I’m a big fan of sash cramp heads for their sheer versatility. Whether you prefer to say clamp or cramp; these heads can be fitted a length of wood pre-drilled with a series of holes. Wooden bars will always be stronger than some of the cheaper aluminium clamps you can buy today and the real beauty is that you can keep several lengths of pre-drilled wooden bar, but you might then only require a small collection of set of clamp heads, which can then be interchanged to suit the projects you are working on.
In recent years, I’ve been fortunate enough to have bought a few of these for some very reasonable prices on eBay. You’ll occasionally find that some of the older heads require 12mm holes, where most of the modern ones are suited for 10mm but there’s a bigger problem I’ve noticed with some of the newer sash clamp heads from Record or Irwin and I’m going to address that with a solution in this post.