I have been thinking about the motor today. One of the things that crossed my mind was the fact that it doesn't have an external fan.
Given that I'm going to run it from a VFD, I'm just wondering if there will be sufficient throughput of cooling air at lower speeds. I will still be using the gearbox so it won't be running that slowly. Maybe a solution will be to install a separate external fan (like a large computer fan). I don't really want to modify the motor to fit a fan directly to the output shaft.
That was my worry when I put the VFD on my Holbrook, I took the last couple of inches from a chemical drum as an adaptor and fitted a hefty fan, used a programmable relay output on the VFD to switch it OFF over a certain output frequency (35 Hz) so it stays on and cools the motor between uses (and reminds me to switch off at the end of the jobs). I'll post a pic later!
Dave H. (the other one)