# hybrid cam tuning ? thats baffling me!



## WCork (Apr 22, 2010)

You have a hybrid cam like a Hoyt. So a buss cable (cable with the yoke legs), a control cable, and a string. Say your specs of the bow are all good. DW an DL both where they need to be. But your top cam is slightly under-rotated and your bottom draw stop is hitting before the top cam. I was told you could add twists to the yoke cable legs which will help fine tune your top cam so it advances the top cam even or just before the bottom stop hits the peg. 

Why is this!? How does twisting the yoke legs advance the top cam but not affect the bottom cam? Does it affect the bottom cam but not as severely as it does the top? It doesn't make sense to me, because the yoke legs aren't even attached to the top cam, but the buss cable is attached to the bottom cam. Sorry if I'm overthinking this guys, but hoping someone can shed some light for me. 

One last question....for the longest time I couldn't figure out how twisting/untwisting the buss cable affected the top cam. Is it because they are slaved together by the control cable....so the top cam has no choice but to rotate? 

Thanks to you tuning geniuses out there for clearing this up in advance!


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## huntertroy (Feb 16, 2010)

I am far from a tuning genius but the buss cable controls the bottom cam, by twisting the buss cable you are actually slowing down the bottom cam to make both stops hit at the same time


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## dwagoner (Sep 27, 2007)

shortening the buss rotates it while the control keeps the top cam connected to it but its moving top cam also. you could have shortened control also, or depending on how many twist you needed to adjust, could split them between the two.


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## Hannes (Jun 8, 2007)

If you twist the buss cable the A2A length is going to change. If it isn't correct then yes twist the buss cable. However if the A2A is correct and the bottom cam is hitting the stop before the top cam you have to take out twists in the controle cable. 

If the A2A is correct and the top cam is hitting the stop before the bottom cam you need to put twists in the controle cable.

Hope this helps.


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## SonnyThomas (Sep 10, 2006)

Forget the yoke. You want to twist whichever side of the yoke to correct cam lean, fine, but otherwise leave it alone.

I began tuning the Hoyt Cam & 1/2 by going by the bottom as it has the fixed cable draw stop. You check as you go. Here's a example; If the top cam (actually a oval wheel) hits before the bottom, add a twist to the cable that feeds into the module of the top cam (or flat track for it). If the top cam isn't hitting with the bottom cam remove a twist. And you may only need a half twist when really getting finicky.
Now that you a example; You use it as a guide if you wish the adjust the bottom cam to the top.

Normally, when I had the cam & 1/2 system tuned the buss cable would be slightly off center of the reference hole and the control cable would be slighty off center the other way of the reference hole.

The Hoyt cam & 1/2 cam system is not really slaved together, not if you have a yoke. So the bottom would be the independant as ties into the top limb.


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## dwagoner (Sep 27, 2007)

SonnyThomas said:


> Forget the yoke. You want to twist whichever side of the yoke to correct cam lean, fine, but otherwise leave it alone.
> .


sonny youd be surprised if you need to shorten the buss how just a few twist in the yolk can change the length, i did this recently as i dont build them with alot of twist already so i adjusted it there and originally my top cam was off a good 1/4" so added 3 twist to both side of yolk and got top cam back close, took that much up...

NOW it does depend on how your bow is already in relation to specs but it can be effective to adjust the length without adding more twist to whole cable and changing the look of the twist in the string if you dont want that to change. but this was the first time i did that myself and was pretty shocked, both cables still same twist and got the bow spec'd out quite nicely......


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## SonnyThomas (Sep 10, 2006)

Not really disagreeing with you, Dennis. I don't build strings and of course you know that. My strings comes pre-twisted and pinned and I start with that. Rarely do I have to add more than one twist to sync/time a bow so one twist over the length of a cable doesn't effect the look of twist. Aggrevating are some strings or rather the yokes, some too short. I've had to overly twist one side to correct cam lean.

And then the Kitchen Sink tuning came about.....


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## dwagoner (Sep 27, 2007)

thats why on alot of bows i prefer to make longer yolks, easier on the lean.....


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## ron w (Jan 5, 2013)

by twisting only one side of a yoke, you are changing the length of the cable....what you take out of one side you have to give back on the other to maintain the same cable length.
if you draw an upside-down equilateral triangle on a piece of paper, it demonstrates the yoke and axle on a bow. when you short one of it's sides, the adjacent corner will drop and the bases center will drop by one half of the corner's drop. it's the simple explanation of the value of "cosine" in trigonometry.
the longer the yoke, narrower the base of the triangle is, in relation to the length of the sides of the triangle, so, the more effect this definition of cosine demonstrates a change to center of the base. the longer yoke requires more twisting to affect a change in length, and that makes more adjustability and accuracy of the change, because each twist changes the length of the side less, which makes for finer change in length per twist.


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## nuts&bolts (Mar 25, 2005)

ron w said:


> by twisting only one side of a yoke, you are changing the length of the cable....what you take out of one side you have to give back on the other to maintain the same cable length.
> if you draw an upside-down equilateral triangle on a piece of paper, it demonstrates the yoke and axle on a bow. when you short one of it's sides, the adjacent corner will drop and the bases center will drop by one half of the corner's drop. it's the simple explanation of the value of "cosine" in trigonometry.
> the longer the yoke, narrower the base of the triangle is, in relation to the length of the sides of the triangle, so, the more effect this definition of cosine demonstrates a change to center of the base. the longer yoke requires more twisting to affect a change in length, and that makes more adjustability and accuracy of the change, because each twist changes the length of the side less, which makes for finer change in length per twist.




LOOONG yokes.

Makes Kitchen Sink soooo easy.


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## ron w (Jan 5, 2013)

yup, yup, yup.!


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## ron w (Jan 5, 2013)

the other thing is that the hybrids are all about straight nock travel.....not level nock travel. there is a difference. it's almost a necessity to have a draw board to really set them up to their highest potential. the kind of board that you can record nock travel on, with a marker or pencil or indicator against the riser, so that you can actually see exactly how the nock runs as it goes from full draw to brace. level or not, is less important than straight or not.
you either have to have the riser held rigidly and record how the nock moves, then make adjustments until the nock travels straight or the nock attached to a straight track of some sort and let the riser rock as the bow goes from full draw to brace and make adjustments until the riser doesn't rock. 
the point is, you need to graphically be able to see the path the nock makes as it moves or what the nocks makes the riser do. 
the only other way is to group tune and that is entirely dependent on your shooting skills.


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## WCork (Apr 22, 2010)

Good info. Thanks ron w


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## Alpha Burnt (Sep 12, 2005)

How about some pics to go with the words, Ronw? I like peetchers!


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## ron w (Jan 5, 2013)

I con't do no peetchers !.....

if you can read you can think.


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## Alpha Burnt (Sep 12, 2005)

Ok, thanks


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## 02transam (Nov 14, 2013)

If nock is traveling towards top cam then top cam needs to be slowed down?


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## thwackaddict (Sep 1, 2006)

ron w said:


> the other thing is that the hybrids are all about straight nock travel.....not level nock travel. there is a difference. it's almost a necessity to have a draw board to really set them up to their highest potential. the kind of board that you can record nock travel on, with a marker or pencil or indicator against the riser, so that you can actually see exactly how the nock runs as it goes from full draw to brace. level or not, is less important than straight or not.
> you either have to have the riser held rigidly and record how the nock moves, then make adjustments until the nock travels straight or the nock attached to a straight track of some sort and let the riser rock as the bow goes from full draw to brace and make adjustments until the riser doesn't rock.
> the point is, you need to graphically be able to see the path the nock makes as it moves or what the nocks makes the riser do.
> the only other way is to group tune and that is entirely dependent on your shooting skills.


So does this usually get your vertical adjustments perfect when bareshafting/BH tuning? Or do you still have to go 1/2 twist here or there?


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## ebag600 (May 28, 2014)

ron w said:


> the other thing is that the hybrids are all about straight nock travel.....not level nock travel. there is a difference. it's almost a necessity to have a draw board to really set them up to their highest potential. the kind of board that you can record nock travel on, with a marker or pencil or indicator against the riser, so that you can actually see exactly how the nock runs as it goes from full draw to brace. level or not, is less important than straight or not.
> you either have to have the riser held rigidly and record how the nock moves, then make adjustments until the nock travels straight or the nock attached to a straight track of some sort and let the riser rock as the bow goes from full draw to brace and make adjustments until the riser doesn't rock.
> the point is, you need to graphically be able to see the path the nock makes as it moves or what the nocks makes the riser do.
> the only other way is to group tune and that is entirely dependent on your shooting skills.



would u be able to set up a draw board say vertical then attach a pen or pencil or something to the knock then when u drew the bow back it would draw a line on the draw board either straight or off depending on knock travel?


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## nuts&bolts (Mar 25, 2005)

ebag600 said:


> would u be able to set up a draw board say vertical then attach a pen or pencil or something to the knock then when u drew the bow back it would draw a line on the draw board either straight or off depending on knock travel?


Way too complicated
to build a nock travel measuring device.

Not needed for a shooter.

Nock travel measuring device
is more for a cam designer to perfect the cam shape, profile.

For a shooter,
you are ONLY interested in results...

where you flatten your arrow groups as MUCH as possible.


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## nuts&bolts (Mar 25, 2005)

ebag600 said:


> would u be able to set up a draw board say vertical then attach a pen or pencil or something to the knock then when u drew the bow back it would draw a line on the draw board either straight or off depending on knock travel?


You want the vanes to do ZERO correction,
as little work as possible,
when tuning for CAM SYNC.

So,
you want THIS result at 20 yards.

ONE arrow tube has VANES for steering correction.
OTHER arrow tube has ZERO vanes, ZERO steering correction...so (NO tape at the back end...you want ZERO air disturbance).



If you get THIS result,
fletched and bareshafts....DIFFERENT point of impact...fletched are ONE height....bareshaft are a DIFFERENT height..

you have cam SYNC troubles...

just put the bow in the press
and twist the CONTROL cable,
the top end loop

and try 1/2 twist LESS
and try 1 full twist LESS

or

try 1/2 twist MORE
and try 1 full twist MORE.

WHATEVER it takes
to change the twists in the CONTROL cable (top end loop)
making the control cable a little bit SHORTER
making the control cable a little bit LONGER

until you get THIS result.



FLETCHED arrow NAILS the top edge of a strip of masking tape
at 20 yards.

BARESHAFT arrow NAILS the top edge of a strip of masking tape.

PERIOD.
END of story.

No need to document the nock travel with a nock travel measuring device.

IF you want to make a nock travel measuring device...


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## nuts&bolts (Mar 25, 2005)

THIS is what a nock travel measuring device looks like.

Built by Old Buck.



SINCE you want to measure NOCK travel....

you MUST lock down the riser, to measure NOCK travel.

A nock travel device, measures how the LIMBS bend.
A nock travel device, measures how the CAMS interact with the limbs, how the CAMS rotate and pay out bowstring (think two fishing reels).



The BLUE thing is very very sophisticated.

The LONG arm is a balance beam, to keep the pen vertical...like the wings on an airplane.

The pen holder is a two piece floating design.






LOWER TECH model (nock travel device...no pen system, must eyeball the nock travel),
not by Old Buck.







So,
to be ABSOLUTELY CLEAR.

BOTH devices above
are NOT draw board.

*THESE are NOCK TRAVEL measuring/NOCK TRAVEL DISPLAY devices....
as such,
the RISERS are LOCKED down.*


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## Ruttin BUX (Aug 13, 2008)

tag


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