Milling Holes

Milling Holes #

Holes can be milled with a flat end mill or they can be drilled using a drill bit.

Milling allows for non-round holes and avoids having to switch tools when there are multiple hole sizes in the PCB layout.

The process of creating an .nc file for milling holes looks like this:

graph LR A[Open
Drill File]-->|.drl|B[Generate
Geometry] B-->|.drl_mill|C[Generate
CNC Job] C-->|.drl_mill_cnc|D[Export
G-code]

Open Drill File #

  1. Choose File | Open Excellon, then select the drill file. The holes should immediately be plotted as red circles.

Generate Geometry #

  1. In the “Project” tab, double-click the .drl list item
  2. Using the Shift key, select all of the tool numbers shown in the “Tools” list
  3. Verify that the settings under “Create CNC Job” match what was entered in the “Exellon Options” section of Configuring FlatCAM
  4. Enter the diameter (in mm) of your flat end mill in the “Tool dia” field
  5. Click the “Generate Geometry” button under “Mill Holes”

Generate CNC Job #

  1. In the “Project” tab, double-click the .drl_mill list item
  2. Change the values in the “Create CNC Job” section:
    • Cut Z: -1.7 (the thickness of the PCB blank)
    • Travel Z: 2.0 (how high to raise the end mill when it’s not cutting)
    • Feed Rate: 100 (mm/min)
    • Tool dia: 0.79248 (1/32" flat end mill)
  3. Tick the “Multi-Depth” checkbox and set “Depth/pass” to one third of the “Cut Z” value. (0.57 in our case.) This will require three passes for each of the cuts, which can make the job easier on the machine and the bit.
  4. Click the “Generate” button under “Create CNC Job”

Export G-code #

  1. In the “Project” tab, double-click the .drl_mill_cnc list item
  2. Click the “Export G-Code” button
  3. Select a destination folder for the file and give it a name that includes the bit to be used for this job. For example, millholes_1_32_flat.nc