From time to time I buy a few of those very cheap woodworking F clamps, those woodworking clamps sold at DIY centers that are so cheap that one wonders if they are worth it. I think quality woodworking clamps are always a must have if we can afford them, but these cheap clamps work for me. Although they have the disadvantage of leaving a big mark on the wood of the workpieces I clamp, unless I protect the workpieces with wooden blocks or pieces of plywood.
The old model of F clamp had a flat solid piece (a tilting round plate) on the upper part of the screw in the movable jaw. That piece was hooked on a ball that is the end of the screw. That flat round tilting plate didn’t mark the wood as much as the new model, and it was not as necessary to be adjusting wooden blocks between the metallic clamp jaws and the workpieces to be clamped.
Also in newer models sometimes the top part (the tilting round plate) comes loose on the ball, so the top part falls leaving the screw without a surface to press against the wood. But this usually happens only in a few rare cases. The biggest problem is that instead of a smooth surface to press against the wood, the tilting round plate on the end of the screw has an horrible non flat plate.
And it’s that awful non flat plate (made of a simple metallic sheet) that is the main responsible that now these woodworking F clamps leave that awful mark on the wood. That is why a simple solution like this one we are going to see will make the work in our home workshop more easy.
All we need is a 1 cm thick piece of plywood from which we can cut pieces 10 cm long by 3 cm wide. We need two of these pieces of plywood for each clamp. I made 20, to improve 10 cheap woodworking clamps. Now I am going to drill three 5mm holes in each piece using the drill press. The distance between the holes at the ends must be enough so that the metal bar of the F clamps can pass between them. With a narrow chisel I cut the remains between the holes. And again in the drill press I clean the hole by moving the piece to the sides with the drill bit turning inside. This is how I finished making a slot in the plywood pieces (the new pads to cover the jaws of the clamps) to fit the metal bar of the cheap F clamps.
I sand the sides of the plywood piece a little (a simple drill powered disk sander makes the job easier) and I already have the pads ready to fix and improve the cheap clamps.
It is also necessary to disassemble the fixed jaw of the clamps. To do this it is necessary to remove the protuberance or rivet, it can be different from one clamp to other, at the bottom part of the metal bar of these clamps. It is a fairly simple task to do with the grinder machine. I just have to be careful not to have close wood cuts, wood shavings or others that can catch fire with the sparks that are generated.
Don’t miss how to make a -> simple wooden clamp rack for these woodworking F clamps.
Another advantage of this simple trick is that, when clamping, these plywood pads make it easier to apply the pressure in the direction we want, this is parallel to the metal bar. And the thing is that these cheap clamps sometimes have the “nut thread” into witch the screw screws tilted to one side. These pads made of plywood sheets allow to play a little with the clearances and to better adjust the direction of the pressure exerted by these woodworking F clamps. That’s also a great improvement.