Tools & DIY / Guide
Woodworking Clamps: Jaw Opening and Throat Depth Explained
Choose a woodworking clamp by measuring how far its jaws open and how far they can reach in from the edge of a workpiece.
A clamp can open wide enough to go around a project and still miss the point where you need pressure. Measure two distances before shopping: the gap the jaws must span and the distance from the edge to the spot where the pads must land.
Allow room for pads and setup
Measure the workpiece with any blocks or protective pads in place. If you’re holding several pieces together, include their combined thickness. A little extra opening makes it easier to position the clamp without starting at its limit. Check that the jaw faces sit squarely where the project needs support.
Choose a clamp that reaches the pressure point
Throat depth is how far the jaw reaches in from its bar or frame. A deeper clamp can reach the middle of a wide piece. A compact clamp can be easier to place among other clamps near an edge. Match the shape of the clamp to the access around the project.
Practice on a dry assembly
Before gluing, set the parts together and see how many hands you need to position the clamps. Check for contact with the workbench and for marks on a scrap of the same wood. Plan where each clamp will sit before the glue goes on. That test gives you a reason to buy a particular size instead of an assortment.