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Third Axis

114K views 122 replies 112 participants last post by  Jake_h223 
#1 ·
Can someone please explain third axis tuning?
 
#3 · (Edited)
3rd axis adjustment on your sight

LiteSpeed1 said:
Can someone please explain third axis tuning?
LiteSpeed1:

2ND AXIS

2nd axis on your sight is basically making sure the bubble level
on your sight reads level when the bow is vertical.

This presumes that your string is vertical when the bow is also vertical.
You essentially figure a way to hold your bow vertical (use a bow vise),
and then check to see that your bubble level in the sight is also reading vertical.

If not, then adjust the bubble level with the 2nd axis adjustment,
to make the bubble level on your sight read level, when the bow and bowstring are vertical.

3RD AXIS

Ok, so now we understand what 2nd axis is on your sight.

So, what is 3rd axis?

Remember your sight ring is on a threaded rod?

Well, what if the entire sight ring was mounted on a door hinge?

Yup. What if the entire sight ring could swing like a door?
You could swing the door towards you or away from you.

Well, let's say we swing the door towards you 45 degrees.
The bubble level still reads level, i.e., the threaded rod is still horizontal.

You know what will happen on a steep uphill shot?
Even if you aim uphill, and your bow is not tilted left or right,
the bubble level will lie to you and force you to tilt your bow.

Try this with a 24-inch level. Hold the level in your hand so that it is still horizontal, but the angle between the level and your arm is 45 degrees, as if you swung a door towards you. Raise your arm towards the ceiling.
The bubble level will not stay in the middle.

Adjust the third axis on your sight is the same as adjust the door swing so that it is 90 degrees.

HOW TO ADJUST 3RD AXIS



3rd axis will affect uphill shots (NFAA field rounds) or downhill shots (from a treestand).

Imagine that your sight ring is a door. If you bump your sight ring into a tree, the sight ring may bend towards you like swinging a door closer to your face. Let's say the sight ring "door" opened towards you 45-degrees. The bubble still reads level when you hold the riser straight up and down.

Now, hang a weighted string from the ceiling.
Kneel down on your knees, load an arrow in a safe spot, come to full draw and anchor.
Line up the weighted string with the left edge of the riser and your limbs.

Take a look at the bubble.
The riser and limbs are vertical because you are lined up with the weighted string.
If the sight ring threaded rod is bent towards you or away from you,
the bubble will not read level even though you are not canting the bow.

Adjusting the 3rd axis of a bow restores the sight ring door swing
back to 90 degrees, perpendicular to the sight frame.
The best way to check is kneeling down on your knees,
aiming up at a weighted string hanging from the ceiling.

If your sight has 3rd axis adjustment, then adjust away.

If you sight does not have 3rd axis adjustment,
you will need to use shims to adjust the entire sight or just the sight ring.
 
#9 ·
LiteSpeed1:


Now, hang a weighted string from the ceiling.
Kneel down on your knees, load an arrow in a safe spot, come to full draw and anchor.
Line up the weighted string with the left edge of the riser and your limbs.

Take a look at the bubble.
The riser and limbs are vertical because you are lined up with the weighted string.
If the sight ring threaded rod is bent towards you or away from you,
the bubble will not read level even though you are not canting the bow.
when lining up the weighted string with the edge of the bow, are you aiming up, or just horizontally??

thanx!!
 
#4 ·
Thanks nuts&bolts.
 
#8 ·
another way is to get a level door frame, (target sight only method) place your sight bar level with the door frame, adjust 2nd axis there, point your scope at the ceiling and check it agian
 
#11 ·
Check out HTM for 3rd axis adjustment

WWW.HTMbowsights.com

I shot terrible at my first IBO this weekend at Bedford , IN
I was right on with all my yardage estimates but was shooting left on uphill and right on down hill shoot.
I never had shot at these steep of angles.

I heard that a company would check you 3rd axis alignment at the vendor building. I went and found this company called HTM.

They were selling a machine that every serious archery shop should have.
the HTM precision 3rd axis bow vise. They were able to adjust my bow on site and show me that I came to the IBO unprepared.

I might have to buy this for my home.
 
#12 ·
WWW.HTMbowsights.com

I shot terrible at my first IBO this weekend at Bedford , IN
I was right on with all my yardage estimates but was shooting left on uphill and right on down hill shoot.
I never had shot at these steep of angles.

I heard that a company would check you 3rd axis alignment at the vendor building. I went and found this company called HTM.

They were selling a machine that every serious archery shop should have.
the HTM precision 3rd axis bow vise. They were able to adjust my bow on site and show me that I came to the IBO unprepared.

I might have to buy this for my home.

That is one of the best third axis tools I have seen.....
 
#15 · (Edited)
It's there to compensate for vertical tilt like when you're angling down in a tree stand or angling up when shooting a long distance shot.

When the bow is dead vertical (checked usually in a bow vise with a second level) you tilt the bow forward or back and check to see if your sight level is still centered. If not, that's when you use the 3rd axis adjust.
 
#19 ·
This is pretty simple, this is for a right handed bow so the opposite is true for left.

If the bubble is to the right while aiming up hill the housing needs to be turned clockwise about the axis (away from the riser)

Just the opposite is true for a downhill shot if aiming down hill and the bubble is to the right you need to move the housing counterclockwise (towards the riser)

Hope this helps.

Aloha
 
#20 ·
3rd axis

For those who have read N & B but still dont understand let me describe it as I understand it.
First u need sto set your bow vertical, I do this by cutting a piece of aluminium angle or even a piece of wood drilling a hole in one end and bolting it to the stabaliser hole and then locking the other end of the angle or wood into a vice. (I use this system for tying nocks, setting peeps etc) using a small bubble level (say 6")set the bow vertical by putting the level on the sight window and rotating the bow until set.
Place the level vertical on the vertical bar of the sight and without moving teh bow set the bar vertical by undoing the 2 screws and rotating the bar. You have now set the 1st axis.
Look at the scope bubble, if that is displaced left or right then undo the locking screws and adjust the scope up or down until the bubble is level. You have now set the 2nd axis.
Now remove the bow from the vice and set the bow against a vertical surface say a door or wall with the bottom cam and stabaliser on the floor Use your 6" level to set the bow vertical on the string or sight window. The bow will be angled forward onto the stabaliser . Check where the scope bubble is , if it is left or right loosen teh 3rd axis screws and move the scope forward or back until bubble is in the middle. Now set your bow vertical i.e. the stabaliser straight up once again check bow is vertical. Check out he scope bubble, in this case if you did the previous adjustment correctly teh bubble should remain in the middle -if not adjust and recheck the previous setting.
You have now set the 3rd axis
To explain the third axis try a simple test. Hold the bow in front of you as if you were shooting it. Hold it with the bow hand alone lets adjust the bow so that he scope bubble is in teh middle. Now twist your wrist say toward the right, still keeping the bubble in teh middle. Now keeping your wrist twisted raise you arm upward. In this case (assume right handed) then bubble will move to the left. If you were shooting uphill and your scope was twisted toward you then thi what will happen and you would rotate you bow to get the bubble back in the middle which would be wrong and the arrow ould land to the left of the target??
 
#21 ·
Heres a real simply way to set both the 2nd and 3rd axis. Get youself a quality metal faced carpenters level, simply secure the level ("LEVEL") vertically in a vise. Take you're sight bracket and hold it against the side of the level, now adjust the 2nd axis so it is also level (the bubble in you're sight), this will be done by rotating the sight housing clockwise or counter clockwise. Now holding the sight mounting bracket against the level, piviot the front of the sight upward and downward, you will now adjust the 3rd axis, the sight housing will need to either need to be moved inward or outward to make sure the sight bubble stays level as you piviot the front of the sight up and down. Hope this simple version may be of some help. Good Luck!
 
#25 ·
I understand what was said. Yet I have a question...

What effect, if any, does this adjustment have on shooting horizontally ? Does one have to compensate for the 3rd axis adjustment in ANY way ??

Stay Safe,
Franz
 
#26 ·
"Effects of Canting"

First question (answer):
There is no effect on Horiz. shooting, as you have already corrected the sight adjustment for that particular angle (lets say 0° (horiz.)). This would hold true for any angle of shot, whether uphill or downhill. Shooting at the "exact" same angle for each shot will allow the arrows to "group" similarily, but the group will just be displaced. Don't forget gravities effect on those extreme up or down shots, as they would naturally be "High".

Second question (answer):
No!, If you are a target shooter and always shoot on level ground.
Yes!, If you are a BowHunter, where you may need to shoot at any angle, or any angle that may not be the same as that of which you sighted the bow in at.

Most people here are confusing "Cause" with "Effect".

The "Cause" = A mis-aligned 3rd axis. (the axis perpendicular to the riser face).
If the axis of the bubble level isn't perpendicular to the "Riser's" face, then the bubble level will have one of its endcaps pointing towards, or away from the shooter. This is not a problem shooting on level ground, because reguardless of the endcaps orientation on this horiz. plane, it is still level with the ground, and will read "true level" reguardless how you spin around. The problem is when you need to rotate the bow in a vertical manner to shoot up or down.

Lets say you are a Right-handed shooter, and the your sight bumped a tree, as mentioned earlier in this post. The impact has bent the sight back towards the shooter. The bubble level's left endcap is now closer to the shooter than the right endcap. Now, if you rotate the bow upward for a shot, you can visualize that the left endcap will be now be lower than the right endcap. The shooter see's the bubble displacement to the right, then cants the bow to the right (CW) to compensate. Thus the "Effect"

The "Effect" = Canting. (Canting (with regards to archery) = rotation about the axis of the shooting arm).

The effects of canting can be simulated on level ground.
To simulate this overall effect, and its magnitude on your shot displacement, take your bow and shoot a few arrows on level ground to establish a baseline group, keeping your bubble level reading horizontal. Next, cant your bow slightly, either right or left, like you see the Indian's doing on TV during a buffallo hunt on horseback (how is that for descriptive). Cant the bow until the bubble on your level just touches it farthest extreme. I use this example, because you will need to duplicate this canting angle for each shot if you expect to get the same size group. Don't be affraid to cant your bow 45° or more (like the Indian's), just figure out a way for you to reproduce that cant angle for each shot. Now take a few more shots. Notice that your "group" should have remained the same size, but your "Group" placement on the target has changed.

Typically, if you "cant" the top of the bow to the right (CW), the shot will displace to the right, and a left "cant" (CCW) will displace a shot to the left. In both cases the vertical shot displacement will typically be lower.

This is the same effect you have with canting a rifle, twisting it right (CW) or left (CCW) . The reason for the shot displacements have to do with the horiz. (windage) & vert. (drop) adjustments you have "dailed-in" on the sight.

Image you have "Zero" windage, and +12" of drop adjusted into your sight. Now exaggerate the effects of canting by rotating the bow/gun/sight a full 90° (CW). You now have 12" or more of right windage, and "Zero" for drop. Your shot would land approx 12" to the right and 12" low. You can see by this example, that the further the shot the worst the error, mainly due to the ever increasing trajectory corrections needed in the sight.

Sorry this was so long, but I hope this helps answer all those remaining question on this subject.
 
#27 ·
Bow-Captain - excellent definition and description. Well done!
 
#28 ·
i don't even look at my level when shooting to tell you the truth, i'm not a target shooter, just a bow hunter.but is this 3rd axis an attempt to get the sites at a 90 degree angle with the riser? b/c if so THAT i get...:set1_thinking:
 
#31 ·
Ok, do you have to have a third axis sight to accomplish this? Otherwise you are putting shims in, correct?
 
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