MGH_PA

Ok, although I made it through Calculus in high school, my math skills still are sub-par[8D] I shoot RH anyways, so this question is more or less for fun, and to finally understand a problem I've been racking over for about 15 minutes now. When fletching straight offset, there's often a degree recommendation (2-3, 4-6, etc). My question is how do you actually calculate the distance required for the front and/or rear of the fletch to offset from the centerline? At first, I just tried basic Trig. Given a 2" fletch (blazer) offset 2 degrees. Sin 2 x 2. Then I realized that you're not working on a 2d plane, but a 3d plane (the fletch base begins to curve and follow the contour of the shaft as it's offset), so that formula wouldn't work. I saw a poster over on AT mention that for a 2 degree offset on a 2" blazer, you would need to vary the front or the rear of the vane 1/16" from the centerline. How is that calculated? It's probably very simple, but I can't for the life of me figure it out.

Rick James

Matt, your overthinking this. [8D]

Take a vane and put it in the clamp. Without putting glue on the vane, find the spot where you can put as much offset as you can get and still have solid contact the whole way down the vane on the shaft. Solid contact is what matters, that's what is going to make the glue stay effective. Once you have found this spot, keep it there and set the jig there, and fletch all of your arrows there. I don't know if you can do it on a Bitz, but I mark it with a sharpie on my jo jan so I can get it to the same spot if I decide to do a different offset for another arrow/fletch.

rybohunter

^^^^what he said.

I have all sorts of marks on my bitz for different fletch/shaft combos

mez

I would guess 99% of people fletching arrows don't have a clue what degree offset they are using. I've been doing my own for years and don't have a clue. Like Rick said, get as much as you can while maintaining contact.

MGH_PA

Lol! Sorry guys, should have been more clear. I understand the concept of offset, and how you want a balance between solid base/shaft contact and vane offset/twist, I'm just wondering where the degree standards came about? What is 2 degrees? How do you know it's 2 degrees? Like I said, I'm fletching RH, and I've already got my new jig set up with good fletch contact. This question is more or less out of curiousity. Did somebody just pull these degree numbers out of their you know what, or can you really calculate what 2-3 degress offset truly is? For instance...the new Bohning jig that was at ATA this year is allows for perfect 3 degree offset on all blazer vanes. How are the degrees calculated?

Centaur 1

On my Bitz I put marks with a fine sharpie to the sides of the zero line. 1 deg is about .09" or just under 3/32". If your 1 line to the left of zero at one end and one line to the right at the other end, then you would have approx. 2 degrees of offset.

MGH_PA

How did you calculate the 1 degree offset on the shaft to know that you had the dial set just right? What I'm saying is...you marked above the dials, correct? How did you know where you were marking was truly 1 degree offset on the shaft?

KodiakArcher

If you get a protractor and put the zero (flat) edge down the centerline of the shaft starting at the tail of the fletch and then read the angle at the front of the fletch you get the degrees of offset. (The degrees that the fletch is offset from the straight centerline of the arrow.)

MGH_PA

Not a bad idea at all. I was just always wondering why people were always throwing these 2-3 degree numbers around without knowing that that distance actually was (therefore really knowing whether or not it was truly 2 degrees, 3 degrees, etc.

Centaur 1

Hey Matt,

It's hard to be exact but my method is close. The adjustable part of my Bitz jig is approximately 5" long. 5 times the sine of 1 degree = .087. That's about one human hair less than 3/32". I took a fine tipped sharpie and marked 3 lines on either side of both zero lines that are 3/32 apart. Then just give as much offset as you can while keeping good contact with the arrow shaft. When you're done count how many lines you are off from being straight, with each line of offset you'll have approx one degree.

Mike