Machining
CNC Machining
Milling, engraving, and routing cockpit panels on the Stepcraft D600 — materials, tooling, feeds, and workflow for home builds.
Stepcraft D600 — Machine Overview
The Stepcraft D600 is a desktop CNC router with a 600 × 400 × 80 mm work envelope. It runs on a ball-screw driven gantry with NEMA 17 stepper motors, giving it 0.1 mm positioning accuracy suitable for panel cutouts, countersinks, and shallow engraving. It is a hobby-grade machine — not a Haas — but it handles MDF, acrylic, soft aluminium, and PCB material reliably when fed conservatively.
| Specification | Value |
|---|---|
| Work area (X × Y × Z) | 600 × 400 × 80 mm |
| Positioning accuracy | ± 0.1 mm |
| Spindle options | Stepcraft HF-500 (500 W, up to 25 000 RPM) or Kress FME 800 |
| Compatible software | UCCNC (recommended), Mach3, Universal GCode Sender |
| CAM software | Fusion 360 (free for hobbyists), Estlcam, VCarve Desktop |
| Collet sizes | ER11 — accepts 1, 2, 3, 3.175 (1/8"), 4, 6 mm shank bits |
| Materials (typical) | MDF, acrylic, POM, HDPE, soft aluminium (6061), PCB material, wood |
| Controller | Stepcraft USB CNC controller (UC100 / UC300ETH compatible) |
The D600 has a relatively light gantry for its travel. Keep depth of cut (DoC) conservative — especially in aluminium — and use climb milling (conventional milling direction) to avoid deflecting the spindle carriage. Aggressive cuts cause chatter and dimensionally inaccurate slots.
Why CNC for Cockpit Panels?
Laser cutting handles thin sheet material cleanly but cannot produce countersinks, pockets with variable depth, or real 3D profiles. CNC routing fills those gaps. In a typical cockpit build the two processes work together: the laser cuts acrylic legends and thin MDF panels; the CNC router handles the structural aluminium sub-frame, thicker MDF backing plates, and any part that needs a recess or stepped edge.
| Operation | Laser (Omtech 60W) | CNC (Stepcraft D600) |
|---|---|---|
| Cut thin sheet (≤ 5 mm) | Fast, clean, no fixturing | Possible but slower; laser preferred |
| Cut thick sheet (6–20 mm) | Not possible (60 W limit) | Yes — MDF, acrylic, aluminium |
| Engraving text / legends | Faster, finer detail on paint | V-carve engraving on bare aluminium or wood |
| Pockets / recesses | No | Yes — instrument bezels, LED recesses, countersinks |
| Holes (drilled) | Yes (fast, clean on thin sheet) | Yes — and can interpolate to any diameter |
| Aluminium panel work | Not suitable (reflects CO₂ beam) | Yes — 1–3 mm aluminium with correct feeds |
| 3D profiles / chamfers | No | Yes — ball-nose 3D toolpaths |
Tooling for Cockpit Panel Work
The Stepcraft D600 uses ER11 collets (1/8" / 3.175 mm shank is most common for hobby tooling). A small starter set covers the majority of cockpit panel operations.
| Bit type | Diameter | Material | Cockpit use |
|---|---|---|---|
| Flat end mill (2-flute, upcut) | 3 mm, 4 mm, 6 mm | MDF, acrylic, soft wood | Panel outline cuts, pockets, slot cutting — the most-used bit for general panel work |
| Flat end mill (2-flute, downcut) | 3 mm, 4 mm | MDF, plywood, acrylic | Top surface finish — downcut pushes fibres down, preventing tear-out on the visible face |
| Single-flute upcut (O-flute) | 3 mm, 6 mm | Acrylic, HDPE, POM | Plastics and soft materials — single flute clears chips faster and prevents melting |
| V-bit (60° / 90°) | 3.175 mm shank | MDF, aluminium, acrylic | V-carve engraving of panel legends and instrument scales directly into the material |
| Ball-nose end mill | 2 mm, 3 mm | MDF, soft aluminium | 3D profiling, chamfers, rounded bezels |
| Single-flute end mill (ZrN coated) | 2 mm, 3 mm | Aluminium 6061 | Aluminium sub-frame parts, instrument panel blanks — ZrN coating prevents aluminium welding to flutes |
| Drill bit (straight shank) | 2 mm, 2.5 mm, 3 mm, 4 mm | All | LED holes, screw pilot holes, mounting holes — faster than interpolating small circles |
| Countersink | 6 mm, 90° | MDF, aluminium | Flush M3 or M4 panel mounting screws |
Never use wood router bits (large radius, 1/4" shank) on the Stepcraft D600 — the spindle and gantry are not rigid enough to handle the lateral load. Stick to 3.175 mm (1/8") or 6 mm shank bits at conservative feeds.
Feeds & Speeds
The Stepcraft HF-500 spindle runs 5 000–25 000 RPM. For most panel materials the correct approach is high RPM, slow feed, shallow depth of cut. The machine lacks the rigidity to take deep cuts, but at shallow DoC it produces clean edges without chatter.
| Material | Bit | RPM | Feed (XY) | Depth per pass | Notes |
|---|---|---|---|---|---|
| MDF 6 mm | 3 mm 2-flute upcut | 18 000 | 800 mm/min | 1.5 mm | Dust extraction essential — MDF dust is a respiratory hazard |
| MDF 12 mm | 4 mm 2-flute upcut | 18 000 | 900 mm/min | 2 mm | Use tabs on the contour — thick MDF can lift at the end of the cut |
| Acrylic 3 mm | 3 mm O-flute (single) | 16 000 | 600 mm/min | 1 mm | Single-flute clears chips; conventional (climb) milling leaves cleaner edge |
| Acrylic 6 mm | 3 mm O-flute (single) | 16 000 | 500 mm/min | 1 mm | Multiple shallow passes; flood cool or pause to let material cool if edge looks melted |
| Aluminium 1.5 mm (sheet) | 2 mm single-flute (ZrN) | 20 000 | 300 mm/min | 0.3 mm | Use WD-40 as cutting lubricant; vacuum chips frequently to avoid re-cutting |
| Aluminium 3 mm | 3 mm single-flute (ZrN) | 18 000 | 250 mm/min | 0.3 mm | Many passes; patience required. Result is clean commercial-looking aluminium panel |
| POM / Delrin | 3 mm 2-flute upcut | 16 000 | 1 000 mm/min | 2 mm | Machines beautifully — good for custom knobs, throttle detent plates, bearing housings |
| V-carve engraving (MDF) | 60° V-bit | 20 000 | 500 mm/min | 0.3–1.0 mm (depth controls text width) | Engrave first before any profiling cuts |
Always run a dry air cut (spindle off, raise Z 10 mm above material) before the first real cut on a new job. Watch the toolpath trace over the workpiece and confirm it matches your design. Catches fixture mistakes and wrong zero positions before material is wasted.
Workholding & Fixturing
Work that moves during a cut is the primary cause of ruined parts on a desktop CNC. The Stepcraft D600 bed has T-slots — use them. Clamps and double-sided tape together give belt-and-braces security for panel work.
| Method | Best for | Notes |
|---|---|---|
| T-slot clamps (step clamps) | Thick sheet (MDF 12 mm+, aluminium) | Clamp at the edges, outside the cut area; at least 4 clamps for anything over 200 mm |
| Double-sided carpet tape | Thin sheet, acrylic, PCB material | Apply tape to a flat spoilboard; press work firmly for 30 s. Reliable for shallow engraving and light cuts; lifts under heavy lateral load |
| Spoilboard + screws | MDF panels, production runs | Screw a 6 mm MDF spoilboard to the bed; screw the workpiece to the spoilboard through waste areas that will be cut away |
| Tabs in toolpath | All profiling / contour cuts | Leave 0.5 mm high × 4 mm wide tabs at 4–6 points around the contour; cut manually with a flush-trim saw or chisel after the job |
| Vacuum fixture | Thin, flat sheet production runs | A spoilboard with a routed grid connected to a shop vac — excellent hold-down for thin aluminium without edge clamps in the way |
Set your Z zero on the top surface of the workpiece, not on the spoilboard. If the material is not perfectly flat the spindle may plunge too deep on the first pass. Surface-probe with a 1 mm depth test cut on a waste area first when working with material that may have bowed.
Toolpath Strategy for Panel Jobs
A typical cockpit panel job combines three toolpath types in the correct order. Running them in the wrong sequence — particularly cutting the outline before internal features — shifts the workpiece and ruins registration.
| Order | Operation | Toolpath type | Detail |
|---|---|---|---|
| ① | Engrave legends | V-carve / engrave | V-bit at shallow depth; text remains sharp if done while the workpiece is fully supported by surrounding stock |
| ② | Drill or interpolate all holes | Drill / circular pocket | LED holes (typically 3–5 mm), M3 pilot holes, countersinks — all while the panel is still one piece |
| ③ | Pocket internal cutouts | Pocket (inside profile) | Switch and indicator cutouts; set tabs = 0 on small inner pockets since the waste drops away into open air |
| ④ | Profile the outer panel | Contour (outside profile) | Always last; use tabs to prevent the panel shifting when almost freed from the stock |
Kerf compensation and tolerances
| Feature | Compensation | Notes |
|---|---|---|
| Panel outer profile | Outside offset = + ½ bit diameter | The cutter centre travels outside the profile line so the finished part matches the design dimension |
| Internal pocket (switch hole) | Inside offset = − ½ bit diameter | Cutter travels inside the pocket boundary; add 0.1–0.2 mm clearance to design for fit |
| Circular holes | Circular interpolation, diameter = target − 0.1 mm first pass | Measure after the first cut, then take a spring pass (same toolpath, 0 depth) to bring to final size |
| Press-fit parts | Test cut in scrap first | CNC dimensional accuracy is ± 0.1 mm; a press-fit typically requires ± 0.05 mm — finish with a file or reamer |
CAM Workflow — Fusion 360 to UCCNC
Fusion 360 is the recommended CAM tool for Stepcraft D600 jobs. It is free for personal use, integrates CAD and CAM in one application, and produces clean G-code via a post-processor. UCCNC on the Stepcraft controller reads standard G-code natively.
Step-by-step from design to cut
| Step | Tool | Detail |
|---|---|---|
| 1. Design panel in Fusion 360 | Fusion 360 CAD | Model at 1:1 scale; create a flat sketch for each machining operation on its own layer |
| 2. Set up the CAM setup | Fusion 360 Manufacture | New Setup → Milling; set WCS origin to top-left corner of stock, Z = top of material |
| 3. Define toolpaths | Fusion 360 Manufacture | Add 2D Engrave → 2D Drill → 2D Pocket → 2D Contour in that order; assign tools with correct feeds from the table above |
| 4. Simulate | Fusion 360 Manufacture | Run the simulation and watch for collisions, wrong offsets, or missed features before post-processing |
| 5. Post-process to G-code | Fusion 360 → Stepcraft post-processor | Use the UCCNC / Mach3 post-processor (available free from Autodesk post library); outputs .nc file |
| 6. Load into UCCNC | UCCNC on the Stepcraft PC | File → Load G-code; jog to work zero; set X0 Y0 Z0 to top-left corner of material surface |
| 7. Air cut check | UCCNC | Raise Z 10 mm, set Z-override to +10 mm, run the job — watch the spindle trace the toolpath above the material |
| 8. Cut | UCCNC | Reset Z, start spindle, press Cycle Start; stay present — desktop CNCs can have unexpected Z plunges if the G-code has an error |
Save the Fusion 360 CAM setup for every panel you make. When a panel needs to be remade (common when iterating a design), regenerate the toolpaths in under a minute rather than setting up from scratch.
Cockpit Applications — What the D600 Is Used For
| Component | Material | Operations | Notes |
|---|---|---|---|
| MCP / FCU panel blank | 3–6 mm MDF or 1.5 mm aluminium | Switch cutouts, LED holes, engraved legends, panel profile | MDF: quick and cheap for prototypes; aluminium: permanent panel that takes paint and resists warping |
| Overhead panel sections | 6 mm MDF | Grid of switch holes, large cutouts for multi-switch modules, profiled edge | At 600 × 400 mm, the D600 can fit a full B737 overhead section in one setup |
| Glareshield / coaming | 12 mm MDF + 3 mm acrylic face | Pocketed recesses for annunciator modules; profiled curved edge | Multi-material: CNC the MDF structural piece; laser cut the acrylic overlay separately |
| Instrument panel blank | 1.5–2 mm aluminium 6061 | Round instrument holes (3.125" standard), screw holes, panel profile | Circular interpolation for 79.4 mm instrument holes; finish edges with a deburring tool |
| Throttle quadrant body | 12–18 mm MDF or POM | Lever slot, detent pocket, pivot bearing housings | POM gives a smooth lever feel; MDF is easier to shape and paint |
| Rotary encoder knob blanks | POM or aluminium | Outer profile, shaft hole, knurling pass with V-bit | CNC-machined POM knobs look and feel significantly better than 3D-printed equivalents |
| Sub-frame mounting rails | 20 × 20 mm aluminium extrusion or 3 mm aluminium flat bar | Bolt hole pattern, countersinks, notches | Aluminium extrusion can be clamped flat and drilled / slotted accurately for cockpit frame assembly |
| Spoilboards | 18 mm MDF | Vacuum grid, dog-hole pattern, surfacing pass | Surface the spoilboard flat with a large surfacing bit (20 mm) first — fixes any bed tramming error |
Safety & Dust Extraction
CNC routing generates more debris than a laser — chips, dust, and occasionally flying broken bits. Personal safety and machine maintenance both depend on good dust extraction and a clean working posture.
| Hazard | Mitigation |
|---|---|
| MDF fine dust (formaldehyde binder) | Dedicated dust shoe on the spindle + shop vac with HEPA filter; wear FFP2/N95 mask when changing material |
| Acrylic and POM chips | Chips are larger and less hazardous than MDF dust; still use dust shoe to keep chips off the lead screws |
| Aluminium chips | Sharp — wear gloves when clearing chips by hand; vacuum regularly during the job to prevent re-cutting |
| Broken bit ejection | Safety glasses mandatory when the spindle is running; stand to the side, not directly in front of the spindle |
| Workpiece lifting during cut | Use tabs on all profiling cuts; verify clamps are tight before starting; never reach over a running spindle |
| Lead screw and rail contamination | Brush or vacuum chips from the rails after every session; re-lubricate ball screws with light machine oil monthly |
A dust shoe around the spindle collet is the single most effective upgrade for the Stepcraft D600. Printable designs are available on Printables and Thingiverse for the D600 specifically. Connect it to a shop vac via a 38 mm hose and MDF dust becomes a non-issue.