Tuning experts explain this!!!!plz

[ChrisM]

Ok I have a new back set Hill Tembo.  64@26 66" long.  I draw an honest 25.5".  My arrows are 55-60 tapered Fir cut to 26"BOP. I am not a new had at hill bows just new hand at backset.  I have only shot a string follow before at a lighter weight.  
Now the question.  With a 125 gn point this bow will put the arrow 5 feet to the right (right handed shooter) at point on distance and with a zwickey eskimo it will drill right were the tip is held.  Now if I add point weight the field points will start moving left but no matter the weight up to 190gn the broadheads will group with each other.  Hitting right should be too weak but I am already stiff and weakening the arrow makes it act stiffer.  I had not noticed this until I shot long distance yesterday.
So what is going on here?  
Oh yea I forgot to add I have two  65-70 tapered spruce that I cut to 26" BOP and with 125gn they hit just to the right by about 6" at point on distance.

[ChrisM]

190 gn points do fly with some wobble.

[Brianlocal3]

It does not make a lot of sense in all honesty, but Rick Welch actually prescribes, in some instances , to add point weight to make a fletched arrow move left. McDave explains it very well over in shooter form forum.  I'm not smart enough to repeat it, all I know Is it made sense to me.

[ChrisM]

Brian it seems kinda opposite from what I have always experienced.

[Brianlocal3]

I'm in the same boat brother. I had left issues for a while so I kept adding weight,  no fix.  I read McDaves post so I tried some 85 gr  instead and BAM A fix

[ChrisM]

I think I may have solved it.  As usual once I finally ask I make a break through.  I ripped feathers off of a shaft and tried bare shafting.  Well 125 seemed weak.  But what if it was a stiff shaft reading weak.  Well on goes 190 grain point.  That arrow went so far right so fast that it totally missed the back stop at 15 yards and is some place under the grass in the pasture.  So I russeled around my shop and found some 60 65 parallel cedar shafts that I made up and never used probably 8 yrs ago.  Well 26" Bop and bam 125 gn shooting right where it should with field point and broadhead.  Guess I was weak after all.  So much for Stu's calculator.

[Rossco7002]

I have found the calculator to be dead on with carbon and aluminium but with wood - not so.

Glad you figured it out Chris!

[Hud]

Check website for tuning,  www.acsbows.com  or  www.elitearrows.com   the >proper arrow
If yours are 55-60 spine at 28 they would be very weak. At 26", still too weak for 64 lbs IMO. I have a similar weight and shoot 65 - 70 with a B50 string material.  

Pay attention to their recommendations. also, if you use FF string, up the spine by 5 lbs. Add 5 lbs when adding fp wt. over 145 gr. over 170 added another 5 lbs.

[kennym]

Glad you got it!

The center cut makes a lot of difference!

I have a bow that is cut past center and at 45# , needs a 60/65 wood shaft....

[Prairie Drifter]

I have found that I need 10 lbs more spine than the calculator says, but with wood only. carbon and aluminum, it's pretty close.