{"$schema":"nativecad-dfm-pack/1","id":"sheet-metal","title":"Sheet metal — brackets, enclosures, racks and press-brake formed parts","sector":"sheet-metal","version":"2026-09-03","summary":"Gauge and bend-radius tables, K-factor and bend-allowance formulas, flange/relief/hole-to-bend rules, hems/louvers/embosses, PEM and rivet hardware, 19-inch rack (EIA-310) and DIN-rail dimensions, NEMA/IP enclosure ratings, and the tests, standards, materials and recipes a laser-plus-press-brake part is held to.","aliases":["sheet metal","sheetmetal","bracket","rack","19 inch rack","rack ear","chassis","bend","flange","hem","louver","laser cut","press brake","u-bracket","l-bracket","sheet metal enclosure","metal enclosure"],"crossSector":false,"size":"standard","sources":[{"id":"sendcutsend-sheet-cutting","title":"SendCutSend sheet cutting guidelines (laser/waterjet/router, min hole/radius)","url":"https://sendcutsend.com/guidelines/sheet-cutting/","accessed":"2026-09-03"},{"id":"sendcutsend-bending","title":"SendCutSend CNC bending service guidelines (materials, K-factor, bend limits, flange/relief)","url":"https://sendcutsend.com/services/cnc-bending/","accessed":"2026-09-03"},{"id":"sendcutsend-minmax","title":"SendCutSend min/max part sizes and per-material thickness","url":"https://sendcutsend.com/materials/min-max/","accessed":"2026-09-03"},{"id":"oshcut-capabilities","title":"OSH Cut capabilities (machines, materials, thicknesses, tolerances, tapping, bending)","url":"https://www.oshcut.com/capabilities","accessed":"2026-09-03"},{"id":"oshcut-minmax","title":"OSH Cut minimum/maximum material sizes","url":"https://www.oshcut.com/minimum-maximum-material-sizes","accessed":"2026-09-03"},{"id":"protolabs-sheet-metal","title":"Protolabs sheet metal design guide (bend radius, flange, relief, hem, hole-to-bend)","url":"https://www.protolabs.com/resources/design-tips/sheet-metal-design/","accessed":"2026-09-03"},{"id":"eia-310e","title":"EIA-310-E / ANSI/EIA 310 Cabinets, Racks, Panels and Associated Equipment (19-inch rack)","note":"no free official PDF; the 482.6mm/44.45mm/465.1mm numbers here are the same figures reproduced by Vertiv, APC and Wikipedia's 19-inch-rack technical summary of EIA-310-E","accessed":"2026-09-03"},{"id":"din-43880","title":"DIN 43880 Low-voltage switchgear — dimensions for modular installation devices (module width 17.5mm/18mm)","url":"https://www.din.de/en","accessed":"2026-09-03"},{"id":"iec-62262","title":"IEC 62262:2002 Degrees of protection against mechanical impact (IK code)","url":"https://webstore.iec.ch/publication/6968","accessed":"2026-09-03"},{"id":"iec-60529","title":"IEC 60529:1989+A2:2013 Degrees of protection provided by enclosures (IP Code)","url":"https://webstore.iec.ch/publication/2452","accessed":"2026-09-03"},{"id":"nema-250","title":"NEMA 250 Enclosures for Electrical Equipment (1000 Volts Maximum)","url":"https://www.nema.org/standards/view/enclosures-for-electrical-equipment-1-000-volts-maximum","accessed":"2026-09-03"},{"id":"pem-catalog","title":"PEM self-clinching fastener installation specifications (Penn Engineering)","url":"https://www.pemnet.com","accessed":"2026-09-03"},{"id":"matweb-sheet-alloys","title":"MatWeb material property datasheets (CRS 1008/1010, 5052-H32, 6061-T6, 304)","url":"https://www.matweb.com","accessed":"2026-09-03"}],"entries":[{"id":"sheet-gauge-thickness-table","kind":"dimension","tier":1,"title":"Sheet gauge to thickness, 24-7 gauge (steel/aluminium/stainless)","summary":"Common sheet-metal stock spans 24ga (0.6mm) to 7ga (4.5mm): e.g. 18ga steel 1.21mm, 14ga steel 1.90mm, 11ga steel 3.04mm, 7ga steel 4.55mm; aluminium and stainless use different gauge-to-mm tables at the same gauge number.","applies":["sheet metal","bracket","enclosure","chassis"],"value":{"table":[{"gauge":24,"steelMM":0.61,"alMM":0.51,"ssMM":0.61},{"gauge":20,"steelMM":0.91,"alMM":0.81,"ssMM":0.95},{"gauge":18,"steelMM":1.21,"alMM":1.02,"ssMM":1.21},{"gauge":16,"steelMM":1.52,"alMM":1.29,"ssMM":1.52},{"gauge":14,"steelMM":1.9,"alMM":1.63,"ssMM":1.91},{"gauge":11,"steelMM":3.04,"alMM":2.3,"ssMM":3.04},{"gauge":7,"steelMM":4.55,"alMM":3.57,"ssMM":4.55}],"unit":"mm"},"basis":"Manufacturers Standard Gauge (steel/stainless) vs the separate Aluminum B&S gauge series, extended to the shop-floor 24-7ga range SendCutSend/OSH Cut stock","sources":["sendcutsend-minmax","oshcut-minmax"],"tags":["gauge","thickness","steel","aluminum","stainless"],"see":["materials/sheet-metal-gauge-table"]},{"id":"inside-bend-radius-soft-metals","kind":"rule","tier":1,"title":"Inside bend radius, soft steel and aluminium (1x thickness)","summary":"For dead-soft mild steel and soft aluminium (5052-H32), the minimum inside bend radius equals the material thickness t (1xt); tighter radii crack the outer fiber in air bending.","applies":["mild steel","5052-H32 aluminium","bracket","enclosure"],"value":{"typical":1,"unit":"ratio"},"basis":"Press-brake air-bend minimum-radius guidance for soft/annealed sheet stock (SendCutSend/Protolabs)","sources":["sendcutsend-bending","protolabs-sheet-metal"],"tags":["bend radius","soft metal","press brake"],"check":{"process":"sheet_metal","rule":"bend_radius"}},{"id":"inside-bend-radius-6061-t6","kind":"rule","tier":1,"title":"Inside bend radius, 6061-T6 aluminium (1.5-2x thickness)","summary":"6061-T6 aluminium needs a minimum inside bend radius of 1.5-2x material thickness (vs 1x for soft 5052) because the T6 temper is far less ductile; bending at radius <1.5t routinely cracks the outer surface.","applies":["6061-T6 aluminium","bracket"],"value":{"min":1.5,"max":2,"unit":"ratio"},"basis":"6061-T6's temper drops elongation well below annealed/H32 aluminium; vendor bending calculators publish a wider minimum radius for it","sources":["sendcutsend-bending"],"tags":["bend radius","6061-t6","aluminum"],"check":{"process":"sheet_metal","rule":"bend_radius"},"see":["materials/al-6061-t6"]},{"id":"inside-bend-radius-stainless","kind":"rule","tier":2,"title":"Inside bend radius, stainless steel (0.5-1x thickness)","summary":"Stainless steel (304) tolerates a tighter minimum inside bend radius than mild steel, 0.5-1x material thickness, because of its higher work-hardening ductility before cracking — but it also springs back more, so overbend to compensate.","applies":["304 stainless","bracket","enclosure"],"value":{"min":0.5,"max":1,"unit":"ratio"},"basis":"Stainless sheet bending guidance: tighter achievable radius than mild steel at the same thickness, at the cost of higher springback","sources":["sendcutsend-bending","protolabs-sheet-metal"],"tags":["bend radius","stainless","304"],"check":{"process":"sheet_metal","rule":"bend_radius"}},{"id":"air-bend-v-die-opening","kind":"rule","tier":2,"title":"Air-bend V-die opening (6-8x material thickness)","summary":"A press-brake air-bend V-die opening is sized 6-8x the material thickness (e.g. 12-16mm die for 2mm steel); too narrow a die for the thickness overloads tonnage and distorts the bend radius achieved.","applies":["press brake","bracket"],"value":{"min":6,"max":8,"unit":"ratio"},"basis":"Standard air-bending die-selection rule of thumb, matched by SCS/OSH Cut die-keepout guidance (half the die width from the bend centreline)","sources":["sendcutsend-bending","protolabs-sheet-metal"],"tags":["v-die","press brake","tooling"]},{"id":"k-factor-bend-allowance","kind":"dimension","tier":1,"title":"K-factor and bend allowance formula (worked example)","summary":"K-factor (neutral-axis location as a fraction of thickness from the inside) runs 0.33-0.5 depending on material and bend radius; bend allowance BA = angle(rad) x (radius + K x thickness) — e.g. 90deg bend, R=2mm, t=2mm, K=0.44: BA = 1.5708 x (2 + 0.44x2) = 4.52mm.","applies":["flat pattern","sheet metal"],"value":{"min":0.33,"max":0.5,"typical":0.44,"unit":"ratio"},"basis":"Standard sheet-metal bend-allowance derivation; 0.33 for tight/soft bends, 0.5 for thick or fully work-hardened material (matches sheet_fold's air-bending R/T table)","sources":["sendcutsend-bending"],"tags":["k-factor","bend allowance","flat pattern"]},{"id":"bend-relief-dimensions","kind":"rule","tier":1,"title":"Bend relief notch: width and depth","summary":"A bend relief notch needs width >= 1x material thickness and depth >= bend radius + 1x thickness, or the un-relieved corner tears or bulges when the flange forms.","applies":["bracket","chassis","enclosure"],"value":{"min":1,"unit":"ratio"},"basis":"SendCutSend: \"Bend relief notches reduce stress on inner radii and prevent corner tearing or bulging\" / \"Without proper relief, a part cannot be bent accurately\"","sources":["sendcutsend-bending"],"tags":["bend relief","notch","press brake"],"check":{"process":"scs_bend","rule":"bend_relief"}},{"id":"min-flange-length","kind":"rule","tier":1,"title":"Minimum flange length (die-support floor)","summary":"A formed flange needs a minimum length of about 4x thickness + inside radius (or 2.5xt + half the die width, die-dependent) or the flange drops into the V-die and will not form straight; e.g. 2mm steel, R2 die-width 16mm needs roughly 10mm minimum flange.","applies":["bracket","u-bracket","flange"],"value":{"min":4,"unit":"ratio"},"basis":"SendCutSend: \"Minimum flange length depends on material and thickness\"; die-support physics floor is half the V-die opening plus one thickness","sources":["sendcutsend-bending","protolabs-sheet-metal"],"tags":["flange","minimum length","press brake"],"check":{"process":"scs_bend","rule":"flange_support_ratio"}},{"id":"hole-to-bend-distance","kind":"rule","tier":1,"title":"Hole-to-bend-line minimum distance","summary":"Keep every hole or cut feature at least 2.5x material thickness plus the bend radius away from a bend centreline (>= half the V-die width, per SCS/OSH Cut), or the feature distorts as the sheet stretches through the bend.","applies":["bracket","chassis"],"value":{"min":2.5,"unit":"ratio"},"basis":"SendCutSend: \"keep cut features at least 1/2 the die width away from the centerline of each bend\"; expressed against thickness and radius as the generic die-independent floor","sources":["sendcutsend-bending"],"tags":["hole to bend","die keepout"],"check":{"process":"scs_bend","rule":"hole_to_bend"}},{"id":"hole-to-edge-distance-sheet","kind":"rule","tier":2,"title":"Hole-to-edge minimum distance (sheet metal)","summary":"Keep every punched or laser-cut hole centre at least 2x material thickness from the sheet edge, so the remaining web does not tear out under load or during forming.","applies":["sheet metal","bracket","panel"],"value":{"min":2,"unit":"ratio"},"basis":"Standard sheet-metal punch/laser edge-distance guidance, matched by SCS's own web/spacing recommendations","sources":["sendcutsend-sheet-cutting","protolabs-sheet-metal"],"tags":["hole to edge","edge distance"]},{"id":"min-punch-hole-diameter","kind":"rule","tier":1,"title":"Minimum punched/laser hole diameter (>= 1x thickness)","summary":"A punched hole diameter must be at least equal to the material thickness (die-shear floor) — a smaller punch shears and tears the sheet instead of cleanly cutting; laser-cut holes relax this to 0.5x thickness on some vendor lasers.","applies":["sheet metal","punch","laser cut"],"value":{"min":1,"unit":"ratio"},"basis":"ops/dfmRules.js sheet_metal pack: min_hole_diameter = 1x material thickness; SCS laser publishes 0.5x thickness for their fiber laser specifically","sources":["sendcutsend-sheet-cutting"],"tags":["hole diameter","punch","laser"],"check":{"process":"sheet_metal","rule":"min_hole_diameter"}},{"id":"laser-kerf-width","kind":"dimension","tier":1,"title":"Laser kerf width","summary":"A fiber-laser kerf (the width of material removed by the beam) runs 0.1-0.3mm depending on thickness and material; the minimum internal corner radius and minimum cuttable feature both scale off this number.","applies":["laser cut","sheet metal"],"value":{"min":0.1,"max":0.3,"unit":"mm"},"basis":"Fiber laser kerf published across sheet-cutting vendor guidelines; the beam cannot turn inside its own kerf so a sharper corner comes back rounded at ~kerf radius","sources":["sendcutsend-sheet-cutting"],"tags":["kerf","laser","tolerance"],"check":{"process":"scs_laser","rule":"min_internal_corner_radius"}},{"id":"min-feature-size-laser-cut","kind":"rule","tier":2,"title":"Minimum cuttable feature size on laser-cut sheet (>= 1x thickness)","summary":"A slot, tab or thin web cut into sheet by laser should be at least 1x material thickness wide — thinner features warp from cutting heat or fall out of the sheet before the part is fully cut free.","applies":["sheet metal","laser cut"],"value":{"min":1,"unit":"ratio"},"basis":"Standard laser-cutting minimum-feature guidance; matches the sheet_metal pack's min_wall_thickness floor","sources":["sendcutsend-sheet-cutting"],"tags":["minimum feature","laser","slot"],"check":{"process":"sheet_metal","rule":"min_wall_thickness"}},{"id":"tab-notch-minimum-width","kind":"rule","tier":2,"title":"Tab and notch minimum width (>= 1.5x thickness)","summary":"A tab (for a slot-and-tab joint) or a notch cut into a sheet-metal edge should be at least 1.5x material thickness wide, or it bends or shears off during handling and assembly rather than locating the part.","applies":["sheet metal","tab and slot","assembly"],"value":{"min":1.5,"unit":"ratio"},"basis":"Standard sheet-metal tab/notch design guidance for slot-and-tab self-fixturing assemblies","sources":["protolabs-sheet-metal"],"tags":["tab","notch","slot and tab"]},{"id":"corner-relief-dogbone-sheet","kind":"feature","tier":1,"title":"Corner relief (dogbone/T-bone) for CNC-routed sheet","summary":"A square internal corner cannot be CNC-routed by a round bit; add a 3.175mm dogbone (one bit-radius circle on the bisector) or T-bone relief so a square mating part still seats — cad_corner_relief models this, never fillet the corner.","applies":["cnc router","sheet metal","enclosure"],"value":{"typical":3.175,"unit":"mm"},"basis":"SendCutSend/OSH Cut router guidance: \"standard chamfers and fillets don't solve this; dogbones do\" — filleting a router corner adds material where there is already too much","sources":["sendcutsend-sheet-cutting"],"tags":["corner relief","dogbone","tbone","router"]},{"id":"rack-19-inch-width","kind":"dimension","tier":1,"title":"19-inch rack panel width (EIA-310)","summary":"A 19-inch rack panel is 482.6mm (19.00in) wide overall, with the mounting-hole centres 465.1mm (18.31in) apart — the panel is wider than the hole spacing by the ear width on each side.","applies":["19 inch rack","rack ear","rack panel"],"value":{"value":482.6,"unit":"mm"},"basis":"EIA-310-E standard rack width, reproduced across every 19-inch rack mechanical reference","sources":["eia-310e"],"tags":["rack","eia-310","19 inch","width"]},{"id":"rack-unit-height-1u","kind":"dimension","tier":1,"title":"Rack unit (1U) height","summary":"One rack unit (1U) is 44.45mm (1.75in) tall; panel heights are specified in whole U (1U, 2U, 3U...) and a panel's actual height is slightly under nU to clear the rail (e.g. 1U panel is typically 44.20mm).","applies":["19 inch rack","rack panel","rack ear"],"value":{"value":44.45,"unit":"mm"},"basis":"EIA-310-E defines 1U = 1.75in; three rack-unit hole groups repeat every 44.45mm","sources":["eia-310e"],"tags":["rack","1u","eia-310","unit height"]},{"id":"rack-mounting-hole-pattern","kind":"dimension","tier":1,"title":"Rack mounting hole spacing (6.35/15.88/15.88mm repeat)","summary":"Within each 44.45mm (1U) rack-rail hole group there are three holes spaced 6.35mm (0.25in), 15.88mm (0.625in), 15.88mm (0.625in) apart, repeating every U; hole centres sit 465.1mm apart across the rack width.","applies":["19 inch rack","rack ear"],"value":{"table":[{"gap1":6.35,"gap2":15.88,"gap3":15.88}],"unit":"mm"},"basis":"EIA-310-E universal hole spacing pattern for rack rails","sources":["eia-310e"],"tags":["rack","hole pattern","eia-310"]},{"id":"material-thickness-stock-range","kind":"rule","tier":1,"title":"Material thickness must fall in the vendor's stocked range","summary":"A sheet-metal design's thickness must land inside the shop's stocked range (SCS bending 0.030-0.250in / 0.76-6.35mm; OSH Cut laser 0.02-1.0in depending on material) — an unstocked thickness is refused, not approximated to the nearest stocked gauge.","applies":["sheet metal","laser cut","press brake"],"value":{"min":0.76,"max":6.35,"unit":"mm"},"basis":"SendCutSend CNC bending stocks 0.030-0.250in material; thicker or thinner stock is not on their bending line","sources":["sendcutsend-bending","oshcut-minmax"],"tags":["material thickness","stock range"],"check":{"process":"scs_bend","rule":"material_thickness"}},{"id":"part-envelope-sheet-laser","kind":"rule","tier":1,"title":"Sheet part envelope (minimum and maximum flat size)","summary":"A flat laser-cut part must be at least ~0.1in (2.5mm) and no larger than the vendor's sheet: OSH Cut sheets to 119in x 47in (3023 x 1194mm), SendCutSend bending flats 0.375in x 1.5in minimum up to 30in x 44in maximum.","applies":["sheet metal","laser cut","flat pattern"],"value":{"min":2.5,"max":3023,"unit":"mm"},"basis":"OSH Cut/SendCutSend published sheet and flat-blank size limits","sources":["oshcut-minmax","sendcutsend-minmax"],"tags":["part envelope","sheet size"],"check":{"process":"oshcut_laser","rule":"part_envelope"}},{"id":"min-internal-corner-radius-sheet","kind":"rule","tier":1,"title":"Minimum internal corner radius, cut sheet","summary":"An internal (concave) corner cut into flat sheet should carry a radius of at least 0.5x material thickness — sharper corners are the notch a formed part cracks from, and on a router route a truly square corner is not cuttable at all without a relief.","applies":["sheet metal","laser cut","bracket"],"value":{"min":0.5,"unit":"ratio"},"basis":"ops/dfmRules.js sheet_metal / oshcut_laser: min_internal_corner_radius = 0.5x material thickness","sources":["sendcutsend-sheet-cutting","oshcut-capabilities"],"tags":["internal corner","radius","stress riser"],"check":{"process":"sheet_metal","rule":"min_internal_corner_radius"}},{"id":"hem-types-open-closed-teardrop","kind":"feature","tier":2,"title":"Hem types: open, closed, teardrop","summary":"An open hem (180deg fold, gap left) needs a minimum inside diameter of one material thickness; a closed hem folds flat against itself; a teardrop hem leaves a small rolled gap for a wire or panel edge to hook into — all measured at the fold, not the free edge.","applies":["sheet metal","edge finish","safety edge"],"value":{"min":1,"unit":"ratio"},"basis":"Standard sheet-metal hemming practice: minimum inside radius before the tooling crushes the fold flat","sources":["protolabs-sheet-metal","sendcutsend-bending"],"tags":["hem","open hem","closed hem","teardrop hem"]},{"id":"curl-feature-sheet","kind":"feature","tier":2,"title":"Curl (rolled edge)","summary":"A curl rolls a sheet-metal edge into a partial or full circle (e.g. a hinge knuckle or a safety edge) with inside radius typically 1-3x material thickness; tighter curls need progressive tooling rather than a single press-brake pass.","applies":["sheet metal","hinge","edge finish"],"value":{"min":1,"max":3,"unit":"ratio"},"basis":"Standard sheet-metal curling practice for hinge knuckles and rolled safety edges","sources":["protolabs-sheet-metal"],"tags":["curl","rolled edge","hinge"]},{"id":"louver-dimensions","kind":"feature","tier":2,"title":"Louver minimum height and spacing","summary":"A stamped/formed ventilation louver needs a minimum formed height of 1.5x material thickness to open enough airflow area, with louvers spaced at least their own height apart so the press-brake or stamping die does not collide between adjacent forms.","applies":["ventilation","enclosure","louver"],"value":{"min":1.5,"unit":"ratio"},"basis":"Standard sheet-metal louver forming guidance: formed lip height and die-to-die spacing on a progressive louver punch","sources":["protolabs-sheet-metal"],"tags":["louver","ventilation","spacing"]},{"id":"emboss-dimensions-sheet","kind":"feature","tier":2,"title":"Emboss depth and radius","summary":"A stiffening emboss (raised bead) in sheet should use a depth no more than 3-4x material thickness with a radius at least equal to thickness at the transition, or the sheet thins excessively at the corner of the emboss and cracks.","applies":["sheet metal","stiffening bead","panel"],"value":{"max":4,"unit":"ratio"},"basis":"Standard sheet-metal embossing/bead-forming guidance limiting local thinning at the bead radius","sources":["protolabs-sheet-metal"],"tags":["emboss","bead","stiffening"]},{"id":"countersink-max-depth-sheet","kind":"rule","tier":2,"title":"Countersink maximum depth in thin sheet (<= 0.6x thickness)","summary":"A countersink formed or cut into sheet metal should not exceed about 0.6x material thickness deep, or the remaining wall under the countersink is too thin to hold the fastener head without dishing or punching through.","applies":["sheet metal","countersink","fastener"],"value":{"max":0.6,"unit":"ratio"},"basis":"Standard sheet-metal countersink guidance: a countersink deeper than ~60% of thickness leaves an unsupported thin annulus","sources":["protolabs-sheet-metal"],"tags":["countersink","fastener","depth"]},{"id":"spot-weld-flange-width","kind":"rule","tier":2,"title":"Spot-weld flange width (>= 3x thickness + 8mm)","summary":"A flange intended for resistance spot welding needs a minimum width of about 3x material thickness plus 8mm, to clear the weld nugget and electrode tip without the flange edge distorting or the nugget breaking through to the free edge.","applies":["spot weld","weldment","sheet metal assembly"],"value":{"min":8,"unit":"mm"},"basis":"Standard resistance-spot-welding flange-width guidance for sheet-metal weldments","sources":["protolabs-sheet-metal"],"tags":["spot weld","flange","weldment"]},{"id":"rivet-flange-width-sheet","kind":"fastener","tier":2,"title":"Rivet flange width and hole size","summary":"A pop-rivet flange needs a hole ~0.1mm over the rivet shank (1/8in shank -> 3.3mm hole) and enough flange width either side of the hole (>= 2x hole diameter to the edge) to keep the rivet from tearing out under shear.","applies":["pop rivet","seam","sheet metal assembly"],"basis":"Industrial blind-rivet hole-size chart and standard edge-distance practice for riveted seams","sources":["pem-catalog"],"tags":["rivet","flange","seam"],"see":["hardware/pop-rivet-hole-sizes"],"value":{"min":2,"unit":"ratio"}},{"id":"pem-standoff-hole-sheet","kind":"fastener","tier":2,"title":"PEM self-clinching standoff/nut hole sizing","summary":"A self-clinching PEM nut or standoff needs a punched hole sized to its own series (e.g. CLS M4 = 5.41mm) and a minimum sheet thickness of roughly 1.5x the fastener's pitch diameter, or the sheet cannot resist the fastener pushing out under torque or shear.","applies":["pem","standoff","self-clinching nut","chassis"],"basis":"PEM (Penn Engineering) self-clinching fastener installation specification, CLS series","sources":["pem-catalog"],"tags":["pem","standoff","self-clinching"],"see":["hardware/pem-self-clinching-nut-holes"],"value":{"min":1.5,"unit":"ratio"}},{"id":"powder-coat-thickness-allowance","kind":"tolerance","tier":2,"title":"Powder-coat build-up allowance (60-120 microns per side)","summary":"Powder coat adds 60-120 micrometres of finish per side (2-4 mils) — mating features, press-fit holes and thread clearances must be sized before coating to still fit after, or masked during coating.","applies":["powder coat","finish","enclosure"],"value":{"min":60,"max":120,"unit":"um"},"basis":"Typical powder-coat dry-film-thickness range for a single coat on fabricated sheet metal","sources":["protolabs-sheet-metal"],"tags":["powder coat","finish","tolerance"]},{"id":"masked-threads-powder-coat","kind":"process","tier":2,"title":"Masking threaded holes and mating faces before powder coat","summary":"Tapped holes, PEM hardware and any face that must stay flat or conductive (ground straps, bus-bar contacts) are masked with silicone plugs or tape before powder coating, then unmasked — an unmasked M4 thread gains 60-120um of coating per side and will not accept the mating screw.","applies":["powder coat","threaded hole","grounding"],"basis":"Standard powder-coat shop practice for threaded and electrically-conductive features","sources":["protolabs-sheet-metal"],"tags":["masking","powder coat","thread"]},{"id":"galvanised-vs-stainless-corrosion","kind":"material","tier":2,"title":"Galvanised steel (G90) vs stainless for corrosion resistance","summary":"Hot-dip galvanised G90 carries 0.90 oz/sq ft zinc per side (~23um) and resists corrosion sacrificially — cheaper than stainless, but the coating is consumed at cut edges and welds; 304/316 resist through the bulk at 2-3x the cost.","applies":["outdoor enclosure","corrosion resistance","chassis"],"value":{"value":23,"unit":"um"},"basis":"ASTM A653 G90 coating designation (0.90 oz/ft2 total both sides, hot-dip galvanised sheet)","sources":["matweb-sheet-alloys"],"tags":["galvanised","g90","stainless","corrosion"]},{"id":"flat-pattern-export-note","kind":"process","tier":2,"title":"Flat-pattern export for shop quoting (contour DXF)","summary":"Export a folded sheet-metal body as flat-dxf (cad_export_body format 1 of 4 layers) — OUTLINE, BEND_UP/BEND_DOWN centrelines, TANGENT keepouts and a TEXT bend schedule — the file a laser-plus-brake shop quotes from.","applies":["flat pattern","dxf export","quoting"],"basis":"NativeCAD sheet_fold/sheet_box report a developed flatPattern alongside the solid; flat-dxf is the format vendors like SendCutSend/OSH Cut accept","sources":["sendcutsend-sheet-cutting","oshcut-capabilities"],"tags":["flat pattern","dxf","export"]},{"id":"tolerance-laser-cut-profile","kind":"tolerance","tier":2,"title":"Laser-cut profile tolerance (+/-0.1mm)","summary":"A fiber-laser-cut sheet-metal profile holds about +/-0.1mm (+/-0.005in) on cut features under typical shop tolerances; thermal expansion on long thin parts (especially aluminium) can widen this on the longest dimension.","applies":["laser cut","sheet metal","tolerance"],"value":{"value":0.1,"unit":"mm"},"basis":"OSH Cut/SendCutSend published laser-cut profile tolerance","sources":["oshcut-capabilities","sendcutsend-sheet-cutting"],"tags":["tolerance","laser cut"]},{"id":"tolerance-bend-angle","kind":"tolerance","tier":2,"title":"Press-brake bend angle tolerance (+/-0.5deg to +/-1deg)","summary":"A single press-brake bend holds about +/-0.5 to +/-1 degree of angular tolerance on bends up to roughly 600mm (24in) long; longer bends or thin/springy material (polycarbonate, stainless) widen the achievable tolerance.","applies":["press brake","bend","tolerance"],"value":{"min":0.5,"max":1,"unit":"deg"},"basis":"SendCutSend published angular bend tolerance (+/-1deg on bends up to 24in)","sources":["sendcutsend-bending"],"tags":["tolerance","bend angle","press brake"]},{"id":"tolerance-bend-to-edge","kind":"tolerance","tier":2,"title":"Bend-to-edge tolerance (+/-0.25mm)","summary":"The distance from a bend line to a cut edge or feature holds about +/-0.25mm (+/-0.015in) after forming — springback and sheet slip in the brake are the dominant error sources, not the original laser-cut accuracy.","applies":["press brake","bend","tolerance"],"value":{"value":0.25,"unit":"mm"},"basis":"SendCutSend published bend-to-edge tolerance (+/-0.015in / 0.381mm, here rounded to the commonly quoted 0.25mm shop figure)","sources":["sendcutsend-bending"],"tags":["tolerance","bend to edge"]},{"id":"din-43880-module-widths","kind":"dimension","tier":2,"title":"DIN 43880 module widths (17.5mm and multiples)","summary":"DIN 43880 modular devices (breakers, terminal blocks) on TH35 DIN rail are sized in module widths of 17.5mm (a full module) or 18mm depending on manufacturer convention; an enclosure sized for N modules needs an internal width of N x 17.5mm plus end-clamp clearance.","applies":["din rail","enclosure","electrical panel"],"value":{"value":17.5,"unit":"mm"},"basis":"DIN 43880 modular device width standard for low-voltage switchgear on TH35 rail","sources":["din-43880"],"tags":["din 43880","module width","din rail"]},{"id":"nema-ip-enclosure-ratings","kind":"standard","tier":2,"title":"NEMA 1/3R/4/4X/12 vs IP enclosure rating conventions","summary":"NEMA 1 (indoor) < NEMA 12 (dust/dripping) < NEMA 3R (rain/sleet) < NEMA 4 (hosedown) < NEMA 4X (plus corrosion resistance); NEMA is a North American test rating, IP (IEC 60529) a numeric code — NEMA 4 maps loosely to IP66, not interchangeably.","applies":["enclosure","outdoor equipment","electrical panel"],"basis":"NEMA 250 enclosure type definitions vs IEC 60529 IP code — different test regimes producing loosely comparable outcomes","sources":["nema-250","iec-60529"],"tags":["nema","ip rating","enclosure","ingress"]},{"id":"rack-ear-thickness","kind":"dimension","tier":2,"title":"Rack ear (rack mount flange) thickness","summary":"A 19-inch rack-mount ear is typically 2-3mm thick sheet steel or aluminium — thinner ears flex under the mounting screws and misalign the rack-hole pattern; 2mm is common for light equipment, 3mm for heavier chassis.","applies":["rack ear","19 inch rack","chassis"],"value":{"min":2,"max":3,"unit":"mm"},"basis":"Common commercial rack-ear gauge across 1U-4U equipment","sources":["eia-310e"],"tags":["rack ear","thickness","rack mount"]},{"id":"rack-rail-hole-pattern","kind":"dimension","tier":2,"title":"Rack rail hole pattern: 7.1mm square or M6 tapped","summary":"A rack rail's mounting hole is either a 7.1mm (0.28in) square hole (for a cage nut) or an M6 tapped hole directly — the same 465.1mm horizontal spacing and 3-hole-per-U vertical group applies to both conventions.","applies":["rack rail","19 inch rack","cage nut"],"value":{"value":7.1,"unit":"mm"},"basis":"EIA-310-E universal square-hole rack rail convention, alongside the common M6-tapped-rail variant","sources":["eia-310e"],"tags":["rack rail","square hole","m6","cage nut"]},{"id":"slot-orientation-forming","kind":"rule","tier":2,"title":"Slot orientation relative to a bend line","summary":"Cut a slot so its long axis runs perpendicular (90deg) to an adjacent bend line, not parallel — a slot parallel to and close to a bend concentrates strain and is far more likely to crack when the flange forms.","applies":["sheet metal","slot","bend"],"basis":"Standard press-brake design guidance on slot orientation relative to grain direction and bend lines","sources":["protolabs-sheet-metal"],"tags":["slot","orientation","bend"]},{"id":"crs-1008-1010-sheet","kind":"material","tier":2,"title":"Cold-rolled steel CRS 1008/1010 (sheet stock)","summary":"CRS 1008/1010: 7.87 g/cm3, yield ~180-280MPa, UTS ~300-365MPa — the default cheap, weldable, formable sheet-metal steel for brackets and enclosures where corrosion resistance is handled by paint or plating.","applies":["sheet metal","bracket","enclosure","weldment"],"value":{"table":[{"density":7.87,"yield":220,"uts":330,"elongPct":32,"costClass":1}]},"basis":"MatWeb 1008/1010 cold-rolled sheet datasheet; SAE J403 low-carbon composition","sources":["matweb-sheet-alloys"],"tags":["steel","1008","1010","cold rolled"]},{"id":"hrpo-steel-sheet","kind":"material","tier":2,"title":"Hot-rolled pickled and oiled steel (HRPO)","summary":"HRPO: hot-rolled steel that has been acid-pickled to remove mill scale and lightly oiled to prevent rust in transit — cheaper than cold-rolled for thicker gauges (>= 11ga / 3mm) where CRS surface finish is not required, common for heavier structural brackets.","applies":["structural bracket","heavy gauge","weldment"],"basis":"Standard steel-service-centre product description for HRPO sheet/plate stock","sources":["matweb-sheet-alloys"],"tags":["steel","hrpo","hot rolled"]},{"id":"galvanised-g90-sheet","kind":"material","tier":2,"title":"Galvanised steel G90 (sheet)","summary":"G90 hot-dip galvanised steel: CRS base with 0.90 oz/sq ft total zinc coating (~23 microns), giving corrosion resistance for outdoor/damp enclosures at a fraction of stainless cost; welds and cut edges lose the coating and need cold-galv touch-up.","applies":["outdoor enclosure","hvac","corrosion resistance"],"value":{"table":[{"density":7.87,"coatingUm":23,"costClass":1}]},"basis":"ASTM A653 G90 designation for hot-dip galvanised sheet steel","sources":["matweb-sheet-alloys"],"tags":["steel","galvanised","g90","corrosion"]},{"id":"al-5052-h32-sheet-see","kind":"material","tier":2,"title":"Aluminium 5052-H32 for sheet-metal forming","summary":"5052-H32: 2.68 g/cm3, yield 193MPa, UTS 228MPa — the standard sheet-metal aluminium alloy, chosen over 6061 for forming because it bends to a tighter radius (1x thickness vs 1.5-2x) without cracking.","applies":["sheet metal","bracket","enclosure"],"basis":"MatWeb 5052-H32 datasheet; the alloy vendors stock specifically for its forming ductility","sources":["matweb-sheet-alloys"],"tags":["aluminum","5052","sheet metal"],"see":["materials/al-5052-h32"]},{"id":"ss-304-2b-sheet","kind":"material","tier":2,"title":"Stainless steel 304, 2B finish (sheet)","summary":"304 stainless in 2B (cold-rolled, bright, mill) finish: 8.00 g/cm3, yield 215MPa, UTS 505MPa — the standard corrosion-resistant, food-safe and washdown sheet-metal stainless, at 0.5-1x thickness minimum bend radius.","applies":["food equipment","washdown enclosure","chassis"],"basis":"MatWeb 304 annealed datasheet; 2B is the standard commercial sheet mill finish","sources":["matweb-sheet-alloys"],"tags":["stainless","304","2b finish"],"see":["materials/ss-304"]},{"id":"test-ik-impact-sheet-enclosure","kind":"test","tier":2,"title":"IK mechanical impact rating (IEC 62262) for a sheet enclosure","summary":"IK07 (2J) is a common minimum for indoor sheet enclosures, IK10 (20J) for public/outdoor gear — a steel hammer dropped on the face; geometry response is thicker gauge or a rib/emboss behind the impact zone, since a flat panel dents below IK08.","applies":["outdoor enclosure","public-space equipment","rack panel"],"value":{"min":2,"max":20,"unit":"Nm"},"basis":"IEC 62262 IK code, impact energy by rating","sources":["iec-62262"],"tags":["ik rating","impact test","enclosure"]},{"id":"test-ip-ingress-sheet-enclosure","kind":"test","tier":2,"title":"IP ingress rating test (IEC 60529) for a sheet enclosure","summary":"IP54 (dust-protected, splash-protected) is a common indoor minimum; IP65/IP66 (dust-tight, jet-protected) needs gasketed seams and cable glands — the geometry demand is a continuous gasket groove/flange at every seam and penetration.","applies":["enclosure","outdoor equipment","gasketed lid"],"basis":"IEC 60529 IP code test methodology (dust chamber, water jet/immersion by digit)","sources":["iec-60529"],"tags":["ip rating","ingress","gasket"]},{"id":"test-rack-ear-load-deflection","kind":"test","tier":2,"title":"Rack-ear / shelf load-deflection test","summary":"A 1U rack shelf loaded to 20kg at mid-span should deflect no more than about 2mm to avoid visible sag and connector strain at the rear of mounted equipment — tested as a static load on the front rack ears with the rear unsupported, the worst case for a cantilevered shelf.","applies":["rack shelf","rack ear","structural"],"value":{"value":2,"unit":"mm"},"basis":"Common commercial rack-shelf load-deflection acceptance figure (20kg static load, <=2mm sag) used across server/AV rack-shelf datasheets","sources":["eia-310e"],"tags":["load test","deflection","rack shelf"]},{"id":"standard-eia-310","kind":"standard","tier":2,"title":"EIA-310-E: 19-inch rack cabinets and panels","summary":"EIA-310-E defines the 19-inch rack system: 482.6mm panel width, 465.1mm hole spacing, 44.45mm rack unit (1U), and the 6.35/15.88/15.88mm three-hole vertical repeat — every 19-inch rack ear, shelf and blank panel dimension in this pack derives from it.","applies":["19 inch rack","rack panel","rack ear"],"basis":"ANSI/EIA-310-E Cabinets, Racks, Panels, and Associated Equipment","sources":["eia-310e"],"tags":["standard","eia-310","rack"]},{"id":"standard-nema-250","kind":"standard","tier":2,"title":"NEMA 250: enclosure type ratings","summary":"NEMA 250 defines NEMA 1/3R/4/4X/12 enclosure ratings by a North American test regime (rain, hose, dust, corrosion, ice), distinct from IEC 60529's IP code — used wherever a UL/NEMA-listed enclosure is specified over an IP-rated one.","applies":["enclosure","electrical panel","outdoor equipment"],"basis":"NEMA 250 Enclosures for Electrical Equipment (1000 Volts Maximum)","sources":["nema-250"],"tags":["standard","nema 250","enclosure rating"]},{"id":"recipe-1u-rack-ear","kind":"recipe","tier":2,"title":"Recipe: 1U rack ear with EIA-310 mounting slots","summary":"Build a 44.45mm (1U) tall, 2mm-thick rack ear as a folded sheet-metal L-bracket via cad_sheet_fold: a 25mm front mounting flange over a 90-degree R2 bend into a 20mm side flange running the full 1U height.","applies":["rack ear","1u rack","19 inch rack"],"basis":"Combines rack-19-inch-width, rack-unit-height-1u, rack-mounting-hole-pattern and rack-ear-thickness into one buildable part","sources":["eia-310e"],"tags":["recipe","rack ear","1u"],"recipe":{"prompt":"Model a 1U rack ear: 44.45mm tall, 2mm thick, folded 90 degrees with a 25mm mounting flange and a 20mm side flange","steps":[{"tool":"cad_sheet_fold","args":{"thickness":2,"width":44.45,"baseFlange":25,"bends":[{"angle":90,"radius":2,"flange":20}]},"note":"L-shaped rack-ear profile: 25mm front mounting flange, 90deg fold over R2, 20mm side flange, extruded 44.45mm (1U) along the bend line — EIA-310 mounting holes/slots would be a follow-up cad_drill_hole/cad_pad pass on the folded face"}],"expect":{"volume":4419.43,"faceCount":10,"watertight":true,"note":"measured 2026-09-19: agrees with the kernel on the CADSF-1630 corpus sweep — volume inside the 0.5% band and faceCount exact"}}},{"id":"recipe-u-bracket-two-bends","kind":"recipe","tier":2,"title":"Recipe: U-bracket with two bends and mounting holes","summary":"Build a 2mm-thick U-bracket (channel) 40mm wide: 30mm base flange, two 90-degree bends over R2 into 25mm side walls, using cad_sheet_fold — base flange doubles the side-flange length per SendCutSend's U-channel guidance (base >= 2x flange).","applies":["u-bracket","channel","bracket"],"basis":"Combines inside-bend-radius-soft-metals, min-flange-length and bend-relief-dimensions into one folded channel","sources":["sendcutsend-bending"],"tags":["recipe","u-bracket","channel"],"recipe":{"prompt":"Model a U-bracket: 2mm steel, 40mm wide, 30mm base with two 90 degree bends over R2 into 25mm side walls","steps":[{"tool":"cad_sheet_fold","args":{"thickness":2,"width":40,"baseFlange":25,"bends":[{"angle":90,"radius":2,"flange":30},{"angle":-90,"radius":2,"flange":25}]},"note":"left wall (25mm) as the starting flange, +90 bend into the 30mm base, -90 bend back into the right wall (25mm) — a symmetric U-channel"}],"expect":{"volume":7153.98,"faceCount":14,"watertight":true,"note":"measured 2026-09-19: agrees with the kernel on the CADSF-1630 corpus sweep — volume inside the 0.5% band and faceCount exact"}}},{"id":"recipe-folded-enclosure-base","kind":"recipe","tier":2,"title":"Recipe: folded enclosure base with corner relief","summary":"Build a 200x120mm sheet-metal enclosure base, 1.5mm thick, with 40mm walls folded up on all four sides (cad_sheet_box) and a 10mm inward lip on the north/south walls, corner-notched automatically by the box verb.","applies":["enclosure","chassis","tray"],"basis":"Combines sheet-gauge-thickness-table, inside-bend-radius-soft-metals and corner-relief-dogbone-sheet into one folded chassis","sources":["sendcutsend-bending"],"tags":["recipe","enclosure","chassis","sheet box"],"recipe":{"prompt":"Model a folded sheet-metal enclosure base: 200x120mm, 1.5mm thick, 40mm walls on all four sides with a 10mm inward lip on north and south","steps":[{"tool":"cad_sheet_box","args":{"thickness":1.5,"base":{"length":200,"width":120},"flanges":{"n":{"bends":[{"angle":90,"radius":2,"flange":40},{"angle":90,"radius":2,"flange":10,"notch":{"gap":10.5}}]},"s":{"bends":[{"angle":90,"radius":2,"flange":40},{"angle":90,"radius":2,"flange":10,"notch":{"gap":10.5}}]},"e":{"bends":[{"angle":90,"radius":2,"flange":40},{"angle":90,"radius":2,"flange":10}]},"w":{"bends":[{"angle":90,"radius":2,"flange":40},{"angle":90,"radius":2,"flange":10}]}},"notch":{"gap":0}},"note":"chassis base with inward lips on all four walls; N/S lips notched to clear the E/W lips' reach"}],"expect":{"volume":91391.66,"faceCount":54,"watertight":true,"note":"measured 2026-09-19: agrees with the kernel on the CADSF-1630 corpus sweep — volume inside the 0.5% band and faceCount exact"}}}]}