Thread: help please
06-15-2007, 08:33 AM #1
I have two martin courgar bows. one is a 2000 fury X. 56# at 27 dl. shoots like a dream. the other is a 2003 cougar with nitous X cams. 48#at 27dl. it is a nightmare. will not group good. timing on cams is perfect. BH is right. the only thing I can find wrong is the ata is out by about 1/8 inch. on the left side. when I adjust it to equal the right side the cables on the right have a LOT less tenison on them. this dont seem right. would appreciate any help. also have put on new string and cables.
06-15-2007, 10:08 AM #2
- Join Date
- Apr 2005
Even though the timing may look right you need to bare shaft tune the bow. This will help you grouping some. You need to establish your center shot first by eye ball or with instruments. I would then do a slight walk back with a couple of fletched arrows.
I am going to paste some instruction on bare shaft tuning.
Bare Shaft Tuning
This technique is used for release shooters. The primary requirements are a target butt that will hold an arrow the way it entered the target. I usually use a foam wall at my local club, but a block or some other such target will work too. The cable(s) and string need to be of the correct length and the bow should be within specifications. Dual cam bows should have the cables of equal length. This tuning process may not work for floating yoke cable bows.
The other requirement of this process is to using properly spine arrow shafts. A computer program should be used to determine the proper spine, arrow shaft length and point weight. These shafts can be float tuned prior to assembly to ease this process(see float tuning below). The arrow should be match for overall weight prior to fletching. The arrow should be properly aligned and squared on the bow. A Golden Key Futura, Tru-Center Gauge should be used to align the rest.
The purpose of bare shaft tuning is twofold. The first part is to adjust the bow for an ideal launch. This means trying to stick the arrow in the butt without the nock being kick up, down, left, right or some combination. All of this shooting HAS to be done with the target at shoulder height. The purpose of this is to reduce drag by relieving the correctional control of the fletching during the launch and flight. This also allows the use of smaller fletching to reduce flight drag and trajectory loss. The second part determines the high spots in the arrow spine and allows the grouping of the arrows to improve. Float tuning provides this same benefit, but is static. The type of tuning is dynamic and therefore is the final step. Basically, float tuning will get you close, but bare shafting is conclusive.
To start, shoot a couple of arrows at 10, 15 and 20 yards to get an approximate sighting adjustment. It is not necessary to pinwheel the target but to try to keep the arrows on the target. After you have sighted in at 20 yards, notice the way the arrows are hitting the target. If the nock is high-left we need to start making adjustments. Leave one arrow in the target as a reference.
Why the nock is high and left is because of sight timing or tuning problems which is causing the string to push the nock a little up and to the left. The arrow eventually stabilizes, but is now in this nock high left flight attitude. Without the benefit of the fletching to correct it, it will remain in this attitude. This attitude is causing a lot of drag because the arrow surface area is wind planing.
To correct this we will added a half twist to either the top or bottom cable(s). Shoot a couple of arrows at the target. Compare these arrows to the reference arrow, if the nock is lower then you are on the right track if the nock is higher you are on the wrong. If you are on the right track, added another half twist to the cable and shoot the arrow again until it becomes level. If you end up with an arrow is either a little high or a little low, keep the slightly high setting. It is better to go over the launcher than through it.
To correct the left-right flight we will added a half twist to the left side of the split cable(s). If you are using a shoot through then add a half twist to each of the left cables. Keep shooting and twisting until the arrow is gong straight into the butt.
The next part of this tuning is to group tune the shafts. This would be best done with a Hooter Shooter, because your results will vary with your skill level. Assembling the arrow by float tuning may to some degree make this tuning method unnecessary, but if a consistent flyer is found it can be correct to some degree based on the shooter’s expertise.
I would use several targets during this procedure. I prefer the NFAA single spot target. Start at 10 yards and shoot a couple of arrows. If they seem to be in a common group remove them and set them aside. Shoot a couple of more. If they impact in the same holes as the first two, set them aside also. If one is out, shot it again. If it consistently is impacting away from the others set it off by itself. Continue shooting the arrows until you have separated the ones which group together from the one which don’t.
Now, move the nock on one of the non-grouping arrows by turning the nock a quarter of a turn. If it come into the group then set it with the others, if it doesn’t turn it another quarter and continue shooting and turning the nock until it does. If it refuses then change the nock and try again.
Now, more to 15 yards repeat this shooting and rotating the nock until you have all the arrows grouping. At this distance you should move the nock only about an 1/8th of a rotation. Finally, move to 20 yards and repeat this process this time rotating the nock about a 1/16th of a rotation.
If you are a reasonable shot, this process is quite amazing. You will almost want to forget fletching arrows. But, fletched arrows do work better. Once you have established the nock position, mark the shaft with a permanent marker. Use this mark as a reference for you **** feather when fletching.
Float tuning is a process to determine the heaviest part of an arrow, which in turn is the stiffest part. This is done by construction of some plugs and floating the arrow shaft in a pan or bath tube to determine this high spot.
The easiest plug to construct by using a small wooden dowel. Chuck the dowel in an electric drill and rotate it on a flat sheet of sandpaper or file to produce a taper. Insert the finished plug into each end of the arrow shaft and then float the arrow shat in the tube. Spin it several times and determine the side which come up the most often by looking at the label. Mark the shaft at the nock end with a small dot and align the nock to it. Your results will vary from shaft to shaft some will have a definite high spot and others will have a best 3 out of 5.
06-15-2007, 10:13 AM #3
- Join Date
- Jul 2006
- Saylorsburg PA
good post Deezlin. If that doesn't work call Martin, they have some great customer service and I'm sure they'd be more then willing to help in any way possibleNo I'm not dead
06-15-2007, 10:49 AM #4
- Join Date
- Apr 2005
I would like to make this correction. I would start the bare shaft at about 10 yards and then try to make some adjustments before moving to 20 yards. If you have an arrow kicking hard out of the bow it will wind plane very far off of target. I have had some shafts with a hard left kick to wind plane as far as 3 feet off target to the right in 20 yards. You need a big target butt or you need to preceed very slowly making a shot or two progressively stepping back. When you get close to perfect make half twist adjustment only.
The real secret to bare shaft tuning is a very good uniform release. That is why it works so well in a Hooter Shooter. After 20 yards, I see no real reason for going any further, as it becomes real touchy and wind and other factors get involved.
I like to keep a couple of bare shafts around and shoot them for release practice. The slightly change of FOC between the bare shafts and fletched arrows really doesn't have any impact within 20 yards.