Spine located located shaft, why?

Discussion in 'General Crossbow Discussion' started by Vital Limits, Dec 16, 2017.

  1. Vital Limits

    Vital Limits Member

    I often get asked or looked at strange when first mentioning finding the first dynamic spine in and shaft. So here is something I have learned to pass along..

    Your shaft has a natural bending point that during the launch the shaft will want to flex towards the weak or easier found side of the bending point., but what many don't realize there often more than 1 bend of the shaft, often there are 2.. 1 of the bending points that feels more like going over a pot hole which you dont want and the other like a gradual dip in the road, that is the one you want mark as the dominate bend, why, you want more predictability in the launch which translates to better consistency as finding the dominant bend on all your shafts can help reduce and or eliminate culling of the arrows.

    With vertical bow the spine location is more ideal placed up or down since the energy of the bow is generated vertically. It does not matter the direction up or down just that it is and the arrow leaves on the same bend.

    For cross bows this becomes more critical since a rail is now involved. The spine location mark on weaker side always faces downward with cock vane in rail. What this does is during launch cycle the bolt's natural bend can cause the bolt to flex up ward off the rail or minimize pressure as apposed to if the bend was unkown and happened to be reverse the flex would apply pressure downward on the rail causing more pressures, friction adding more resonance into the shaft causing over all performance loss.. For better performance spine location can be a huge deal and it can aide to better gains complimenting the null point of the shaft whether in vertical or cross bow types..

    The dynamic bend is important and spine stiffness can be critical as we want the shaft to react ( bend ) during launch of the bow.
     
  2. xcaliber

    xcaliber Active Member

    I have done a whole lot of testing, and being a tool & die / product engineer I find this whole spine indexing to be hog wash. I never do it, and all of the big arrow manufacturers don't do it either. It is trying to determine hysteresis basically which would mean everything is always the same including the results. Not happening! My shooting buddy could not his spine indexed arrows any better than my non indexed arrows at 50 yards. This was on more than one occasion. Sell it if you can, I'm not buying into it!:cool:
     
  3. Vital Limits

    Vital Limits Member

    What methods of spine indexing was used?

    Yes manufactures do it also as well as pro archers and there is other problems that can occur from shooting spine indexed or not..
     
  4. Vital Limits

    Vital Limits Member

    For reference other, Scorpyd one of the leading manufactures in cross bows sells a Spine located arrow..
     
  5. xcaliber

    xcaliber Active Member

    I'm not 100% sure. He paid a fee for each arrow, and zero difference was noticed between mine & his. I have been making my own arrows now for nearly 30 years. I put my vanes on a batch lined up to the straightness labels, and have very good accuracy out to 50 yards. I have found squaring the ends adds more to consistent accuracy than anything else I do. I don't wish to downplay anything folks seem to think adds to their success, but for me, I'm not in. Some claim they weight match too, never seen any reason other weighing the final products. I have never had a swing of more than 2 grains. Lucky I guess.
     
  6. xcaliber

    xcaliber Active Member

    This is off hand shooting at 50 yards with none indexed arrows. I will challenge spine indexing results at every chance. It does zero for me.
    Deer_Target_Matrix_50_Yards.jpg
     
  7. Vital Limits

    Vital Limits Member

    The weight matching can be time consuming and added cost,, with good components and building methods that can be very close I agree within 2-3gns.. With Spine location I find that many people who had issues with it were doing it in a less accurate way. Many who use the Ram Spine tester which is what I did before the PAPS is not accurate as I quickly realized the spine is not measured accurately in that method therefore the jig is not really doing what it is supposed to do.. The floating in water method is a crap shoot as most shafts ( BE, Elements, Victory, GT, CT, DCA, Eastons etc, ) will have 2+ spine locations, so which one is floating at that point is the issue. Some pro's I've surprisingly seen using a press find spine, but again which one are they finding, what I'm saying is the spine is to be felt, so you can tell the difference between the 2 and choose which one to mark for location. Victory puts out a spine located shaft, so they say, but through testing I have found that to be inaccurate as every time you cut the shaft the spine location changes, therefore flex direction changes,, it can't be the same and since there is a bending point that can change there is either an inconsistency in the shaft or not, it is easily proved on accurate jigs that there is a bending point that changes location in the shaft when cut and or possible when components are added.

    Not saying you can't get good results on a non spine located arrow, but usually for most I've talked to about it and my own experience there is culling of the arrows that comes into play when shooting non spine located shafts, you may get a few really consistent arrows and few ok ones and the rest are for squirrels.
     
  8. Vital Limits

    Vital Limits Member

    Challenge accepted.. My off hand shooting , vertical bow, @ 92.83 yards. 2.25 inch group,, in wind.. It would of been under 1 inch had my nose didnt itch.. 469gn Concept 2.0 , spine located..

    Nice shooting at 50yrds though ..

    Concept 2.0 2.25inch group 92.83 yrds in wind.jpg Concept 2.0 2.25inch group 92.83 yrds in wind.jpg 2.0 con 2.jpg
     
  9. Vital Limits

    Vital Limits Member

    Guy I built arrows for, Element Typhoons, 60yrds. on circles,
    CO Alloway at 60yrds Element Typhoons firenokc concept system.jpg
     
  10. Vital Limits

    Vital Limits Member

    70 yrds, about 1.5 inch..

    70 yrds CT Cheetahs.jpg
     
  11. Vital Limits

    Vital Limits Member

    90 yrds,,, Ct Cheetahs 5580 shaft 90yrds.jpg
     
  12. Vital Limits

    Vital Limits Member

    All vertical bow btw..
     
  13. xcaliber

    xcaliber Active Member

    You win! I can't even see 100 yards!:eek::D:cool:
    I'm not trying to discredit indexing, just for me I see no benefit really. I'm not a tournament shooter, and I'm really not that good of an archer compared to some I shoot with. If it made 50% better than where I'm at, I would still be sub-par compared to many. Just saying. Now my sniper shooting buddy still cannot see a difference within 50 yards at the range, so I think I just make mine good enough to fool him!;)
     
    bbahunter and Vital Limits like this.
  14. Vital Limits

    Vital Limits Member

    This was a closer one from a guy I built arrows for, I forget how far, but I think 40 yrds, I could be wrong. VL Element 1.jpg
     
  15. xcaliber

    xcaliber Active Member

    If i have some time when I drive out to Delaware in the spring, I might just spend an hour shooting with you though.:cool: I would have to limit my beer drinking time with Bruce though!:p
     
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  16. Vital Limits

    Vital Limits Member

    Other building methods help the spine location stuff big,, through better components in bow, rest and arrows so far in vertical bow in one build I can get efficiency down below 10% out to 50 yrds.
     
  17. Vital Limits

    Vital Limits Member

    That would be awesome,, keep me posted when you are in the area.. I'm only about 40 min from DE.. I just got done building a new rig I gotta tweak a little, but I think its gonna be a screamer in a quiet kinda way..lol!
     
  18. Vital Limits

    Vital Limits Member

    Here is glimpse of my new rig..

    XP ti 2.jpg Xp Ti 1.jpg
     
  19. Vital Limits

    Vital Limits Member

    It depends at what yardage they group at, what kind of group are we talking and how many arrow will group consistently within themselves, getting the same arrow to hit the same hole is a given.. You could tinker and get some better consistency, but that doesn't necessarily mean efficiency gains ,, Example,, let say you did nock turning to death and got the spine all consistent,, what is it consistent with,? Is it faced so that during the launch the bend is facing down, up or to the side, it can all have consistency. See you can have consistency within an error as a broken clock is right twice a day, but that doesn't mean it's working at full potential.. 20-30 yrds imo is minimal in vertical bow world ( 40-50 yrd in X bow ) . From my experience for the most part many shooters comfort level is a 20-30yrd shot, why, because without any kind of tuning and for most hunters I meet consistency fades out the further you get past 30 yrds..

    With the Archery industry building these faster pricey bows for the most part in my experience the shooting ability of the 20-30 yrd comfort zone is still the same as when I was a kid , why,, as an industry as a whole in sales the technology of the components haven't caught up to meet the demands of the bow, many base everything on the shaft. I have built a BE Challenger with typical factory blazer, BE parts, done on Ram Testers and had them weigh 4gn less than a Concept 1.0 build and had a Conservative more drop on POI at a distance of 50 yrds, over 8 inches.. The 1.0 was a more efficient build being stabilized in flight. The arrow / with the bow build stacked 5 yrds on my first pin, meaning my 20-30 yard pin set up was now a 30-40 yrd pin.. 1/2 inch high at 20 was still dead nuts at 30+ yrds. My TRX bow1.jpg
     
  20. xcaliber

    xcaliber Active Member

    Nice Bow!
     
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