As I mentioned in the previous post, one of the primary reasons for a missing knob base is a traumatic fall that results in the bending of the knob screw (or threaded rod, depending on the plane) and a partial break of the knob’s flared base.
Take, for example, this U.S.-made plane. After removing the brass nut at the top of the knob and unscrewing the knob itself, I discovered that the short threaded rod had bent backward. One quick solution is to use a pair of pliers to bend it back into place. However, this method risks cracking or breaking the cast iron boss stud where the rod is embedded.
A more cautious approach is to remove the rod entirely and carefully flatten it with a few blows from a brass mallet on a copper surface. In my case, I placed a copper liner over my compact anvil to protect the threads from damage. Another option is to straighten the rod using padded liners in a bench vise.
Next, we tackle fixing the missing portion of the wooden knob base. I secured the knob between two cushioned vise jaws — in my case, the magnetic jaws of my bench vise. Using a small block plane, I shaved the broken area until it was completely flat. You can achieve the same result with a chisel, sandpaper, or a file.
Once the surface was prepped, I found a suitable piece of scrap wood and cut it diagonally to match the slope at the knob’s base. Before gluing the new wood to the knob, I used a bar clamp between the top of the knob and the patch piece’s base. This prevented the parts from sliding out of alignment during clamping. Anytime you glue two diagonal parts, the glue tends to act as a lubricant, causing unwanted movement.
Once the glue dried, I clamped the knob in the vise again and began shaping it. I used a rasp and a file to shape the neck of the knob, gradually refining the shape. To deal with the socket hole at the base of the knob, I turned to my high-speed rotary tool, equipped with a sanding drum, and carefully removed the excess material until the socket matched the plane’s boss. After the final sanding, a few coats of finish brought the restoration to a close.
Next time, I’ll show how I restored the rosewood knob of my Record SS #4 plane.
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