# Nitrous X cam timing question



## AllenRead (Jan 12, 2004)

That seems to be a lot of movement for just a half twist. I don't get that much on my NX Scepter. A half twist is barely noticable.

Are your cables already twisted up a lot? 

What type of string material are you using and how many strands are your cables?

The only other thing you might try is working with your tiller.


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## PB26 (Dec 31, 2006)

Thanks for the response. 

I bought the bow second hand off of AT, and the previous owner put WC cables on them. They are twisted up pretty good, that's for sure -- wouldn't want to see them twisted any more than they are. The bow string, on the other hand, looks like I imagine it should, though perhaps a bit undertwisted.

The factory specs of the bow are:

ATA: 40.25
BH: 6.5

My ATA is 41, and my BH is 7.5, so clearly it is not in specs (shoots great though!). With the limbs maxed out I'm at the proper 60# max, with 70% let-off, which I hear is about as much as can be squeezed out of the Nitrous cams.

Any suggestions on how I should go about getting the bow in specs, which may perhaps help my timing problem?

Thanks.


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## AllenRead (Jan 12, 2004)

I suspect that both your strings and cables are too long.

Contact Martin for the correct lengths on that bow.

Something is not making sense. Is the 7.5" brace height with the limb bolts turned all the way in?


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## PB26 (Dec 31, 2006)

AllenRead said:


> I suspect that both your strings and cables are too long.
> 
> Contact Martin for the correct lengths on that bow.
> 
> Something is not making sense. Is the 7.5" brace height with the limb bolts turned all the way in?



Thanks very much again for replying. 

Actually the BH is just over 7" with the bolts maxed out -- I forgot to max them out when I did my measurements.

The sticker with the string and cable lengths is still on the bottom limb, so it's hard for me to believe that WC could have dropped the ball on the lengths. 

Let me ask this: I don't have a tool to place 100# of pressure on the strings and cables for measurement purposes. Is there a known ballpark figure of how much the string will lengthen when it goes from being pulled tightly, but just by hand, to being put under 100# of pressure?


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## PB26 (Dec 31, 2006)

"The more twisted they are the more an additional twist will shorten the length of the string."

I plucked that from one of your posts in another thread -- now I see what you were getting at in your first post here.


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## AllenRead (Jan 12, 2004)

PB26 said:


> The sticker with the string and cable lengths is still on the bottom limb, so it's hard for me to believe that WC could have dropped the ball on the lengths.
> 
> Let me ask this: I don't have a tool to place 100# of pressure on the strings and cables for measurement purposes. Is there a known ballpark figure of how much the string will lengthen when it goes from being pulled tightly, but just by hand, to being put under 100# of pressure?


As a first step, don't worry about the 100 # of tension. Just take off one of the cables, untwist it to where it has 1 to 1 1/2 twists per inch and measure it. The more tension that you can put on it the better, but just get the length with it straightened out. Hooking it over a nail and pulling it tight is enough at this point.

It is probably significantly over the length on your riser. If it is you will want to check the length of the string. Fortunately, it's a Martin so if you don't have a bow press, you can just back out the limb bolts until it is loose enough to remove the string. Be sure to back them out evenly. Loosen one bolt 2 or 3 turns and then the other 2 or 3 turns.

Again straighten out the string and compare the length of it to the factory specified length.


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## PB26 (Dec 31, 2006)

Great. Thanks again for the help.


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## Deezlin (Feb 5, 2004)

PB26 said:


> Thanks for the response.
> 
> I bought the bow second hand off of AT, and the previous owner put WC cables on them. They are twisted up pretty good, that's for sure -- wouldn't want to see them twisted any more than they are. The bow string, on the other hand, looks like I imagine it should, though perhaps a bit undertwisted.
> 
> ...


I don't know if the bow had WC's or not. I probably could tell if I saw them. If they are, they are definitely not the right lengths for the bow. I would take them off and measure them. They should be about 1/8" less than the length specifications from Martin. 

With the brace a half of an inch over and the a2a long, you have the cams over rotated. The nose of the cam is pushing out and causing the additional brace height. The cables might be too short and the string is too long. I really don't see how the string is going to be twisted up that short, though.

When you get through getting the bow in spec. it will probably draw shorter. Do you have additional modules holes available?


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## PB26 (Dec 31, 2006)

Deezlin said:


> I don't know if the bow had WC's or not. I probably could tell if I saw them. If they are, they are definitely not the right lengths for the bow. I would take them off and measure them. They should be about 1/8" less than the length specifications from Martin.
> 
> With the brace a half of an inch over and the a2a long, you have the cams over rotated. The nose of the cam is pushing out and causing the additional brace height. The cables might be too short and the string is too long. I really don't see how the string is going to be twisted up that short, though.
> 
> When you get through getting the bow in spec. it will probably draw shorter. Do you have additional modules holes available?


I'm fine as far as module holes go. I'm a 29" draw so I have another inch to play with on the long side.

It seems that the string is fine, but the cables appear too long. To get them to factory length I have to twist them up so much that the two colors are almost "bunching" over each other. 

I gather that you're a string making guru. When I was shooting an Allegiance, I had some all black strings made up for it and the shop tech that made them said that it's better to make them so that when installed there are only two or three total twists in them. In other words all the strands look just about like parallel lines straight up and down. Do you agree with this method?

On another note, have you gotten a chance yet to try out the spreaders? I'm curious to learn if you got them to work properly.

Thanks.


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## Kstigall (Feb 24, 2004)

Measure your draw length on this bow. Have someone mark an arrow for you at full draw. Is your draw length fairly close to the draw slot on the cam? Probably not. 

If someone twisted or untwisted the cables/string in any one direction to time the cams they could have totally got the bow out of spec.

With the limbs maxed out does the poundage match what the bow should be?

A few things. 
With the limbs bottomed out.
1) Take the cables off and make sure each one is about the *right* length and that they ALL are the _same_ length. If there is a lot of twists try to untwist the short ones.
2) Do the same with the string.
3) After re-installing the string/cables lay an arrow against the cam and check for cam lean. Twist or untwist the cables to get rid of the lean. Depending on the twists in the cables as to whether a half twist or 2 whole twists will get the cam straight. You can also untwist the cables. Do a little on each end.
4) Get your nock point set farily close to square to a bit high.
5) Adjust the cables to get the cams timed close enough so you can shoot it a couple dozen times.
6) Brace and a-to-a should now be close. If it isn't close enough for you twist and untwist cables to get it closer.
7) You may have to change the draw length on the module to get it right for you.
8) Shoot a couple dozen arrows.
9) Fine tune the cam timing by adding or removing twists in _both _cables at one end and/or the other. Increasing cable length by removing twists will make your draw length shorter. Shoot a few arrows between tweaks.

- tweak cam rotation and peep aligment by adding or removing twists in the string. 
- start tuning nock height and rest

** Set timing by drawing the bow with your release. Your grip, nock point and how/where you attach your D-Loop or release will effect cam timing.*

Disclaimer: The above is off the top of my head and isn't meant be everything that could done or the exact method for doing it. There are a few different ways to get things done and I'm NOT claiming to be all knowing!!
If you disagree with the any of the above that's fine, by sunset today (or earlier) I might disagree with some of it myself.


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## nuts&bolts (Mar 25, 2005)

PB26 said:


> I'm fine as far as module holes go. I'm a 29" draw so I have another inch to play with on the long side.
> 
> It seems that the string is fine, but the cables appear too long. To get them to factory length I have to twist them up so much that the two colors are almost "bunching" over each other.
> 
> ...


Deezlin is a string making guru
and he manufactures a very impressive string jig
and he manufactures a very very impressive power serving winder.

I would respectfully DISAGREE with your shop tech
about finished strings and the degree of twist.

Finished strings usually will have 1 twist every 2-inches
or
1 twist every 1.5 inches
or
1 twist every 1.0 inch.


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## thenson (Mar 23, 2004)

Some good advice above... and this might be a bit off the wall, but if the tips above don't fix the problem, then this might be something to check into.

Since you bought this bow 2nd hand, there may have been some work done on it...

> check the limbs to see if they match.
> check the cams to make sure they match (don't laugh, I had a bow that had mis-matched cams once, not a Martin)
> if you did the above with the strings and you get them to the factory spec' lengths and still have the problem and the limb bolts are nutted... you might want to check for a bent riser... I've heard more than once about so-called bow techs mis-using a bow press.

But, if it is shooting well, you might just adjust tiller to get the stops to hit at the same time and then check tuning with walk-back or paper tuning. If you offset tiller and it tunes and shoots fine, then just enjoy...

thenson


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## PB26 (Dec 31, 2006)

Thanks for all the great advice -- extremely helpful.


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## EXTREME 1 (Jan 24, 2004)

go to the martin website and click on the tech caption on left side then go to the click on the 06 models and click on Nitrous cam and it will open the web page with all the info on strings and cables. Then you need to match up what limbs you have and cam module and poundage to get the correct string and cable length.


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## PB26 (Dec 31, 2006)

Ron Harmon said:


> go to the martin website and click on the tech caption on left side then go to the click on the 06 models and click on Nitrous cam and it will open the web page with all the info on strings and cables. Then you need to match up what limbs you have and cam module and poundage to get the correct string and cable length.


Thanks for the reply. Now I'm thoroughly confused. I looked up the 2006 Nitrous cam chart, and I couldn't match what I have to what's on the chart. 

I have the "B" cams, and the limbs are the 45-60# Elite, recurve style limbs. On the sticker on the bottom limb it says:

String: 56.25"
Cables: 42.75"

Now, the limbs I have say "7M" on them. On the 2006 chart, however, the only limbs that match the measurements on my sticker are the M-67 Elite limbs. But they are called "7H."

http://www.martinarchery.com/chart/2006chart/nitrous.php


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## Kstigall (Feb 24, 2004)

The 7M limbs, according to the chart you displayed, would max out at about 57-58 lbs.


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## PB26 (Dec 31, 2006)

Thanks. But how did you arrive at that number? 

More importantly, I'm wondering if I should still go by the string lengths on the sticker, and if the factory ATA and BH still apply as guidelines. 

Was this some kind of non-standard, 'by-request' custom bow that I bought?

Thanks for all the very helpful replies.


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## Kstigall (Feb 24, 2004)

The numbers on the limbs represent 5 lb. increments. 
The letters represent 2.5 lbs increments within a given "number" limb.

If 7H = 60 lbs. then 7M = 57.5 and 7L would = 55 lbs.
If 8L = 60 lbs. then 8M would = 62.5 lbs. and 8H would = 65 lbs.

I'm sure there's more to the limb-riser-cam combos but that is the way it plays out. I don't know that it would be wise to put 8L's on as a replacement for 7H's . Maybe it's OK, I don't really know, but that's not what you're interested in anyway.

Brace heights will be somewhat different between the "A", "B" and "C" cams.


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## PB26 (Dec 31, 2006)

Ok, thanks for the info.


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## shootsadiamond (Apr 1, 2006)

*cont...*

So I have basically the exact same issue. I have a 06 SC ELite. 28.5 draw Nitrous B cams. 7H elite limbs. I got the riser/cams 2nd hand from here (basically brand new) and the limbs are brand new direct from Martin.

I followed the advice above and measured my cables and string.
spec - 56.25 string - measurement 56
spec-42.75 cable - all four pretty close to 42.6

Installed and maxed bolts - ata=41.25, BH = 6.9
-put about 6 full twist in each cable
-ata=41.00 BH = just over 7

The cables and string are basically new and WC and seem to be pretty close to spec measurement. Can't put too many more twist in the cables. I could twist the string. I have yet to shoot this bow outside of my garage, so dont really know how it is shooting.

What do I do next? This is the first time I have dealt with Xcams and have never had a problem getting bows specs in line. 

thanks

Also if anyone has a pic of X cams installed with correct specs, I would like to see the approx orientation they should have to the limbs to get an idea of if they are under/over rotated.


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## EXTREME 1 (Jan 24, 2004)

here are a few pics for you to look at, its a 07 S4


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## EXTREME 1 (Jan 24, 2004)

here is another


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## EXTREME 1 (Jan 24, 2004)

and another


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## EXTREME 1 (Jan 24, 2004)

here is another 1


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## EXTREME 1 (Jan 24, 2004)

and another view


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## EXTREME 1 (Jan 24, 2004)

1 more pic


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## shootsadiamond (Apr 1, 2006)

*thanks extreme*

mine are a little different, don't know if they are older or something. One other question - i have about 1.25 gap between the inside cables. Is this right? I cant shoot my blazers thru that and guess I will need a new arrow/vane for this bow. here is some pics of mine, maybe someone has some help.


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## nuts&bolts (Mar 25, 2005)

shootsadiamond said:


> mine are a little different, don't know if they are older or something. One other question - i have about 1.25 gap between the inside cables. Is this right? I cant shoot my blazers thru that and guess I will need a new arrow/vane for this bow. here is some pics of mine, maybe someone has some help.


You can use something called a 
Doovawapi from Barnsdale Archery. It's an aluminum cable spreader
for the X cable shoot through system or any shoot through system.

http://www.archerytalk.com/vb/showthread.php?t=257757&referrerid=22477

The spreader looks like a horseshoe.

The narrow part of the spreader allows the cables to feed into the cam draw length modules much straighter.

The wide part of the spreader gives you tremendous room for blazer vanes.


You can send an email to Dave Barnsdale at this webpage.
http://www.barnsdalearchery.com/contactus.html

If you want to purchase a set of cable spreaders,
then Dave will send you his email address for payment via Paypal.

I have a set of cable spreaders on my Martin S4 with the Furious X cam system, and I have a set of cable spreaders on my Martin Razor X cam system.



Now, 
back to the Nitrous X cam timing.

The draw length module has a flat part.
You want the flat part of the module to contact the cables
at full draw, at the same time.

Easiest way to check this is with a draw board.


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## EXTREME 1 (Jan 24, 2004)

yep here is a pic of some spreaders I installed on Heavy Darts bow and another thing you can do is install the wider axles and spacers to get the cables farther apart, the wider axle pins come with extra wide bushings to go along with the ones you already have on your bow.


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## EXTREME 1 (Jan 24, 2004)

one more pic


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## nuts&bolts (Mar 25, 2005)

PB26:

You need to build yourself a draw board.
Only way to fine tune the cam timing.

"_The top cables hit the draw stops about 1/8" after the bottom cables do. So I put a 1/2 twist into each of the cables that are attached to the bottom cam (i.e. 1/2 twist to the loops attached to the top limb axles). But then when I do this I get the reverse effect: the top cables hit 1/8" before the bottom cables do. _"


Simple solution.

I just did this on my Martin Razor X with B size Nitrous cams.

I added a 1/2 twist to the cable end loops on the top axle.
Top draw length module was in perfect contact with the draw length module.

BUT,
the bottom module was maybe 1/8th inch off, as in not in contact with the cable.



I removed 1/2 twist to the cable end loops on the top axle.
Bottom module was now in perfect contact with the cable,
BUT
the top module was off by 1/8th inch.


SOLUTION:

Move the d-loop down about 1/8th inch or maybe 3/16th inch.
You have added some more bowstring above the d-loop.
You have subtracted some bowstring below the d-loop.

Now, you can add or remove 1/2-twist to the cable end loops on the top axle, 
AND
the draw stops will hit exactly at the same instant.


TOP CAM at full draw, while held in the draw board.











BOTTOM CAM at full draw, while held in the draw board.












Here are some shots of the Barnsdale spreaders.


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## shootsadiamond (Apr 1, 2006)

*thanks*

and thanks and one more time thanks...
Now I got to get around to finding that thread about building a draw board and get it done.
thanks to Deezlin for answering my questions too.


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