Arrow spine chart

[Beendare]

FWIW, I'm playing with going back to a lighter bow. I just haven't had time to shoot my 55# bow much, then when I do my middle finger gives me grief.

I had an arrow that tuned well in that same weight...but is was a 340 with a lot of tip weight- 557g or so set up for a long PO shot...but it had a fairly big gap at 20y- not optimal.

Now that I'm addicted to the speed, I decided to drop down about 100g and I'm testing a few combinations of arrows, trial and error tuning.

I have the 2 that tune [shoot a bare shaft perfect at 20y- looks like it floats, beautiful!] ...so for the heck of it I ran them both in the Stu Miller arrow spine chart and Dang, if they weren't within a pound. I've had it close before but haven't used it in so long I figured I would give it a go.

Essentially you plug in the specifics of the bow and arrow, and if they are within a couple pounds, it should tune. These two arrows were a pound apart from the bow poundage. Bingo dead on.
Here's one of then that tuned

so the 33.5" arrow with std insert and 75g tip tunes...but I want to use a 100g, so I dialed back the arrow length to 32"- thats it, within a pound. My new arrow. 32" 400s, std insert 100g BH.

Heres where I added tip weight to 100, then just kept dialing back arrow length until they are close.


A little lighter than I wanted at 400g but with a 2 blade it shouldn't be a big deal. I have shot a couple critters with 435g in my 55# and its blows through them effortlessly. Perfect arrow flight with a 2 blade and so far the extra arrow weight hasn't mattered- but it's a small sample size.

It's one heck of a nice tool if you get the numbers right.

Here's a link to the 3 rivers version 3RIVERS

 

[LostArra]

Don't tell my wife that Stu Millers chart would have avoided the hundreds of arrows of varying spine, length and insert weight I've got in Home Depot buckets in my man cave. And that's just the carbons and some aluminum. My collection of wood shafts resembles cord wood.

 

[TNKnoxville]

That is a great tool I've used over the years. Only issue is if it doesn't have your bow listed your results can be iffy. I've found some of the generic bow info didn't match my real world results. But, it was way better than guessing and ending up with a pile of arrows like Lost ARRA said!!!!!

I have a shed full of them. Been using them as tomato and pepper plant stakes....lol

 

[Beendare]

My collection of wood shafts resembles cord wood.

Oh man, you and me both.
Thats one of the reasons I went to the cheap Chinese carbons....then found they were equal to the Eastons but with a better finish.

So the calculator gives me another option for a slightly heavier arrow that should tune; 400's, cut 31" with 125g point- 415g TAW- I'm going to test that today. I need to kick it into high gear, Elk hunt is in 5 weeks.

I was shooting for about 450g, but you know how that goes with Trad bows, they like what they like.

 

[Beendare]

Has anyone plugged in their tuned setups to the chart, I'm curious if it was accurate for you?

 

[GLB]

That particular chart gets me close most of the time, the issue with it that it over compensates point/insert weight. Adding and subtracting front end weight certainly does change dynamic spine but not as much as this program indicates.

 

[Beendare]

Bingo.
I cut some arrows 31 inches as it seemed like I was going to make that work with just a slight adjustment and tip weight.
The chart has 125g within 1/2 a pound and they shoot good But they seem like they might be just a hair stiff. so I put 145s on there and bingo!

Bareshafts float at 15y. It looks like my gap was going to be right at a half an inch to 5/8 of an inch at 20 and 25 yards- nice. The first group shows that my knocking point either needs to go up or down just a tiny bit as the bare shaft is low. But dang those arrows fly well.

Plus my arrow is closer to the weight I wanted. these are 434g. I wasn’t as concerned about arrow weight as perfect arrow flight but preferred it closer to 450 than 400.

Pic of First group at 25, inside 4”, I’ll take it-

Turns out, tuned arrows make me look like a better shot than I actually am- grin i had been scattering them before I had a bareshaft tuned arrow. Btw, the 145g arrow is 4# weak in the stu milker calculator vs 1/2 pound diff for the 125. So there goes my, the chart is right on comment- grin.

I am pumped though, I thought I was going to be spending a bunch of time on this that I don’t have.