Sharing what I've learned about Binary Cam Timing
03-16-2006, 05:51 PM
#1
Thread Starter
Join Date: Oct 2005
Location:
Posts: 519
Sharing what I've learned about Binary Cam Timing
Many of you may already know what I’m about to share, but for those who have not tuned their binary cam cables as much as I have been lately; I hope this thread helps provide some insight to adjusting the cables on these binary cam bows. I’m new to archery, don’t know much, and this is my first attempt to verify best accuracy with my bow via bare shaft tuning. I do enjoy testing each change in bow tune to understand why and what each adjustment does to the bow and how they affect accuracy. If you have the basic tuning skills understood and feel comfortable twisting your cables, this post may be beneficial. If you’re like me and find that the listed data for cam timing isn’t providing you with the level of accuracy you wish to find then cam timing may be the right direction to head in.
The last few days I have been spending several hours (once again) adjusting cable tension on my binary cam bow to see what the benefits are in accuracy. Each cable adjustment has been followed by a nock height and center shot adjustment when required. All my testing was done at 10-15 yards with bare shaft arrows with no wind. Please keep in mind that bare shaft tuning shows any flaws in shooting form, so you have to be careful in interpreting the results of your arrow pitch/angle in target in relation to how you felt about the quality of the shot. I learned it’s best to take a few shots before interpreting the results and making any one adjustment. I also learned that bare shaft tuning has to be at a perfectly level position and it also took it’s toll on the 3 shafts I used for testing. After spin testing the 3 arrows used for testing, I don’t believe they can be considered pro shafts anymore.
PROBLEM:
First off, there’s a chart floating around that we have all seen that lists what timing marks you should have on your bow as a general guideline or reference point. I made a few calls to verify how many cam dots/marks “should” be showing past my limbs and I was told 5.5 top and 5.5 bottom. If using a drop away rest tied to the down buss cable, I should be 5.5 on top cam and 6.0 on bottom cam. Now here is where it gets interesting. I changed my cam location with what was recommended, and was shooting approximately 1-inch groups at 10-15 yards with a bare shaft arrow. That is not good in my book for that close of a range, so I proceeded to make several adjustments to gain better accuracy. I already had my bow super tuned a few weeks ago from trial and error at 60 yards, but wanted to try the listed information to see if my accuracy got better. In short, since I have used the listed data my accuracy has gotten worse. I have been back and forth and all over the board with these cams and keep verifying the same results. I now know where to leave the cams.
SOLUTION:
I made half twists to cables as required to always keep top cam at the recommended 5.5 dots showing past limb, but bring the bottom cam in a direction from 6 dots down to 4.75 dots showing past limbs. I headed in this direction because it’s the direction that I knew gave me good accuracy at 60 yards. This direction was completely the opposite of what was listed on the binary data. As I brought the lower cam from 6 dots to 5 dots past limb, I started hitting a “sweet spot” in my accuracy. For my bow 4.75 dots showing past bottom limb and 5.5 dots showing past top limb gave me bare shaft arrows that were shooting in the same exact hole as the previous arrow from 10 yards. I had to shoot 1 arrow at a time to prevent damage to arrows. This minor increase in accuracy may not sound like much, but as you know, when you can make small increases at closer ranges it will give you large gains at longer ranges.
CONCLUSION:
My point is not to say the charts or data floating around is incorrect information for all bows. As we all know, it’s impossible to give any guidelines that will provide the best accuracy for each and ever persons bow. The binary data listed, provided above average accuracy in my opinion for my set-up ( I did find worse locations). My point is that if you’re looking to squeeze all the accuracy you can out of your binary cam bow, you have to find it yourself with the proper arrows for your bow and poundage. Don’t get caught up like I did in how many dots are showing past your limbs, and try and copy somebody else’s bow tune. I wanted to throw this idea out there for those who are new like me and strive to reach the best tune from their bow. In closing, I’m not saying your timing dots will be like mine and I’m not saying that the listed data won’t provide you with acceptable accuracy under most conditions. I just think that if you like to tune, you may want to at least try a few different positions with your cam timing in either direction to see if you can increase your accuracy. The results may shock you and may speak louder than anything else recommended.
The last few days I have been spending several hours (once again) adjusting cable tension on my binary cam bow to see what the benefits are in accuracy. Each cable adjustment has been followed by a nock height and center shot adjustment when required. All my testing was done at 10-15 yards with bare shaft arrows with no wind. Please keep in mind that bare shaft tuning shows any flaws in shooting form, so you have to be careful in interpreting the results of your arrow pitch/angle in target in relation to how you felt about the quality of the shot. I learned it’s best to take a few shots before interpreting the results and making any one adjustment. I also learned that bare shaft tuning has to be at a perfectly level position and it also took it’s toll on the 3 shafts I used for testing. After spin testing the 3 arrows used for testing, I don’t believe they can be considered pro shafts anymore.
PROBLEM:
First off, there’s a chart floating around that we have all seen that lists what timing marks you should have on your bow as a general guideline or reference point. I made a few calls to verify how many cam dots/marks “should” be showing past my limbs and I was told 5.5 top and 5.5 bottom. If using a drop away rest tied to the down buss cable, I should be 5.5 on top cam and 6.0 on bottom cam. Now here is where it gets interesting. I changed my cam location with what was recommended, and was shooting approximately 1-inch groups at 10-15 yards with a bare shaft arrow. That is not good in my book for that close of a range, so I proceeded to make several adjustments to gain better accuracy. I already had my bow super tuned a few weeks ago from trial and error at 60 yards, but wanted to try the listed information to see if my accuracy got better. In short, since I have used the listed data my accuracy has gotten worse. I have been back and forth and all over the board with these cams and keep verifying the same results. I now know where to leave the cams.
SOLUTION:
I made half twists to cables as required to always keep top cam at the recommended 5.5 dots showing past limb, but bring the bottom cam in a direction from 6 dots down to 4.75 dots showing past limbs. I headed in this direction because it’s the direction that I knew gave me good accuracy at 60 yards. This direction was completely the opposite of what was listed on the binary data. As I brought the lower cam from 6 dots to 5 dots past limb, I started hitting a “sweet spot” in my accuracy. For my bow 4.75 dots showing past bottom limb and 5.5 dots showing past top limb gave me bare shaft arrows that were shooting in the same exact hole as the previous arrow from 10 yards. I had to shoot 1 arrow at a time to prevent damage to arrows. This minor increase in accuracy may not sound like much, but as you know, when you can make small increases at closer ranges it will give you large gains at longer ranges.
CONCLUSION:
My point is not to say the charts or data floating around is incorrect information for all bows. As we all know, it’s impossible to give any guidelines that will provide the best accuracy for each and ever persons bow. The binary data listed, provided above average accuracy in my opinion for my set-up ( I did find worse locations). My point is that if you’re looking to squeeze all the accuracy you can out of your binary cam bow, you have to find it yourself with the proper arrows for your bow and poundage. Don’t get caught up like I did in how many dots are showing past your limbs, and try and copy somebody else’s bow tune. I wanted to throw this idea out there for those who are new like me and strive to reach the best tune from their bow. In closing, I’m not saying your timing dots will be like mine and I’m not saying that the listed data won’t provide you with acceptable accuracy under most conditions. I just think that if you like to tune, you may want to at least try a few different positions with your cam timing in either direction to see if you can increase your accuracy. The results may shock you and may speak louder than anything else recommended.
03-16-2006, 06:15 PM
#2
Boone & Crockett
Join Date: Oct 1998
Location: Hughesville, PA USA
Posts: 18,322
RE: Sharing what I've learned about Binary Cam Timing
Interesting. But may I ask, was this out of a Shot Machine or you doing the shooting? Could it be possible that you hit a peak in body and mind while testing rather than minor bow adjustments bringing human error into play?
I'm new to the Binary cam of my Allegiance and after tinkering with dual and single cam Hoyts for the past ten years, I'm curious.
I'm new to the Binary cam of my Allegiance and after tinkering with dual and single cam Hoyts for the past ten years, I'm curious.
03-16-2006, 09:01 PM
#3
Super Moderator
Join Date: Feb 2003
Location: Southeast Central Illinois USA
Posts: 6,969
RE: Sharing what I've learned about Binary Cam Timing
Since I don't know anything about the Binary cam system.......and this question is directed to veteran dual cam archers who now shoot a binary cam system, is their much of a difference at all in keeping the Binary cams in time compared to the dual cams? Being that I shot dual cams up until 2000, I really never had any real problems keeping my dual cam bows in time except for a couple of high country bows, and I believe those problems were because of the string quality. The newer string materials available today do not stretch like the old fast flight strings.
03-16-2006, 09:08 PM
#4
Super Moderator
Join Date: Feb 2003
Location: Southeast Central Illinois USA
Posts: 6,969
RE: Sharing what I've learned about Binary Cam Timing
One other question since Mildot brought this up about the binary cam system. Doesn't the binary cam system stay in time much better and longer even with slight string stretch, than the old dual cam bows? If not, I can see no advantage.
What I am suggesting is this.............with the advent of 452 and other string materials, are we possibly overrating the hybrid cam, the one cam, and binary cam systems in comparison to true dual cam systems of old?
What I am suggesting is this.............with the advent of 452 and other string materials, are we possibly overrating the hybrid cam, the one cam, and binary cam systems in comparison to true dual cam systems of old?
03-16-2006, 09:53 PM
#5
Nontypical Buck
Join Date: May 2004
Location: Albany, NY
Posts: 4,679
RE: Sharing what I've learned about Binary Cam Timing
There is a difference between what I call correct timing, and correct syncronization. The cams will always keep in perfect syncronization and roll over at the same point in the draw cycle on a binary cam (as far as I have seen messing around with mine and other peoples bows, and from what I have read). You can however throw the bow out of timing and the optimal position for the best efficiency fairly easily, and getting it back into optimal position can be like herding cats (darn near impossible it seems at times[8D]).
03-16-2006, 10:40 PM
#6
Giant Nontypical
Join Date: Feb 2003
Location: Jackson, Missouri
Posts: 7,051
RE: Sharing what I've learned about Binary Cam Timing
MilDot, I think you only confirmed what most BowTech shooters are experiencing; in fact, while working the BowTech booth at the Illinois Deer Expo with Pat -- the man who handles most of the tech support for BowTech -- I asked him a question regarding the dots, and he basically said that too many people were putting too much stock in them... and he was going to suggest to have them removed for '07. I think he may have been kidding just a bit with that remark, as I know some people -- like yourself -- find them useful as a reference point. His premise was too many people were making too big a deal out of them.
Coug, if you can get your hands on a copy of the most recent issue of Bowhunting World, there's a great sidebar on page 18 about "String Stretch & The Twin-Cam Bow." I'm gonna try to keep from re-typing a lot of it here, but if you need me to, I will. Some great points about twin cams and their offspring actually being less sucseptible to string stretch than single cams... especially with -- as you noted in your second post -- the advent of more quality strings.
Obviously, as Rick pointed out above, the binary cams are slaved together, which minimizes sychronization issues; you've still got to check for tuning issues, i.e., centershot, correct nock-point height, etc.
Being that I shot dual cams up until 2000, I really never had any real problems keeping my dual cam bows in time except for a couple of high country bows, and I believe those problems were because of the string quality. The newer string materials available today do not stretch like the old fast flight strings.
Obviously, as Rick pointed out above, the binary cams are slaved together, which minimizes sychronization issues; you've still got to check for tuning issues, i.e., centershot, correct nock-point height, etc.
03-16-2006, 11:24 PM
#8
Nontypical Buck
Join Date: Aug 2004
Location: Bradford, Ontario
Posts: 2,205
RE: Sharing what I've learned about Binary Cam Timing
This is quite informative. When making changes did you also shoot through a chrono to see the effect on FPS ? I think what you are doing is what some pros like Crackers do when doing thier magic, but as already stated you would almost need a Hooter Shooter to remove the human error factor on accuracy. What all of this proves is that a quality string and cable is quite important to keep everything in tune to your personal settings . Any stretch would possibly have quite an effect.
03-17-2006, 09:15 AM
#10
Nontypical Buck
Join Date: Feb 2003
Location: WEST PALM FLORIDA
Posts: 2,890
RE: Sharing what I've learned about Binary Cam Timing
Cougar , the two systems are diferant .
twisting cabels on the binarys has nowhere near the efect on nock travel that twisting the cabel on a twin does , creep tuneing does not realy apply to the binarys , like it does to a dual system
Milldot , there is an effect on letoff when you change the cabel lengths , ie twist them , Im pretty sure the more missmatched they are the greater the letoff .
twisting cabels on the binarys has nowhere near the efect on nock travel that twisting the cabel on a twin does , creep tuneing does not realy apply to the binarys , like it does to a dual system
Milldot , there is an effect on letoff when you change the cabel lengths , ie twist them , Im pretty sure the more missmatched they are the greater the letoff .