I replaced the Noctua fans with Panasonic ASFP80391 fans that have 50% more airflow. I can now do continual milling for several hours without the spindle servo going above 40°C and without the casting of the head going over 45°C.
The machine is now in a state where it works great and I can make parts all day.
However the spindle is a limiting factor. It goes out of balance which causes vibrations if I go above 3000 rpm. Given that this machine was originally designed with a max rpm of about 3200 that's probably to be expected.
The way forward here is probably to buy a completely new spindle (without a quill) designed for higher rpm's. There seems to be a lot of BT30 spindles available online. However spindles for the larger BT40 taper which this machine uses seems a bit harder to find. I've sent out a few inquiries for pricing to see if I can buy a spindle from a known brand for a decent price.
The machine is now in a state where it works great and I can make parts all day.
However the spindle is a limiting factor. It goes out of balance which causes vibrations if I go above 3000 rpm. Given that this machine was originally designed with a max rpm of about 3200 that's probably to be expected.
The way forward here is probably to buy a completely new spindle (without a quill) designed for higher rpm's. There seems to be a lot of BT30 spindles available online. However spindles for the larger BT40 taper which this machine uses seems a bit harder to find. I've sent out a few inquiries for pricing to see if I can buy a spindle from a known brand for a decent price.