Was running some #'s for my TallTines thats on the way.

Should be low 60#'s @ my 29" draw.

Made up some Axis trad 340's with a footing. The calculator said I would be way under spined with even a 100 grain field point??? It didnt have TallTines listed as an option so I used a Schafer recurve instead.

I really hope that I just put something in wrong, but I'm lost any ideas?

In order for the calculator to give you a good base to start from you need to have all your numbers put in correctly. You can't substitute one bow for another if your bow is not listed you should go to the generic recurve and put in the proper info.

Ill give that a shot, thanks for the heads up.

Does that arrow sound like it should be in the ballpark? I will leave the shafts full length and bare shaft tune, have a field point test kit ready to go as well

You also have to mess with the "personal form" cell in order to get the calculator dialed in for you.

Good Luck!

~Shan

I've never understood that personal form part. It drastically changes the #'s if you play with it (the one on 3 Rivers that is)

I generally have the most trouble with my release but am not sure which # to use to quantify that

I have never been able to get it to work either.

Once I figured out that my personal form factor was in the neighborhood of minus 15 all the numbers made sense and it seems to work fine.

STU's calculator generates a theoretical optimal dynamic spine requirement for a bow & also calculates the configured arrows dynamic spine. I personally believe it is very accurate and useful. However, we each have unique form & the data going in the calculator must be accurate for the best results. Critical bow data like riser cut/strike plate thicknesses, string type, dynamic bow efficiencies goes into it, consistent draw length (no creeping or extra pulling, just good solid consistent bad tension), accurate draw weight, etc... In addition, its very important to enter arrow data in correctly. Sometimes using footings & wraps etc require some custom entries to get the weight & distribution accurate. "IF" you have everything entered in correctly it should be pretty close. If not, then you can tweak your arrows characteristics through bareshaft tuning to finalize your setup. After you have a working arrow you can enter that arrow into the calculator to reveal it's dynamic spine. Now you can use the form adjustments to effectively calibrate the STU calculator to adjust the bow & now user's dynamic spine requirement to match the arrow. Theoretically now you can use the form adjustment factor on all of your future setups or adjustments. This affectively should take the theoretical optimal setups and calibrate them to your unique form & efficiencies. Hope this helps. Another way to streamline the process is to take a setup that you know is optimal for you on a different bow/arrow and enter it in the calculator. If the calculator is showing differences, tune the form factor til they agree. Now you have a form factor to use for other setups...

CAUTION - Just make sure everything is entered correctly & accurately before you believe the calculator needs the form factor and adjust it OR you will chase your tail... :-)

You need to tune then enter all your info and then adjust the personl form factor till it brings the scale into alignment. You will need to plug in the numbers from a bow you know is tuned and shoots well to get your PFF, then use that number for your new bow.

QuoteOriginally posted by Robert Armstrong:
You need to tune then enter all your info and then adjust the personl form factor till it brings the scale into alignment. You will need to plug in the numbers from a bow you know is tuned and shoots well to get your PFF, then use that number for your new bow.

This is the best way to use the calculator imo.

I've never understood that personal form part. It drastically changes the #'s if you play with it (the one on 3 Rivers that is)

I generally have the most trouble with my release but am not sure which # to use to quantify that

I have worked with the calculator a lot.  I have found that if I put in the exact-precise data, it is very, very close or deadon.  The centershot variable is very important.  If your bow is listed in the list, that is what the maker says he cuts centershot too, but not every bow is the same on handmade bows.  

You have to put in the variable for the exact bow and arrow you are evaluating.  It works for me, and I do not use the personal form factor.  

The spine calculator, just like an Easton arrow chart, is only a starting point to get close.  You still have to tune your set-up with bare shaft.  I have found it very accurate, much more than a chart, but I also shoot off an arrow rest and make sure I have no clearance fletching issues in tuning.  

It sounds like you do not have the actual bow yet.  I have been where you are.  Wanting to be prepared.  I have also found that to get the exactness of data that the calculator requires, I have to have the bow in my hands and shooting it.  I need the exact weight at my draw with that bow.  I need the exact draw length for me with that bow.  I need the exact centershot.  I measure my leather for strike plate with a pair of dial calipers, so I enter in the exact thickness.  As long as I enter in the "exact" information, the tool has worked for me.  When I first used it, I made assumptions about data.  I have realized that will not work.  It has to be exact and factual info you put in.  It is a precise instrument that has been extremely helpful to me.

Hmmmm.  Thought I responded to this one, but maybe I forgot to hit send, or maybe it was pulled.  Don't know.  

Regardless, don't toss in the towel yet.  I think the 340s, cut to one inch longer than your draw, with a light point might be just the ticket for your set up.  I'd certainly recommend waiting until you get the bow and give them a try before purchasing something else.

The best way to determine your form factor is to input all the info for a setup you've shot that you know shot perfectly.  Adjust the form until those numbers match and you should be pretty close.

With that said, I think most all the carbon arrow need to be used with a form factor of -10 to -15.

I know there are a lot of people who don't like the calculator.  But I use it very, very frequently.  Once I had my form factor set, it is shockingly close even with bows that are cut way off from center (Hill Style for example).

Also couldn't agree more about making sure the info you enter is accurate.  As my boss likes to say about performance monitoring software we use...."garbage in, garbage out."

The calculator is a mixed blessing for me. It is a start but I usually end up using a lighter point than calculator wants me to. That is with carbons anyway. I have better luck with alum arrow setups. I rather have a buddy watch me bareshaft than use the form factor. Seems I can adjust form factor to get what results I want.

I'll give the 340's a shot seeing as I already have them. I keep getting mixed replies about higher FOC flight in wind. (Was hoping to use 200 grain points @ least, but seems like a lot of people feel the higher foc arrows dont fly as well in the wind.

The point may end up where I was aiming, but it would be at an angle=bad penetration. I think I would rather calculate for windage and just aim into the wind a little more and still have an arrow that hits the animal straight on

I find mine do just fine, even with very long fletching.  I can get 35% or more FOC, and at that point the wind can't mess with them too much.

Gets pretty windy here in MT, specially pronghorn hunting out in the prairies

My arrows weigh a quarter pound.  That might have a lot to do with it.

Haha yea I suppose. Im hoping to get real close to 10gpp