For stand up puzzles, I use either a #5 or #7 reverse tooth blade, both Flying Dutchman and Olson. The problem is painting between the pieces. If you leave them plain, they will slide better. If it is one of those puzzles that you just feel compelled to paint between the pieces, use some wax to help them slide better. I use Howards Feed N Wax. It is available in lots of places like Home Depot, Lowes, True Value and a lot of grocery store cleaning isles where the furniture polish is.