Late in the nineties, my combination machine was probably one the last delivered without advanced tool lock on the spindle moulder but the machine required such mechanism so that the variable frequency drive could safely run the motors. I merely copied the lock device available some years later on the same machine. The bushing holds two pins sliding into the matching recesses in the shaft. Whatever the rotation direction the tool can not drag the lock bolt at slowing down time.

I am not mechanically inclined so the tricky work was to bore the two recesses on top of the shaft. After due consideration I decided to bolt the power drill below the power feed unit arm that could provide a robust base as well as adjustments. But the power feed unit allowed for play and locking the power drill plumb vertical over the table as well as preventing the column from rotating turned out a very hard task. The brace locking the power drill was made from hard wood.

The good news came from the spindle moulder adjustments. The shaft lock enabled a 180° interval between two rotating positions and the lift mechanism allowed for a slow rising of the spindle while boring. I spend much time to drill but despite I worked thoroughly one of the two recesses didn't get parallel to the shaft. Anyway the top bushing smoothly slid into the holes.