Toolpaths by Type and Use

Before going further, it is helpful to understand how 2D toolpaths are classified in most CAM software. Table 7.1 lists the common 2D toolpaths by type and common use. For example, 2D contour, chamfer, and fillet toolpaths are often accomplished using the 2D Contour menu selection. Of course, where each function is located will be slightly different depending on the CAM product, but this list is appropriate to most modern CAM.



Common Uses



  • Finish face of part.

Island Facing

  • Finish face with open sides and bosses.

2D Contour


  • Loops.
  • Partial loops.
  • Single edges.
  • Stick (single point) fonts.
  • Create dovetail, keyset, or saw cut.


  • Create chamfer using tapered mill or center drill.
  • De-burring.


  • Creating fillet using Corner Round tool.



  • Remove excess material.
  • Machining TrueType (outlined) fonts and logos.

Slot Mill

  • Straight slot.
  • Arc slot.



  • Create spot drill, drill, tap, bore or reamed hole.

Circular Pocket Milling

  • Making holes greater than .75 in diameter.

Thread Mill

  • Create ID threads over .75 in diameter.
  • Create milled OD threads of any size.

Table 7.1: 2D Toolpaths and Common Uses

It is probably obvious to you now that manufacturing is an exceedingly complex process. Many factors influence every decision and often more than one solution to any problem. Manufacturing is also a win/lose game. Either the part is right (within tolerance) or not. Don't be overwhelmed by the choices for now. Some knowledge and experience will help you settle many of these variables and greatly simplify the job of planning CNC processes.

2D Machining Features Example

Figure 7.5 and Table 7.2 show the operations and machining sequence to CNC mill this part.

Figure 7.5: 2D Machining Features Example




1FaceIt is common practice that the first machining operation roughs and finishes to the highest flat surface of the part. Face paths overlap the sides of the loop selected.
22D ContourMachine outside loop.
32D ContourMachine outside of boss.
42D PocketUse Pocket to rough and finish enclosed loops.
5Slot MillMill slots.
6Circular Pocket MillMachine the center hole through. You could also use a Drill operation to make this hole, but would center-drill the hole first.
7ChamferUse 2D Contour, Chamfer function and a chamfer tool (or center drill) to make this 45 degree chamfer.
8FilletUse 2D Contour, fillet function and a corner round tool to make this fillet feature.
9Spot DrillSpot drill all holes to:
  • Ensure subsequent drill does not wobble and thus is located precisely.
  • Create chamfer for this hole.
10DrillDrill to make hole. Do this before the Circular Pocket Mill so the Spot Drill conic still exists.
11Circular Pocket MillCreate counterbore.

Table 7.2: 2D Features Example