PRECIOUS METAL CASTING & JEWELRY CAD/CAM
Jewelry Lost-Wax Casting Shrinkage & Sprue Feed Calculator
Compute multi-stage casting shrinkage scaling factors, master mold compensation percentages, cast metal alloy weights from wax models, and minimum sprue feeder gate diameters for 14k/18k gold, sterling silver, and platinum.
1. Alloy & Process Shrinkage
Desired final dimension after polishing (e.g. ring diameter, bezel width).
Material lost during magnetic tumbling, filing, and final rogue polish.
2. Wax Pattern & Sprue Feeder Sizing
Measured weight of 3D printed resin / injected wax pattern (assuming density ~1.0 g/cm³).
Thickest solid cross-section of the jewelry piece.
CAD Scaling & Pre-Shrunk Dimensions
BALANCED FEEDTotal Cumulative Shrinkage
1.90%
Combined volumetric loss
CAD Scale Factor Multiplier
101.94%
Multiply 2D vector / 3D model by this
Target CAD Pre-Cast Size
20.54 mm
Includes polishing buffer
Min Prong / Wall Limit
0.80 mm
Safe minimum post-shrink
Metal Yield & Sprue Specifications
Estimated Metal Cast Weight
15.68 g
14K Yellow Gold
Min Main Sprue Diameter ($D_s$)
3.1 mm
$\ge 1.25 \times T_{\max}$ to avoid porosity
Sprue Gate Cutoff Margin
0.50 mm
Sawing & cleanup clearance
Flask Button Metal Needed
23.5 g
Tree base + 50% reservoir
Jewelry CAM & Laser Engraving Layer Spec
CAD_SCALE_PROFILE: Apply scale $+1.94\%$ globally to all vector geometry
BEZEL_SEAT_OFFSET: Enlarge gem stone seats by $+0.20$ mm for shrinkage fit
HALLMARK_STAMP: Minimum stroke width $= 0.25$ mm to survive tumble polish
SPRUE_ATTACHMENT: Target heaviest node ($T_{\max} = 2.5$ mm)
BEZEL_SEAT_OFFSET: Enlarge gem stone seats by $+0.20$ mm for shrinkage fit
HALLMARK_STAMP: Minimum stroke width $= 0.25$ mm to survive tumble polish
SPRUE_ATTACHMENT: Target heaviest node ($T_{\max} = 2.5$ mm)