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06-27-2006, 08:00 PM

#8

Len in Maryland

Join Date: Feb 2003

Location: Baltimore Maryland USA

Posts: 1,385

RE: paper tuning question

This is from the link provided above.

Quote:

Center Shot:

There is only one place for the rest to be set. That is on the true center shot. If you are expecting the arrow to come out of the bow dead straight, the only way this can happen is if the rest is dead inline with the travel of the string. On an accurately made bow with no limb twist either at rest or full draw this is a simple measurement to make. Simply put a bit of masking tape half way up the limbs. Measure from the side of the limb to the face of the cam and transfer this measurement to a line in the tape. Then with an arrow in the bow, stand back and line up the string with the line just to the right for a right handed archer. Because most bows particularly the latest fashion for split limbs do have some limb twist at full draw, this measured centershot is seldom the precise working center shot, but will be a good starting point.

Now let's dissect this paragraph.

First they say that there is only one place for the center shot and then they start with a few caveats but miss several more. Then they say,"On an accurately made bow with no limb twist either at rest or full draw this is a simple measurement to make.", but again fail to analyze the full complication of really identifying the location of the center shot.

They finally get to the real meat of the subject with the last statement "...this measured centershot is seldom the precise working center shot, but will be a good starting point."

While they mention limb twist, they fail to mention such things as misaligned axles, cam lean, cam bushing wear (which can amplify cam lean), static verses dynamic cam lean and limb twist. Then there is the issue of risers bending under full load. Consideration should also be given to the fact that some cam designs run the string in a line that is NOT parallel to the limbs or riser.

The best advise they gave was part of a sentence: "...stand back and line up the string...". Of course, you have to 'guess' as to where to line it up. Then, and only then, do you proceed to 'adjust' the centershot until you find that 'sweet spot'.

Of course, some of the others things that have to be considered when paper tuning are arrow straightness, arrow spine, nock alignment, type of rest and the characteristics of that rest which can dictate proper installation of that rest, proper form, proper release, proper draw length, etc., etc., etc.

It's not rocket science, but it can much more complicated than most give it credit; that is, if it's done properly.

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