Originally Posted by mmdquilts
I have mine tipped out at the bottom just a little to help things stay on
It is helpful to have a slant towards the top-- out at the bottom more than the top- so the angle keeps the blocks from being totally verticle.
I found that different size blocks may need pins. It also matters with how many seams that keep the block off the flannel. The flatter the blocks lay the easier it is for them to stay on the flannel.