Optimum Binary Cam Position

jrb CO · 03-21-2005, 10:18 PM

OK Bowtech gurus.

There are no obvious (to me) timing marks on the new binary cams. I am sure some of you have played with this system to determine the optimum rotation for these cams. There is nothing in the Bowtech manual as a reference.

The rotation is slightly different on my Defender and my Allegiance, although the cams are the same. On both, the bottom cam is just slightly ahead of the top cam.

Can anyone describe or post a picture of the optimum position. Thanks!

WA Shooter · 03-22-2005, 12:18 AM

Can't help you with the cam timing, but wanted to know how you would compare the draw cycle of your Defender to that of a single cam bow. I'm considering a new bow and like the specs of the Defender but I have heard the draw cycle is not as smooth as the Freedom Cam BowTechs.
I haven't been able to get the the shop to shoot one myself yet.

pdq 5oh · 03-22-2005, 06:08 AM

BowTech are working on some measurements for cam positioning at brace. It obviously will vary from bow to bow, even though the same cams are used.
Re: draw of F cams compared to E cams: the draw curve of both cams is very different. The weight is at the front on the E cams. Then drops at the back, into the valley. There is no hump to pull through. The F cams draw like a conventional single cam, though more smoothly than many. You need to shoot both to really understand this. It will most likely come down to a preference. IMO, both cams are extremely quiet, and recoil/vibration is very low.

jrb CO · 03-22-2005, 10:52 PM

Well, I received an email from a kind individual that showed the correct position for the cams. When I balanced the cams to this position, the letoff changed significantly. In order to achieve the near 80% letoff from the factory, the bottom cam was quite a bit ahead of the top cam initially. This allows the draw peg (on the top cam) to contact later and thus increase the valley and percent letoff. The letoff dropped to 65% or less when I balanced the cams symmetrically, even though the post was at max letoff position.

So for my next queston, is it OK for the cams to be out of sync like this? I really would like 75% - 80% letoff, but the only way I can achieve it is by unbalancing the cams. I do gain 1/8" draw, which I am not happy about by doing this.

Are there other tricks out there for fine tuning letoff or draw length with this system? I know some of you are tempted to tell me to adjust the position of the draw stop, but remember I have to "untime" the cams just to get to 78% with the post maxed. I have found that tiny adjustments in the draw stop post make for large changes in letoff with small to moderate changes in draw length.

PABowhntr · 03-23-2005, 08:15 AM

Maybe I am missing something here but didn't everyone's Bowtech bow come with timing marks placed onto the cam at the factory with a black marker? Wouldn't this help with both timing and synchronization?

sjb3 · 03-23-2005, 11:38 AM

PABOWHNTER, I had to change from a 30" to a 30.5" draw. Bowtech sent new cams, but dealer didn't have a clue as to where to set the new cams,and with these cams never being on a bow they were not marked. Was thinking maybe this is where some of the unmarked cams are coming from. I dinked with it for a few weeks, put new string and cables on it, still don't think I'm grtting 80% l/o. The l/o does'nt matter to me because I don't like 80% l/o, but where ever its at now the Old Glory is a tack driver. I just figured put it back to specs. and it should be close. Haven't had any problems since. I think the Old Glory is the most accurate bow I've ever owned.

Blodg · 03-25-2005, 05:40 PM

jrb, I don't believe that the cams need to be out of sync for you to get the proper letoff. When you twist the top cable attached to the front of the cam I would simply do the same thing with the bottom cam. This way they will both match and twisting the bottom one does not affect the draw length.

To answer your question, you will gain some draw length to get more letoff, no way around it.