I recently acquired a very cheap KING PDM 30 Mill-Drill much like the typical RONG FU round column RF-31 and have been slowly getting it into a usable condition. The lack of a spindle lock for tool changes was annoying so today I machined a wrench to fit the spline on the spindle to make it easier. Turned out nicely and fits very well and should be very useful until I get around to doing an air powered drawbar.
PS yes I do have a CNC mill in the shop so that makes this sort of thing easier. It certainly could have been done on the mill drill though just a little more work. Heres a short video of one pass on the profile cutout.