Sorry, don't have a tutorial but by george, I think you've got it...cutting the tip off makes the "top" of the triangle wider, so that after you sew on the two adjacent triangles you still have a point left that is about one quarter inch from the side of the strip. If you look at the top of the ruler that Kriscraft put in her post you may be able to see the reason more clearly...the large black triangle will be your finished triangle size and the clear edges are the seam allowances...you can see where with the tip cut off and the seam allowances "taken off" you have the black point a quarter inch from the edge of the strip.