This video details the process of setting up and operating a new small-scale CNC milling machine, primarily intended for fabricating custom PCBs. The creator walks through the challenging journey of designing a gear in FreeCAD, generating G-code, and troubleshooting numerous operational problems with the machine. These difficulties include software frustrations, machine errors, tool positioning issues, and Z-axis zeroing mistakes. Despite these setbacks, the video highlights the machine's precision build quality, featuring linear glides, lead screws, and closed-loop stepper motors, ultimately demonstrating a successful gear milling operation. The creator concludes by reflecting on the steep and continuous learning curve inherent in mastering CNC machining.
Summarizing the CNC Milling Journey: From Design to Operation
0:00 Building a Small CNC for PCBs: The creator embarked on building a smaller CNC milling machine, specifically for the purpose of accurately milling custom PCBs, a significant upgrade from previous hand-making methods.
0:00:35 Machine Control and Software Selection: The machine is controlled via a simple hand pendant, eliminating the need to learn new control software. However, selecting a suitable CAD program was a challenge, leading to the adoption of FreeCAD after ruling out Fusion 360 due to its licensing terms for income-generating content.
0:01:03 FreeCAD Design Workflow: The video demonstrates the step-by-step process of designing a gear in FreeCAD, which involved using a custom gear program, exporting it as an SVG, importing it into the Sketcher, converting the imported geometry, and then using "pad" (extrude) and "pocket" tools to define the gear's shape and teeth.
0:01:54 Setting the Zero Reference: A crucial design step highlighted was correctly setting the Z-axis zero reference on the material's top surface by padding the design downwards (in the negative Z-direction) to ensure accurate milling depth.
0:03:17 FreeCAD CAM Frustrations: The creator expressed significant frustration with FreeCAD's CAM mode, describing it as unintuitive and difficult to learn due to numerous unexpected behaviors and features that didn't work as expected.
0:04:27 Operational Challenges and Errors: The actual milling process was plagued with multiple issues, including incorrect tool positioning, the machine entering a "weird state" (requiring the execution of vendor-provided example files to clear the error), errors in Z-axis zeroing, and an accidental machine shutdown.
0:07:52 Automated Tool Changes: A commendable feature of the CNC machine is its automated tool change system, which conveniently moves the head out of the way for safe tool swaps and then automatically performs Z-probing to measure the new tool's length.
0:10:06 Effective Dust Collection: The machine incorporates a transparent dust collection system with a brush, efficiently connected to a homemade shop vacuum setup, effectively containing milling debris.
0:10:52 Successful Gear Milling: Despite the numerous obstacles and errors encountered, the creator successfully milled a precisely cut gear, validating the machine's capability.
0:11:06 Machine Build Quality and Features: The CNC machine boasts a robust construction, featuring linear glides for precise vertical movement, lead screws, and a quiet, high-precision milling spindle capable of accuracy down to a tenth of a millimeter. It utilizes closed-loop stepper motors on some axes, which provide feedback on synchronization but can also exert significant force.
0:13:00 Overall Frustrating but Improving Experience: The creator admits that the entire CNC experience was even more frustrating than depicted (due to editing out mistakes), but notes that the learning curve is becoming less steep, especially when using dedicated CAM software (as opposed to FreeCAD).
0:13:40 The Steep Learning Curve of CNC: A significant takeaway from the video is the demanding and continuous learning curve associated with CNC machining, with the creator emphasizing that these specialized skills require regular practice to retain.