# CNC Setup Sheet — Bass Surface Drum ## Tools assumed - **Plasma or fiber laser** for the clamp ring (4 mm plate) and lug brackets (3 mm sheet) - **Slip roll** with 400 mm minimum forming radius for the frame cylinder - **Press brake** with 4 mm-radius punch+die for the top-edge bearing flange - **Bead roller** with 6 mm round bead die for the bottom-edge stiffening bead - **TIG welder** with argon shielding, ER70S-2 filler - **Spot welder** OR M5 button-head + countersunk holes for the internal doubler attachment If any of those tools is unavailable, see `../fabrication-plan.md` for the substitution table. ## Operations summary | Op | Part | Machine | Setup | Cycle (est.) | |----|---------------|-------------|------------------|--------------| | 1 | frame-flat | shear or laser | one cut from 2600×150 stock | 2 min | | 2 | clamp-ring | laser/plasma | nested at center of 900×900 plate | 8 min | | 3 | lug-bracket × 6| laser/plasma | nested on 500×250 sheet | 6 min | | 4 | doubler | shear | offcut from frame stock | 1 min | | 5 | frame top flange | press brake | 4 mm radius punch + die | 4 min | | 6 | frame bottom bead | bead roller | 6 mm round die, 3 passes | 6 min | | 7 | frame roll-up | slip roll | 3 passes; check round at each | 20 min | | 8 | frame seam weld | TIG bench | tabs interlocked first, then full pass | 15 min | | 9 | doubler attach | spot welder | 6 spots | 2 min | | 10 | lug-bracket bend × 6 | press brake | 3 mm radius punch + die | 6 min | | 11 | lug-bracket weld × 6 | TIG | jig to frame at 60° spacing | 30 min | | 12 | clamp-ring deburr | by hand | edge break + corner break | 5 min | | 13 | final deburr + paint | hand + spray | matte black enamel | 30 min | Total shop time: ~2.5 hours plus paint cure. ## Nesting plan See `operations.csv` for tool-by-tool nesting. The plan minimizes machine changeovers by grouping all plasma/laser cuts first, then all press-brake bends, then all roll operations, then welding. ## Tolerances - Frame OD after roll: **800 mm ± 1.0 mm**, out-of-round < 1.5 mm. Tighter is better — the more circumferentially-even the rim, the more even the head tension. - Bearing flange radius: **4 mm ± 0.5 mm**. - Stiffening bead depth: **3 mm minimum** (must be visible from inside the frame). - Bolt-hole position on clamp ring: **PCD ± 0.5 mm**, hole-to-hole angular ± 0.5°. - Lug bracket bolt-hole position on frame: ± 1 mm acceptable (the M10 clearance hole absorbs small misalignments). ## Safety - Slip-roll: pinch hazard. Two operators for a 2600 mm blank; the trailing edge must be supported on a roller stand. - TIG arc: standard arc-weld PPE. The frame seam is a long-pass weld; consider a back-purge to reduce sugaring on the inside. - Bead roller: hand-pinch hazard. Use push sticks for the last 100 mm. - Heavy lifting: a finished frame weighs ~4 kg; the clamp ring ~14 kg of 4 mm plate. Two-person lift recommended for the clamp ring.