Fine Tuning -- the false weak

[smokin joe]

As my artificial shoulders get stronger and stronger, I am able to shoot a little more bow.

I have a Bear TD that has not been used since my shoulders began to go bad a few years ago, but now that I am getting stronger I decided to give it a try.

It is an A-wood riser bow with #1 limbs marked 47 pounds at 28" -- that would make it 48 or 49 pounds at my draw length. I remembered that these particular limbs were very, very smooth on the draw with an A-mag riser I used to have them on years ago. They ought to be great on the wood riser.

Well, I started experimenting with some bare-shaft arrows I had on hand. I tried a 500 carbon with 200 grains up front. It shot a little noisy and a touch weak. So, I went to a 400 carbon with 290 grains up front -- still weak. Then a 400 with 250 up front, same result. So, I trimmed 1/4 inch off of the 400 shaft, still weak. I reduced the weight up front some more, still weak.

This was not making any sense.

Then I noticed that my side plate had developed a pretty obvious skid mark that looked like years of wear. What's that all about? Well.....just maybe.....

Then I thought that maybe I was getting side bounce off of the sight window. I looked at the riser very carefully and noticed that it was cut a bit less than center shot. Maybe the arrow spine needed to be a bit weaker to clear the riser during paradox. Maybe I was getting a false-weak reading from the shaft bouncing off of the side plate because everything I was trying to shoot was too stiff.

So, I went back to the 500 spine shaft at 29.5" and loaded up the front with a 100 grain insert and a 190 grain point ------- perfect bare shaft flight. And the bow became almost totally silent.

It just goes to show you that the charts and bare shaft calculators are not necessarily right. The individual bow knows what's right -- and I just needed to understand what it was trying to tell me.

Now I'll make up some arrows for this bow, and I will surely hunt with it.

I just wanted to share that sometimes the shaft and point weight combination that "should" work actually won't work --- and that bare shaft tuning is a process that will lead to the best possible combination of arrow shaft and point weight.

[Hoosierarcher88]

I literally just went through this. Kept thinking weak toll i replaced my side plate and noticed wear almost immediately. I had some 30" .400 spine shafts and tried them with my 300 grain tips instead of my 28.5" 400's and boom the "weak" reading went away. I had a false reading not only for stiffness but also for nock height.

[McDave]

I've had bows that are seemingly twins tune for different arrows, not only point weight, but a whole spine group difference in shaft.  Like you say, you just have to keep tuning until you get there, wherever “there” may be.

[smokin joe]

It is strange for sure.

I typed that arrow into the 3-R Spine Calculator just to see what it turns out to be. It came up as a dynamic spine in the high 30s.

That same riser with Rose Oak limbs five pounds heavier shot a dynamic spine more than 15 pounds heavier.

Each bow has its own personality....and I am liking how this combination feels and shoots. It might end up being my hog bow this next winter.

[BigJim]

If you want a more reasonable arrow weight, try some 600's. Although it's possible that you aren't drawing as far as you used to...or at least not yet.

I find that more guys have this false weak problem than true weak. hence the reason there are so many shooting spines that are way too stiff.
It is also possible to get a perfect bare shaft from an arrow bouncing off the bow.. seen it many times. Sometimes you can hear the arrow hitting the bow (usually) but sometimes the rest material muffles it pretty good.

BigJIm

[katman]

Certainly agree, listen to what the results of a dynamic spine change tell you. If unexpected or opposite result go the other way. Certainly does get a head scratch at first.

[Car54]

Well said guys.  Thanks

[smokin joe]

You know, Jim, I might not be drawing as far as I once did with the shoulder joints God gave me. The geometry of the artificial shoulder joints might be a bit different. I mean, just 1/4 inch per side would result in a 1/2 inch difference in draw length since both of my shoulders have been replaced.

[BigJim]

smokin Joe, don't forget that even though you can shoot that bow, it is heavier to you now and tends to cause shooters to crunch up a little. Once you get back in the swing and that bow feels like butter, your draw may expand back to where it was.

BigJIm

[jonsimoneau]

Recently had this exact same issue. I was having a hell of a time tuning a set of arrows. Normally this process is very easy for me. Kept getting weak impacts with bare shaft and could not get it out. Finally realized that the bow sounded louder than normal as well and the light bulb went off. Went down a spine.

[T Folts]

After tuning i shoot through paper to fine tune. Or ill do it early if i cant get good flight. It will tell you what is going on. Its not for everybody but works for me.

[DanielB89]

One of my most challenging parts of tuning is the guy holding the bow.  I have shot every spine imaginable out of a #50 bow.  When I was in my prime, my absolute best shooting, I was shooting either a .350 full lengthish, or a cut down .400, but with 150-175 grains up front. 

I feel like that is stiff, but I also feel like my release could get so crappy that the more stiff shaft would help stabilize the arrow.  I could shoot a .350 spine arrow out of my bows with 4 - 3" fletchings and they would fly like darts.  I've come to realize I don't know anything about tuning anymore haha, and i'm always envious of those guys who make it look easy!

The bottom line is that if the hand letting the string go isn't consistent, then neither will the arrow flight.

[smokin joe]

Jim: I do think you are right. As I get stronger I will get back to my longer draw length. Shoulder replacement takes a heck of a toll on the muscles and tendons surrounding the joint. A lot of damage gets done during the surgery, and it takes a lot of time and work to get things healthy again.

[Miikka]

I had the same problem the other day but with a little caviad. I had good flight with 3*5" feathers but decided to tinker a bit to see how I would do with bareshafts. I stripped one arrow of feathers and noticed it hit 10" left of the fletched group with nock right of impact (I shoot left handed). So I trimmed the arrow 1/4" and tried a couple of times to get it to fly with no succes. Of to the cutter again and 1,5" later when I was at a point where a broadhead would contact shelf when drawn to anchor. So I stripped three more arrows to shoot a group and to see If I had achieved anything with the tuning. The three newly stripped arrows flew like lasers and had no consievable tuning issues. I was fortunate enough to not get the one arrow to tune, had I done that I would have made the others to match the "tuned" arrow. Always shoot more than one bareshaft when tuning.

[Friend]

Different bows may be individualistic as we are and as some shafts are.

My best tunes personally start at around 15#s under-spined and have gone down to 20#s under-spined.

[Petrichor]

Man glad top know I'm not the only one.   Normally tuning is pretty easy for me but this last batch drove me nuts.

[oz]

No way, wish I had read this a week ago.  Things are making more sense now, I have a new plan for weekend shooting.

oz

[deadsilence]

You guys have any advice for this? I have tried moving my nock down but even at level they are still nock high. The lower I go the more the arrows separate.  This is a bear takedown a riser 57# with a full length gold tip 400 with a 20gr insert and 150gr tip

[McDave]

I would guess that you have a false nock-high, which is similar to a false weak, but in this case it is caused by the arrow shaft rebounding off the arrow rest.  It is not always possible to get level bare shaft flight, due to equipment and/or form issues.  In that case, your goal should be to tune for the minimum amount of nock high you can achieve before the shaft starts rebounding off the arrow rest.  So you start really high, maybe 3/4-1” above square, and work your way down in 1/8” increments until you reach a point where you either achieve level bare shaft flight or else reducing the nock height doesn't result in any further reduction in the nock high, and that's where you stop.  I suspect false nock high whenever I see nock high with a nock point of 3/8” or less, although it can occur at higher nock points as well.

Once you know approximately where the crossover point is, you can tune further by moving the nock point in 1/32” increments.  I have seen cases where level bare shaft flight can be attained by moving in 1/32” increments where moving in 1/8” increments missed the sweet spot.

[Bisch]

Yep, the charts and calculators are just tools to get you in the ballpark. Only personal tuning will tell you the absolute truth!!!

Bisch


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