Last time I tried to get some work done on the mill I was defeated trying to get a fan set up. This time I found a fan in my junk pile that works.
here. Then I replaced it here. Although it has been sitting for over a year the fan still works from it. It is labelled as a brushless fan but I figured that the designers wouldn't have gone to the trouble to drive the fan with some kind of waveform and it could be driven with plain DC.
It turns out my guess was correct. So I now have a fan to go in the case. It was even exactly the right size for the mounting holes.
Now I just need to work out the toolchain to turn a CAD drawing into code to run on this machine. Getting it onto the machine should be fairly easy as it runs a quite up to date version of Linux so I can just set up an NFS share or similar for loading up programs.