{ "version": "2026-10-20", "license": "Dimension sheets: CC BY 4.0. Standard and published-size files: CC BY 4.0. Xem Studio's own designs (files_license = Xem Studio Design License): free to use and sell things from, not to redistribute as files — https://xemstudio.com/license/. Other publishers' files: their own license, linked beside them.", "slug": "birds-mouth-joint", "name": "Bird's mouth joint (rafter seat)", "kind": "hardware", "category": "Joinery", "group": "Scarf & splice joints", "year": null, "question": "How deep is a bird's mouth cut?", "tags": [ "joinery", "woodworking joint", "3d printable", "connect 3d prints", "no glue", "stl", "step", "scarf & splice joints" ], "aliases": [ "birds mouth", "bird's mouth cut", "birdsmouth joint", "rafter seat cut", "boca de pájaro", "corte de pájaro", "Kerve", "Sparrenkerve" ], "overall_mm": { "length": 153.6, "width": 80, "height": 106 }, "official_cad": false, "xem_status": "free-files", "les": false, "free_files": 3, "url": "https://xemstudio.com/objects/birds-mouth-joint/", "sheet_txt": "https://xemstudio.com/objects/birds-mouth-joint/sheet.txt", "sheet": { "basis": "Xem Studio design — geometry computed in the generator from traditional proportions", "overall_mm": { "length": 153.6, "width": 80, "height": 106 }, "notes": [ "Woodworking joint drawn for 3D printing: the parts lock together by shape, so a print can be joined without glue or screws. Drawn at true size with the parts line to line (zero gap) in their assembled position — add your printer's fit allowance to the mating faces (your AI or slicer can do this).", "The V notch that seats a sloping rafter on a wall plate: a level seat cut and a plumb heel cut." ], "table": { "columns": [ "dimension", "value" ], "rows": [ [ "stock", "20 × 20 plate, 15 × 30 rafter" ], [ "parts", "plate, rafter" ], [ "pitch", "30°" ], [ "notch", "seat cut and heel cut, about a third of the rafter depth" ], [ "assembles", "the rafter sits on the plate" ], [ "holds", "the rafter from sliding off the plate" ] ] } }, "sheet_text": "Bird's mouth joint (rafter seat) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/birds-mouth-joint/ (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)\nBasis: Xem Studio design — geometry computed in the generator from traditional proportions\nCatalog version: 2026-10-20\n\nOverall (mm): length 153.6, width 80.0, height 106.0\n- Woodworking joint drawn for 3D printing: the parts lock together by shape, so a print can be joined without glue or screws. Drawn at true size with the parts line to line (zero gap) in their assembled position — add your printer's fit allowance to the mating faces (your AI or slicer can do this).\n- The V notch that seats a sloping rafter on a wall plate: a level seat cut and a plumb heel cut.\n\ndimension value\nstock 20 × 20 plate, 15 × 30 rafter\nparts plate, rafter\npitch 30°\nnotch seat cut and heel cut, about a third of the rafter depth\nassembles the rafter sits on the plate\nholds the rafter from sliding off the plate\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Xem Studio: Joinery design (geometry computed in the generator from traditional proportions) — web — Xem Studio design — https://xemstudio.com/\n\nFree files (Xem Studio Design License, Xem Studio; STEP + STL, 3 parts): https://xemstudio.com/files/hardware/birds-mouth-joint/index.json\nAPI: https://xemstudio.com/api/geometry?object=birds-mouth-joint\n", "sources": [ { "publisher": "Xem Studio", "title": "Joinery design (geometry computed in the generator from traditional proportions)", "url": "https://xemstudio.com/", "formats": [ "web" ], "license": "Xem Studio design", "license_verified": true, "hosted": false } ], "xem": { "status": "free-files", "sheet_free": true, "mesh_price_usd": null, "step_price_usd": null, "tolerance_mm": null }, "related": [ "half-lap-joint", "watari-ago-cogged-joint" ], "fits": [], "dimensions": "exact (nominal, no printing tolerance)", "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.", "mating": [], "faq": [ { "q": "How deep can a bird's mouth be?", "a": "No more than a third of the rafter depth." } ], "files_license": { "name": "Xem Studio Design License", "holder": "Xem Studio", "url": "https://xemstudio.com/license/", "note": "Xem Studio's own design: free to use, print, modify and sell things made from it; not to be republished or redistributed as files." }, "offers": [ { "file": "birds-mouth-joint-plate", "formats": [ "step", "stl" ], "price_usd": 0, "license": "Xem Studio Design License", "step": "https://xemstudio.com/files/hardware/birds-mouth-joint/birds-mouth-joint-plate.step", "stl": "https://xemstudio.com/files/hardware/birds-mouth-joint/birds-mouth-joint-plate.stl", "note": "Wall plate (20 × 20)" }, { "file": "birds-mouth-joint-rafter", "formats": [ "step", "stl" ], "price_usd": 0, "license": "Xem Studio Design License", "step": "https://xemstudio.com/files/hardware/birds-mouth-joint/birds-mouth-joint-rafter.step", "stl": "https://xemstudio.com/files/hardware/birds-mouth-joint/birds-mouth-joint-rafter.stl", "note": "Rafter 15 × 30 at 30° with the bird's mouth notch" }, { "file": "birds-mouth-joint-assembled", "formats": [ "step", "stl" ], "price_usd": 0, "license": "Xem Studio Design License", "step": "https://xemstudio.com/files/hardware/birds-mouth-joint/birds-mouth-joint-assembled.step", "stl": "https://xemstudio.com/files/hardware/birds-mouth-joint/birds-mouth-joint-assembled.stl", "note": "All parts in their assembled position (each part its own solid)" } ], "markdown": "https://xemstudio.com/objects/birds-mouth-joint/index.md" }