paper tuning problems

[sambow]

I am trying to paper tune my compound bow in the manner described in various articles and Larry Wise’s book.

The problem I have is that the only way I can get the bow to tune well ends up with a starting arrow position which is against all the text books. For example the rear of the arrow ends up 12 to 15 mm below the point and all articles I have read say the rear of the arrow should never be below the point. Also when I draw lines down the limbs to correctly align the string (ie making sure it remains approx 3/5th of the way across the limbs all the way down to allow for the offset cams) the point of the arrow ends up approx 10mm inboard of centre line whereas all text books say for compound it should be on centreline or a little bit outboard. But with this configuration which is against all the rulebooks I get nice 6 to 10mm vertical tears.

So I thought I would try to get things roughly “text book” right ala Larry Wises initial setup guidelines. I set the arrow visually to centreline and used a vernier against the longrod to make the arrow dead horizontal. The result is massive 50mm diagonal tears. The other thing I notice is with the arrow set on centreline, if I draw the string then look down the line of the arrow and compare it to the line of the longrod (various ones tried) the longrod is skewed off at a massive angle to the line of the arrow and is in no way parallel to the line of the arrow as I would expect it to be.

The whole thing is doing my head in.

Can anyone share their experiences. Does anyone else have a good paper tune which is text book wrong? Could it be the bow? Could it be me? I would welcome any thoughts.

[Bald Eagle]

Have a word with Ben at Merlin, he will sort you out. If your tiller is equal, the string in line with the rest/arrow, nocking point level, it should be ok. I think it was Ben that told me not to get "hung up" on paper testing a few years ago. When I set up Bowtech bows, I use the above method and it work fine.

[stever]

Originally Posted by sambow

The other thing I notice is with the arrow set on centreline, if I draw the string then look down the line of the arrow and compare it to the line of the longrod (various ones tried) the longrod is skewed off at a massive angle to the line of the arrow and is in no way parallel to the line of the arrow as I would expect it to be.

The whole thing is doing my head in.

Can anyone share their experiences. Does anyone else have a good paper tune which is text book wrong? Could it be the bow? Could it be me? I would welcome any thoughts.

Hi Sambo,
I have and so have many others, found great problems in finding a 'longrod' who's screw thread is correctly centered. They are a rare animal indeed. Personally I use a lazer to set the arrow to string relationship and found that this is the only way I ahve found to be sure. With my own set up, the laser was used to set up the arrow but the longrod was about 1 inch out to the left, using a spirit level I then found that the longrod was also 1 1/8 inch leaning down. IMHO dont trust the long rod or the screw hole in the long rod. Hope this helps.

[phil_r_58]

The tiller can cause the nock point problem. Also have you checked the timing on the cams/wheels ? I have seen this before. A lot of bows have little timing marks on the cams to help you check.

I have had two bows brought to me where

1) the draw length adjustment was in different slots, on a wheel that had 3 draw length slots.

2) a browning 6t6, where the inner modules that adjust the draw length were based on it rotating and being secured in screw holes, again, they where in different holes on each end of the bow.

If you draw the bow slowly, can you feel the cams coming over the peak independently ?

The advice to chat to Ben or Chris is good.

[ThePinkOne]

Forget the paper tune and do a walk-back if anything. (Remember with paper tuning, hand-torque can cause more left-right tears than anything else.) Also remember if nocking point is too low you can get a response like too high as it kicks up off the launcher.

WRT nocking point, what is your nock travel like?

Got to be honest all I've ever done is a basic walk-back, I put the rest of the effort into tuning me. Seems to work.

P.

[geoffretired]

Sambow, paper tuning may not be the best way to tune a bow for good groups but in this case it is telling you something, I feel. I would be concerned if my nocking point was below the level of the arrow rest.
At full draw are both cams on their stops? At a point just before full draw do the cams and cables show equal gaps?
Are you using a release aid and could that be interfering with the arrow on release?
At rest, your arrow will appear to point uphill when the bow is upright; at full draw how does the arrow appear? Can someone look at that for you?
With regard to the arrow being parallel with the longrod at rest then skewing through the draw;the arrow must be on the bow's true centre line to start with, or it will skew as you draw. Skewing by a large amount seems to say that it isn't close to centre from the start; or the bow is being gripped tightly and the string is being pulled back to one side.

[Quadratus]

Sambow

Originally Posted by ThePinkOne

Forget the paper tune and do a walk back...

YMMV but my experience is that paper tuning is not just a complete waste of time, but seriously misleading. As you have found, it can give ludicrous results like the one you described. Forget it.

[Watch_Man]

I agree with Stever in that you cannot trust a longrod hole. My wife's bow was setup that way and the first time she shot it you could see there was a problem from the amount of windage she had to use (and this was indoors). A check found the arrow perfectly aligned with the longrod, however when a laser was put on it we found that the longrod was off center by more than 1/4" from where it joined the bow to its tip.

[jimlee]

When you say that on full draw the arrow and longrod are skewed at a severe angle, do you mean that when the bow is at rest the arrow and longrod are roughly in line? If this is the case it indicates that you are tourqueing the bow quite badly. As others have said, don't use the longrod to set your nocking point, either use a bow-square or see if the arrow is running slightly nock high when compared to the arrow shelf of the bow.

Cheers, Jim.

[pantherman]

I agree with Jimlee on this. If your arrow if in line at rest and off at full draw you have a problem. Most likely your torqueing the bow. Could also be cam lean or twisted limb, but these are rare.
On the paper holes, if you are needing to drop your nocking point below square my guess would be wheels out of tune. The nocking point must be rising as you shoot. When paper tuning you must get the nocking point correct first, if you can't most likely the arrow is hitting the rest, so mostly giving nock high holes. Move back and see if the arrow hole changes. Talc the arrows see if your hitting the rest. Remember it is still very possible to have a bad loose with a release aid!!!!
(PS never found the long rod hole to be anything but straight on a Merlin, of course I may just be lucky).