I use a tree, but it's not foolproof, either if something breaks or slips. The first one I made, I didn't use long enough woodscrews to put it together with. I had a bow pulled to about 26" when the faceplate pulled off the tillering tree, the bow shot across the shop and bounced off the ceiling and wall. At least with a tree, you're standing further away. I was lucky that the bow didn't come flying in my direction. I never realized until then just how much energy is stored in a drawn bow. I clamp my bow to the tree when I'm tillering now.