Yet another tuning question....

[Unleashed]

I have a Phase 4 29 that I had setup by a shop last year with GAS Ghost strings and it shot broadheads very well. I did a 4 mile movement during elk season and wore a thin spot on the string so I put on some 60X strings I had purchased prior to the GAS strings last year. I spent a ton of time spinning the cables to get the ATA and timing corrected and then another 4 twists chasing a straight peep. I finally have the strings stable enough to keep the peep straight but can't get a consistent broadhead flight. Today while shooting, my broadhead would land 2-3" left of my field point once and the next time it would turn hard left, impacting 12-14" inches left of my field points at 50yds. I could see the arrow drifting in flight like I was shooting in 30mph winds. I am shooting 28" 300 spine arrows with 200 grains up front for a total weight of 512gr, 75lb/27" draw and single bevel Iron Wills. To throw one more wrench in the equation, both vented Iron Wills and Slick Trick Viper Tricks land closer to the field points with just a slight favor left. I would just switch broadheads but want to know what is causing the errant flight and still have some work to get the favor left out. I just got a top hat kit in today and plan to move the cams further to the right. At full draw on the draw board the shaft is pointing left. Obviously I'm pretty new to all this so any advice would be much appreciated.

 

[Mighty Mouse]

Inconsistent broadhead flight can be caused by insufficient fletching or weak spine.

What vanes are you using?

I would think 300 would be sufficient at your specs, but if you wanted to test the effect of stiffening the dynamic spine, you could reduce draw weight a bit and see what happens.

Once you get consistent broadhead grouping, bringing BH's rightward to match FP's should be a simple matter of adjusting rest windage and/or swapping top hats.

Edited to add: Also number your arrows and keep track as you shoot to see if there are consistent fliers. If there are, put them on a spinner to check for a bent insert or broadhead ferrule. If the fliers spin true, try nock indexing to bring them inside the rest of the group.

 

[Skerhunter]

A lot going on here - did you confirm timing after you changed cables/string? If not get that in spec before doing anything else. Also something to note - you should always measure your new strings/cables before putting them on and confirm they are in spec. Your comment about needing a ton of twists to set ata is slightly concerning.

 

[Unleashed]

Inconsistent broadhead flight can be caused by insufficient fletching or weak spine.

What vanes are you using?

I would think 300 would be sufficient at your specs, but if you wanted to test the effect of stiffening the dynamic spine, you could reduce draw weight a bit and see what happens.

Once you get consistent broadhead grouping, bringing BH's rightward to match FP's should be a simple matter of adjusting rest windage and/or swapping top hats.

I'm running TAC Driver 2.75" vanes. I have a Phase 4 33 at 60lbs that group these same arrows/broadheads like a field point. I was really surprised that it would shoot such a stiff spine at that weight. Of note, I put ABB strings on the 33 at the same time that I put those 60X on the 29. I was setting the ATA and timing on both at the same time but I had to fiddle with the 29 at least 3 times more to get it set. The 33 shoots lights out but the 29 keeps giving me fits.

 

[Billy Goat]

Twisting cables on those bows is a PIA, it takes a while for things to settle out because of how much serving they have. This will only be giving up/down issues tho for the most part as the timing is controlling the vertical nock travel. It's always good to measure stuff, both as it comes off, and before you put it on. Set your string and cable to the lengths that you are removing unless you have gotten a lot of creep, then go back to factory spec. Most of mine have a little bit of d-loop material in a cable to get timing right where I want, when it's really close, it will shorten a cable just a fuzz. When making string or cable adjustments on those bows, after an adjustment, shoot them about 5 times, then double check.

Keep in mind the yoke splitters are supposed to be 90 degrees to the string. The little flat across the top, perpendicular to your string, especially on a 29, it will have the cable coming off out of center, but it helps with cam lean.

A left/right issue is generally in horizontal nock travel, cleaned up with cam lean and centershot. Needs to be a consistent reaction tho, it sounds like you aren't there.
You are probably on the weak side with 200 up front on a 28" 300 spine shaft and 75# pushing it. Cut shaft shorter, reduce weight on the front or on the bow. You can't get too stiff. I personally found that the SW cams seemed to push a spine fairly hard.

 

[KyleR1985]

Possible rabbit hole to peek down:

I have a phase 4 with gas strings. Spent the summer tuning it, got it tip top. Going on a 10 day back country hunt, and wanted a spare string in my pack just in case. Bought a set of phantom strings.

The gas strings are twisted in the direction that causes the arrow to have a natural counter clockwise rotation. Was all set up to fletch all my arrows left hand offset and helical. When I put the new strings on, had the bow bare shaft tuned, I shot my one left fletch arrow. I couldn’t get it to act right.

Did a slow mo video to see if I could catch what was happening, because I was pulling my hair out.

Instantly recognized the arrow not rotating immediately and looking like a noodle.

Right fletched an arrow, cleaned it up immediately.


Kind of a bummer I hadn’t considered that the strings might be twisted the opposite way. But here we are.

Have a handful of left hand zingers in my pack with the strings. If I have to make a change I can boil water, strip wrap and fletches, and have left fletch arrows in about ten minutes.





None of this matters at short distances probably.

But something you might check out.

 

[KyleR1985]

Twisting cables on those bows is a PIA, it takes a while for things to settle out because of how much serving they have. This will only be giving up/down issues tho for the most part as the timing is controlling the vertical nock travel. It's always good to measure stuff, both as it comes off, and before you put it on. Set your string and cable to the lengths that you are removing unless you have gotten a lot of creep, then go back to factory spec. Most of mine have a little bit of d-loop material in a cable to get timing right where I want, when it's really close, it will shorten a cable just a fuzz. When making string or cable adjustments on those bows, after an adjustment, shoot them about 5 times, then double check.

Keep in mind the yoke splitters are supposed to be 90 degrees to the string. The little flat across the top, perpendicular to your string, especially on a 29, it will have the cable coming off out of center, but it helps with cam lean.

A left/right issue is generally in horizontal nock travel, cleaned up with cam lean and centershot. Needs to be a consistent reaction tho, it sounds like you aren't there.
You are probably on the weak side with 200 up front on a 28" 300 spine shaft and 75# pushing it. Cut shaft shorter, reduce weight on the front or on the bow. You can't get too stiff. I personally found that the SW cams seemed to push a spine fairly hard.

As a reference point I shoot 30” draw 75lb on Phase4 29. Rip tko 300 cut 27-5/8 c2c, 225gr up front. Total arrow weight 510-540gr depending on vanes and wraps and nocks.

Have shot this arrow across an elite, prime, and Mathew’s at 30” draw and draw weights ranging from 74-80lbs with no issue tuning.

I did come down to 29.5” draw this year as this bow seems to be just a hair long for me at 30.


Not saying you’re wrong, every person and bow is different. And I definitely agree with you that there’s no harm really in being too stiff on a compound.


My general rule is to follow spine chart for my specs, then go to the next spine up as a starting point. Arrows cut as short as possible.

 

[Bump79]

I'm a simple guy. You're properly spined and fletched so if everything is in time and there isn't fletch contact then I'd just move my rest ever so slightly left. Top hats to move right if you're out of centershot.

 

[Unleashed]

All great information and suggestions. I never knew how complicated bows could be. I've got 25 years of competition shooting from USPSA/IPSC & 3-Gun to the more technical PRS so I know how to go down a rabbit hole, both bad and good!

I changed the top hats to push the cams all the way to the right and then had to move the rest ever so slightly right for a CS of 3/4". The arrow flight looks way better and I'm now within an inch of field points at 40yds. However, my peep is turning again and I have zero confidence in these 60X strings. Cam timing changed just a touch too. I have some Gas strings on the way but will only have 5 days from the time they arrive until I jump in the truck for CO. I'll keep shooting these strings and hope they settle down....maybe they need more than 500 shots to take a set. At least I have the 33 to fall back on as it continues to shoot great, I just didn't want the extra length and weight if I didn't have to.

 

[S.Clancy]

It's possible the 60x came out of spec. Did you measure the strings before installing them?

 

[Unleashed]

It's possible the 60x came out of spec. Did you measure the strings before installing them?

I wish I had. I didn't know any better at the time. I have lost 2fps in the past 200 shots, so there's that. I find that baffling considering that last year I pulled my Z7 out with the still factory strings and it hadn't lost a beat since 2011. I've been shooting both the 29 and 33 all day and although the 29 is shooting better, it still throws some errant fliers that I can't explain. I'm putting the Gas strings on the 29 when they come in Tuesday. The 33 shoots so well that I'll carry that if I can't get the 29 squared away.

 

[Skerhunter]

“Errant fliers” - will be repeatable if you have a bad arrow or component. Mark that arrow when it happens. If it’s not repeatable it’s your form.

If your peep is turning it’s not in your string properly and will always be an issue, pretty easy fix (move more strands of string to other side of peep).

I wish I had. I didn't know any better at the time. I have lost 2fps in the past 200 shots, so there's that. I find that baffling considering that last year I pulled my Z7 out with the still factory strings and it hadn't lost a beat since 2011. I've been shooting both the 29 and 33 all day and although the 29 is shooting better, it still throws some errant fliers that I can't explain. I'm putting the Gas strings on the 29 when they come in Tuesday. The 33 shoots so well that I'll carry that if I can't get the 29 squared away.

 

[doc holiday13]

Your best bet is to start with timing. Paper tune with FP. Shoot broadhead. IF broadhead is hitting left or your paper tune indicates non bullet hole, you need to shim. I JUST had this issue yesterday. I was slightly out of time and i needed to shim to correct the broadhead flight because The broadheads flew perfect a few months ago

 

[Unleashed]

So, after at least 25 hours of tuning, changing arrows, shooting, losing my mind....I finally found the problem. I decided to upgrade my release when I first started getting ready for the season and went with the UV Button. After changing everything on my bow and arrow setup I finally decided to go back to my old release with a floating head. All my errant fliers, shifting groups, and other fuckery went away! I was torquing the string with my anchor point. Makes sense why the 33 wasn't as affected as the 29 and why I could see arrows every now and then doing some weird stuff in flight.

I do appreciate all the solid advice and certainly implemented most of it! It will help as I move forward in this adventure, now that I don't feel like selling my bows anymore