Update 03Apr22 Please download this model from the Printables 3d model repository: Print 137792

This is a C-spanner to help remove a chuck exert from a woodturning lathe spindle. My lathe's instructions specifically say not to use the indexer to lock the spindle when removing a chuck. Only one knock-out bar bar is supplied, which can either lock the spindle or fit the removal hole on the exert. Another bar or a C-spanner is required.

Specifically, my exert is a Charnwood VIPERIC, which adapts an M33x3.5 spindle to a chuck with 1"x8tpi thread. I'm pretty sure that this will work with any of the Charnwood M33x3.5 exerts, but I don't have any of the others to try. The diameter of the exert, and therefore diameter of the C-, is 48mm. The removal hole is 10mm diameter.

A metal peg takes the strain and is screwed into a 25mm long M8 x 1.25 (standard coarse metric thread) threaded hole in the handle (my prototype was narrower and all plastic and just burst apart at the first attempt).

For the metal peg I used a stainless steel M8 bolt that I cut down to a thread length of 27mm. I ground away the hex head to a round bar to fit into the exert removal hole. The head protrudes 10mm from the handle, but 8mm would probably be OK if using an M8 x 25mm bolt. (A socket cap bolt would also work but its 13mm diameter cap will still need grinding down to size!)

There's a hole across the end of the handle to allow for hanging it on a hook.