In my last blog I detailed the conversion of a manual rotary axis into a CNC rotary axis. I finally got some time to mount the rotary axis on the mill, configure the stepper in Mach3 and run it through some tests. The parameter for the g-code command to position the rotary axis is a positive or negative number ranging from 0 to 360 degrees. Positive numbers rotate clockwise and negative numbers rotate counter clockwise.
I started by creating a 3 dimensional object using Solidworks and designed a projectile that will eventually be milled in metal for a coil gun project that I’m working on. I decided to do the cut in wood since this was the first project using the rotary axis and I wasn’t sure how it would work out.
The next step was to export the solidworks object as a sterolithography file (STL). The STL file was imported into MeshCam, choosing the 4-axis option with 8 index positions. MeshCAM lets you create toolpaths from your 3D files quickly and easily. Meshcam generated G-code that would instruct the CNC machine to cut the entire object by indexing the rotary axis and using the regular X,Y and Z axis’ to position the endmill attached to the spindle. For my next experiment I’m going to try increasing the number of index positions by a much larger number.
Three Dimensional projectile created in Solidworks. Its size is .50 caliber and 1.5 inches in length.
In this MeshCam screenshot, the yellow lines indicate the 8 rotary axis positions between which the material is removed to create the object.
For my next rotary axis experiment I will try to optimize the cutting path by selecting a much larger number of indexes and cutting an object in aluminum.
Karl P. Williams