Most hobby machines have a limited RPM range and limited feedrate capabilities.

Now we have to consider the type of machine you are running. Using the same end mill as in the previous calculation you get an RPM of 7,640 which, as you would expect, is double the previous result.Īgain when you calculate the feedrate it is double the previous result at 61 in/min. A SFM, on a benchtop mill or router, of 500 would be a safe starting point. Next we can consider machining some aluminum stock. A high helix endmill designed for Aluminum, suitable for high feed milling So now we have a good starting point of 3,820 RPM with a feedrate of 30 inches/min. 002” X 4 flutes = 30.56 inches/minute feedrate. Now you can use the second formula using the rpm we just calculated,ģ,820rpm X.

So if we had a 4 flute cutter this would be. Again a good starting point using a good quality endmill would be. To calculate the feedrate we need to find out the feed per tooth or the feed per rev. 25” (¼”) dia endmill results in an RPM of 3,820. Using 250 SFM in the formula above, with a. I am going to recommend that you only use carbide endmills when machining metals, they are inexpensive enough and make the task a lot easier than using HSS (high speed steel) endmills.Ī safe starting point for a good quality carbide endmill machining a typical ‘soft’ alloy steel would be approximately 250 SFM. (a HSS endmill will be considerably slower, around 120) To use these simple formulas, you need to find out what ‘SFM’ (surface feet / min) that your milling tool is designed to operate at with the particular metal you are milling.

Camworks feeds and speeds