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Discussion Starter #1
Within the context of ease of tuning, I’m trying to understand if today’s 2 track binary cam manufacturers distribute timing directions for their bows that are unnecessarily complicated.

Here’s the deal. If the 2 track binary cam setup is essentially 2 perfectly symmetrical cams that are slaved together and only rotate (and rotate at equal rates mind you) while the other cam is rotating, why is a drawboard necessary to check cam timing? I understand that a drawboard is necessary to ensure that the stops are both hitting the limbs simultaneously but why can’t you determine that a 2 track binary is out of time by checking the bow AT REST by looking at the positioning of the control cables in relation to the cams or taking some string post-to-control cable measurement AT REST???

If the bow is out of time at full draw while in a drawboard, it should be equally out of time AT REST, right?

It seems obvious to me that the manufacturers of 2 track binaries cams setups (Strothers, New Breed, Elite, Obsession, etc) should include timing marks on the cams so a guy can check for timing while the bow is AT REST….like the CPS system on the older Dartons.

I must be missing something. What is it?
 

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I would think the difference would be in the position/height of the nocking point on the string as to how the cam rolls and is timed. JMHO, but I always time with a draw board and even with the older Bowtechs (Tribute, 82nd, etc) the timing dots aren't the same on top and bottom once timed correctly.
 

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Discussion Starter #3
I would think the difference would be in the position/height of the nocking point on the string as to how the cam rolls and is timed. JMHO, but I always time with a draw board and even with the older Bowtechs (Tribute, 82nd, etc) the timing dots aren't the same on top and bottom once timed correctly.
Not sure I follow what you're saying. If the binary cams are perfect mirror images of each other and they're slaved together with 2 control cables ensuring identical movement behavior, if the cams had timing marks then you could tell if the bow what out of time AT REST, right?

I guess I just don't see why you have to yank the bow back to full draw on a draw board and then try to take these akward measurements (not to pick on New Breed, but check out their timing directions on their website...holy cow) when you could just make a quick visual inspection while the bow is AT REST.

Anyway, thanks for your input; I'm in the mkt for a new bow and I'm trying to get my arms around what I can expect if I go the binary route.
 

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Because the nock is not in the exact center of the string, closer to top cam, then more string has to unwind from the bottom cam than the top cam to keep level nock travel thruout draw.
That is why you need to sync cams and make sure draw stops contact at same time at full draw. That is why I think that timing and or syncing cams at full draw is necessary.
 

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if the cams had timing marks then you could tell if the bow what out of time AT REST, right no , it wont, timeing marks will not be the same . because of cable guard and nock is not exact center of string measure nock to top cam them bottom
 

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Not sure I follow what you're saying. If the binary cams are perfect mirror images of each other and they're slaved together with 2 control cables ensuring identical movement behavior, if the cams had timing marks then you could tell if the bow what out of time AT REST, right?

I guess I just don't see why you have to yank the bow back to full draw on a draw board and then try to take these akward measurements (not to pick on New Breed, but check out their timing directions on their website...holy cow) when you could just make a quick visual inspection while the bow is AT REST.

Anyway, thanks for your input; I'm in the mkt for a new bow and I'm trying to get my arms around what I can expect if I go the binary route.
You are ASSUMING the the top and bottom limb are a PERFECT match for stiffness.

Better to not assume,
build a simple draw board,
and use the draw board to confirm,
that everything is working the way it should be.
 

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Discussion Starter #8
You are ASSUMING the the top and bottom limb are a PERFECT match for stiffness.
I'm no mechanical engineer by any stretch, but isn't a potential difference in limb stiffness compensated for by the binary cams being slaved together by 2 control cables?

In other words, 1 binary cam can only move by the same amount and same speed as the other. Thus, timing measurements at full draw should convey the same message as timing measurements at rest.

How does the position of the nock on the string affect the behavior of binary cams rolling over? Hmmm....if the nock is intentionally set high on the string and then the string is drawn, does the top binary cam roll over faster than the bottom?

If so, then that's my answer.

Please confirm.
 

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In not so many words yes. But as N&B stated on the limb deflections if the top limb is slightly stiffer than the bottom limb it will naturally take more string from the bottom cam because their is less resistance. Tuning a binary cam system is not that bad and is pretty straight forward. In a "perfect" world the timing dots would work but we all know nothing is perfect.
 

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Throw in a drop away rest, tied to the down cable....and timing is off :)
 

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I'm no mechanical engineer by any stretch, but isn't a potential difference in limb stiffness compensated for by the binary cams being slaved together by 2 control cables?

In other words, 1 binary cam can only move by the same amount and same speed as the other. Thus, timing measurements at full draw should convey the same message as timing measurements at rest.

How does the position of the nock on the string affect the behavior of binary cams rolling over? Hmmm....if the nock is intentionally set high on the string and then the string is drawn, does the top binary cam roll over faster than the bottom?

If so, then that's my answer

Please confirm.

Limb deflection would only show a difference at rest. Your correct drawing the bow would only work in a balance of weight between the two limbs.
You need to sync the cams at full draw. You can time one at rest and the other will be close if they are in sync and the limbs are a match in deflection.

You can draw the bow within reason anywhere and both cams will finish the draw at the same time.

You need a draw board or a good solid hook so you can see the dots or a reference at full draw before the limb stops interfere. then its also easier to set the stops even incase one limb is weaker then the other at full draw.
 
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