Sentinal tuning suggestions
 

Any and all suggestions welcome. Having trouble getting my Sentinal to tune and not sure why? Had the bow for a little over a month. Put on Winners Choice string and cables and have been getting everything settled.

71#, 28.5 inch draw shooting a loop. Limb driver rest set at true center with a laser. 28 inch Full Metal Jackets 340. 125 grain FP's and 125gr Slick Trick Mags.

Got everything settled and left shop with a good paper tear. Bow shoots great, arrows touching at 20 yards and 3-4 inch groups at 40.

Started tuning process and decided to try bare shafting as I have never done this. At 20 yards bare shafts hit 5 inches to the right of fletched shafts. Fletched shafts are straight in the target, bare shafts are severely tail left. Bare shaft groups arrows all touching. Thought a weak spine reaction was odd with these arrows and this set up. Same arrows I used with the 82nd and that tuned easily.

Tried broadheads, they grouped 5-6 inches to the right of the FP's. Groups were tight. Tried brining them together adjusting the rest but not having any luck. I've moved the rest 1/4 inch and gained maybe an inch with the groups. I'm going to run out of windage adjustment on my sight pretty quick.

I haven't been able to get any lighter FP's to adjust my spine, I'm going to try that this weekend. Not sure what else to do?

Fletched with Blazers and I've checked for vane contact and not seeing any.

AA,shows marginally weak,but that is assuming 100% match in efficiency with the program.Try lowering poundage to 65#'s and see what happens.

Your spine is showing too far out for different weight fieldpoints to fix.

Plus,I put no stock in setting center with a lazer.

I gave you a 1" overdraw on the program,that is assuming your rest is about 1" behind the berger hole.

I'll reset the rest tomorrow with walk back and start over.

1 inch is too much with my limb driver I just went and looked and would be 1/2 at the most.

Think it is just a spine issue? I think they are awful far out of line for it to be spine?

It does seem like quite a bit for no more than you are showing weak.

Lower poundage a couple pounds.Reset center with walkback and then try again to broadhead tune.

I know that the computer programs love to rccomend really stiff arrows, and I cannot argue with the arrows showing a weak reaction, but IME with the 09 & 08 Center Pivots, they like a little bit weaker spine than you would think. My Commander likes a 400 spine (28.5/72 pounds) and the Admiral liked a touch soft as well. Both of these setups tuned easy peasy with the LD, running centershot straight down the middle of the grip, leveling the bow, rest , then nock point with the arrow in question.

Also make sure your LD cord is fairly stiff at tension and the LD attachment is as close to the cam as you can get it. On some bows It's a very fine line between the cord being too lax, and too tight.

I know it goes against common theory, as you're getting a weak arrow indication, but sometimes it's really an indication of the arrow being too stiff. You could try making adjustments opposite of what you'd think.

I always bare shaft tune my setups and get a tail-left bare shaft, which would indicate a weak arrow, but most times it's just the opposite. I can usually confirm this by shooting a stiffer spine and the reaction gets worse---farther right and angled harder.

Two things. One, I rarely shoot a bow maxed out. Two, if my bare shaft planes to ne side or the other I rarely ever move my rest. I adjust the draw weight up or down. This allows me to see just which way I need to go. From experience I usually know anyway whether to add or subtract weight.

As an example, I have a Martin Moab that I'm shooting at 47# and 26.5" draw. Theoretically I should be shooting about a 600 spine. I tried a 560 (ACC 3-18, 27" shaft) and it wasn't good. Arrow planed to the right, tail-left. Weak arrow? I then shot a 500 (ACC 3-28) and then a GT 22 Series (300 spine), In each case the planing got worse, with the arrow planing farther right and tail left at about 45 degrees. All this shows me is that I was not getting a weak arrow reaction, but one that is too stiff. Without moving the rest, but adding draw weight I was able to get things straightened out better.

I have an older version of Easton's Tuning Guide and reading the next to last paragraph on page 13 describes this fairly well. In assense it says that releae shooter sometimes get an opposite indication then that of finger shooters when bare shaft tuning. Make your adjustments accordingly.

Well went and shot some groups this am before work. I haven't moved anything yet but arrows grouping to the right as I go back. Pretty close at 30 yards and about 2 inches right at 40.

Jeff,have you tried a fixed blade broadhead tune yet with that setup? Sometimes everthing tunes great untill a broadhead is added to the equation.

I agree that sometimes we get the opposite reading from what we really need and I also agree that sometimes we need to make adjustments in arrow spine that defies logic.



I am actually suspecting that the 340 is the proper spine by the time he has lost efficiency of the rotating module down to his draw length.This is why I said turn the poundage down and recheck,that is a free adjustment.

Well I am having no luck guys. This is frustrating. Can't get the walk back tune done. I'm real close but out of windage adustment on the sight. Arrows are still drifting right as I go back. Good at 10, 20, 30 and off about an inch at 40. Rest is almost out of adjusment to the left and sight is. Broadheads still 3-4 inches right of field points.

Cranked down 5 pounds and bare shafts still 5-6 inches right of fletched, cranked down another 2 lbs and bare shafts didn't move still grouped 5-6 inches right with bad tail left. (Mean decreased draw weight when I said cranked down.)

Valid point. And no I have not- I shoot mechs :D