Hi Your Ice sculptures are very nice but do you realise how long Large detailed 3D toolpaths can take.? Air cooled spindles have short duty cycles (the time they can run in one go) and Even at -5 I don't think they will run constantly for the length of time you'll need to cut a large detailed Ice sculpture.?

I would be looking at how long your Models will take to cut and if the spindle will run this long without needing a rest period.? @ -5 it may not be overly long but still you'll need to factor it into the Job and possibly how you toolpath the Job.!