CNC Lathe Pawn Piece

Summary
I designed and machined a custom chess pawn from 6061 aluminum using a CNC lathe. I modeled the pawn in SolidWorks and wrote all the G-code by hand. My goal was to create a clean, symmetric part with smooth contours while controlling every step of the machining process. The finished pawn matched the model closely and had a crisp aluminum finish.

Goals
I wanted to design a pawn that looked accurate, machined well in 6061, and followed good turning practices. A major goal was gaining experience with hand written G-code so I could understand every tool move, radius, and feed change. I also needed to plan tool access around the curved profile and avoid collisions, chatter, or clearance issues. The aim was to have both the part and the code reflect solid planning and consistent execution.

Challenges
One challenge was dealing with tool interference along the pawn’s tight curves and small radii. This required careful planning of tool approach, insert geometry, and cutting order. Since the program was hand coded, I had to troubleshoot it line by line, catching mistakes in coordinates, arcs, decimals, and clearance moves before running the machine.

Details

Turning Geometry: Contours, Radii, and Tool Access
The pawn’s shape is made of smooth curves, tight transitions, and a few sharp breaks, so tool access was one of the most important parts of the design. I modeled the full contour in SolidWorks, then divided it into sections that a standard turning tool could reach without rubbing or colliding with the insert shoulder. Since the part was cut from 6061 aluminum, I planned light finishing passes to create a clean reflective surface.
I turned the base to size first to set a reference, then worked upward through the profile and blended each radius into the next. The tighter curves near the top needed extra attention because the insert nose radius had to fit without overcutting. Careful step-downs and controlled feed rates kept the profile smooth and symmetrical.

Hand Coded Toolpaths: Motion Control and Troubleshooting
Hand writing the G-code meant the entire shape had to be translated into exact points, lines, and arcs. I used G02 and G03 moves for the rounded features and straight G01 lines for the transitions. Since the part was aluminum, I tuned feeds and speeds to balance chip control and finish quality.
Hand coding created its own set of challenges. A missing decimal, an incorrect arc direction, or an aggressive retract move could cause problems, so I reviewed the code block by block and checked clearances mentally. Debugging small errors was part of the process. Once the program was clean, it ran reliably and produced the correct geometry without changes at the machine.

Workholding and Process Flow
The pawn was turned from 6061 round bar stock. I began with facing and roughing to create a stable cylinder, then moved into the detailed contour cuts. I kept the stick-out short to avoid chatter and held the bar firmly to maintain alignment.
Since the profile narrows near the top, I saved those thin sections for the end to prevent deflection. A final finish pass along the full contour blended all features together and left a smooth, uniform surface with a natural aluminum shine.

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