Contributors to this thread:
Why does yoke tuning work?.
The last two bows I've tuned which are both 2012 Hoyt's with RKT cams required quite a lot of yoke tuning to get them tuned. Both bows were set to center shot and then I twisted the right hand yoke to induce cam lean at brace (both bows are right handed). With the cam perfect at brace I was getting about a 1" left tear in paper and broadhead flight was terrible. Th induced cam lean cleaned up the arrow flight. There's no question this worked since both bows are now shooting extremely well.
Can anyone explain what this does and why it works?
Because you are putting opposite cam lean in force to counter act natural riser torque at the shot.
You set center shot first? To a given point or do you find it by tuning. I shoot a 2 Hoyts. I adjust the yoke to try to eliminate/minimize cam lean. It can be a compromise between lean at rest and lean at full draw. Then I set centershot..buy adjusting the rest in or out to get a decent tear. I don't look for perfect here...I go to a walk back or "French" tune and fine tune with broadheads.
I can see that "tuning" the yoke would change the pressure point on the arrow during the power stroke. (i.e. moves the nock point left or right). It seems like a difficult way to accomplish what you are looking for..and excessive twisting of the yoke can mess up your basic timing and syncronization of the cams.
If it works great...would like to hear more.
Center shot was set using a laser centering tool....
Also, I've never had to induce cam lean prior to these two bows....
I have never used a laser for center shot. I set with a ruler or by eye and shoot it in. I have never found a factory figure for centershot..exactly correct for any bow I have owned.
Have you put the bows on a drawboard and watched what happens throughout the draw and then upon let down? It is surprising how much things move around. When I tune the yokes I look at the cam lean at full draw and at rest and twist to minimize it across the full draw. We may be doing the same thing. You set the centershot and then induce cam lean to match your setting. I minimize the cam lean and move (induce) the centershot to fit that condition.
Changing the tilt of the cam simply changes the nock travel of the string line vs the riser. By adjusting cam lean you can move nock travel from inside out to outside in.
Vary rarely will the theoretical perfect string line from top cam/wheel to the nock at full draw give a perfect tune. This is due to manufacturing tollerances of bows. You can never have two limbs, axel holes and risers that are all perfectly the same. Hoyt and PSE split limbs double down the need to micro adjust cam lean to get good dynamic nock travel.
Often the newer Hoyts and PSE split limb bows require the top cam to lean outward to get centershot nock travel.
It's all about string travel.
What they said, string travel. Riser torque, cable pressure from the cable guard, even differences in limbs, etc. My bowtech has both an upper and lower yoke.
Yoke tuning the way I understand it is just a way to try and get a rough tune like a paper tune as close to centershot or centerline as possible. When you move on to a finer tune such as broadhead tuning, etc. you still make the finer adjustments with the rest, but shouldn't have to move it much off of the center.
Thanks guys, makes sense.
So does yoke tuning affect center shot settings? In other words should center shot be reset after yoke tuning?
I've always understood center shot to be the "setting" that allows the strings power stroke to be in perfect line of the arrow. Or as "perfect" as possible. Other than "factory" recommendations for a specific bows CS, I assumed (a mistake I know it can be) that you must tune broadheads and walk back etc to "find" that specific bows true CS.
While 11/16" and 3/4" are often recommended,, it seems they are starting points and one may end up off these marks and still get great broadhead/FP flight and equal impact sites. This to me s finding the perfect center shot.
Now is CS in respect to only horizontal nock travel o does I take into account vertical also?
The very last thing I do is set center shot. Do what you can with the bow you have to reduce unwanted string travel, THEN adjust the center shot as you fine tune. I like to adjust yokes so that I find the "happy medium" in cam lean. Not plumb at brace, not plumb at draw, but somewhere between. Usually a little closer to plumb at brace than at full draw when I'm done tuning.
All kinds of things can be "counter tuned" out, even bad form and hand torque. I know some guys who shoot underspined shafts because that's the only shafts that'll flex enough to counter their hand torque. When someone else shoots their bow, it tears a wicked hole, but for them, it shoots fine(under ideal conditions).
My philosophy has always been to tune the bow to shoot as well as it can by itself, then good form will be rewarded.
Any initial center shot setting is just that. A starting point. Your body is part of the shooting machine, including your good and bad habits.
Murphy's Law of physics (For every action there is an equal and oppisite reaction)