On a band saw, I want to resaw some Port Orford cedar decking (5 1/2" x 1 1/2" x whatever length) to basically get two thinner boards of equal thickness from one, e.g. 5 1/2 x 11/16" x whatever length. I want to maximize my yield and therefore minimize the loss on thickness. Ideally, 1 1/2" split into two less 1/2 the size of a saw kerf (theoretical 1/8")should yield 11/16" (3/4" - 1/16") without planing. I'm finding that the method of setting my fence so it placed the blade smack in the middle of the width of the board proved problematic.
Resaw_diagram2.jpg
I tried to approximate the one half mark, then by hand turning the bandsaw wheel and pushing the work into the blade I create a light cut, almost a scar or sratch, of where the line is. I then flip the wood piece upside down and do the same thing. If my fence is exactly 1/2 the wide of the board away from the center of the blade, the both scratch marks will be in the same place and the pieces should be of equal thickness in an ideal cut. If they are off, then I need to nudge my fence 1/2 the distance between the two scratch marks to resolve the distance between them.
What I found was using this eyeball blade-scratch method, I couldn't accurately nudge the fence so that both cuts were in the same "trench" [saw cut]. When I thought I was close enough, I proceeded with the cut only to learn come planing the pieces that I was off by good deal as one piece planed and the other did not start planing until the 3rd run-through on the planer; basically one piece was several 16ths thicker. I take light cuts on my planer.
Does anyone have a method they use to basically place a fence 1/2 the thickness of a given board from the center of the blade? I like techniques that do not require setting to some ruler, but rather by fit or slight of hand using geometry. Like some other tricks of the trade, I'm guessing there is some manner which does not require squinting and determining if two saw kerfs are perfectly in alignment or not.
This leads into another problem I'm wondering about: how do you determine the center point of a rectangle that is not a square? A combination square with a 45 degree angle accomplishes that task for squares. If I mark the center point of a rectangle, then I could try aligning the blade in front of the center-point mark while holding the piece securely against the fence and then locking the fence once that sweet spot is arrived at.