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Thread: Super-tuning single cam bows...

  1. #1
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    Super-tuning single cam bows...

    Hi all.

    Here is my current process for super tuning single cam bows. I have refined this process by tuning about 20 bows now with a wide range of arrows and broadheads. This is worth doing even if you plan to shoot mechanical heads as you will ensure you get optimal power to your arrow.

    One of the major differences I have found is that cam lean must be correct to get bullet holes. And I do not adjust the rest side-to-side until I get the cam lean right for bullet holes through paper. Also, I will only shoot a bare shaft through paper. Fletching prevents getting a clear picture of how the arrow is flying.

    If someone with experience with other cam set-ups, I'd like to hear how they differ. I'm not a Mathews fan boy, but I do own all Mathews bows which happen to be single cam bows. I have setup and tuned several Hoyt's that my friends own, but only did one twin-cam bow. Bowtech's are rare in southern California - I've only seen one.



    Tools I use include bow press, bow vice, string level, arrow level, allen wrenches, paper tuning rack, and tape measure.

    Ray

    Super Tuning your Single-cam Bow

    1. ensure arrows are stiff enough and straight, broadheads spin true, and fletching adds spin to the arrow
    2. ensure string is in good shape
    3. get bow into spec: ATA, cam timing, limb poundage, cam lean
    4. set-up rest so that arrow is even with burger button, centered on string/cams (11/16" from riser to center of arrow on Mathews)
    5. for single-cam bow, set-up nock point so nock is 1/8" to 3/16" high
    6. shoot a bare shaft through paper until you get perfect bullet hole. Adjust cam lean until left/right tears are gone. For nock-left tear, add twists to right yolk. For nock-right tears, add twists to left yolk. Adjust rest up or down for nock-high or low tears. Principle is to move the arrow point to be in front of the arrow nock by adjusting the rest.
    7. set top sight pin to top of sight guard. adjust sight gang so top pin is on at 20 yards with field points
    8. On a windless day, broadhead tune at 20 yards, make micro adjustments to rest to move broadheads to field points, adjusting sight pin gang as necessary
    9. broadhead tune from 30, 40, 50, 60, ... 100, set appropriate sight pin as necessary. I like Muzzy 3 blade for tuning because 1) they have practice blades that are easy to remove from target and 2) if they fly good, so do most other fixed heads.


  2. #2
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    Agreed with everything stated..
    i do have a goofy one thought, i super tuned my diamond nitrous, but to get broadheads and field points to fly together i have to have a tiny high tear through paper..

  3. #3
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    Quote Originally Posted by bowhuntermitch View Post
    Agreed with everything stated..
    i do have a goofy one thought, i super tuned my diamond nitrous, but to get broadheads and field points to fly together i have to have a tiny high tear through paper..
    I've read that persistent high-tears on single cam bows may be due to an overly stiff spine. I've not yet had any problem with arrow spine being too stiff. However, I have run into problems with spine being too weak.

    Although I'm an avid reader/researcher, I've learned much of this the hard way - shooting hours and hours, day after day at the range, in my garage, etc until my arms can't take it any more.

    Another common misconception is to use side-to-side arrow rest adjustments too early before you get the cam lean correct. You can get decent arrow flight by doing that, but I got better results by starting with eveything in line, then getting cam lean right, then making micro adjustments to the rest only during broadhead tuning.

    Edit: I used the term "cam lean," but it is more correctly "idler wheel lean" as the yolk attaches on either side of the idler wheel. I'm not sure how I came to call it cam lean.

    Ray

  4. #4
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    First, great write up. Thanks for taking the time to share that

    But that just looks like run of the mill tuning to me

  5. #5
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    Posting to bookmark this. I may be adding an inexpensive single cam bow to my stable.

  6. #6
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    Nice job, but I do have one question. Are you talking about Cam lean or Idler lean. The cam on a Mathews bow should always be very close to parallel with the string. The Idler wheel on the other hand should always be close to straight up and down at full draw, and at rest have some lean.

  7. #7
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    Quote Originally Posted by crackedup View Post
    Nice job, but I do have one question. Are you talking about Cam lean or Idler lean. The cam on a Mathews bow should always be very close to parallel with the string. The Idler wheel on the other hand should always be close to straight up and down at full draw, and at rest have some lean.
    Yes, it is idler wheel lean. I've always heard it called cam lean, but I should have called it idler wheel lean. The yolk attaches on either side of the idler wheel, so that is what we are adjusting.

    I have never seen a tuning guide that start with idler wheel lean adjustment to get bullet holes. They usually start with adjusting your arrow rest.

    Also, if you get it to shoot bullet holes through paper with a bare shaft, you can put on a mechanical or a lower profile fixed head and it will probably group field points and broadheads pretty well - at least under 50 yards.

    Ray

  8. #8

    Thumbs up

    Good write up / info.
    Paper tune, try different broadheads, fletching, or shafts; don't move the sight for broadheads.
    Mathews Drenalin LD 30" draw 61# 413 gr. arrow @ 273 fps / 68# KE / .50 momentum
    Mathews Drenalin LD 30'' draw 59# 325 gr. arrow @ 292 fps / 62# KE / .42 momentum

  9. #9
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    This might be common knowledge but I didnt know any of it so I appreciate the write up. Thanks. I will be printing this and adding to my Archery 3 ring binder.
    Bear Truth 30" 75#, Muzzy 100 grain 3 Blade, Gold Tip 7595 with Gator Wraps and Orange and Blue Blazers

    If your not a Gator, You are Gator Bait...

  10. #10
    Great post Ray. I see way too many people start tweaking their rest before making sure the bow is spec'd out and the string is tracking true.String track is the cause of 90% of the tuning problems, imo.
    "When they come for my guns, I will pry their guns from their cold dead fingers."

  11. #11
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    bump

  12. #12
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    Quote Originally Posted by krieger View Post
    Great post Ray. I see way too many people start tweaking their rest before making sure the bow is spec'd out and the string is tracking true.String track is the cause of 90% of the tuning problems, imo.
    Hi Krieger.

    Yes, and things get pretty strange when you try to patch an idler wheel lean problem by shifting the rest.

    I often hear of guys who say they just can't get a bullet hole and I'm pretty sure it is due to either 1) idler wheel lean or 2) spine problem. You rarely hear about how to adjust your idler wheel properly.

    Ray

  13. #13
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    I am just starting to play around with tuning my mathews bow and my wife's mathews bow. I was just wondering about one measurement you gave in #4 (11/16" from riser to center of arrow on Mathews). In the mathews manual it says to start at 13/16" from the riser to center of the arrow.
    Actually, I always align the string, cam, wheel and arrow so they are all in allignment. I do it by eyballing down those various points. It ends up being 11/16" on both of my current type of bows (Mathews LX and Mathews Conquest). If it came out at 13/16", then that is where I would start. Remember, this is just the starting point, but you will use it to get your idler wheel lean correct and your rest height correct. I don't adjust the rest side to side until after I get bullet holes with bare shaft, then start doing broadhead tuning. And if you get bullet holes with bare shaft, when you go to broadhead tuning, you will not have to make much rest adjustment at all - usually less than a 32nd of an inch in any one direction. In your case, I would start with what the manufacturer recommends for you to start at 13/16" unless you want to eyeball it like I do.

    Also, I have read several places about setting the nock up to 1/2" above the 90 degree point to start out. Why do you do this and not set it perpendicular initially?
    Single cam bows have vertical string travel due to the cam, but this only happens from below where the cam is. Dual cam bows both travel so the nock does not move up and down during the release, so I would expect that you start the nock point level for dual cam bows. It does not hurt to start where they recommend because you are going to change it after shooting your bow and only to improve the flight of your arrow and broadheads.

    Have fun! It is fun and rewarding to do your own equipment and to be self-sufficient. And if you have any questions, I'm always happy to help.

    Ray

  14. #14
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    Nice write-up

    However, If i set my rest at 11/16ths on my SBXt, and idler wheel tuned, i bet the string would fall off before I got a bullethole.

  15. #15
    Thanks

  16. #16
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    Quote Originally Posted by HammyAbeer View Post
    Nice write-up

    However, If i set my rest at 11/16ths on my SBXt, and idler wheel tuned, i bet the string would fall off before I got a bullethole.
    SBXT must be one of the 13/16" models. Like I said, I prefer to eyeball it so the string, cam, idler wheel, and nocked arrow are all in line. That should work in any case. Any specific measurement is likely to be right for some models of bows.

    Ray

  17. #17
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    My new LX string and cable arrived today from H&M. I'm gonna go put them on right now!

    Ray

  18. #18
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    Interesting read. I shoot custom strings on most of my Mathews bows and have my string guy make a floating yoke. I really haven't had any issues with idler lean, though I do typically look for it.

    I have had great results just "bench tuning", starting with the d loop at dead level (and thru the center of the berger button hole) and centershot set with a guage......9 times out of ten I can just go out and walk back tune right off the bat, generally with broadheads. I have never worried about my broadheads and FP's hitting the same place. But by walk back tuning the fixed blade broadhead first, the FP's and expandables generally follow and shoot in the same hole all the way out.

    I've had great luck going with a fairly stiff arrow. In fact, I have yet to have a problem with "too stiff" since I started shooting carbon about 10 years ago. I have however gotten burned "too weak", especially with Gold Tip arrows. Great arrows, but their spine charts were always on the weak side IMO.

    Gotta love the single cams, though....Even a rookie can get them shooting good, and if you spend the time Ray does, you can have a true tack driver.

    Thanks for a good thread.
    manybows

    Technical Training: Replaces Cocksure ignorance with thoughtful uncertainty.

    The only thing worse than packing meat is not packing meat. Dwight Schuh

  19. #19
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    Good post Ray!

    Lots of Mathew shooters look at other things besides the idler when they can't get consistent, good arrow flight, and it can cause problems if it's not set right.

    You mentioned cam timing, but you forgot to mention Mathews cams HAVE timing holes, and yes, a single cam bow CAN be out of tune.

    If you fiddle with it long enough, you will find a sweet spot in your cam rotation, and if you have a quality aftermarket string, it most likely will not move.

    My cams work best on my Drenalin slightly under-rotated.


    Very helpful post Ray!
    Quote Originally Posted by gun870guy View Post
    I wish more of you daisies actually went out and failed and learned something on yer own. This isn't a place to learn bowhunting from some J@ck@$$.

  20. #20
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    Quote Originally Posted by Lonestar63 View Post
    ...a single cam bow CAN be out of tune...if you fiddle with it long enough, you will find a sweet spot in your cam rotation...My cams work best on my Drenalin slightly under-rotated.
    Wow! I have not tried setting the cam forward or backward from recommended timing. I always set the cam timing as part of the "get the bow in spec" part and assumed it would behave best where it was designed to.

    That is interesting your Drenalin works best slightly under rotated.

    Ray

  21. #21
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    Last night, I put my new H&M string on my LX. I set it to spec, then set the rest where I explained above, then I never moved it. I only adjusted idler wheel lean (via twisting the yolks) and nocking point (by removing and reattaching the D-loop. Now it shoots perfect bullet holes. Tomorrow, I'll head to the range and do broadhead tuning.

    I always set the initial idler-wheel-lean so when I place an arrow on the shelf side of the idler wheel, the arrow is perfectly parallel to the string. That is usually pretty close to right. I had to add a few twists to the left (the side without the shelf).

    Ray

  22. #22
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    How do you determine idler lean? Just by looking at the idler while the bow is undrawn, while you draw it, on a draw board, or while someone else draws it?

  23. #23
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    Quote Originally Posted by manybows View Post
    Interesting read. I shoot custom strings on most of my Mathews bows and have my string guy make a floating yoke. I really haven't had any issues with idler lean, though I do typically look for it.
    I've seen these floating yolk on other bows and wondered if they would be better or worse. 1) you don't have to adjust lean, but 2) you can't adjust it if you need to. I would expect that, as long as your limbs are consistent in strength and not twisted, the floating yolk would be better.

    Quote Originally Posted by manybows View Post
    I have had great results just "bench tuning", starting with the d loop at dead level (and thru the center of the berger button hole) and centershot set with a guage......9 times out of ten I can just go out and walk back tune right off the bat, generally with broadheads.
    My experience is consistent with yours except that I invest the time to get bullet holes through paper with a bare shaft to ensure I'm super close before I start shooting broadheads. If I get it shooting bullet holes with bare shafts at my shop, it is usually good enough to shoot broadheads and fielld points together for most hunting situations. However, I like all my bows to be tack drivers (like you said), so I do the minior tuning of the arrow rest to get Muzzy's and field points together out to 100 yards.

    I started on this quest when my buddy bought a brand new Mathews Switchback (four years ago) which was set-up by a pro hunter who has his own shop. It would not shoot broadheads with field points no matter how we adjusted the arrow rest. I suspected the broadhead, the arrows, (and tried all variety of alternatives), but nothing fixed that problem. He took it back to the pro shop-owner twice, but he could not get it done correctly. Finally, I read about setting idler wheel lean and tried it. Adding twists to the right yolk reduced the left tear, so I kept doing it until I got bullet holes. Then the problem was fixed and I was able to make his bow a tack driver too.

    Quote Originally Posted by manybows View Post
    I've had great luck going with a fairly stiff arrow. In fact, I have yet to have a problem with "too stiff" since I started shooting carbon about 10 years ago. I have however gotten burned "too weak", especially with Gold Tip arrows. Great arrows, but their spine charts were always on the weak side IMO.
    Amen! My experience is exactly the same! I just bought a dozen Victory 350s that were correct for my bow by the spine chart, but there is no chance they will fly right out of my bow. I really need the 300s. I've always been able to shoot the stiffest arrows made with no problem.

    Quote Originally Posted by manybows View Post
    Gotta love the single cams, though....Even a rookie can get them shooting good, and if you spend the time Ray does, you can have a true tack driver.
    Great point! They really are simple and easy. While I was trying to figure them out, I kept telling myself, "this isn't rocket science, it is just a bow and arrow."

    So, Manybows, have you tuned dual cam or cam and a half bows? How are they different than single cam?

    Ray

  24. #24
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    Quote Originally Posted by Ray.Klefstad View Post
    Wow! I have not tried setting the cam forward or backward from recommended timing. I always set the cam timing as part of the "get the bow in spec" part and assumed it would behave best where it was designed to.

    That is interesting your Drenalin works best slightly under rotated.

    Ray
    Same with my switchback.. I just tried the parallel rule of thumb (again) and it put it all out of whack

  25. #25
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    Quote Originally Posted by hoggin03 View Post
    How do you determine idler lean? Just by looking at the idler while the bow is undrawn, while you draw it, on a draw board, or while someone else draws it?
    The main point of this thread is it can only be set correctly by achieving bullet holes through paper with a bare shaft.

    Cam timing and ATA can be set properly by static setup and measurements.

    You can eyeball the setup for initial rest windage (arrow, string, cam, and idler wheel all in alignment) and elevation (arrow even with the burger button).

    You can set the initial idler wheel lean setting by placing a straight edge (like an arrow) against the shelf side of your idler wheel, then seeing how well it parallels the string. I look at the point near the nocking point. I start with the arrow pretty much parallel to the string, then do dynamic adjustments from there.

    But then comes the shooting a bare shaft through paper and twisting yolk to remove nock-right or nock-left tears. You can raise or lower the nocking point to remove nock-high or nock-low tears.

    Ray

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