletched arrows, means fletched arrow groups will be LARGER than your TRUE accuracy potential.



Draw length and ANCHOR are JUST right. Draw forearm is pointing in the SAME direction as the arrow. When you do this, you get TIGHTER fletched arrow groups and you have a BETTER chance that bareshafts will hit inside the fletched arrow group.


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## primal-archery (Jun 25, 2011)

Good info


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## Etheis (Sep 28, 2013)

There are also plenty of other reasons why a bareshaft wil not hit with fletched. 
Incorrect center shot. Arrow rest could be too far inside the power path of the string or it could be too far outside the power path of the string. If a bareshaft is hitting to the right of the fletched arrow for a right handed shooter. It means your center shot could be too far out to the left. Common knowledge would think that a shaft with no steering correction would hit left of center shot is to the left. For a compound bow with release you would actually move the rest right to fix this issue nock left or impact right of fletched or left tear through paper. 

For a compound bow that has a bareshaft left of fletched group nock right, for a right handed shooter. Would mean the rest is too far inside the power path of the string. So to fix this we could move the rest to the left farther out away from the riser to correct this issue. Nock right impact left of fletched or tail right tear through paper.


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## Etheis (Sep 28, 2013)

Then we have the tool of the yokes on some bows. Some systems have two yokes on top limbs and bottom limbs. Some only have yoke legs on top limbs. Assuming everything else is correct center shot/form/DL we can utilize these yokes to make horizontal grouping even better, we can even use these yoke legs to make small fine vertical adjustment bareshaft grouping even better also but will save vertical for a different thread.

So for a right miss tail left with bareshaft impacting to the right of fletched means you have too much can lean like this / too much load on right limb, too much twist in right yoke so what we can do to make fletched and bareshaft come together for a tail left impact right we can put twists IN the left yoke and take twists OUT of the right yoke leg to make our bareshaft and fletched come together, to fix this tail left impact right of fletched with bareshaft or same as tail left through paper.

So for a left impact tail right of bareshaft, bareshaft missing left of fletched our cam lean is too much of this \ too much tension on the left limb tip. Too many twists in the left yoke leg not enough in the right. So to fix this tail right impact left of fletched with bareshaft we would begin to put twists IN the right and take twists OUT of the left yoke leg until our horizontal grouping with fletched and bareshaft come together, to fix this tail right impact left of fletched or tail right tear through paper.

Be careful when putting twist in yoke legs because they can mess with vertical grouping through changing cam sync.


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## nuts&bolts (Mar 25, 2005)

YOKE tuning that has gone WAY WAY TOO FAR, to fix a LEFT paper tear (right handed shooter). He tried BARESHAFTS and BARESHAFTS were missing right of fletched.





So, if you are tuning at ONLY 10 yards or ONLY 20 yards and your bareshafts are missing 8-INCHES RIGHT of fletched arrows....DO NOT YOKE tune. FIX your form, FIX the draw length (it's too long) with NO yoke tuning. Dial in the draw length SHORTER say 1/4-inch shorter, OUT OF SPEC for 20 yard tuning. Then, save the YOKE tuning (a little goes a LOOOONG ways) for 60 yard tuning, where you YOKE tune a half twist or 1 twist.



LEFT yoke leg is twisted SOOOO tight, for 20 yards tuning, the cam is getting CLOSE to derailing at full draw. At full draw, the cam leans MORE LEFT, for a right handed bow, so the cam lean is going to be even MORE severe, at full draw.


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## Etheis (Sep 28, 2013)

Yep in general yoke tuning is just a cover up in form flaws and draw length flaws


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## TMan51 (Jan 25, 2004)

Etheis said:


> Yep in general yoke tuning is just a cover up in form flaws and draw length flaws


Not sure that is entirely the case.

When everything looks right, and there are still problems with lateral distribution or flyers, yoke tuning can compensate for small differences in limb deflection, or dynamic spine at a limit. I am pretty sure that's the case, because I've swapped limb positions and the problem goes in the other direction. Compounds have multiple available adjustments that can affect horizontal and lateral point of impact. When I play with the adjustment options, I sometimes see that one adjustment has more affect than the others. Not always, but often enough to make it a practice when a bow doesn't respond to plan. 

As the thread has so far avoided physics directly: http://www.tap46home.plus.com/mechanics/

It's a pretty fair read, and most of the references are available on line.


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## Etheis (Sep 28, 2013)

TMan51 said:


> Not sure that is entirely the case.
> 
> When everything looks right, and there are still problems with lateral distribution or flyers, yoke tuning can compensate for small differences in limb deflection, or dynamic spine at a limit. I am pretty sure that's the case, because I've swapped limb positions and the problem goes in the other direction. Compounds have multiple available adjustments that can affect horizontal and lateral point of impact. When I play with the adjustment options, I sometimes see that one adjustment has more affect than the others. Not always, but often enough to make it a practice when a bow doesn't respond to plan.
> 
> ...


Like I said GENERALLY and you can get away with much more dynamic spine variance than you think with a compound bow. I've proven this over and over again, you can have a very over spined arrow and tune to it just fine with perfect center shot and no need fo exvisseive lean or any extra yoke tuning. If your limbs are to are per manufacture spec there should be no reason why you should have to yoke tune for deficiency between limbs, now PSE bows have certain limb deflection numbers you have to stay with in per limb combination, now if you have the wrong limb combinations then yes you will have to yoke tune out extra for that if you will, but if you want it done correctly and alleviate the excessive lean or tune. I will stick to my statement and say generally or MOST of the time when people yoke tune they are covering up form flaws or other issues like I said originally. Like I said before there ALWAYS exceptions. 

There is also swapping shims to find the ideal tune.

There are also adjustable cable rods and flew guards out there to help achieve good results.


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## TMan51 (Jan 25, 2004)

Etheis said:


> you can have a very over spined arrow and tune to it just fine with perfect center shot and no need fo exvisseive lean or any extra yoke tuning.


Without adoubt.

My bear Kodiak came with a Berger mounting hole, and I could adjust for moderate amounts of spine variance by moving the position and/or adjusting tension.
My first Jennings 4 wheelers could be adjusted for both features, plus tiller and timing, and that changed very little through the T-Star, and Hoyt ProVantage series.
The Redline and concurrent generations of cams were much the same, but somewhere around that time, my flippers turned into prong type rests, losing button tension as an option.

Then I busted a couple fingers in a dirt bike accident and transitioned to a wrist strap release.

When hybrid cams became available, with a floating yoke, I was seeing some adjustments that were non-typical for centershot, and the extra speed required more attention to tuning to have good bare shaft flight at extended distances, more than 30ft, to 20yds or so. The best source for much of the new bow developments was AT/JAVI.

Through that entire 30 year period I never even considered yoke tuning, and I was able to get excellent results with bare shaft and BH tuning exercises. And with few exceptions, probably still could.

The exceptions come through with static yokes, and the reality that many bows arrive with excessive cam lean, from the factory. Some are so bad day one, that I'd be afraid to shoot them for fear of jumping the cam. Judging from the number of threads, my experience there is hardly unique. Starting with rigging that has at least the appearance of good alignment at rest, most bows will shoot to plan with no more attention to the yoke. When they don't, and center shot is obviously out of alignment with the plane of the sight and center of mass on the riser, yoke tuning can make a big difference.

Is it always necessary? No.
Is it a useful addition to the tuning mix? Almost certainly.


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## Etheis (Sep 28, 2013)

TMan51 said:


> Without adoubt.
> 
> My bear Kodiak came with a Berger mounting hole, and I could adjust for moderate amounts of spine variance by moving the position and/or adjusting tension.
> My first Jennings 4 wheelers could be adjusted for both features, plus tiller and timing, and that changed very little through the T-Star, and Hoyt ProVantage series.
> ...


You bet. A lot of bows come out of factory with some horrible lean, maybe we are discussing the same point just going at it from different angles, I'm talking about after we get the bow from factory we set bow to spec and no lean at full draw, tune for max poundage and DL. After all that is done them we tune for arrow flight, we are not so far away and are trying to prove the same point I believe


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## Glamsland (Apr 14, 2015)

Nuts & bolts ; you have said earlier that you should change the drawlenght a litle at the time to test the drawlenght with bareshafts. GROW the braceheight to lenghten the dl an SHORTEN the braceheighr to shorten the dl. This with the cables. But is it the same thing to shorten the braceheight with the limb-bolt? Increasing or decreasing the drawweight? This will shorten the brace and shorten the draw a tiny bit?
Runar


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## nuts&bolts (Mar 25, 2005)

Glamsland said:


> Nuts & bolts ; you have said earlier that you should change the drawlenght a litle at the time to test the drawlenght with bareshafts. GROW the braceheight to lenghten the dl an SHORTEN the braceheighr to shorten the dl. This with the cables. But is it the same thing to shorten the braceheight with the limb-bolt? Increasing or decreasing the drawweight? This will shorten the brace and shorten the draw a tiny bit?
> Runar


For a parallel limb tip bow, or a past parallel limb tip bow, limb bolt changes to draw weight will have no effect on draw length. If you have a LONG ATA bow, that is not parallel limb tip, then sure, give it a try...long ATA bow with more vertical limbs.


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## bowtechky (Jan 30, 2013)

Tagged


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## TMan51 (Jan 25, 2004)

Etheis said:


> maybe we are discussing the same point just going at it from different angles,


Probably 

My thought is that a tuner that understands the options is more likely to have the results they want. My next thought is that the transition to truly fast bows available today, a shooter needs to use most of the options to get things to fly. 30 years ago I had no problem getting bare shafts, fletched shafts, and fixed blade heads to land where I wanted them to, at 210-225fps. Shooting with fingers. I don't think my form has drifted that far out, but at 290fps-320fps, small degrees of "pilot error" need a well tuned system to land a shaft where you need it.


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## Etheis (Sep 28, 2013)

TMan51 said:


> Probably
> 
> My thought is that a tuner that understands the options is more likely to have the results they want. My next thought is that the transition to truly fast bows available today, a shooter needs to use most of the options to get things to fly. 30 years ago I had no problem getting bare shafts, fletched shafts, and fixed blade heads to land where I wanted them to, at 210-225fps. Shooting with fingers. I don't think my form has drifted that far out, but at 290fps-320fps, small degrees of "pilot error" need a well tuned system to land a shaft where you need it.


Yep, you can about make a bow do anything you want through the tuning tools that are available with some systems today, some more limited than others, a perfect tune in my book is when the shooter and bow work together through proper form, DL, and grip. Then a good balance on the bow there are certain boundaries I like to stay within for a properly tuned bow, if we have to go outside those boundaries then I look into breaking down a shooters form and fix his/her form flaws, some of my customers have been amazed at how badly you can throw off a bareshaft with just a simple grip change. Its all a balancing act


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## zernzm08 (Feb 1, 2009)

Tag


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