I use it all the time. It works great for me. BUT!!! You have to put in the correct data. And I do not buy my arrows pre cut. I trim to suit while bare shaft tuning.

Sent from my SM-G892A using Tapatalk

 

I use it all the time. It works great for me. BUT!!! You have to put in the correct data. And I do not buy my arrows pre cut. I trim to suit while bare shaft tuning.

Agreed, I do too. It gets me close….I always allow for some error starting soft.

A critcal measurement is centershot. Get that wrong and its way off.

 

That’s what I’m worried about with a vintage bow versus a current production.

 

Their spine calculator is accurate for the Easton Axis Traditional arrow shafts for my recurve. Even the calculated arrow weight is pretty close.

But I think the calculated speed is off.

 

Even entering generic recurve/longbow gets me really close with customs.

Sent from my SM-G892A using Tapatalk

 

I have found it to be very accurate

 

I have a "qSpine" app that allows you to put more information in about your bow and arrow setup than you think is necessary. It takes into consideration the smallest details such as the weight of your peep or the degree offset of your vanes, to give you an idea of how the arrow selection you want to run meshes with the spine of the arrow you shoot. I placed all my information I had in about my bow and arrows and was able to determine which spine would match the best. I also went and chronoed my bow (since the app only asks for ibo speeds) to see how accurate the fps calculations were that they gave me for the arrow setup I used in the program and was surprised to see that it was an exact match. Very impressed and will be used as a fact checker for future arrow builds.

 

Doesn't qSpine only work for compounds? It asks for ATA and letoff %

I've found the 3Rivers tool to be very accurate on production bows. I built an arrow for my Super Kodiak based on the calculator and found that I only had to trim off 1/8" from the shaft to get it perfect.

 

vintage vs current production has no bearing on spine requirements.

old bows have just as much performance as current production bows (often more)

ive used the 3rivers calculator,
and as said,
it will get you close (with the correct inputs,
centershot being a critical parameter)

i tune like alot here,
start with the arrows too long,
and slowly trim down till you get good bare shaft flight,
then i put on some broadheads,
and fine tune till they hit with the bare shafts.

but i shoot woodies mostly.

 

I have had very good luck with it but I mainly use it to get the right spine arrow. I get my shafts full length and then trim them myself to tune the arrows

 

It’s fun to use, and tells you a lot. Almost every arrow setup I settle on comes out weak in the calculator. . .but tunes just fine with bare shaft.
Interesting to play with the settings and see how much it changes. Centershot and draw weight being the big ones. Most people estimate those, and you want to be dead on or the calculator won’t be accurate.

 

The best way to use it is to already have an arrow and bow who works great for you. Put the info in the calculator using the arrow working best for you. Verify the difference between the two parameters : Bow dynamic spine and Arrow dynamic spine. If the difference is more than 2, go down the page and enter the personal form calibration until you get that required difference. Keep that in mind when you enter the info for other bow and arrow.

 

I also find that modelling the insert as both insert and a footing of the same length but with zero or 1 gr weight also makes it much closer.

 

I use the calculator all the time. I don’t use the form factor feature. Like said, be sure the info you enter is dead nuts on. You may have to measure that sight window to be sure it’s center shot or ? .
make sure your draw length is correct. No, the speed results IMO are wishful thinking.