Yesterday I finished the brassware. The last step in completing it was slotting the pin heads, otherwise they were impossible to screw into the drill outs.
In order to slot the pin heads I had to make a tool that allowed me to fit the cutter onto my mill. It was a simple attachment that fits into the 20mm mill collet and then takes the cutter on a shouldered slot with a washer, and the cap held on with a 8mm hex bolt.
Here is my slot cutter attachment with the cutter attached.
Here is the cutter in action
Here are the shouldered pins with a 1.2mm slot cut into the heads 2mm deep.
And here are the pins in the legs of the step ladder. Inside view.