Paul L Mohr

Ok, the deal with arrows and spine goes sort of like this. Your Terminators have a size designation on the arrow. It is 45/60 which means it is intended to be used with draw weights between 45 and 60 lbs. However this does not take into consideration your draw length or effeciency of your bow. Other arrows use different numbers. Some like Eastons use the amount of spine deflection as the model number, some like carbon express go in the opposite direction (sort of confusing huh). And aluminums use the outside diameter and wall thickness (2213 means it is 22/64 in daimeter with a 13 thousandths wall thickness).

The arrow also has a Spine Deflection rating which is the amount the arrow will bend with a specific weight aplied to it and supported at a specified distance. This is an industry standard and all arrows should be measured the same way. This is what the Programs and charts use to pick an arrow. They will do a calculation and see what spine you need for your bow, then list arrows that have that spine rating.

Just because your arrows say 45/60 on them doesn't mean they will only work with draw weights from 45 lbs to 60 lbs. If you look at Carbon Expresses chart they are listed for a lot of different set ups. If you had a 27 inch draw length they are listed all way from 30 lbs to 75 lbs!! I am going to guess this arrow at 30 lbs is going to be pretty darn stiff if cut to the AMO length. And at a 29 inch draw length they would spine up to 63 lbs and with a 31 inch draw length the chart shows them being good up to 57 lbs. That is very wide range that this one particular arrow can be used for.

My program shows the CX 250 arrows (which is a simular spined arrow) being good from 55 lbs to 70 lbs for hunting with your draw length and bow. You could get away with even more draw weight for a target set up. That is a pretty wide range of use for one arrow. Now if you compare that with aluminum arrows I list almost 20 different arrows that will work with spine deflections ranging from .365 to .426! And this is leaving your arrow length set to 28 inches which is a tadd long. If you were to go playing with the arrow length you could get even more combinations.

The same thing applies to your carbon arrow. It lists it working for a number of different draw lengths at your draw length, and that was again at a 28 inch arrow length. Lets say you got some arrows already, like you did, and they were stiff or weak for your set up and were 28 inches long. You could alter the length of the arrow to increase the daynamic spine or break it down. Lets say you wanted to shoot 300's out of your bow because they weigh more or are easier to get in your area. If you were to shoot them at 29 or 30 inches they would spine better. To be honest they would probably work anyway though even at 28 inches.

Now lets say you have the 45/60's like you do and decided you wanted to crank up your weight and take all the stuff your string to get more speed. That would make them a bit weak for you set up. If you cut them to 26 inches instead of 28 they would spine better. Not to mention weigh less and be faster.

I bet I have you completely and utterly confused you now.

Paul

MonsterBuckDreams

Truthfully, I am, but it is expected with loads of new info coming in all at once. I will re-re-re-read everything to see if I can make more sense of it. I'm sure I'll have more questions for you.

Hey, not sure if you're a car guy but since you're helping me with your program, I just thought I'd post this program I piloted for you. Enter specs of a car and the program spits out performance figuresfor that car.

http://www.angelfire.com/alt2/crx/

MonsterBuckDreams

OK, the first quote above tells me I'm already at the top of the weight range because my 4560's are intended for use between 45 and 60 pounds. This means I only have the option of turning down the poundage on my already 60# bow if I want to use this particular arrow. Then in the second quote, you're saying that I'm at the bottom of my weight range? And that since my arrows are a tad stiff, I need to turn my bow up to 65 pounds for my arrows to spine correctly? My interpretation if this is that my arrow is too stiff at one point but too limp at another? (hmmm, sounds like the story of the average guy's life) I'm confused. Please clarify. Thanks.

-Heu

Paul L Mohr

You didn't read everything I wrote. This is a summary of the first and third paragraphs.

Draw weight and the size of your arrows is not the only factor in spine. Your draw length and the length of the arrow also play into. Along with other things like cam type and other specifics of the bow. Even the type of release you use and if you use a string loop or not has an effect on what spine will work best.

What I meant was that according to my program your arrows are a tadd stiff and if you wanted you could probably get away with adding some more draw weight if you wanted. I would shoot them and see how they work first though. Like I said, this is not an exact science, and I am coming to the conclusion my software is not as accurate as I believed it was. It doesn't really do what I thought it would do as far as calculations go. You still need to experiment a little to get it perfect.

From what I can tell though those arrows should work well with your set up.

I normally pick an arrow I want but start with it a bit long, and set my bow in the middle of my weight range. Then I tune from there. This way I can either adjust my draw weight or shorten the arrow until I get the spine I want. I will be honest though, the difference in performance from where I started to where I ended is pretty minimal and takes a lot of tinkering, time and effort. In most cases you are not going to change tip weight, cut an inch off your arrow or add a few pounds of draw weight and see a dramatic difference in performance or accuracy. The place where you will see the largest improvement will be in fixed blade flight.

And remember you can't tune any better than you can shoot. If you are shooting 4 or 5 inch groups at 20 yards don't expect getting your spine right or tuning to shrink your groups to 1 or 2 inches. Proper form and well matched arrows are much more important for accuracy.

Paul

MonsterBuckDreams

Actually I did read that, I readall yourposts a good few times each over the course of the passed week. Most everything made sense except I just got hung up on what I quoted directly above. Though you did say that just 'cause an arrow is rated 45-60 doesn't mean it will only work in that range, I thought that if anything I'd be at the top of that range instead of the bottom. It totally conflicts with manufacturer specs, not to say that the program calculations are totally wrong. One would just presume that since the arrows are rated 45-60 and the bow is already set at 60, that the direction to go would be down.

At any rate, this means that I need to either crank up my poundage or start taking weight off my string so the bow will shoot faster, thus breaking downand weakening the arrow spine?

This also means that since the arrow is too stiff, going from 100 to 125 grains is actually helping my situation and making the arrow less stiff right?

Paul L Mohr

Well just because the arrow says 45-60 doesn't really mean anything. That may be for a 30 inch draw length and a 29 inch arrow. If you shorten the draw length or shorten the arrow then it's dynamic spine will be stiffer.

Using the 125 grns tips shouldn't hurt anything, as a matter fact I think that is how I figured it in the program.

I would not change anything, just use those arrows with your current set up. If you have problems then you could try turning the poundage up and see if that solves it. Or like I said you could probably get away with adding some draw weight if taking some things off your string if you wanted to gain some speed. I would strongly caution against adding draw weight just gain a few FPS though. It will only make it harder to shoot your bow and the speed increase most likely will not even be noticed.

Leave everything as is for right now and shoot the bow for a while. Shooting a slightly stiff arrow normally will not effect anything. Heck shooting a really stiff arrow usually doesn't effect things too much. It is when you get into shooting too weak of an arrow with broad heads when tuning becomes a nightmare.

Quit worrying and just get out there and shoot!

Paul

MonsterBuckDreams

I actually did get some shooting time in and the results are inconsistent at best. To avoid hitting the nocks off, I shoot 3 arrows at 3 separate 1 inch orange dots. When my arms were still fresh, there wasone time when I put an arrow in each of those dots. Later as my bow arm tired and the cold set in, I started making paper plate sized groups. That's obviously just 'cause I was fatigued.

Here's where it became "inconsistent"... I waited a half hour to rest upthen resumed shooting.Half thearrows made it within an inch or soof the orange dots but the other half were scattered in paper plate sized groups (left right high and low). I did just recently make a peep sight change too so maybe I have to give my eyes shooting time to get used to it.

The thing that worried me more so than the inconsistency though was the fact that once in a while I could see the arrow flying crooked whereas with the CX maxima 250's there was never atime when I could actually see the arrow flying crooked. I kept track of the arrows too and the intermittent crookedness wasn't limited to just one arrow. It was random.