# What determines nock travel?



## Jabwa (Dec 10, 2004)

What causes vertical deviations in nock travel and what causeshortizontal deviations in nock travel.
My opinion at this time is that horizontal nock travel deviations are the result of cam lean, while vertical deviations are due to the cam or cams not taking up string at an even rate throughout the draw cycle.


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## alaz (Mar 8, 2009)

I would imagine hand torque could play a role, but if you are just talking about mechanical issues...I am curious as well.

Perhaps riser issues?
Limb twist?


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## fletched (May 10, 2006)

Up/down nock travel is dictated by the cam design. If you have a cam design that produces good nock travel then the cam timing/position can effect it.

Left right nock travel is dictated by the cable gaurd and limb twist. A cable gaurd pulls the limb tips in that direction which can cause unequal balance and limb twist. This changes the front/back angle of the cam. This causes the string to track at an angle.


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## Jabwa (Dec 10, 2004)

Interesting. That is my opinion also.
Now, if left right travel is determined by the sideways pull of the cable guard, left/right nock travel should be greater on a shorter ATA bow because of the more severe angle which will twist the limbs more at full draw when cable force is at its peak. If this is true, it would seem that the independent adjustment of the split limbs on the PSE X-bows would go a long way toward correcting this.
As far as up/down nock travel, it would seem that the manufacturers could design a cam that would produce straight nock travel, however a cam would be specific to a certain ATA because of the different proportions of string above and below the nock on different ATA bows.
WHEW! I've done a lot of thinking here (maybe too much) and want to see what others think of these ideas.
CONSTRUCTIVE COMMENTS ONLY PLEASE! I already know I'm a bow tuning nut case (LOL!).


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## fletched (May 10, 2006)

Most short ata bows haver shorter limbs on them. Short limbs are harder to misalign and twist. As for as independent limb adjustments, it would depend on how stable the limb and limb pocket pocket is. I like the new destoyer with the spit harness binary. This will make it tunable for limb twist and the flex roller gaurd will help reduce the hard sideways pull. The binary will keep the up/down nock travel in check.


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## edthearcher (Nov 2, 2002)

*nock travel*

go to utube try to find a slo motion picture of a bow being shot, there are plenty of them on video. than maybe you will change your opinion


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## Jabwa (Dec 10, 2004)

Who are you referring to? 

As far as a split harness binary, sounds like the old twin cam to me! Two cables with yokes that could be adjusted to take out limb twist.


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## alaz (Mar 8, 2009)

edthearcher said:


> go to utube try to find a slo motion picture of a bow being shot, there are plenty of them on video. than maybe you will change your opinion


Do you mean the Destroyer? If so I did see a thread on here about that. Just was not sure how reliable those type of videos are.


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## Jabwa (Dec 10, 2004)

I looked up the Destroyer and I just had to laugh! Newbies will think this is a totally new design, but they have just brought back the old twin cam! I remember speed testing the new (at the time) unicam against the twin cam on the same bow. The twin was faster hands down, but harder to tune and noisy. Mathews has figured that out finally and now Bowtech has reinvented the twin cam.


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## fletched (May 10, 2006)

Jabwa said:


> I looked up the Destroyer and I just had to laugh! Newbies will think this is a totally new design, but they have just brought back the old twin cam! I remember speed testing the new (at the time) unicam against the twin cam on the same bow. The twin was faster hands down, but harder to tune and noisy. Mathews has figured that out finally and now Bowtech has reinvented the twin cam.


I just read you thread and had to laugh! 

The older two cam bows were hard to keep in time if you went over 65% letoff. The higher letoff unloaded the cables too much and made them nearly impossible to keep in time.

The destroyer has around 80% letoff and doesn't have this problem. You can take out or add twist to one cable and it doesn't throw everything way out of timing like on the older two cam.

On a binary cam system, you can grab the string above or below the nocking point and pull it back without changing the timing. You can do this with a destroyer. If you try this with an older two cam bow, it will change the timing.

SInce you are a keyboard engineer then explain why the letoff doesn't effect the timing and explain why it doesn't effect the timing when you grab above or below the nocking point.


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## Jabwa (Dec 10, 2004)

Not an engineer, but I am a retired scientist and never take anyones word for anything without testing. In fact, most of my shooting has been at paper in the basement with a large number of bows and arrow combinations.
With regard to the short ATA bows, my sights are always-I repeat- always considerably to the left of the arrow when relaxed. At full draw they are in line with the arrow.
When I do the same with a bow 40" ATA or more, the sight is either in line with the arrow or just visible on the left side of the string when relaxed. The sights are in line with the arrow at full draw. I am a right handed shooter and there is one caveat: the bow must be properly tuned with a correctly spined arrow and it must shoot a bullet hole at 5 yards.
What this says to me is that the short ATA bows have much more cable guard torque than long ATA bows. I also am of the OPINION that the more severe angle of the cables on short ATA bows result in a change in the vertical alignment of the cams at full draw when compared to when the bow is relaxed. In my OPINION this affects lateral nock travel.


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