Guys, I have been playing with bareshafting for the last several months. Trying to get form right bareshafting different shafts etc. I thought well, I will give stu miller's calculator a try.
I have a black widow 50# bow at 28" draw. I have been bareshafting 35/55 gold tips. I realized after I finally settled on my form that I was short drawing. Saying this, it put me back to square one with the arrows. I finally think that my form is good enough to do this. I have been practicing Rick Welch's accuracy factory methods, and I have a longer draw with decent back tension. Thus the reason my arrows are out of spine. Well, I have settled on a 30" 35/55 with 175grain head, 14 grain insert, 5 inch shield cut feathers and double dog wraps that I am figuring weigh 30grains. They are still shooting just slightly stiff for my first few shots, but when I settle in they are showing dead on or weak. I have ordered some 20gr and 50gr inserts so that I can make sure I am slightly weak. I will then fletch and shoot.
Saying all this, Stu's calculator says that this particular 30" gt 35/55 with 175gr head has dynamic spine of 48#, and arrow dynamic spine of 72#. It says the arrow weighs 487gr, 9.0gpp, 15.5 foc, and 38.9lbs of energy The calculator suggests that the two spines should be within 2# of each other. However, my bare shafting is saying that I am a 20-50gr of weight away from perfect flight.
I guess my question is does Miller's calculator work for in most cases or is it giving me false info. I am just trying to do this the cheapest way, but I also want it to be right. Thanks for any help with this.
I've always thought any spine calculator was meant to get you a pretty good arrow if you didn't want to bare shaft. Bare shafting is showing you what really is, as opposed to what somebody thinks it should be. I'll bet there are people whose arrows would be tuned with your setup with anywhere from a 125 grain point to your 175 grain point or even heavier, because different people shoot the bow differently, different bows have different efficiency, and will require differently tuned arrows.
For example, I have two sets of limbs for my DAS Dalaa: 45# and 55#. I carefully tuned the bow with the 55# limbs, and decided based on bare shaft tuning that 3555 gold tips cut to 29" with a 125 grain point shot perfectly, so that's what I hunted with. When I got back and wanted to use the bow more for targets, I put on the 45# limbs. I initially tried GT 600 ultralights, but never could get them to fly right, so just for fun, I shot the same arrow I used for hunting, and got perfect bare shaft flight. There is no reason, logically, why I should be shooting the same arrow with the 45# and 55# limbs, but that is the arrow that gives me the best flight, so that's what I'm going to use.
I think that if you are bare shaft tuning, you have already gone beyond any spine calculator, and ought to go with what you see.
I have a few buddies that shoot Widows very close to your set-up and most all of them shoot a 29.5" 35/55 GT with a 50 gr brass insert and a 125 gr point.Factor in the extra stiffness wraps and as you already know, you are close. Widows, are cut 3/16 past center and from what I've seen, like an arrow that is a little stiff. I do like Mcdave said and go with what the BS is telling you, good luck.
Thanks guys, I bit the bullet today and bought a variety of points at different weights, and bouth 20 and 50 grain inserts. I shot more bare shafts this evening and got the same results which is good. It means that I am consistent. I am about a 1/4 inch nock right which is showing me that I am a little stiff. I hope the 20 grain insert will help. If it fixes the problem and I am consitently 1/4 inch nock left, then I am going to stick with it or shoot the 200gr field tips that I purchased. I don't figure that 5gr will change things. Thanks again, it has taken me a while to get the bare shaft thing, but I backed off and practiced getting consistent form. This has made my bare shafting fruitful.
When I fist got the bow, I thought that could go out bare shaft and bam, I had it. I found out that I was not doing anything in a consistent manor, so when I started doing things properly, the arrows started telling me. I started back at square one yesterday with much better results. I will say that the most difficult part is getting a decent anchor without having a fletching for my second anchor point. Thanks
Don't argue with the arrow. H
This is a dumb question, however, what is your draw length and what is the limb length of your widow? IMHO it will make a difference.
My draw is a touch over 28. Like 28.25 The bow is a 60 inch psax.
Don't argue with your arrow or compass.
Stu's calculator wasn't close when pluggin in numbers for my Widow.
But my arrow is.
I don't have a Widow, but I put three different bows trought Stu's calculator. They were all bareshafted to perfection, so I knew what the values should be.
Stu's calculator was scary accurate!
Did you take the centercut option into account? Most recurves are 3/16 past center cut, which makes, whith strikeplate - 1/8 in Stu's calculator
Stu's calculator worked pretty well for me but I had to make sure I entered the right info as well. Your draw length needs to be known for sure and how the shelf is cut is important. I am shooting a 49@28 PSAX but I draw to almost 29.5. I ended up with 55/75's and building my shelf out just a bit. I went with the calculator to help get me in the area instead of bareshafting because I was having some form issues and my release really sucked so my bareshafting wasn't telling me what I needed to know.
Good luck.
Don't forget to consider the thickness of your shelf material. If your bow is cut -3/16 and you use calf hair which is about 1/16"thick then use -1/8" and not -3/16 on the bow inputs. It will make a big difference, also use recurve and not performance recurve on bow inputs
WE can I find Stu's calculation program? Is it available for Download? Thanks!
That should read Where instead of We Sorry!
What would you classify an ACS LB as on the calculator?
here is the link http://heilakka.com/stumiller/
Spurs, based upon your draw length and arrow point weight i would think you are under spined. Try a 55-75 with your point weight set up. Hope i have helped.
I have used stu before and had everything exact even measured with feeler gauges shelf to arrow contact and it was 10-17 pounds off from what bare shafted the best. It always has my arrows way to stiff just for kicks i tried the arrow it said and it shot a whole lot less than perfect for me.
I should have said i shoot 35-55s 29" with a 125 point field and broad head out of a MAiii 60",50#@29"and pull against the point or about 29".
6 different bows, three different people and Stu's calculator put us real close in all cases.
Here is best tutorial I know of as far as tuning a bow and bareshafting
http://www.acsbows.com/bowtuning.html
I had been putting performance recurve in and just changed it to recurve it is pretty close at this setting within 5 lbs. Should get you close enough to do some bare shaft testing.
Good stuff, I will have been putting performance recurve in as well.
I bare shafted my 56" PSA III before I knew of Stu's spine calculator. WHen I enter the data for the arrow I shoot the tool proves to be almost right on.
I think the best benefit of the Stu's calculator is that once I know what dynamic spine flys from any given bow, I can use his tool to change shafts and when the new shaft matches the known good shaft things pretty much fall into place.
I have found that Stu's Dynamic Spine Calculator was very accurate for my widow. I have also used the calculator for two of my buddies who also shoot widows and again the results are very close. It should give you a good starting point.
These are my observations and experiences,as always ... your mileage may vary.
Freeze
P.S.
I am now in the process of tuning a Morrison Mini-14 ILF with W&W INNO Power limbs, and the calculator is WAY off from my bare shaft observation. This may be due to the adjustment and variability of pre-load with ILF risers.