One of the ealier post in this thread was so kind as to send this link for us .
http://www.camcadtech.com/truemill_speeds_and_feeds.htm
It is a web version of the spreadsheet that I was given by SurfWare pretty much. If you are running a TM and are limited to 4000 RPM. Then I would scale things down to run at 4000 and 35 to 40 inches per minute, 1/2 to 3/4 in deep. It takes good sharp TiALN coated carbide end mills to run the Truemill effectively in steel.

The color of your chips will be your guide. I look for gold colored chips that tell me that I am taking most of the heat out of the cut with the chip, If I run too hot then the chips turn blue, I like to stay at the point were the majority of my chips are gold. you will of course get blue chips when you hit thin spots and there is not enough metal to asorb the heat in the chip. Running the TiALN coating works only without coolant as it doesn't slick up until you are in your higher cutting tempatures and will blow off the edges with coollant shock if you are running wet. This was hard for me to learn, I have a bucket of endmills that failed early becuase I was using old ideas with new technology. A good tool salesman set me straight.

I am running mostly endmills that I buy from a couple of sources I first located through ebay. Carbide Cutting Tools SC Inc is the one I use the most. If you are running the new 10-12K machines then I think that specially designed tools like those from Swift Carb for Truemill will pay.

Hopes this helps and good luck.

Eagle

True mill does give as much to old or smaller VMCs as it does to new big SS VMC.