Fifty years at the bench, written as numbers
These are the defaults Snap2Cast applies. Factory plans can replace any value with the workshop's own.
Claws and rails
| Stone width W | Claw Ø | Bearing rail Ø | Gallery rail Ø | Claws |
|---|---|---|---|---|
| 1.0 – 2.0 mm (melee) | 0.40 – 0.50 | 0.45 – 0.50 | — | beads or 4 fine claws |
| 2 – 4 mm | 0.50 – 0.70 | 0.50 – 0.66 | 0.44 – 0.60 | 4 |
| 4 – 9 mm | 0.70 – 1.20 | 0.66 – 1.10 | 0.60 – 1.00 | 4 (marquise/pear: tips + sides) |
| 9 – 20 mm | 1.20 – 1.50 | 1.10 | 1.00 | 5 – 6, tip claw on pear and marquise |
Rule used by the generator: claw Ø = 0.10·W + 0.30, clamped to 0.5–1.5 mm. A claw ends 0.55 Ø above the crown-mid line, pre-bent, so the setter has metal to close without filing it away. A marquise or pear always gets a claw on the point: the point is the stone's weakest place and the setting's strongest grip.
Seats
Seat (bearing) at one third of the pavilion depth below the girdle is wrong for calibrated goods; use the girdle plane itself: the bearing rail sits with its top 0.10 mm under the girdle and the pavilion rests on the rail's inner edge. Clearance: stone outline + 0.05 mm all round, girdle slot ±0.10 mm. Less than that and the setter grinds the seat; more and the stone rocks.
Pavé
Pitch = stone Ø + 0.20 mm (0.15 for 1.0 mm and under). Beads Ø 0.45–0.50 raised 0.25 above the surface, four per stone, shared; never under 0.45 in gold or 0.5 in silver. Azure every stone over 1.1 mm (Ø ≈ 0.5 × stone) for light, cleaning and weight. Minimum wall beside a pavé line 0.30 mm; a line closer than that to an edge needs a cut-down wall instead of beads.
Shanks and heads
Shank minimums for a daily-wear ring: 1.5 mm wide × 1.2 mm thick at six o'clock in 18k; 1.6 × 1.3 in silver; 1.4 × 1.1 in platinum. Comfort-fit inside radius ≥ 0.6 mm. Head height above the finger: 2–3 mm for clusters, 4–7 mm for solitaires (crown must clear the knuckle of the next finger). Finger clearance under a head 0.2 mm. A head wider than 6 mm needs an under-gallery of 0.7 mm or a bridge; openings under every stone.
Printing
Castable resin: 25 µm layers, parts table-up, supports on eyelets and claw bases only, never on seats or the inside of a shank. Milled wax for anything with a wall under 0.4 mm. Wire minimum 0.5 mm on resin printers, 0.6 mm for safety. Group one of each unique part on the plate; print duplicates in quantity only after the first casting proves the file.
Casting
Apply shrinkage as a uniform scale in the print software: 1.5 % for 22k and 18k gold, 2.0 % for 14k and silver, 1.2 % for platinum (gypsum-free investment). Sprue 1.5–2.0 mm on a 3 g ring at the heaviest section (shank bottom), never at the head. Resin burnout: hold at 150 °C 60 min, ramp 1.5 °C/min to 370 °C hold 120 min, ramp to 730 °C hold 180 min, cool to flask temperature: 480–520 °C for 18k, 580–620 °C for 14k white, 620 °C for silver; platinum needs its own investment and a centrifugal cast.
Allowances
Polishing removes 0.1–0.2 mm. Model high-polish surfaces 0.1 mm proud and rings an eighth of a size small, or the finished piece ends thinner and larger than drawn. Fill any gap under 0.3 mm in the model; the caster cannot. Do not model milgrain: leave a 0.3 mm edge for the setter to roll. Lettering: block strokes 0.5–0.7 mm, 0.35 mm deep; nothing inside a ring.
Finishing and setting
Allow 4 % metal loss from sprue cut, pre-polish and setting. Stones go in after pre-polish, rhodium after setting. The job card lists each stone's shape, size, count and carat so the setter and the buyer read the same ticket. Finished ring sizing: ±¼ size at the first cast is normal; adjust the model, not the ring, before the production run.