Roland SRM-20 Desktop PCB Mill

Quick-Reference Operator Card

1. Pre-Flight Safety & Setup Checklist

  • [ ] APPROVED SUBSTRATE ONLY: Use ONLY FR-1 (Phenolic Paper) PCB blanks, Machinable Wax, or High-Density Foam. STRICTLY PROHIBITED: FR-4 (Glass-Reinforced Epoxy) — produces toxic, carcinogenic glass dust and destroys micro-bits.
  • [ ] PERSONAL PROTECTION: Wear an N95 respirator or dust mask during cleanup and vacuuming to prevent inhalation of micro-particulates.
  • [ ] BED TAPE COUPLING: Apply high-tack double-sided tape across the substrate back. Ensure zero overlapping layers and zero air gaps. Press down firmly for 15 seconds.
  • [ ] CLEANUP PROTOCOL: NEVER use compressed air nozzles. Compressed air forces abrasive dust into lead screw threads and bearings. Use a vacuum with a soft brush attachment.

2. Standard 5-Step PCB Milling Workflow

  1. EXPORT CAM FILES (Mods / FlatCAM)
  2. Traces (1/64” \ \text{Bit}): Cut Depth = 0.12\text{ mm}, Speed = 3.0\text{ mm/s}, Offsets = 4.
  3. Outlines (1/32” \ \text{Bit}): Cut Depth = 1.70\text{ mm}, Speed = 1.5\text{ mm/s}, Step-Down = 0.35\text{ mm}.
  4. MOUNT SUBSTRATE & SET X/Y ORIGIN Tape FR-1 board securely to the surfaced bed. In VPanel, use directional arrows to move the carriage to the lower-left corner of the workpiece. Click Set Origin: X/Y.
  5. MECHANICAL Z-ZEROING (Gravity Drop Method) Install the 1/64” bit into the collet shaft. Lower Z-carriage to within 2-3\text{ mm} of the board. Loosen the set screw, let the bit drop gently under gravity onto the copper, apply light finger pressure to the substrate, and re-tighten set screw. Click Set Origin: Z.
  6. EXECUTE CUT JOB Close the transparent interlock door, click Cut in VPanel, select your .rml or .nc file, and press Output.
  7. VACUUM & DEBURR After spindle stops, vacuum phenolic dust. Carefully pry up board using a spatula and lightly scrub copper traces with fine steel wool to remove burrs.

3. Tooling & Speeds/Feeds Matrix (7,000\text{ RPM} Baseline)

Substrate & Operation Tool Geometry Cut Speed (mm/s) Max Pass Depth Operational Rule
FR-1 Traces Isolation 1/64” \ (0.4\text{ mm}) Flat 3.0\text{ mm/s} 0.12\text{ mm} Run 4 offsets to prevent solder bridges across SMD pads.
FR-1 Fine Traces 30^\circ \ \text{V-Bit} \ (0.1\text{ mm}) 2.0\text{ mm/s} 0.10\text{ mm} Ideal for \<8\text{ mil} clearance; extremely fragile tip.
FR-1 Outline & Cutouts 1/32” \ (0.8\text{ mm}) Flat 1.5\text{ mm/s} 0.35\text{ mm} Multi-pass contour cut; ensures clean edge separation.
Wax 3D Roughing 1/8” \ (3.175\text{ mm}) Flat 20.0\text{ mm/s} 1.50\text{ mm} Rapid material removal for 3D molding masters.
Wax 3D Finishing 1/16” \ (1.58\text{ mm}) Ball 15.0\text{ mm/s} 0.20\text{ mm} Sets fine surface finish; stepover 10-15\%.

4. Rapid Troubleshooting & Recovery

Issue / Error Root Cause Immediate Corrective Action
Trace Uncut / Copper Remaining Bed uneven, tape overlapping, or Z set too high. Re-zero Z-axis 0.02\text{ mm} lower in VPanel or re-tape board ensuring zero tape overlaps.
1/64” Bit Snapping Instantly Plunge rate too fast or bit struck bed during jog. Always use step jogging near bed. Verify Z plunge rate in Mods is \le 2.0\text{ mm/s}.
Traces Lifted / Torn Dull bit or cut depth too deep into phenolic core. Replace endmill; ensure cut depth does not exceed 0.12\text{ mm} into FR-1 substrate.