I had a drunkards path ruler that did not fit together well at all. found out after cutting many of them out. one should be able to lay the "pie" small piece over the larger "arc" piece fitting the 1/4 inch seam allowance and getting the sides perfectly square. That did not happen. all my lovely christmas fabric cuts. I finished the quilt top and gave it to charity. tossed those rulers out.
Now i check that....