anybody use the Dynamic spine calculator to pick arrow

[valleysniper]

Does anybody actually use this? Seems way off when I used it, unless I'm doing something wrong

[valleysniper]

maybe I could just use some help, obviously I'm not doing something right

[Trenton G.]

No I don't trust it. I've heard that it can at least get you close, but that has never been the case for me.

[Red Beastmaster]

Never.

[UrsusNil]

It's right on the money for me.

[bluemelonchitlin]

I tried it. Didn't really help any.
Like Stu Miller's calculator-it's overrated.

[Miikka]

Works like a charm to get to the right ball park. I usually get close enough to tune with braceheight and maybe shelf pad. It's very rare that I have to start playing with arrow lenght or point weight. Just my 2 cents.

[valleysniper]

well, I must be completely messed up, After filling in the info...although the one I used didn't have a Blacktail so I used a Bod Lee takedown....it showed I needed to go up a whole arrow spine and lose about 125 gr of point weight from what I tuned it at. I am at a loss

[Ray Lyon]

For my Blacktail of 48 lbs @28” and 28” draw with 29 inch arrows and 245 grains of point/insert it had me using an Easton Axis Traditional 340 shaft.  A 500 size shaft and same point/insert combination shoots bullet hole paper tune.  Get a test shaft kit and keep it around to make your selections based on ‘real world’ results, which is your own style and form and bow setup

[M60gunner]

I use the 3R version to get an idea what to start with. Every once in awhile I hit the 2 values dead on. I have also been known to “adjust” the specs to my will, like getting 2514 shafts to fly out of a 50# bow. If you’re bow isn’t on the list enter the generic version. I make up bows using ILF limbs and various risers.

[Friend]

Has worked great for me for years on a multitude of bows and has been an excellent tool in changing arrow specs.

[Wheels2]

Yes, but.....
I use the updated version.  Not the one on 3Rivers.  The one I use allows input for centershot, string strand count and material, etc.
I still fudge it a bit as my Border shoots pretty far above recommended spine.  By experience, I have learned that I have to apply a factor of 1.2 to the results.  So if the calculator indicates a recommended spine deflection of 71# (Average) I know that I actually need something of 80+#

[yeager]

I’ve used Stu calculator many times and has worked for me. I’ve even checked it by bare shaft shooting/trimming and it has been spot on.

[Babbling Bob]

Find it a great tool.  Learned a lot working it often for fun by trying different weight amounts up front, lengths, and draw weights among my rack of bows etc.  Glad I practiced with it as I have used it enough now to be comfortable with it as a tool to match my bows well and it has been close enough to help me choose options for my arrows.

[J. Cook]

I've used both and they've been very close for me.  I have found (over the years) that most people that have real trouble tuning using the calculation methods typically are overestimating their actual draw length. 

This could be the case here to since you said the calculator is recommending a much stiffer arrow that what is actually working.  To have it work for you - you have to know your actual draw length, and the side plate thickness / center-shot of your bow. 

I'm not saying you don't know your draw length, but rather offering some potential reasons.  I have found that most people overestimate their draw length until actually checked. 

[BAK]

After over 50 years of doing this I really don't see the point.  If it seems to help you, then by all means.

[George Vernon]

Two suggestions.

First, as others have stated, confirm your inputs with actual measurements.  Folks I've helped in the past have put in the wrong amount of center shot, thickness of the strike plate, and actual draw length.  The results they get don't look like anything they see when they shoot.  If the bow you are using is listed in the menu, then the centershot measurement is made for you.  You will still need accurate input for the strike plate thickness.

If your input data is correct, then the second area is use of the 'personal form factor'.  I encourage folks who have a current arrow setup that flies well, to put in all the measurements associated with that setup.  Run the calculator.  If the spine measurements are off by more than a couple of pounds, go to the personal form factor at the bottom of the input page.  It will accept positive and negative values.  So pick one and see if the spine measurements get closer together or further apart.  Keep inputting slightly different values until the spine measurements get within a couple of pounds.  Whatever 'personal form factor' you used that gets you close is the PFF you should use for all other bow/arrow combinations.  The PFF is simply a way to customize the model to your way of shooting. If a PFF of '0' is used you are relying on the 'average' values used in the model.  If you are not 'average', you will likely have to use a PFF determined by trial and error. 

For example, if you have a 'perfect' release with your current setup that you know flies well, and use a PFF of zero, the results will likely show an arrow that is under spined.  If you pluck the string like a you're playing a guitar, the PFF of zero will likely show over spined using the input from your current setup.

The PFF is a way you can customize the model to reflect how you shoot.  Don't expect it to match anyone else but you.  It's a great tool if used properly.

[Huntschool]

I used Stu's a number of years ago and found that it worked well for me based on my form factor.  I saved all my "configurations" so that I had a base to work with.  One must remember the "garbage in-garbage out" concept.  If your measurements are good then I think it will yield some good information that you need to apply to testing.

Just my thoughts