How to read a Dashboard with Ball Nose Endmills

Categories: Using MillMax

With 3D milling, the three axes can cut to different depths, and create different shapes typically in die and mold work. The axial and radial cutting depths are usually light, but the tools are also often longer and more flexible. They deflect, vibrate and are prone to chatter. Tap-testing and Dashboards will locate the best speeds for stable cutting, surface finish quality and accuracy, all vitally important to 3D and contour milling. 

The endmills used for 3D and contour milling are typically ball or bull nosed. While the graphic on the Dashboard is that of the a square endmill, the axial depth of cut and stepover (represented by the radial width of cut) are applicable. Because they vary during the part program, set the width and depth of cuts to worst possible condition. Find a green stable zone within the SFM limits set by the manufacturer. To calculate the cusp height and to maximize feed rate (with axial chip thinning) and surface speed use this calculator:

https://www.taptest.co/ball-mill-calculator.html

In MillMax, make sure "Ball Nose" is checked in the Tool Details section of setup. 

If the cut is light enough all speeds will likely be green. Focus on the Accuracy (SLE) and Surface Finish (CDD) gages to find the best speed. the best accuracy will be the brightest green on the SLE gage and the best surface finish will be at the speed closets to the bottom of the CDD gage.

To tap-test a ball nose endmill, attach the accelerometer just above the radius where the diameter is maximized.