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7. Computer-Controlled Machining

Group Assignment

  • do your lab’s safety training
  • test runout, alignment, fixturing, speeds, feeds, materials, and toolpaths for your machine

Overview

We traveled 240km to Hamamatsu by train to use a large CNC machine. Take-san of Fablab Hamamatsu gave us the safety training and let us go through the necessary tests of the machine.

FabLab Hamamatsu

1. Safety training

  • Prepare yourself: Always wear safety glasses, hearing protection, and safety shoes. Avoid loose clothing, or dangling hair that can get caught in rotating parts. Don’t wear gloves as they can be caught by the machine.
  • Work Tooling: Securely chuck the blade.
  • Secure the board: Secure the board with nails before cutting.
  • Emergency procedure: Don’t leave the machine when it starts. Be ready to press the red stop button on the screen. Also know that you can always stop the machine physically by pressing the machine’s stop button.

2. Tests

2-1. First round

First, Take-san showed us the overall “how-to” flow.

He set the blade to the collet and put the workpiece on the machine. put board on the machine

And then he opened Cut2D software, and drew a simple figure. Cut2D

And then, he first edited the tool and then, set pocket toolpath and then profile toolpath. set profile toolpath

He taught us how to drill holes to nail the workpiece on the machine. holes_to_fix_board

Then we sent the drill toolpath to Mach3 CNC controller and drilled the hole, and Take-san nailed down the workpiece on the machine. take_san_nail

Then, he ran the CNC for the pocket toolpath and then profile toolpath. Finally, we measured the test piece and found that the result was really precise. Design: 100mm -> result: 100.85mm measure result

2-2. Student turn

Now it’s our turn. We designed our own shapes in Cut2D and ran the machine ourselves.

We drew a square as the base shape for our test piece in Cut2D. draw_square

We also drew a circle to test cutting a curved profile. draw_circle

We added drill hole positions to fix the workpiece to the spoilboard before cutting. draw_drill_holes

We added tabs to the profile toolpath to keep the piece from coming loose during cutting. draw_rabs

We loaded the toolpaths into Mach3 and set the origin (X, Y, Z zero) on the workpiece. mach3_set_origin

We ran the CNC program and monitored the machine as it executed the toolpath. mach3_working

We observed the machine cutting. watching closely to understand the feed rate and cutting behavior. cutting2

The cutting was complete. The shapes were cleanly cut, still held in place by the tabs. finished_cutting

We used a chisel and a hammer to cut the remaining tabs and remove the piece from the board. cut_tabs

Finally, we measured the finished profile to check dimensional accuracy. measure_profile