knock high

[Jeff Kruse]

Can someone please tell me what is causing my knock high problem.
I have moved the knock up and down, and can't seem to fix the problem.
Thank you
Jeff

[Diamond Paul]

Jeff, what exactly is the problem?  What you said is pretty vague.  Is the arrow porpoising up and down every time?  Are you bare shafting or shooting fletched arrows?  What bow, what string, what draw length/poundage at your draw, what arrow/length/point weight, and what style (split, three under)?  How high and low have you gone with the nock, and was this done with a bow square to be sure of height?  Ok, a few thoughts.  If your arrow is way too weak or stiff for your setup, then arrow spine, not nock height, could be the issue.  If the arrow is right, then you could have some kind of fletching interference (fletching contact w/ arrow shelf); try turning your nocks to orient your fletching differently on 3 or 4 arrows and shoot each one to see.  I would set my nock 1/2 to 5/8" high when I did this to be sure the arrow is not hitting the shelf.  You could have a very stiff material for the shelf rest, causing your arrow to rebound off it; try something softer, like a rug rest or velcro.  Finally, if you shoot three under, you likely need a pretty high nock point, especially if the bow is tillered for split finger.  It might need to be as much as 7/8" high, or even more.  You might have a form issue, such as a really high elbow on your string arm, which puts excessive downward pressure on the arrow and can cause it to rebound off the shelf when you shoot.  Last suggestion:  especially if you shoot three under, you need to have a second nock set under the arrow nock (good idea even w/ split finger) to prevent the arrow from slipping down as the string "v's" at full draw.  This nock should not be placed flush against the arrow nock, but should be tied on (or clamped, I tie my nocks) to allow maybe a 1/16th" space between it and the arrow nock at rest, otherwise it will pinch the nock when you come to full draw.  That's a bunch of stuff, sorry, but I thought I'd cover everything I could think of.  Good luck, Paul.

[Jeff Kruse]

Paul,
Thanks for the info.
I am leaning towards the shelf material. The bow is a new bear take down supreme, 55 pound. I am shooting the grizzly sticks Alaskans.The tips are 2oo grain, that puts me around 650 grains total.
We started bare shafting, ended up cutting them down to 29.5 inches, which is perfect for total length. We got the left and right working just fine.
I moved the shaft up and down, did not seem to make much difference. The knock is about three eights high of being square, I figured with the tapered shaft, this would be a good place to start.
Any how with feathers on , and when I back up to around 20 yards, the shafts come out and porpous and then they stabilize, and hit the target pretty good.
I wish I could get the porpousing to quit. I shoot with split fingers.
Thanks
Jeff

[McDave]

You need to distinguish between real nock high and false nock high.  You need to start with a nock position that is high enough that there is no question that the nock high is real - say 1" above square, measured to the bottom of the nock (assuming you nock your arrow under the string nock).  As you start moving your nock down the string from that position, say 1/8" at a time, you should see the angle the bare shaft impacts the target begin to move toward the horizontal.  Shoot a number of shots at each position, so you get a good idea of the true angle the arrow is hitting the target, as the target material and form variations will cause differences in the impact angle.  If you don't notice that the angle of impact decreases when you start from a high nock position, then something else is going on.

But assuming the angle of the bare shaft does decrease as you move the nock down, it may decrease down to an angle of 20-30 degrees above horizontal, and then as you lower the nock point further, it will not decrease anymore, or may even increase, or may get erratic, where you get a different angle almost every shot.  This generally means that your bare shaft is bouncing off the shelf, or if you're getting eratic results, it's bouncing off the shelf some of the time.  If that is the case, you need to find the minimum point, just above where the shaft starts bouncing off the shelf, and set your nock point there.  The fletches will easily correct for a real nock high, but not so well for a false nock high.

If you're getting a false nock high, it could be because your drawing elbow is too high and you are pressing down on the nock with your forefinger at full draw.  Or it could be because you are not coming to full draw with good back tension.

[Kingstaken]

Jeff if you cant your bow alot, you could get a false reading making it look like the shaft is high or low when in fact the shaft is to weak or too stiff.
Shoot your bow straight up and down and tell us how the knock is then.

[Jeff Kruse]

Thanks for the info guys,I had to send the bow back to bear,had a little problem with the riser, they forgot to put inserts in for a quiver. And I found a crack in the finish on the top limb. So I packed it up and sent it back yesterday.

I have a question, I wonder if I should take the shelf material off, and cut it down some, On my last bow I had a shelf that was built up a little.If I remember I think I just had a piece of leather, with a smaller piece under it. Any suggestions ?
Jeff

[McDave]

I would try first to make the bow work with the shelf material supplied by Bear.  They are motivated to make the bow work as well as possible, and probably have tried the bow with various shelf materials/thicknesses already.

That said, every bow is unique, and it won't hurt the bow to try different shelf heights/materials.  I once had a Hoyt Gamemaster that had an extreme nock high when shot from the shelf, but could be tuned fine when shot from a rest.  When shot from the shelf at any normal nock position, the bare shafts would actually nosedive into the ground in front of the target.  I didn't want to shoot it from a rest, so I eventually sold it.  I suppose I could have built up the shelf until it was the same height as the rest, but that would have meant at least a 1/2" shelf pad, which I didn't want to do.