OK. First I'm guessing that you mean you draw a diagonal line on the square, sew 1/4" on either side of the line, then cut on the line. Then next step would be to press, then trim the triangles to the correct size. When you do this, make sure that the seam line is exactly in the 2 corners. Be careful when you square up, to make sure it's the correct size. If you are having problems with your triangles being too small, cut your starting squares larger. Sew your HST to another block. If you have used a proper 1/4" seam, the point(s) of the triangle that are in the seam should be 1/4" away from the raw edge. You might want to double check your 1/4" seam.
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