3Rivers spine calculator?

[Stone Knife]

I have been struggling with getting arrows to fly out of my 3 piece Bob Lee. I had been shooting gt3555 with about 195 gr up front cut to 29 my bow is 46 @28 and I draw 27.5 also I have a 8 strand fast flight string. I went and checked out the calculator and it said with my setup I would need 5575 cut to 29.25 with around 200 up front. I made up a few arrows to those specs and they shoot well with broadheads. My question is how much faith do others put into these calculators? When I look at other threads everyone with a setup similar to mine are shooting the .500 spine, what gives?

[kat]

Jim,
    Some people have better luck than others with spine calculators. I don't have a good track record trying to use them. That being said, I also shoot a stiffer arrow than most when shooting carbon arrows.
    It is my opinion that a calculator can't accurately distinguish between forms and releases. I know they try, but no two people shoot the same. In the end, it is what actually works best for each individual.

[slowbowjoe]

Like Kat, and some others, the calculator doesn't work out well for me and my set up. Certainly, it does work for others, like so many elements of our practice.
While I find it a great learning tool to see how dynamics change, letting the calculator dictate my choice would be very frustrating.
My brief experience with carbons, out of a 45# recurve, showed I would have had much better luck with lower spine than the .500's (35/55) I was shooting, full length, with around 200 grains + up front.

[Caughtandhobble]

Looks like it works well for you.  

Seems to work very well form me as long as I feed her the correct information. The calculator will work for most as long as they have consistent form an input the correct information.

My shooting buddy has less than perfect form along with a "different" release, lol. He's very consistent and a very good shot, along with being a very successful hunter. He uses the personal form factor on the calculators with very good results. His arrows simply end up a little weaker spine, but it's hard to argue with success.  

[**DONOTDELETE**]

Hey James,

I don't put a lot of faith in any spine calculators because they can't factor in the bows efficiency or how far too, or past center the shelf is cut.

I've spent some time shooting, & I've even replicated a few Bob Lee risers that were cut 3/16" past center. That shelf location alone makes a huge difference in arrow spine.....

There is also a lot more difference in bow performance out there than a lot of archers realize or really want to admit.... a few fps isn't going to make a difference. 20 fps will change your spine requirements on your arrows.

[Flying Dutchman]

Stu's spine calculator as 3 rivers DO factor the center cut option, even strike plate thickness...as for spine calculators: for me most of the time spot on for woodies and overspined for carbons. I shoot 1535's where the spine calculator sais 3555.

[Bladepeek]

I just plugged some numbers into Stu's calculator. Given a Bob Lee take-down recurve with your specs and your arrow specs that arrow set up comes in right on.

If I change the bow to a Chad Holm 46# drawn my 28", it comes up within 1 # of matching my set up of 29.5" GT3555s with 175gr point and 11gr insert.

I understand it doesn't work for everyone, but seems to fit our needs perfectly. Depending on the specific bow model, I may have to use a form factor of +- 2, but once I have it set up for that bow, I can use just about any shaft I want and cut it or add point weight to get it to match Stu's recommended dynamic spine and it will be right on.

[Stone Knife]

Bladepeek I came up with the same thing and was fortunate that they had my bow specs already in the system.

[Bladepeek]

I know there are a lot of bow hunters that are better hunters and better shots than I who swear at the calculator. That's fine for them. For me, if I am starting from scratch, Stu's calculator gives me a VERY good starting point. Once I have that arrow properly tuned, I can take that dynamic spine reading to the bank. If I want to build a slightly faster arrow, I can poke in a weaker spined arrow with a lighter point that gives me that dynamic spine number and know it will fly just great. If I want to build a "shoot through a telephone pole lengthwise" heavy arrow it works the same way. Saves me a bunch of frustration and wasted effort.

"To each his own", but I constantly give thanks to Stu Miller for putting all that work into building a tool that really helps me.

[M60gunner]

I have a love hate relationship with the calculator. With carbons I can get some pretty wild results. But alum. usually comes in real close first time.
I do think the calculator is a better start than the manufactures charts. The carbon shaft was developed for the wheel bow, we have been pretty good at making it work for "trad" bows but not without some frustration.