Is there a general rule as to when spines will match up for carbon arrows?  

What I mean by that is I was tuning some full length .300 spined arrows trying for high FOC and wanted a certain weight up front.  Well, that weight didn't work.  

How much do you think I will have to take off of a full length .350 spined arrow to get it to match a full length .300 spined arrow?

I know there are a lot of variables(even the actual spine or carbon arrows) from reading other topics, but i am still curious if anyone has done any testing like this..

Daniel

Your guess is as good as mine. I can't get a carbon arrow to work
for me so I will be watching this thread to learn about carbons.

Run some numbers through stu millers spine calculator and it should get you in the ballpark.

Josh, Stu was a lot smarter man than me.. I can't work that thing for the world of me.. haha.

Daniel, I think you're writing off Stu's calculator a bit too soon. I've always found it very helpful, but needed to tweak the "personal form factor" a bit to get the predicted results to match up with actual practice.

Recently, I've revisited my calculations ( I save the ones that work well for me  - have 2 or 3 for each bow).

I found that I have been guilty of the "garbage in - garbage out" syndrom. Couple of examples:

1.  I've been using the "3 5-inch feathers" setting because that is what I use. BUT, I also add a cap wrap, so I weighed the bare shaft and then weighed it again after adding the 3 5-inch feathers and the cap wrap. Came out to 30 grains, so I selected "other" in the fletching block and entered 30 grains in the block below. Stiffened up the calculated dynamic shaft. If I were to put a 1/4" collar on the nock end, that would add some more weight to the nock end and stiffen things even more.

2. I've been entering 11 gr for the standard aluminum inserts because that is what Gold Tip had on their web site (actually, 11.4 gr). Today I weighed the inserts which came to an average weight of 15gr. I use hot melt glue which fills the grooves in the insert so I added another 1 gr. Now I am entering 16gr for the insert weight. Changed things a bit again and came much closer to what I'm seeing on the target.

I find when I put in the actual cut-from-center distance, correct string type info and proper arrow info, I no longer have to fudge the personal form factor.

Pretty long winded, but I will bet you if you have an arrow that flies really well from your bow, you can put the proper information for that arrow in the calculator. If it matches the dynamic power reading for your bow, that's fine. If not, you can change the personal form factor until it matches the dynamic calculation for that "good" setup. That calculated dynamic spine reading becomes your "gold standard".

Now, you can change arrow shaft types/spines/lengths and point weights to get a matching dynamic spine number and have a new arrow that will fly right along with the original arrow.

You're right about Stu being smarter than most of us in building that spread sheet. It took an enormous effort I'm sure, but that's his job as well as hobby. Sure glad he's a trad archer as well as a math/Excel genius. He's created, at least for me, one of the most useful tools I know of for the trad archer.

x2 what Bladepeek says.

Daniel, I'm not sure if you can't figure out how to work it because you don't know what you're supposed to be looking for, or if you just can't get your arrows to work like the calculator says it should - either way, you should really try and figure it out. Super helpful tool.

If you're struggling, send me a PM. I can email you some screenshots with instructions to help you through it, because it's going to be way more accurate than most of us here can tell you.

Alex

I had never really used it. Mainly because of the micro adjustments. So it asks for your cut past center distance, don't have that. As well as how thick your strike plate is.. Don't have that either.

I am not opposed to it, he came up with an amazing system, I just feel like I have to guess too much with it.

Daniel, You're kind of asking people to re-invent the wheel.

Try this. If you have an arrow that flies well out of your bow, just put the info for the arrow into the calculator. Ignore the bow entries. Write down the dynamic spine calculation for the arrow - "54.6#" or whatever it is.

If you are using the same brand of shaft; just a different spine, change the length and point weight as you want to until you get the same dynamic spine reading. It will be VERY close to your first arrow - close enough that you can then make some fine adjustments in length/point weight if necessary. You will at least know what is feasible and what isn't.

Ron

Thanks Ron. I will get back with you when I get it sat up and figured out..

Don't know of any rule for it but I seem to remember it being about 1.5", its been a while since I did it.

I've had to play with deciding between 400 and 500's quite a bit.  If you can get away with a 27" 500 they you might find a 32" 400 shoots similar.  I am not sure of the exact comparison but 4-5" is close.  I would guess the difference between .350 and .300 would be in the same ballpark.  For those of you who can find a copy of Stu's calculator you might see if I am close.  

I can appreciate the question.

Daniel,  I know what you mean about the micro adjustment info that is required to obtain accurate results with any of the calculators---I have no idea how much before or past center bows I am working with are. Without this information the calculator would not give me an accurate outcome--not the fault of the calculator just user (me) error.  I do know that folks on here have good results with the calculator, but my method  is bare shaft tuning.  I have been surprised more than once what a bow tells me it wants arrow-wise, but as one poster said---it is what it is.

Stu's shoes about an 1.5". So I agree with Katman.  Makes sense to me because out of my bow I can shoot CE350 at 32 1/2 or CE 250's at 30.75.

Katman and Pivo,
That is what I was wondering.
The reason I ask is because I have a .300 spined Arrow that I added 250 grain to the front and it was still still at 31". I ordered some .350 spines and wanted to make sure that they would work. I draw to 28.5.

Daniel, I think you could make the .350 work, start full length with your 250gr point and start tuning, if you get to the shortest you can go drop point weight and or build out strike plate.

what they're saying is enter your info length and spine for the .300 if that's the one that's tuned.  Then sub the length/spine info for the .350 and start reducing the length value until the calculated dynamic spine matches up.  Whatever it tells you, I'd only cut half that....you can always cut some more, you can't glue it back on when you've gone too far!