Ashen Pebble

Polyclast behaves similarly to dense micarta or stabilized hardwoods. It creates a fine, powdery swarf rather than long melting strands or brittle shards.

• Rough Shaping: 80 to 120 grit (Ceramic or Zirconia). Cuts rapidly and leaves a clean silhouette.
• Refining Contours: 220 to 400 grit (Aluminum Oxide or Structured Abrasive belts).
• Speed & Pressure: Run grinder at medium to medium-high speed with moderate, continuous pressure. Do not dwell in one spot to prevent localized heat buildup.
• Wet vs. Dry: Works cleanly dry. If using a misting system or dip bucket, water will not swell or degrade the composite.

Polyclast behaves similarly to dense micarta or stabilized hardwoods. It creates a fine, powdery swarf rather than long melting strands or brittle shards.

The two primary mechanical priorities when milling Polyclast are chip evacuation to eliminate heat re-welding and rigid workholding to avoid slab vibration.

Tooling Selection

Material / Coating

Solid Micrograin Carbide (Uncoated, polished flutes, or DLC / ZrN)

High-speed steel (HSS) dulls prematurely on composite aggregates. Polished flutes or DLC coatings prevent plastic buildup and gumming.

Flute Count

1-Flute (O-Flute) or 2-Flute End Mills

3- and 4-flute tools lack the gullet clearance for plastic swarf, packing chips into the flutes and causing localized heat buildup.

Geometry

Upcut Spiral (roughing & pockets)

Downcut / Compression (perimeter profiling)

Upcut geometry pulls swarf out of deep pockets; downcut or compression bits prevent top-edge chipping along faceted clast boundaries.

Ball-Nose / Tapered

2-Flute Ball-Nose (3D contours & scales)

Leaves a smooth, uniform surface across multi-tone aggregate transitions without gouging.

Speeds, Feeds & Cutting Parameters

Baseline parameters for a 1/4" (0.250") 2-flute solid carbide upcut spiral on desktop/gantry CNCs (Shapeoko, Nomad, Avid, Tormach, Haas):

Roughing

16,000 – 18,000 RPM
90 – 120 IPM
1.0× Max Depth of Cut
20% Stepover

Slotting / Pocketing

14,000 – 16,000 RPM
60 – 80 IPM
.5× Max Depth of Cut
100% Stepover

Finish Pass (Walls)

18,000 – 20,000 RPM
50 – 70 IPM
1.0× Max Depth of Cut
0.010" – 0.015" axial stock

3D Contouring (1/8" Ball Nose)

18,000 – 20,000 RPM
60 – 90 IPM
0.030" – 0.05" Max Depth of Cut
8%-12% Stepover

3D Contouring (1/8" Ball Nose)

3,000– 5000 RPM
12 – 18 IPM
Peck cycle: 0.050" retract

Feed vs. Heat Management: Maintain positive feed pressure. Feeding too slowly causes the tool edge to rub and burnish rather than slice chips. Urethane softens when subjected to friction heat; letting a spinning cutter dwell will glaze the surface and weld swarf back into the cut path.

Chip Evacuation & Cooling

Best Practice: Compressed Air Blast (Cold Gun). Direct high-pressure air clears powdery chips from slots and pockets instantly, preventing re-cutting and keeping the cutter cool.

Flood / Mist Coolant: Water-soluble coolant runs cleanly. Polyclast is non-porous and will not swell or degrade in coolant baths.

Dry Cutting: Cleanly supported if paired with high-volume dust extraction at the spindle shoe.

• Drill Bits: Standard High-Speed Steel (HSS) or cobalt jobber bits. Brad-point bits produce exceptionally crisp entries.
• Drilling Speed: Moderate spindle speed (~800–1,200 RPM).
• Technique: Back the scale securely with a sacrificial wood block to ensure zero breakout on the exit hole.Clear chips frequently on deep holes.Counter-bore or chamfer pinholes lightly before driving mechanical fasteners.

• Glue Compatibility: Accepts standard two-part epoxies (G/flex 650, West System, standard 30-minute epoxy) and cyanoacrylate (CA).
• Bonding Prep: Scuff the bonding face with 60 to 80 grit paper to create mechanical tooth; wipe down with isopropyl alcohol (avoid harsh acetone soaks).

Polyclast accepts finishes ranging from a grippy satin carry texture to a high-gloss, stone-like polish

Hand Sanding

Hand-block sand through 320 → 400 → 600 → 800 grit using wet/dry paper. For a durable, tactical/matte grip: Stop at 400–600 grit and buff lightly with a dry Scotch-Brite pad.

Buffing (Wheel Polish) 

Use a clean, loose-muslin wheel running at 1,200–1,800 RPM. Apply light passes with White Diamond or Matchless pink compound. Finish with an untreated, dry muslin wheel for a deep, dimensional luster that exposes the internal strata matrix.

Topcoats / Sealers 

None required. Polyclast is non-porous and naturally waterproof throughout the entire piece. Do not apply hardening oils (Danish oil, Tru-Oil) as they cannot penetrate the surface.

• Respiratory Protection: Always wear an N95 or P100 respirator when grinding, sanding, or sawing composite resin dust.
• Dust Collection: Use standard extraction at the tool rest.