I've always used Stu's old calculator, the one without specific bow models, with great results. With the proper data entered, matching arrows to bows is easy. Well now I've downloaded the latest version that lets you enter your bow model. I have a 45# Samick Red Stag, and when I enter all fields for the bow and the arrows, it reads the same as the old calculator, and the arrows spine correctly for the bow both in the program and when actually shooting.
Here's where I get confused. I have a 40# Samick Sage on the way so I plugged its numbers in to see how far off the arrows for my Red Stag would be in spine. Since the new bow is 5 lbs lighter, I assumed the calculator would tell me they are stiff. Nope. According to Stu, the 40# Sage requires almost 10 lbs. more dynamic spine than the 45# Red Stag. What gives? I entered both with a 28" draw rating, and entered my 26" actual draw length. I entered the same strike plate thickness, and the calculator entered the same centershot on both bows. The only differences in the bows is that the Sage has a 2" longer AMO length and is a takedown, where the Red Stag is a one-piece. They both have recommended brace heights around 8". The only other possible performance difference I can think of is the limb core material, but I'm not sure what each bow is made of. I appears they both have hard maple limb cores, but I'm not certain. Can someone with more knowledge enlighten me? I'm having a hard time believing that a bow which is very similar to another bow, yet 5 lbs lighter, would require 10 lbs more arrow spine. Thanks for reading my rambling. :)
i see lots of issues with "arrow calculators" and one is, are you SURE you know EXACTLY what yer bow's holding weight is at yer draw length? the other, and more poignant, is that it's just far too plebeian generic a methodology for a medium that's fraught with unique ambiguities.
QuoteOriginally posted by Rob DiStefano:
the other, and more poignant, is that it's just far too plebeian generic a methodology for a medium that's fraught with unique ambiguities.
I have no ideal what that means!! :smileystooges: :knothead:
QuoteOriginally posted by L82HUNT:
quote:
Originally posted by Rob DiStefano:
the other, and more poignant, is that it's just far too plebeian generic a methodology for a medium that's fraught with unique ambiguities.
I have no ideal what that means!! :scared: :laughing:
Well just keep the pointy end forward - your half way there.
I know arrow calculators aren't the final word in tuning. Nothing beats getting out in the yard and flingin' arrows at a target. But what I'm asking is, with equal values being entered into the program, why would it say a 40 lb bow needs a stiffer arrow than a 45 lb bow?
QuoteOriginally posted by rod251:
I know arrow calculators aren't the final word in tuning. Nothing beats getting out in the yard and flingin' arrows at a target. But what I'm asking is, with equal values being entered into the program, why would it say a 40 lb bow needs a stiffer arrow than a 45 lb bow?
because software is based on formulaic pre-parsed input = "guesstimate". it's all common sense guesswork, with a hefty emphasis on "guess".
Rob, I'm pickin' up what you're layin' down. But I think the problems you speak of are more along the lines of, "program tells archer use XXX arrow, archer shoots XXX arrow out of bow, XXX arrow flies like crap." What I'm talking about is strictly a software issue. When asked for my actual draw length, I entered 26" for both bows. The centershot entered for both bows was -1/8". The strike plate thickness was the same on both bows. The draw weight rating for both bows was Xlbs@28". The only thing entered differently was the difference in draw weights. Why would this program tell me a lighter bow needs a stiffer arrow? That's what has me stumped.
like i said, it's all in the programming and no one can answer yer question unless the code can be viewed by someone who can understand it all. you need to contact the programmer.
QuoteOriginally posted by Rob DiStefano:
like i said, it's all in the programming and no one can answer yer question unless the code can be viewed by someone who can understand it all. you need to contact the programmer.
I guess so. It would seem that the formula would be linear, spine increasing as rated poundage goes up. Oh well, it'll all come out in the wash this weekend when I have the bow in hand. Thanks for all the replies!
maybe you found a bug in the code. all the better to report it to the programmer!
Sound like a glitch. I have seen some variations, biu not that bad. The one that has me puzzled now is why do I consistently need 20# weak to shoot 400 spine carbon, but when I got some 3555's and set them up I am way weak and it looks like the calculator is real close. :dunno:
Email sent. We will see how this plays out.
i know a few things about computer code. when you think of all the variables a spine calculator program requires, you'll realize why it will fail somewhere along the way for some folks.
I'll have to take your word for it, because if you combine all I know about computer code with a dollar bill, you'll have exactly $1. :D
QuoteOriginally posted by rod251:
I'll have to take your word for it, because if you combine all I know about computer code with a dollar bill, you'll have exactly $1. :D
;)
I remember the good old days with the Easton chart. The chart says try a 2016 cut to length with your choice of head on it. Too stiff? Try a 1918. Still too stiff? A 1916 or an 1818 will be right on. It may seem like a lot, but if you had a good archery shop to work with, it was easy.
The old Easton spine charts of the 60's and 70's were much better than the chart Easton now puts out. The chart now is way off (too stiff) for their aluminum arrow choices.
As an example. With my 42# recurve shooting a 32" BOP aluminum arrow tipped with a 75 grain point weight, the present Easton chart says I should be shooting a 2215 aluminum arrow. My 42# recurve doesn't like this arrow length/point weight setup. It likes a 32" BOP, 2212 aluminum arrow tipped with a 75 grain point weight which isn't even listed as a choice.
Example #2. With my 37# recurve shooting the same 32" BOP length aluminum arrow and 75 grain point weight, the present Easton chart says I should be shooting a 2312 aluminum arrow. But, this bow doesn't like this aluminum arrow length/point weight setup either. This bow also likes a 32" BOP, 2212 aluminum arrow with the same 75 grain point weight and again, the 2212 isn't listed.
Stu's calculator has correctly given me many different aluminum arrow spine choices from a light arrow setup all the way up to a very heavy arrow setup for both of my light poundage recurves.
with any arrow spine/selection software, there will ALWAYS be a measure of 'hit or miss'. it's absolutely impossible to code for all of the hundreds of thousands of interactive possibilities of arrow, bow and archer. that road is fraught with moon crater sized pot holes. wish it was different, but i know better.
so, for some folks the code works great, for others it works sometimes, and for others it could never work. still no substitute for hand's on testing ...
Guess I'm on of the few who have a couple of "dead to nuts" setups that Stu's calculator agrees with using 0 as the Personal Form Factor. Seems to me if the calculator almost always tells you to use a too stiff an arrow, perhaps playing with the form factor might be a way to "calibrate" the calculater to your particular shooting style.
QuoteOriginally posted by rod251:
.
I entered both with a 28" draw rating, and entered my 26" actual draw length. I entered the same strike plate thickness, and the calculator entered the same centershot on both bows. :)
The calculator sets the centershot measurements but it DOES NOT show what it has entered. Set it to a measurement and then change bows, you'll see that the measurement doesn't change in the box ,but does change internally. So to answer your question, the bows have a different center cut to the risers.
As I understand it the Stag is cut to center or "0" and the Sage is cut past center to -3/16".
No glitch in the program, just glitch in info. input....usually is "user error"...I speak from experience! haha
QuoteOriginally posted by Swamp Yankee:
Guess I'm on of the few who have a couple of "dead to nuts" setups that Stu's calculator agrees with using 0 as the Personal Form Factor. Seems to me if the calculator almost always tells you to use a too stiff an arrow, perhaps playing with the form factor might be a way to "calibrate" the calculater to your particular shooting style.
When I read the directions on how to use the calculator after using it a couple of times I found that the calculator is pretty spot on with the zero personal form factor. I am not getting the fps predicted and in fact fall 20 fps short. I'm extremely worried about it can't you tell? The fact that it has so many shafts in its database and in fact turned me on to a great shaft that I had not heard of before is awesome. I feel it's a valuable tool for ballparking arrows into tune. I find it's hard to beat CoolFlex insert glue teamed up with Stu Miller's for keeping arrows tuned to an archer who is getting stronger and more consistent over months of practice. They both save lots of money in wasted arrows shafts.
QuoteOriginally posted by snag:
As I understand it the Stag is cut to center or "0" and the Sage is cut past center to -3/16".
No glitch in the program, just glitch in info. input....usually is "user error"...I speak from experience! haha
I figured something funky was going on. I'm glad you guys figured it out for me. In other good news, I should be able to replace the brass inserts in my current arrows with aluminum inserts and hit my spine numbers for the Sage right on the money. Now I just gotta wait for Mr. UPS man to do his thing. It doesn't help matters that the issue of Fish, Fur, and Game I ordered was out of stock so 3Rivers had to substitute another issue, delaying my order. Oh well.
QuoteOriginally posted by rod251:
I know arrow calculators aren't the final word in tuning. Nothing beats getting out in the yard and flingin' arrows at a target. But what I'm asking is, with equal values being entered into the program, why would it say a 40 lb bow needs a stiffer arrow than a 45 lb bow?
Rodney,
I have a similar problem. I just purchased a 50# @ 28" Quinn Stallion and I draw just shy of 30" so...about 53# at my draw. I had some 2117 cut to 30" with 100 grain points that were tuned to the same type of bow but 45# @ 28" I knew they would show pretty weak when I go to shoot the 50# Stallion...I decided I wanted to see how weak they would be and if I could make them work somehow with Stu's calc. Surprising the arrow shows a much higher dynamic spine than what the bow needs...hmmm it's really strange. So Stu's calc is saying they should be way stiff and when I go shoot they are way weak.
hysterically, for the very most part, all carbon shafting has an incredibly stiff dynamic spine versus it's static spine. many bowhunters are using 500 spine for a 29"+ arrow loaded with 350grs or more up front, out of 50-55# stick bows.
Sage and stage have different center cuts.
sage is -3/16 while the Red stag is 0.
So your tow bows are different from the start. Center cut makes a difference.
If using new DO NOT PUT number in center cut. It is already programed across. Just enter thickness of Strike plate added.
QuoteOriginally posted by Rob DiStefano:
hysterically, for the very most part, all carbon shafting has an incredibly stiff dynamic spine versus it's static spine. many bowhunters are using 500 spine for a 29"+ arrow loaded with 350grs or more up front, out of 50-55# stick bows.
That's funny...the last time I used carbon was out of my Quinn Stallion Classic 40# @ 29" and I draw to almost 30". I was using an Easton 500 Lightspeed cut to 29.5" with a NAP flipper rest and 100 grains with 18 grain standard insert and bareshafted perfect at 15 yards.
QuoteOriginally posted by Flyboy718:
QuoteOriginally posted by Rob DiStefano:
hysterically, for the very most part, all carbon shafting has an incredibly stiff dynamic spine versus it's static spine. many bowhunters are using 500 spine for a 29"+ arrow loaded with 350grs or more up front, out of 50-55# stick bows.
That's funny...the last time I used carbon was out of my Quinn Stallion Classic 40# @ 29" and I draw to almost 30". I was using an Easton 500 Lightspeed cut to 29.5" with a NAP flipper rest and 100 grains with 18 grain standard insert and bareshafted perfect at 15 yards. [/b]
just goes to prove there are some interesting variances in good working setups ... that the software won't catch. :D
An other small thing THE FOOTING BOX if you use an insert longer the 1/2 inch i.e a 100g brass you need work with the Footing Box. You would change it to yes. add the length of the insert longer then 1/2" and leave weight at 0 since you have calculated it in the insert weight.
I think it's a little of both. Use Stu's to get you close and then fieldwork from there. I find that with my wood and carbon arrows, the numbers are right on from the calculator, but I had already done the fieldwork a couple of years before entering the data. I just wanted to try the software for fun.
This is just speculation of course, but I think the difference you're seeing is the result of whatever formulas/data Stu used to factor a bow's efficiency.
You can take two bows that both draw 50#'s @ 28" but one of them may not be as efficient at transferring that energy to the arrow as the other. The less "efficient" bow will require a weaker spine than the more "efficient" bow. The arrow shot from the less "efficient" bow will also be slower.
I know this was kind of long but I've been looking at the same thing on that calculator trying to figure out what's going on.
Hello All,
Les hit the nail on the head. The difference is due to the riser cuts of the two bows. With the Sage being cut 3/16" further in that trumps the draw weight differences by far.
Also, if you ever want to know what specifics the DSC is using for the automatic inputs just click on the "Data Library" tab at the bottom. The top line shows all the details with the bow inputs over to the right hand side. You can see the bows riser cute dimension, the strike thickness, and also the resultant strike position. Also, if you are not sure exactly what static spine so of the shafts are just select the one you want from the main page and you can see it's details also in the Data Library top line.
There is a new version coming out in Jan which has corrected the speed issues. Originally the equations were developed off of shooting bench data which uses a clean mechanical release. I know that none of us have such a great release as that and loose some speed there as well as from slight creep. The new speed calculation will take both of those into consideration as well as the effect of draw length and not just weight at final draw. I know you will be much more satisfied with the new speed number accuracy.
Also the new version will be able to handle tapered wood shafts. Finally figured out how to predict the effects correctly. You will be able to enter final nock diameters and length and the dynamic spine, final weight, FOC% will all change accordingly.
-Stu Miller
Stu,
I know I'm not the thread originator but I still wanted to say thanks for clearing that up for me also (The light is slowly coming on).
Jess
Thanks Stu! I meant to respond to your email yesterday but I got really busy and never got back online.
Glad to hear there will be an updadted version of the calculator coming in January. I'll be looking forward to "putting it through it's paces". :D
That is wonderful news Stu. A tool that keeps getting better and better. I want to thank you for the time and effort you have put into this over the years. It is a great gift to the community.
If anyone is wondering where to get the calculator
here is the address.
http://www.heilakka.com/stumiller/
Sounds great Stu. Can't wait to play with the new one. I love using the caclulator to get me close...takes so much guess work out for me and saves me money.