Spiffy,
We used a Shape Cut for a class I took. The teacher suggested we buy these small sandpaper dots to apply to the ruler around the edges to keep it anchored to the fabric. Works like a charm!!
The Joann's here has a few of them. I have the fat one and the longer one for cutting strips. When you have over 2,000 pieces to cut for a quilt, they really, REALLY come in handy!
BTW, I love your piano quilt in your avatar. Best wishes!