I just got a new bow---a 56" Toelke PIKA. It is 40@29". I draw about 26.5" so around 34/35# at my draw. I immediately found my Heritage 75s (.670 spine) way too stiff even with 200 up front and full length. I had a 1716 (.880 spine) and found it bareshafted decently. I fletched it and then found that no matter how much weight I added to the front it hit 3-4" to the right---I shoot left handed so thought that it was too stiff. I read one of McDave's posts from April of this year and he explained that sometimes we get an opposite reaction with fletched arrows. I dropped point weight from 125 to 100 and like he said my arrow moved to the left as if it was weaker. I very much appreciate the wealth of information that I have gotten on this site---I'd sure be stumbling around in the dark without it.
I ordered some .800 spine predators and hope that they will tune for me. Thanks again McDave!
You said you shoot lefthanded and your arrow was impacting to the right. The general wisdom would be that this indicates too weak (for a LH shooter), rather than too stiff. So you decreased the point weight (stiffening the arrow), and it moved your POI to the left, as one would expect. I don't think this is an example of the reverse effect that I wrote about, but it is does show that we have to keep an open mind when we are tuning with fletched shafts. From what you have stated, I believe your .800 spine predators should work out well for you. good luck!
Wouldnt a right impact indicate a spine too stiff for a lefthander? Point impacting to the right of target and nock left position is what im getting bareshaft.
On second thought, you are correct. I must have been confusing my lefties and my righties. So my theory actually did work! Yay!
Im looking forward to tuning the 800s. I hope they are weak enough as the 1716 is .880 spine-- if not I'll be looking at 900s. When i could get the chronograph to work it looked like speed was only a few fps less than my 42@28 w same arrows i shoot in that bow, so im surprised it is wanting such a weak arrow. I did shoot shorter arrow w lighter tip to rule out a false stiff.
I will be interested to know how the .800's turn out.
The 800s tuned good w 125 point and 38gr outsert. Arrows full length. I put a clicker on this bow yesterday-- first time ive used one. Wow did it tell me about my form. All of a sudden the 800s tuned perfect w 100 gr points and my heritage 75 that just barely tuned w 200 points now tune with 125. Im always learning. I believe the clicker is going to be a great aid in consistent expansion.