Spine tuning arrows
07-16-2007, 12:07 PM
#2
Join Date: Mar 2005
Location: Colorado
Posts: 4,127
RE: Spine tuning arrows
Once you accurately measure your bow's draw weight and your draw length, the various manufacturer's charts are a good place to at least start. I have found that Easton's chart (on their website) is pretty accurate with Easton arrows. I have also heard of folks shooting bare shafts to confirm proper spine, but I have never personally had to do this.
07-17-2007, 05:03 AM
#5
Join Date: Feb 2003
Location:
Posts: 2,413
RE: Spine tuning arrows
Okay, first I spend quite a bit a time figuring out what spine I'm going to need in advance to buying my arrows. The mfgr charts are a starting place, but they do not work in every instance. In fact, they never work for me, so don't rely on them. Something like OnTarget software would be a good choice to get you close.
Then, I spine test the arrows with a spine tester I made. This is not really neccessary with aluminums. I find the stiff side and mark it. If the spine varies in the dozen by more than .010, I mark it as a practice arrow - not to be used with broadheads.
After spine testing, I tune the spine to my setup. I shoot bareshafts to determine the arrow length and draw weight that I need to use. I usually have decided on my tip weight before this. If I misjudged, I may have to adjust tip weight also. I want my bareshafts grouping with my fletched arrows at 30-40 yards. I generally only fletch two arrows when doing this, because I haven't cut the shafts to final length yet. In my opinion, this is the most important part of the tuning process. If you can't get bareshafts to group with your fletched shafts, the spine is not correct or your bow is not tuned. If you want your broadheads to fly the very best, you have to get both of these right. Remember, fletching is only there to correct arrow flight that not correct. Fletching is unneccessary for the perfectly tuned arrow and bow setup shooting field tips.
During the spine tuning process, I will often have to trim the arrow length to get proper spine match. When I trim a bareshaft, I also trim the fletched shafts. On the fletched shafts, my inserts are put in with hot melt so I can easily trim from the tip. Through a combination of trimming length, adjusting draw weight and tip weight, I can always get the bareshafts grouping with the fletched. Though, sometimes I have to micro adjust centershot on the bow during the spine tuning process. Once, I have the spine match I'm looking for, I then trim the whole dozen. I cut from both ends and fletch with feathers applied with a helical.
When it's time to shoot broadheads, I spin test them for straightness and generally do not have to do anything else to get them flying perfectly. This whole process can sometimes take me 3 hours or more, not counting the time to build the arrows. This is why I tend to use the same arrow brand, once I learn it's characteristics. I've done this so many times that I know approximately what I have to do without a lot of experimenting if I stick with one or two brands.
Then, I spine test the arrows with a spine tester I made. This is not really neccessary with aluminums. I find the stiff side and mark it. If the spine varies in the dozen by more than .010, I mark it as a practice arrow - not to be used with broadheads.
After spine testing, I tune the spine to my setup. I shoot bareshafts to determine the arrow length and draw weight that I need to use. I usually have decided on my tip weight before this. If I misjudged, I may have to adjust tip weight also. I want my bareshafts grouping with my fletched arrows at 30-40 yards. I generally only fletch two arrows when doing this, because I haven't cut the shafts to final length yet. In my opinion, this is the most important part of the tuning process. If you can't get bareshafts to group with your fletched shafts, the spine is not correct or your bow is not tuned. If you want your broadheads to fly the very best, you have to get both of these right. Remember, fletching is only there to correct arrow flight that not correct. Fletching is unneccessary for the perfectly tuned arrow and bow setup shooting field tips.
During the spine tuning process, I will often have to trim the arrow length to get proper spine match. When I trim a bareshaft, I also trim the fletched shafts. On the fletched shafts, my inserts are put in with hot melt so I can easily trim from the tip. Through a combination of trimming length, adjusting draw weight and tip weight, I can always get the bareshafts grouping with the fletched. Though, sometimes I have to micro adjust centershot on the bow during the spine tuning process. Once, I have the spine match I'm looking for, I then trim the whole dozen. I cut from both ends and fletch with feathers applied with a helical.
When it's time to shoot broadheads, I spin test them for straightness and generally do not have to do anything else to get them flying perfectly. This whole process can sometimes take me 3 hours or more, not counting the time to build the arrows. This is why I tend to use the same arrow brand, once I learn it's characteristics. I've done this so many times that I know approximately what I have to do without a lot of experimenting if I stick with one or two brands.
