Originally Posted by
dcamarote
AHA! I just saw the name of them on someone else's post; they are called "C" clamps.
C clamps are shaped like a "C", with a screw going from the bottom to the top of the open section. They are usually made of metal (I've never seen any that weren't metal). They come in measurements of height as 2" high to 6" or more. You screw that section tight, and they can be made so tight as to make marks in your table edges. They are used in wood-working to clamp glued sections to dry. I used them to hold my quilt frame sections together. Worked well for that.