Stu's Calculater ???

[Want2no]

Okay, I have a Hoyt Expert 40# at 28"  B 50 string. I draw 27"  Shelf is cut past center, but side plate makes it even (0).  After playing with the variables, I came up with full lenght 35/55 GT Traditionals, 50 gr. inserts, 145gr. point, 3x4 fletch.  I used the Generic recurve option as my bow is not availble from list.  The calculator comes up with .1 lbs diference in arrow dynamic vs bow dynamic spine.  (44.2 and 44.1 respectevly)  When I bareshaft the groups are close but the bare shafts nock points WAY right and flight is not pretty.  Is this acceptable?  
I ask because the opinions on the calculator lead me to believe I should need very little tweaking.  Is this true?

[Hermon]

The calculator is not gospel.  It may or may not get you close because of several factors, the main one being you.  You may have better form than me or worse.  No way to allow for that in the program.  If you are right handed, it sounds like your shafts are way stiff.  I would believe your shooting over the calculator.  Try adding some point weight and see if they fly better.  Good luck and let us know how it goes.

[Prairie Drifter]

If your bare shafts fly nock right, your too stiff(if your a righty).The calc is just a starting point. I never cut carbons to length. I leave them an inch longer than the calc says, and trim if I have to. Sound like you need more point weight to soften the dynamic spine.They should fly off the bow tail slightly left.

The calc is a great tool, but it doesn't work for everyone.

[jamesh76]

Here is a tuning guide.

  http://bowmaker.net/tuning.htm  

I am not so sure about the calculator. There are so many variables like stated above. For me it is easier just get a few different spines and to bareshaft. I have never got the calculator to work for my set ups. Not sure if it is my measurements, my release, form, my correct or incorrect centercut measurement, nocking point, split or 3 under shooting, draw weight or what..... I just cannot get it to work. Too many variables. And whos to prove the the calculations with the calculator are actually right.

I think that the biggest problem with the calculator is that people think that it is   always correct. Well it is not. At least in my case.

Bareshaft tuning is the best way for me to tune my bows.

[Hermon]

I have thought that it would be interesting to use it in another way.  Once you find a shaft that flies perfect for you, enter all the particulars and find the dynamic spine according to Stu.  Then if you want to try a different type shaft, play with the calulator and see what it takes in that particular shaft to come up with the same dynamic spine.

[Friend]

My calcs have you ~8#'s underspinded -asssuming your arrow is 32"s.

I pay little attention to nock impact angle. Pay attention to bareshaft impact point relative to fletch shafts. Once you work to 20 yards and preferably further, the nock entry should have taken care of itself.

Try a 100 grain point to verify if you are actually underspined.

Provide us some feedback how they bare shaft at 20 to 25 yards.

[Bladepeek]

Hermon, I've been doing that same thing. I started with Stu's calculator, the bare shaft came in quite weak. I was already below where I wanted to be on point weight and I had a bunch of the arrows, so I started cutting back. Started flying right right at my absolute shortest length, so I took that calculated arrow spine and used the calculator to find the specs for a shaft 2 steps up in spine with a heavier point that indicated the same. Bingo. Saved a bit of time and I think I now have a "fudge factor" to put me real close when starting from scratch with any arrow.

[Shawn Leonard]

Sorry but you are stiff, you are shooting only 37#s. Even full length those shafts will be stiff even with 195 up front. You could shoot a .600 spine full length with that 195 up front and you would be closer, but still maybe stiff. Stu's calculator has never even got me close, sorry. I have some 37# ILF limbs at my 29"s draw and I shot 30" .600s with 250-275 up front and they flew perfect. Not sure what the length on the 35/55 is full length but if only 30"s you need close to 400 grains on those puppies. Shawn

[Want2no]

Sounds like I have an excuse to buy an new bow  

[mrjsl]

I agree with Shawn. I think I could shoot your arrow ok out of my bow, and it is 59# @ 28.5. I'd expect that arrow to be a little bit weak for me, but not by much.

Stu's calculator says I need an arrow 20-30 pounds stiffer than what works best. I have worked up an arrow that the calculator likes for my bow, and bare shafts shoot more than a foot to the left.

[Smallwood]

Agree with shawn, your too stiff,
try adding a heavier field point to your setup or
try a 15/35(600 spine)instead of a 35/55(500 spine).
Also, if you have an adjustable centershot rest on your bow, you could move it in or out to possibly get it to shoot the arrows you have now.