Hobby CAD, CNC machining, and resin casting (2015)

Original Article ↗ Hacker News Discussion ↗

Hobbyists revisiting a 2015 guide to CAD, CNC machining, and resin casting say its core ideas still hold up, but note major shifts in tooling: better free and open-source CAD/CAM (FreeCAD, Solvespace, Dune3D), more capable hobby CNCs, and big advances in both FDM and resin 3D printing. Much of the exchange contrasts CNC and 3D printing for small, precise parts in metal or cast resin—highlighting CNC’s superior accuracy and surface finish but higher cost, complexity, and workholding challenges, versus 3D printing’s accessibility and speed for many projects. Participants also share practical experiences with machine selection, cutting aluminum vs steel, resin systems and silicones, and why truly capable small CNC rigs rarely come cheap.

Longevity of the Guide & Updated Resources

  • Many readers still find the 2015 guide highly relevant, but note some links/products are defunct.
  • Successor resources and wikis are mentioned (Shapeoko-related docs, Reddit CNC wikis, newer A‑to‑Z guides).
  • Several people report following the guide successfully, especially for wax machining and resin molds.

CNC vs 3D Printing & Resin Casting

  • Multiple comments emphasize that resin casting from CNC‑machined molds yields much higher precision and better mechanical properties than FDM printing.
  • FDM can be tuned but struggles with surface finish and reliable ±0.1 mm accuracy; CNC in hobby setups can achieve ~±0.02 mm.
  • Modern SLA/MSLA printers narrow the gap, but surface quality for casting and long runtimes remain issues.
  • CNC is described as far less forgiving than 3D printing: more ways to crash tools, mis-zero, or mis-fixture.

Tools, Materials, and Capabilities

  • Hobbyists describe machining aluminum reliably on small machines; steel and titanium are seen as much harder and often impractical at this scale.
  • Detailed discussion of how to create hex holes (rotary broaching, milling approximations, punches, or manual filing).
  • Knife blades and small tools are feasible: usually machine soft steel, then heat-treat. High-end steels and complex lock geometries push toward more serious setups.

Hobby CNC Machines & Designs

  • A DIY fully enclosed sub‑$1,000 mini CNC optimized for aluminum is described, positioned as an alternative to 3018‑class machines and larger desktop mills.
  • Debate over cheap 3018/3030 routers: some claim they can cut aluminum with upgrades, others report persistent chatter and poor results.
  • Commercial options like the Milo and Carvera (and Carvera Air) are praised for capability; concerns center on footprint, rigidity, spindle power, and especially software.

Workholding, Process Complexity, and Cost

  • Workholding is highlighted as a major, often under-taught challenge; clamps, vises, soft jaws, jigs, and fixtures dominate real setups.
  • Tape-and-superglue workholding is mentioned as a convenient alternative for some jobs.
  • Consumables (end mills, vises, collets, stock) and tool breakage make CNC notably more expensive than hobby 3D printing.
  • Some suggest outsourcing to services (waterjet, laser, machining bureaus) when local shops won’t take small jobs.