Pattern Making: Wood & Metal Patterns
木模/金属模制作
标签：木模, 金属模, 起模斜度, 收缩率
模样是铸件的"负形"。木模价廉易加工，适合单件；金属模耐用，适合批量。制作须含三要素：①收缩余量（铜合金约 1.5–2%，铸铁约 1%）②起模斜度（1–3°，便于拔模）③加工余量（需机加工面留 2–5 mm）。分模面应设在最大截面处。泡沫模（消失模）则按成品 1:1 直接雕刻，无需斜度。
The pattern is the negative of the casting. Wood is cheap and easy (one-offs); metal lasts for production. Three must-haves: ①shrinkage allowance (Cu alloy ~1.5–2%, iron ~1%) ②draft angle (1–3° for draw) ③machining stock (2–5 mm on faces to be cut). Parting line at the max cross-section. Lost-foam patterns are carved 1:1 with no draft needed. ---