I've now been using my updated Boss Series 1 Bridgeport mill for over 2 years. I've had time to play with all possible speeds and feeds over that time, in everything from 3003 aluminum to 17-4PH Stainless. By now you would think I could set the machine and let it roll until it is done...but I am not even close.
I find the published speeds and feeds are not obtainable. I would assume they are for full flood coolant, which I decided was just too complicated on the Bridgeport to support...even though it came to me with it. I tried mist coolant, but got tired of it rusting all my parts and tools. I am using only forced air cooling.
What happens, I have found, is if the speed and/or feed is even a slight bit too fast, then the tool gets thermal runaway...getting cherry red, gumming the work and breaking flutes if not the entire end mill. I often think I have the correct speed running and all looks good...only to have thermal runaway 10 minutes later for no obvious reason.
Long winded explanation...my question is, has anyone come up with a "real world" rule of thumb for speeds and feeds when running air only?
I find the published speeds and feeds are not obtainable. I would assume they are for full flood coolant, which I decided was just too complicated on the Bridgeport to support...even though it came to me with it. I tried mist coolant, but got tired of it rusting all my parts and tools. I am using only forced air cooling.
What happens, I have found, is if the speed and/or feed is even a slight bit too fast, then the tool gets thermal runaway...getting cherry red, gumming the work and breaking flutes if not the entire end mill. I often think I have the correct speed running and all looks good...only to have thermal runaway 10 minutes later for no obvious reason.
Long winded explanation...my question is, has anyone come up with a "real world" rule of thumb for speeds and feeds when running air only?