Setting your center shot
The following info was shared with me some time back and have proven to be an easy and effective way of setting your center shot (on any bow).
If at all possible, mount your bow in a vise and plumb it in both directions.
Nock an arrow and then place a straight edge against your riser. Another arrow held against the riser with a rubber band works great. Measure the distance between your straight edge and the center of the string. Now measure at the front of your riser from the straight edge to the center of your nocked arrow.
1) Adjust your REST as necessary to get the measurements exactly the same.
2) Adjust your SIGHT so that your pin/reticle is practically hidden behind the string. This is where it helps to have the bow in a vise. Sight "through" the string down the nocked arrow.
3) Remove any target you have on your bale and replace it with a large sheet of white paper.
4) Using either a level or a plumb boob, draw a vertical line on the paper. I like to use a large red marker and make the line about 1/2" wide.
5) Stand very close to your target bale (6 to 8 FEET) and shoot for the vertical line. Do NOT concern yourself with the vertical point of contact (POC) as long as you're hitting the paper.
6) Adjust your SIGHT in very small increments, following the arrow. If you are hitting left of the line, move your SIGHT to the left - if you are hitting right of the line, move your SIGHT to the right.
7) Shoot enough arrows at this distance to know you are consistent and until you can split the line.
8) Now move back to a longer distance. For hunting bows, 35-40 yards is probably enough - target setups 55-60 yards.
If you do not already have a mark or pin for these distances, gradually walk back with your only concern being that you can hit the paper on the bale.
9) At this longer distance shoot for the vertical line again. Do NOT concern yourself with any aspect of the POC except the left/right.
10) Adjust your REST in very small increments, opposite the arrow. If you are hitting left of the line, move your REST to the right - if you are hitting right of the line, move your REST to the left.
11) Shoot enough arrows at this distance to know you are consistent and until you can split the line.
12) Rinse and repeat steps 5-11 until you find the "sweet spot". This will probably only take a couple of repetitions.
Just remember, when setting your center shot, move your SIGHT at the close distance and your REST at the longer distances.
Hope this helps.
Last edited by pragmatic_lee; 10-06-2008 at 09:40 AM.
Yer right, this method does work well. However, if you have a funny shaped riser, like a Slayer, it can be hard to square the arrow to the riser.
Also, if you change the vertical alignment to have the nock point and rest in the apex of the string exactly, it may change centershot. I j=know it doesn't make sense as long as the centershot isn' changed, but I had to redo the centershot on my Pantera NOS X (bfishers) after changing the vertical.
Squaring off the riser is definitely an issue with some risers and is often not easy with any riser. Got to hand it to PSE and the arrow shelf on their risers. Everyone of their bows that I have seen have a line machined into the shelf. Makes for very easy "eyeballing" a starting point.
Originally Posted by flytier17
As far as other changes to your setup, I always like to go back and at least check my center shoot after making any changes. Center shot, while somewhat "static", can change depending on the archer's grip. Something as small as changing the size of the peep may result in enough grip difference that center shot should at least be checked.
Below is an article written by George Chapman and published in the US Archer. He explains this tuning process. worth the read
COMPOUND TECH 300
by George Chapman
This method of tuning makes more sense than any other method of tuning that I have seen or used in my 55 years of archery. This method is based on striking the arrow directly in the center from all directions. This method tunes the bow so that it releases all of its energy evenly to all sides of the arrow. This is called dynamic column loading. This way of supertuning works for one cam and two cam bows.
The first thing I do, is to set the bow's tiller even, then I check the wheels timing, and level and plumb the bow. If it is a two cam bow or two wheel bow, I level and plumb the bow with a level on the string. Because the string runs parallel to the centerline of the riser (see picture). With a one cam bow, you need to level and plumb off the shelf and sight window.
I locate the nocking point by placing a level on an arrow the size the person is going to shoot. I then set the arrow level and place the nocking point there (see picture).
Then I set the center shot of the bow. You can use several methods to set the center shot: by lining the string down the center of the bow, by measuring the sight window, or by lining the arrow up with the stabilizer. (Caution: not all stabilizer inserts run parallel with the centerline of the riser.) Another method is to use TruCenter gauge, but this only works if the bow's machining is all parallel with the center line of the riser. Don't be too picky about center shot because the archer has to shoot in the center shot. This is done by having the archer shoot a dot at 20 yards, setting his or her sight to hit the dot. When this is done, hang a plumb bob from one of his or her arrows in the dot, then back them up to 30 yards or more. Still 'using the 20 yard pin, shoot at the same dot (the arrows are going to hit low). If the arrow hits to the right of the string, you move the arrow rest to the left ... a very small amount. Until the archer is within one-half inch (l cm) of the string. If the arrow hits to the left of the string, move the arrow rest to the right until the arrow hits within one-half inch of the string. This is standard for an average archer. For professional archers the standard is one quarter inch (0.64 cm). What you are doing now is adjusting any torque out that the archer is putting in the bow.
Then I take the archer back to 20 yards and have them shoot a 1" horizontal line to measure the height of the group. If the group is more than 1 inches (3 cm) in height, I put an eighth of a turn in the bottom limb bolt and have them shoot at the line again. The group should be within the 1" standard group height. If not, put one more eighth of a turn in the bottom limb bolt. In over 70 super-tuned bows, I have only had to put a total of 1/4 turn 5 times! The bow is now tuned. Right and left groups within 1" and the group height within 1 1/4", these are the standards for the average archer. For the pro shooter, the group width is 1/2" and standard group height is 1".
I have a couple of closing comments. There are several different ways of tuning but the most misunderstood is paper tuning. People think if you get a "bullet hole," the bow is tuned. The bow is not tuned until it groups. I've seen bows with nocking points 1/2 inch off square that still shot a bullet hole through paper. When you shoot through paper, all that tells you is the arrow went through the paper straight or crooked. If you don't like what you see, back up and it will change.
And, bare shaft shooting is still the best tuning method for the fingers shooter.
This really, really, really worked for me...
I was knocking down 1" groups with my field pts all morning, after tuning a bow by "feel"... then when I put the broadheads on, they were about 4inches low and right, and standard knock adjustment and sight adjustment, didn't group them any better or more accurately on center, I was loosing groupings
I searched bow tuning, and found this, and started over from scratch...following the steps listed above... it worked perfectly... down to the fact that I only had to turn the lower limb bolt about 3/16 of a turn to put me on my horizontal line...
If your broadheads shoot much different than your field pts, try this, it worked for me, so much so that I will only shoot one broadhead at the target at a time...its worth the walk, when your dead center on a 1/2" by 1/2" t line at 20yds.
Marked for future reference.