Originally Posted by gale
She's sewing triangles, not down the center of squares, so she is probably sewing 1/4" away. I agree with Amma to use a leader and chain piece. However, in the future, I would try to sew them the way Scissor Queen mentioned and leave them as squares, sew 1/4" away on both sides of the center, and cut it in half after it's sewn.
Even if she's sewing triangles already cut she should probably still be sewing a quarter of an inch away from the point.