The string is not always in the center of the bow limbs. Devices to set the center shot do not always work because they assume that everything is square, but many times they are not. The bow string should travel in a line that is parallel to the sight window on any well designed bow. Therefore your arrow on the rest should be parallel to the sight window. Put your arrow on the rest and look down on it. Move the rest until the arrow is parallel with the sight window. You can use a block to draw a line on the shelf that is parallel with the sight window and then line your arrow up with the line. Then get back and look at your bow with the arrow on the rest. Line the string up with the center of the arrow and the string should be close to the cam grooves. This is a good starting point. However, your bow might not shoot the best there because of the spine of the particular arrow you are shooting as well as your form.

There are several theories on setting the nocking point. Some say the arrow should be level and some say the nock should be slightly high. The particular rest, arrow, and bow, you are shooting will determine the best place to set the nocking point. Generally you will get better clearance of the rest if the nocking point is slightly high. That causes the arrow to rise up off the rest when you shoot rather than slam down into the rest. Most people today shoot some type of prong type rest. It is hard to tell where your nocking point should be because most bow squares are a different size than the arrow so it will set different in the rest and be either higher or lower than your arrow. A good starting point is to look at the arrow on the rest. The nock should be slightly high so the arrow angles down. The angle will look greater on short brace height bows because the string is so close to the rest. Then use your square to record where your nocking point is located on the string. That will be your starting point.

The biggest problem is the arrow or fletch strikes the rest. The easiest test is the powder test. Spray the fletch area of your arrow with some cheap foot powder. Shoot your bow using your best form. Now look at the fletch of your arrow and you should see if the arrow contacted the rest. There should be only a slight drag mark in the powder between the fletch where the arrow past through the rest. Move the rest left or right until the fletch passes between the prongs without touching them. Move your nocking point up or down if there is a heavy drag mark. Now mark your rest with a pencil and record the nock location on your square.

Sight your bow in reasonably well. Make a cross on your target. Get back as far as you can shoot a decent group. Shoot a 5 arrow group using your best form. Don't change your sights if you are not hitting on the center of the cross. Only shoot for a group. Record the horizontal size of your group. Now move your rest a small amount and shoot again. Keep doing this while recording everything and you will find a place where your groups are the tightest for left and right. Now do the same thing for up and down with your nocking point. Your bow will now be tuned to shoot the best groups regardless of how it tears paper. Record or mark the location of your nocking point and arrow rest. Then sight in your bow.

An out of tune bow will shoot good groups from a shooting machine. A perfectly tuned bow will shoot bad groups from a person with bad form. Spend your time with quality practice rather than playing with your equipment. All a perfectly tuned bow will do is help that bad arrow from missing as much. You will not have that bad arrow if you practice your form. You are only making excuses for yourself if you keep changing your bow because you don't shoot well.