Thangles work better when you trying to do scrappy. Why not just draw your lines on the light wrong side. Either way, you will end up with an even number of 26. Not sure how you are making you HST. You take two squares right side to right side, draw a diagonal line and stitch on each side of that line. Cut on original line and you have two HST with no bias edges. Any basic quilting book will have this information.
Do method 2:
http://www.connectingthreads.com/tut...ngles__d4.html