Split vs. 3 under spine

[xtrema312]

Anyone notice a difference in what your bow wants for spine shooting split vs. 3 under?  I have a bow that wants a stiffer arrow shooting 3 under.  I can't figure out why.

[McDave]

What are the indications you are getting that you should be using a stiffer arrow?

[xtrema312]

Bare shaft tune.

[McDave]

I asked because I got a slight difference in the other direction when I bare shaft tuned.  Bare shaft tuning indicated that I should have a higher nocking point for 3 under than for split fingers, in all cases.  For most bows, I noticed no difference in spine.  For one bow, where the nock point was already pretty high for split fingers, I had to move it up to 7/8" before I was able to get good arrow flight shooting 3 under.  For that bow, moving the nocking point up to 7/8" made the bare shaft that had shot fine at a lower nocking point for split fingers indicate that it was too stiff.  I was never happy shooting that bow 3 under, although it shot fine split fingers, and I eventually sold it.

Now why would you get an opposite indication?  I can think of no mechanical reason having to do with the bow or arrow.  Do you think there could be a change in your draw length or release that could cause you to need a stiffer arrow?  When I attended Rick Welch's class, he changed my anchor at the same time I changed to 3 under, which resulted in almost an inch increase in my draw length, which would of course increase the effective poundage of the bow.  Later, when I attended Rod Jenkin's class, I started using a more dynamic release, which increased arrow speed some and could also result in the need for a stiffer spined arrow.

[xtrema312]

My bare shaft shoots weak or false weak 3 under.  I have applied white tape to the shelf and edge of shelf to show what the shaft is doing.  Split I have been getting a little harder rub contact on the shelf and a little edge of shelf rub mark.  Raising the nock doesn’t fix it.  3 under with no nock change I get light shelf rub on the surface and no edge of shelf contact, but my bare shaft flies weak.  I have read many times that 3 under should take a higher nock set.  I would think if split I am on the shelf good I would be bouncing off the shelf hard shooting it 3 under, but I see no sign of it.  The bare shaft is not hitting way low.  It is just shooting right, right handed shooter, of where it does split finger.  I lighten the point weight and it shoots great 3 under.

I think the arrow I have been shooting in the past is too stiff, and that is why I am having hard shelf contact shooting split.  I have been shooting a weaker shaft with good success and no edge of shelf rub marks now split finger.  However, 3 under is really weak now.  I think my nock could be a little high for split and about right for 3 under.  That would explain why I don’t get a big kick in the bare shaft shooting 3 under.  However, I can’t see where a too high a nock shooting split would make it shoot stiffer than 3 under.  

The only thing I can come up with is something in the release is causing it.  I shoot deep hook and a very similar anchor and form with both.

[McDave]

I don't have any other ideas, but I'm interested in knowing the cause, when you figure it out!

[xtrema312]

I will keep at it trying some different things to see.  I need to try it on another bow to see if it is the bow or me.  I have a few ideas of stuff to try.

[jacobsladder]

not to put a kink in things....but do you have a contact point at the deepest part of your grip? I put a contact point (toothpick) under my rest material and it made a major change in cleaning up my bareshaft flight...may have been just a coincidence..but it worked and my broadhead flight has been excellent also.

[marshall brown]

I had the same problem and until I added a second nock below the arrow. Problem solved then. I had too much finger pressure against the arrow causing the erratic flight. Give it a try.

[xtrema312]

I have a second nock point.  That helped me in the past with some odd tune stuff, but this is different.  Thanks for the idea.

[mikieg]

xtrena312, you gonna b at that expo this year?

[xtrema312]

Kzoo expo?  I sure hope so.  I had a great time last year.  I went all three days.  I have a whole new line up of stuff I want to shoot this year along with some bows I want to try again.

[Lazy Ike]

It's not a problem, it's just the way it is for a lot of people. For me, a bare shaft that shows slightly stiff with split finger, will fly perfect if I soot 3 under.I have two other friends that have played around with it. One has similar results to mine , Other has just the oposite(arrow shows weaker with split finger). Try this sometime.... If you can chronograph your set-up , shoot 5 or 10 arrows split finger and 5 or 10 3 under. For me , 3 under is slightly faster(3 to 4 fps). I think most people will have a bit cleaner release with 3 under but thats only my unscientific opinion.


Ike

[xtrema312]

I have shot a couple of my bows through a chronograph split, but not 3-under yet.  I want to try that.  Maybe this winter.  I think they are faster 3 under based on how hard the hit.  Could be my 3 under is just not flying clean.  I think some chronograph work would tell me something.  

I have had a lot of problems with edge of shelf wear.  I suspect some string torque issues, but even when I have taken great care I have had issues.  I think I have my canting string torque worked out, but may have an issue with pushing down on the string with my index finger shooting split.  I just saw something about that last night when I watched MOBB III. I may not do that 3 under.  This would explain why I can shoot split and 3 under with the same nock point set and not get contact 3 under.

As far as the spine difference between 3 under and split goes, I still don't have it figured out.  If I eliminated the shelf rub of shooting split, which should have bumped the arrow to a weak flight, the arrow should have shoot stiffer 3 under.  However, maybe a clean release and less contact would have picked up speed and caused a weaker shaft, but It doesn't seam like the two changes would have resulted in a much weaker bare shaft.    I would think they would offset some.  I was able to tune the arrow back in with dropping point weight shooting 3 under.  My best guess is that shooting split with a index finger torque issues I was getting a lot of up and down plus side to side arrow flexing that was really effecting my arrow a lot.  3 under cleaned it all up and the difference was so significant that the result was a weak shaft.  

I am also playing with much weaker arrows shooting split than I used to shoot before.  I have expanded my draw another 1/2" and noticed some reduction in shelf rub.  I am now at about 10# spine less than I get on Stu's spine calculator.  My shelf rub is now gone and I am not over weak on my shaft.  I am a little high on the nock set and getting a low bare shaft group.  Now I just need to adjust my nock point back down some to see if I can get bare shaft level or shooting a little high.   I could never do that split, but could 3 under.  

Maybe I have more than on thing going here causing this stuff.  Over stiff shafts and a downward index finger pressure string torque that flexes my shaft on the shot.

[Mark P]

G. Fre4d Asbell recommends split finger because 3 under causes lower limb to flex drasticall more than upper.  This was shown on his DVD Instive Shooting.  I don't know much about this since I'm a newbie, but Fred's advice is good enough for me.

[xtrema312]

Well I still don't know for sure why my arrow is weaker 3 under, but I have figured out a few things in the process, and I think I have a guess.  

When I shot corner of the mouth I had a 28" draw.  I also think I pulled the string out away from center and shot it back out towards the shelf edge because by draw arm was not in line.  This gave me a false weak and I was able to tune and shoot successfully this way.  I also changed my string grip to a deeper hook with all there fingers pointed back this summer.  I think this created a semi 3 under effect plus some down force shaft flex from the index finger.  I didn't notice it because I had shelf clearance.  When I started to change my form and increase my draw length, I stared getting the shelf rub.  About that time I also noticed the 3 under clearing the shelf better with the same nock set and shooting weaker bare shaft.   I now know my more in line release was bringing the back of the arrow travel in line more with the center of the bow and now my over stiff arrow was hitting the shelf.  I wasn't sure that was a stiff shaft issue for sure because I was not bouncing off the riser, and nock height could fix that.  I know some people have said that shelf edge wear is from a too stiff arrow, but I couldn't see how it did for me because I had tuned my arrows and confirmed with point weight changes.  I kind of think with center cut bows you don't get as much paradox and possibly not total bow shelf clearance if your nock is too low.  I think the is why some say your arrow should paradox clear and some make a channel for the fletch between the rest and strike plate.  More point weight helped my arrow with the high nock set.  But that was not explaining the weak shaft 3 under or why I could shoot it 3 under with the same nock set.

I just watched all the MOBB DVD's and picked up a couple things.  First I had a little more draw length in me.  I am now at 30".  I also noted that when most of them talked about deep hook they didn't have all their fingers pointed back at them and they had their lower fingers extended some.  I relaxed may hand and let out my lower fingers some while still keeping the string in the groves of my finger or up on the second pads a little.  I noticed right off my bare shaft was hitting lower now.  The finger change made a big difference.  Now I don't think I am pulling up more like a 3 under when shooting split and not getting down pressure on the top of the arrow with my index finger.    I am getting a better follow through and a lower pull angel feel.  Now I have been lowering my nock point some today and getting a flatter bare shaft flight and still no shelf rub.  I think I have it figure out.  I think the string grip was putting a lot of torque in the sting and causing a lot of arrow flexing I couldn't see.  This was robbing me of a lot of energy.

I still don't shoot as consistent now as I did before all the changes, but I have picked up 2" of draw.  I did really feel like everything is now coming together and the pay off is near.  Just goes to show you that you can not have perfect form and still shoot good as long as you are constant about it.

[jerryb]

Sence shooting 3 under I had to go to a weaker spine. I went from carbon express 150s with a 145gr. tip to a 175gr. tip. But trad 600s shoot like a dart.  :confused: