On 2010-07-29, Gunner Asch wrote:
On Wed, 28 Jul 2010 23:15:26 -0500, Ignoramus6705
wrote:

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

The bottom bearing may..may be a bit dry. What provisions are there on
your machine for bearing lubrication? Every Bridgeport Ive seen has
luber for the bearings.

bearings are permanently lubed.

And no..its not bad at all. Im rather surprised that it was that low,
from a 20-30 yr old machine.

Good to hear.

My Gorton, run at 5000 rpm, wide open, will increase temps to 80' above
ambient. This of course doesnt include..as yours doesnt..the cooling
effects of coolant on the spindle as well as the cutter and work piece.

Well, the coolant does not really get to cool what really matters,
which is the bearings.

I rebuilt the spindle in mine about 6 yrs ago,...somewhere less than 30
hours of actual run time. Probably closer to 5 hours actually.

What sort of bearings did you use?

i