I also want to share with everyone a few tips/tricks I learned this week at a workshop given by Cathy Tomm for putting together half square triangles. If you have a lot of them to do this method certainly speeds up the process without sacrifice to quality. First you need to mark a 1/4" sewing line on the bed of your sewing machine with either painters tape or masking tape. I took my Omnigrip ruler and placed it under my presser foot and lined up the needle with the 1/4" line. To the right of the ruler I placed the painters tape. As you can see Jordie was supervising the operation.
For 2 1/2" finished half square triangles start with 3" squares. Take the Omnigrip ruler and just put a small mark at the top left hand corner where your 1/4" seam would be start. (Sorry for the glare but without the flash the picture was way too dark.) The central line from which you are measuring the placement of the mark is the diagonal line from corner to corner of the fabric.
Take your two pieces of fabric (right sides together) and line up the needle with the mark that you made and line up the bottom point of the fabric with the edge of the painters tape and sew. Keep an eye on the bottom point to ensure it keeps following the edge of the painters tape. You can chain piece all your triangles this way. Once you have done one side, just repeat on the other side (mark starting point and line up with needle, line up bottom point with edge of painters tape and sew ensuring that bottom point follows edge of painters tape). Cut and press triangles as usual.
To trim triangles there is this handy little 2 1/2" Omnigrip ruler. Again sorry for the glare. It took a bit to getting the hang of using it, but once you got it, it does make the trimming process easier than with the bigger rulers. The ruler has a diagonal line marker and you place it along the diagonal of your half square triangle and line things up before cutting.