Flat Lap Discs

Diamond Flat Lap Discs – Precision Diamond Discs for Flat Lap Grinding, Faceting & Cabochon Finishing

Professional diamond flat lap discs for lapidary flat grinding, faceting, and cabochon finishing on flat lap machines. Available in 8" to 18" diameters across a full grit range from 45 to 3000 — covering coarse shaping through fine pre-polish stages. Multiple backing options: magnetic quick-change, PSA sticker, 1/4"-20 screwback master lap, 1/2" master lap, and plain (no backing). Nickel-bonded and sintered diamond constructions available.

🔥 Shop Diamond Flat Lap Discs – From $12.00

Available Sizes & Pricing

Diameter Grit Range Magnetic PSA Plain Master Lap
8" (half disc) 60–320 $15.50 $13.00 $12.00 $24–$31
8" (full face) 60–320 $28.00 $23.00 $22.00 $48.00
10" 45–600 + 1200 + 3000 $45.00 $40.00 — —
12" 45–600 $70.00 $70.00 $70.00 —
14" 45–600 $105.00 $105.00 $105.00 —
16" 45–600 $145.00 $145.00 $145.00 —
18" 45–600 $160.00 $160.00 $160.00 —

Grit Selection Guide

Grit Stage Application
45–80 Coarse grinding Rapid stock removal, rough shaping of cabochon preforms from slab
100–140 Medium grinding Shape refinement, removing coarse grinding scratches
200–270 Fine grinding Surface smoothing, preparing for pre-polish stage
325–600 Pre-polish Scratch removal, surface preparation for polishing pads
1200–3000 Fine pre-polish Near-polish surface quality, minimal scratch depth before final polish

Compatible Applications

  • Lapidary cabochon grinding and shaping on flat lap machines
  • Faceting machine flat lap grinding stages
  • Glass, ceramic, and stone surface grinding
  • Slab surface preparation before polishing
  • Compatible with Genie, Titan, and most standard flat lap machines

Related Tools

Frequently Asked Questions

  • Q: What grit flat lap disc should I start with for shaping a cabochon from a slab?
    A: Start with 60–80 grit for rapid stock removal and rough shaping of the cabochon outline from a slab preform. Progress to 100–140 grit for shape refinement, then 200–270 grit for surface smoothing, and finish with 325–600 grit to prepare the surface for polishing pads. For a finer pre-polish surface, continue with 1200 or 3000 grit before switching to felt or leather polishing pads with compound.
  • Q: What is the difference between half-disc and full-face flat lap discs?
    A: Full-face discs cover the entire lap surface for maximum grinding area and even wear distribution — ideal for large cabochons and slab grinding. Half-disc (8"x1/2") versions cover half the lap surface, allowing two different grits to be mounted simultaneously on a single lap for faster grit progression without changing discs.
  • Q: Which backing type should I choose for my flat lap machine?
    A: Choose magnetic backing for machines with magnetic quick-change plates (Genie, Titan) for instant disc swaps. Choose PSA sticker for standard flat lap platens without magnetic systems. Choose 1/4"-20 screwback master lap for precision faceting setups. Choose plain (no backing) for custom mounting with spray adhesive or water tension on glass plates.
  • Q: Can diamond flat lap discs be used wet?
    A: Yes — wet use with water cooling is strongly recommended for all diamond flat lap disc applications. Water reduces heat buildup, extends disc life, flushes swarf from the disc surface, and improves cutting consistency. Always use adequate water flow during grinding to protect both the disc and the workpiece.
  • Q: How long do diamond flat lap discs last?
    A: Disc life depends on material hardness, applied pressure, and water cooling. On standard lapidary stones (Mohs 6–7), a quality diamond flat lap disc typically lasts 50–200+ hours of use. Coarser grits (45–80) wear faster due to higher material removal rates. Always use water cooling and avoid excessive pressure to maximize disc life.