Jim Park level nock theory - check yours !

[Ozzy]

Had a great Forum dinner at Clare's here in Adelaide on the weekend, & yes, - bows were produced :wink:
Jim & Marcus demo'd the level nock test :-?
Tony Pearce was in a state of shock after his Merlin was tested :oops:
I brought my beloved ProTec along for a checkout on Sunday, - & horror of horrors, - the thing was a mile out of wack :oops: :roll:
C.5 owners beware. Check your bows at full draw. Don't assume if the thing is "somewhere near the middle" of the indicators on each cam that all is well ! :o
Thanks Jim & Marcus. -
& Marcus it took a full 6 twists on the power cable to correct - easy peasy. Would that lengthen the draw a significant amount ? :o

[Flame]

Mine is spot on :D

[Ozzy]

Let me say that I definately noticed high /low shots when conciously pulling against the wall :roll:
1400 here I come !
Never shoot FITA's, but intend to, so no excuses now :roll:

[Marcus]

Yep looked at some old notes and 6 is most likely right.
Glad to see you got it working, did you notice a change in the wall?
Here is an article about tuning your cam 1/2
http://urbanarchery.com.au/articles_display.php?article_id=6

[James Park]

It is a simple test, as those who saw it would note.
We tested Tony's on Clare's table, and Ozzy's on the floor of the squash court at the indoor. Quite a lot of vertical nock travel around the wall in both cases (perhaps Ozzy's had a bit more than Tony's).
I was not surprised to see the results - they were pretty typical of many I have measured. In both cases the wall was soft and the nock travel would have given high and low shots. Both would be significantly more accurate after a little adjustment - basically it is "points for free".

(I should add that Tony's and Ozzy's were by no means the worst I have seen, but probably about the average of what I have measured).

[Harald]

How is the test performed Is it to hold the bow steady and try to line up the nock point while you're drawing with a pencil?. Would the path drawing upp differ from path when letting slowly down?? :roll: :bday:

[Kuru]

But I thought cam.5 didn't need timing :lol:

[bigfella]

So what's the test James?

[James Park]

You will find the test described in other posts (somewhere) on the forum, with pictures. (Try searching on "vertical nock travel", and you should find it somewhere).
I get one person to hold the bow down on a table. I then draw the bow using a cord (so my hand is well away from the string) back to full draw. Then as I pull it into the wall I watch to see if the nock moves straight back or towards the top or bottom cam. If it moves then the timing is not correct. For example, if it moves towards the top cam it means that the top cam is hitting the stop first and then a little while later the bottom one hits the stop. For this bow, the arrows would hit lower on the target as you pull harder into the wall. You then simply adjust the cam timing until the nocking point comes straight back as you pull into the wall.

[2Dogs]

And then as Jim stands there and tells you, you just spent $1500 on a lemon...............simply let go of the Riser, and Vertical Nock travel is no longer an issue.

"By Goooooooooooooolllllllllllllllllllllllllllllllllll lllllllllllllllllllllllllllllllllllllllllyyyyyyyy!" :wink: :lol:

[Zoe]

:rofl:

I guess the length of the golly depends on the height of the table

[2Dogs]

:rofl:.... I never thought of that.....God that would hurt!!!!

[CMB50]

It would certainly hinder your ability to obtain a 'riser'! :o :o :D

[Flame]

:D

[Ozzy]

:rofl:

I guess the length of the golly depends on the height of the table

Yes indeedy :oops:
I did say to Jim when holding my bow after he had drawn it to full draw
"What's it worth if I don't let go" :-?
That cable guard would smart from full draw in the privates :roll: :wink:

[SteveFSA]

I have a 2003 Protec with .5 cam and as others have found I needed about 8 twists in the powr cable to get it timed right. The problem I have is that the bow only has 45lbs max of peak weight when it's supposed to have 40-50lbs.

Other odd things about this bow is the brace height is 9.25" and the ATA is 41". Something is not right but I'm not sure what it is. The bow shoots great but I'm having trouble reaching 90m. Any ideas?

[Marcus]

You must have the XT3000 limbs, or even the LX Pros.
If your poundage is low then you must twist up the control cable. This will lengthen your draw a little and also untime the cams, so you will have to add a few more twists to the power cable.
I have changed weights by 5-10lb by adjusting the control cable and it made little difference to the brace height or draw length.

Also at that BH and poundage unless you have a 32" draw you will struggle to make 90m. Would suggest looking at changing to a Protec XT2000. Plenty of brace height and tons of speed.

[Ozzy]

Marcus, those 6 twists in my power cable to time the cams etc. seems to have lengthened the draw about .5 ".
Is this my imagination ? :o

[Marcus]

No that is normal as you are moving your first stop to match your second stop.
Just adjust the cam module to suit, or untwist both the control and power cables to the desired point.

[Rhythm Willie]

Ozzie,

You may recall how on the purchase of my Ultratec Cam1/2 I figured out that shortenning a harness cable aligned the cams much better. This cable seems to stretch a bit on new bows.The Urban Achery linked article makes plenty of sense. I checked last night & on the draws stops each cable on both inners are parallel & in the groove(you visually checked it on Sunday at the indoors).

You may also remember my surprise at the time that the dealer did not seem to know about how to tune the cam1/2 or the fact that 2004 bows use alignment holes rather than the previous marks on the cams????!!

Dennis(alias RW)

[Harald]

Makes you wonder how the guys managed to rigg a fullrigger sailship...

In the times when the sea was salty and blue, steam engine not invented and the moon was not something you just simply stepped on... 8)

[James Park]

I checked last night & on the draws stops each cable on both inners are parallel & in the groove(you visually checked it on Sunday at the indoors).
I think that checking the cables in the slots at full draw is not necessarily sufficient, and can still leave an error (for example, with the Cam&1/2 the stops are different shapes). Far better to check the Vertical Nock Travel directly, as that way you will know for sure that it is correct.

[2Dogs]

Jim

Did you have a chance to try it on a Spiral Cam?

I think the spiral will get very different results based on weather the top cam is resting against the cable or if it's short of it.

Trouble with the Spiral is that in order to get the Top Cam Cable to touch to lengthen the draw quite about .5 ".

Makes selecting the correct draw bow, extremely difficult

[James Park]

2Dogs,
No, I have not tested a Spiral Cam, but will do so.

[robbo]

You will find the test described in other posts (somewhere) on the forum, with pictures. (Try searching on "vertical nock travel", and you should find it somewhere).
I get one person to hold the bow down on a table. I then draw the bow using a cord (so my hand is well away from the string) back to full draw. Then as I pull it into the wall I watch to see if the nock moves straight back or towards the top or bottom cam. If it moves then the timing is not correct. For example, if it moves towards the top cam it means that the top cam is hitting the stop first and then a little while later the bottom one hits the stop. For this bow, the arrows would hit lower on the target as you pull harder into the wall. You then simply adjust the cam timing until the nocking point comes straight back as you pull into the wall.


Jim, How do you go about it if you shoot with fingers? :-?

[robbo]

Trouble with the Spiral is that in order to get the Top Cam Cable to touch to lengthen the draw quite about .5 ".

Makes selecting the correct draw bow, extremely difficult


Now you tell me. :roll: :D

[James Park]

Jim, How do you go about it if you shoot with fingers? :-?
Same test exactly robbo.

[robbo]

Jim, Doesn't the timing change depending where you hold your fingers?

If you have more fingers underneath the arrow, it rotates the bottom cam more. :-?

Or I could be missing something. :D

[James Park]

robbo,
Yes. I would try the same process but drawing it from where your fingers are on the string.

[robbo]

Thanks Jim, that's what I was meaning, it would be hard to do it in a jig, trying to draw it the same as your fingers.


At the moment I draw in front of a mirror if I can, ( or just look at the cams) And twist the cables untill I get the cams as close as I can by eye.

But this method does not tell me if I have level nock travel. :-?

But I would like to be able to do it a bit more accurately.

[Greg Durward]

I suspect it would not make a difference in tracing nock travel whether the riser is secured on a table with the bow being drawn, or on a vertical surface like a wall and the bow is drawn straight down. But both of these positions negate the effect that gravity actually has on the bow when it is drawn in the normal position. It seems to me that the cams might actually rotate differently because of this. The top of the bow will tend to rotate toward the archer in actual shooting and this will affect the rotatational positions of the cams near full draw when the bow is actually shot. So the results of timing might be different for the non-gravity test and the real-gravity shooting position? Does this make sense Jim? If so, how can your test give accurate results?
Greg

[wareagle]

James, if the bow is held ridged, at what point/distance would you pull the cord from, to be accurate. I guess this would also vary with bow poundage?

[whiz]

Bit of an old thread...

[primal]

I suspect it would not make a difference in tracing nock travel whether the riser is secured on a table with the bow being drawn, or on a vertical surface like a wall and the bow is drawn straight down. But both of these positions negate the effect that gravity actually has on the bow when it is drawn in the normal position. It seems to me that the cams might actually rotate differently because of this. The top of the bow will tend to rotate toward the archer in actual shooting and this will affect the rotatational positions of the cams near full draw when the bow is actually shot. So the results of timing might be different for the non-gravity test and the real-gravity shooting position? Does this make sense Jim? If so, how can your test give accurate results?
Greg


sorry but thats a bit of a daft question as gravities effect of a cam system is so negligible small compared to the other forces involved.

[Archangel]

Bit of an old thread...
Yay for thread necromancy...

[Ozzy]

Bit of an old thread...

Like it's originator I hear you say whizee ? :fist:
:D
Oldie but a goodie. ;)

[whiz]

Well, I guess the coincidence of only hearing about Jim's nock travel revelation a couple of weeks ago, combined with this threads appearance today made me expect that it was a new thread. I was quite surprised to see the dates on the original posts.

Being a recurve shooter, I haven't done much research on compounds other than to say "things have changed a bit"

[Finno]

Jim/Marcus,
How relavent is this to a Commander?
Same check I assume.
What about adjustment?

[James Park]

I suspect it would not make a difference in tracing nock travel whether the riser is secured on a table with the bow being drawn, or on a vertical surface like a wall and the bow is drawn straight down. But both of these positions negate the effect that gravity actually has on the bow when it is drawn in the normal position. It seems to me that the cams might actually rotate differently because of this. The top of the bow will tend to rotate toward the archer in actual shooting and this will affect the rotatational positions of the cams near full draw when the bow is actually shot. So the results of timing might be different for the non-gravity test and the real-gravity shooting position? Does this make sense Jim? If so, how can your test give accurate results?
Greg
Greg,
Yes, I guess gravity would have an effect as it is pulling on the limbs differently (straightening one and bending the other). However I think its effect will be very small in relation to the strength of the limbs. A compound bow is extremely rigid along the line of the riser. Hence, I would ignore it.

[James Park]

James, if the bow is held ridged, at what point/distance would you pull the cord from, to be accurate. I guess this would also vary with bow poundage?
I usually get an old recurve bow string, loop it around the string at the nocking point and pull with the recurve string wrapped around my hand. Hence, I guess about 1/2 metre.

[James Park]

Well, I guess the coincidence of only hearing about Jim's nock travel revelation a couple of weeks ago, combined with this threads appearance today made me expect that it was a new thread. I was quite surprised to see the dates on the original posts.

Being a recurve shooter, I haven't done much research on compounds other than to say "things have changed a bit"
Yes, first did these tests back in about 1995, so it is a pretty old area.

[James Park]

Jim/Marcus,
How relavent is this to a Commander?
Same check I assume.
What about adjustment?
Yes, same test.