I ran my mill for 16 minutes at 3,000 RPM (I get email when my CNC
jobs complete). It was machining a mold prototype for a kids toy. We
will need to cast 18 of them that in wax, and the mold will be made
from Aluminum. But I digress.

After I finished running for 16 minutes, I measured a few temps:

*) Inside the shop - 86 degrees
*) On the variable speed transmission on top -- 105 degrees
*) On the low part of spindle (at the QC-30 collar) 115 degrees. I am
not sure if I fully believe this last measurement. The bottom of the
spindle feels warm to the touch, I can hold it indefinitely, but it is
not comfortable.

Would you consider this temp rise to be excessive?

i