{"$schema":"nativecad-dfm-pack/1","id":"hardware","title":"Hardware — fasteners, threads, holes, inserts, pins","sector":"hardware","version":"2026-09-12","summary":"Cross-sector fastener facts every product pack points at: metric clearance and tap-drill sizes, counterbores and countersinks, thread engagement, inserts, dowels, retaining-ring grooves, edge distances.","aliases":["fastener","fasteners","screw","screws","bolt","bolts","thread","threads","tap","clearance hole","counterbore","countersink","insert","dowel","circlip","rivet","rivnut","pem","helicoil","standoff","t-nut","shoulder bolt","set screw","dowel pin","roll pin"],"crossSector":true,"size":"full","sources":[{"id":"iso-273","title":"ISO 273:1979 Fasteners — Clearance holes for bolts and screws","url":"https://www.iso.org/standard/4183.html","accessed":"2026-09-03"},{"id":"iso-4762","title":"ISO 4762:2004 Hexagon socket head cap screws (head dimensions)","url":"https://www.iso.org/standard/34460.html","accessed":"2026-09-03"},{"id":"iso-10642","title":"ISO 10642:2019 Hexagon socket countersunk head screws","url":"https://www.iso.org/standard/76437.html","accessed":"2026-09-03"},{"id":"iso-262","title":"ISO 262:1998 ISO general purpose metric screw threads — selected sizes (tap-drill = major − pitch)","url":"https://www.iso.org/standard/4167.html","accessed":"2026-09-03"},{"id":"iso-8734","title":"ISO 8734:1997 Parallel pins of hardened steel (dowel pins, m6)","url":"https://www.iso.org/standard/16151.html","accessed":"2026-09-03"},{"id":"din-471","title":"DIN 471 Retaining rings for shafts (groove dimensions)","url":"https://www.din.de/","accessed":"2026-09-03"},{"id":"iso-4032","title":"ISO 4032:2012 Hexagon regular nuts, style 1 (across-flats)","url":"https://www.iso.org/standard/56617.html","accessed":"2026-09-03"},{"id":"protolabs-threads","title":"Protolabs design tips — threaded holes, inserts and thread engagement","url":"https://www.protolabs.com/resources/design-tips/","accessed":"2026-09-03"},{"id":"cnc-cookbook-heatset","title":"Heat-set insert supplier data (McMaster-Carr 94180A series hole sizes)","url":"https://www.mcmaster.com/products/heat-set-inserts/","accessed":"2026-09-03"},{"id":"iso-7379","title":"ISO 7379:1983 Hexagon socket head shoulder screws"},{"id":"din-472","title":"DIN 472 Retaining rings for bores (internal circlips)"},{"id":"iso-8752","title":"ISO 8752:2009 Spring-type straight pins, slotted, heavy duty"},{"id":"asme-b18-8-2","title":"ASME B18.8.2 Taper pins, dowel pins, straight & spring pins, and grooved pins"},{"id":"asme-b1-1","title":"ASME B1.1 Unified inch screw threads (UN and UNR thread form) — UNF series"},{"id":"iso-4017","title":"ISO 4017:2014 Hexagon head screws — product grade A/B (AF across-flats)"},{"id":"iso-228-1","title":"ISO 228-1:2003 Pipe threads for non-pressure-tight joints (BSPP)"},{"id":"asme-b1-20-1","title":"ASME B1.20.1 Pipe Threads, General Purpose (NPT)"},{"id":"pem-catalog","title":"PEM self-clinching fastener installation specifications (Penn Engineering)"},{"id":"bollhoff-rivnut","title":"Bollhoff RIVKLE blind rivet nut installation data"},{"id":"helicoil-catalog","title":"Helicoil / Bollhoff wire thread insert (STI) tap-drill data"},{"id":"ejot-delta-pt","title":"EJOT Delta PT / thread-forming screw design guide for plastics"},{"id":"asme-b18-6-4","title":"ASME B18.6.4 Thread-forming and thread-cutting tapping screws and metallic drive screws"},{"id":"wood-screw-chart","title":"Wood-screw pilot-hole reference chart (gauge vs. hard/soft wood)"},{"id":"t-slot-8020","title":"80/20 Inc. T-slot aluminum extrusion catalog (10/15/20 series)"},{"id":"din-127","title":"DIN 127 Spring (lock) washers"},{"id":"asme-y14-5","title":"ASME Y14.5-2018 Dimensioning and Tolerancing (positional tolerance)"},{"id":"iso-898-1","title":"ISO 898-1 Mechanical properties of fasteners — property classes and tightening torque"}],"entries":[{"id":"clearance-holes-metric","kind":"fastener","tier":1,"title":"Metric clearance holes (ISO 273 fine / medium / coarse)","summary":"Clearance ⌀ medium series: M2 2.4, M2.5 2.9, M3 3.4, M4 4.5, M5 5.5, M6 6.6, M8 9.0, M10 11.0, M12 13.5 mm. Fine is ~0.2 mm tighter (M3 3.2, M6 6.4), coarse ~0.4 mm looser (M3 3.6, M6 7.0). Use medium unless told otherwise.","applies":[],"value":{"table":[{"size":"M2","fine":2.2,"medium":2.4,"coarse":2.6},{"size":"M2.5","fine":2.7,"medium":2.9,"coarse":3.1},{"size":"M3","fine":3.2,"medium":3.4,"coarse":3.6},{"size":"M4","fine":4.3,"medium":4.5,"coarse":4.8},{"size":"M5","fine":5.3,"medium":5.5,"coarse":5.8},{"size":"M6","fine":6.4,"medium":6.6,"coarse":7},{"size":"M8","fine":8.4,"medium":9,"coarse":10},{"size":"M10","fine":10.5,"medium":11,"coarse":12},{"size":"M12","fine":13,"medium":13.5,"coarse":14.5},{"size":"M16","fine":17,"medium":17.5,"coarse":18.5}],"unit":"mm"},"basis":"ISO 273 table; medium series is what cad_drill_hole type 'clearance' cuts","sources":["iso-273"],"tags":["clearance","hole","bolt","metric"]},{"id":"tap-drills-metric-coarse","kind":"fastener","tier":1,"title":"Tap-drill diameters, metric coarse","summary":"Tap drill = major − pitch: M2 1.6, M2.5 2.05, M3 2.5, M4 3.3, M5 4.2, M6 5.0, M8 6.8, M10 8.5, M12 10.2, M16 14.0 mm. Model a tapped hole as its tap-drill cylinder plus a callout; never model the helix.","applies":[],"value":{"table":[{"size":"M2","pitch":0.4,"tapDrill":1.6},{"size":"M2.5","pitch":0.45,"tapDrill":2.05},{"size":"M3","pitch":0.5,"tapDrill":2.5},{"size":"M4","pitch":0.7,"tapDrill":3.3},{"size":"M5","pitch":0.8,"tapDrill":4.2},{"size":"M6","pitch":1,"tapDrill":5},{"size":"M8","pitch":1.25,"tapDrill":6.8},{"size":"M10","pitch":1.5,"tapDrill":8.5},{"size":"M12","pitch":1.75,"tapDrill":10.2},{"size":"M16","pitch":2,"tapDrill":14}],"unit":"mm"},"basis":"ISO 262 coarse pitches; ~75 % thread engagement drill","sources":["iso-262"],"tags":["tap","thread","drill","metric"]},{"id":"counterbore-shcs-iso-4762","kind":"fastener","tier":1,"title":"Counterbore for socket head cap screws (ISO 4762)","summary":"Counterbore ⌀ / depth for SHCS (DIN 974-1, head flush): M3 6.5/3, M4 8/4, M5 10/5, M6 11/6, M8 15/8, M10 18/10, M12 20/12 mm — depth = head height k; add 0.5–1 mm if the head must sit below the surface. Through hole = medium clearance.","applies":[],"value":{"table":[{"size":"M3","headDia":5.5,"headHeight":3,"cboreDia":6.5,"cboreDepth":3},{"size":"M4","headDia":7,"headHeight":4,"cboreDia":8,"cboreDepth":4},{"size":"M5","headDia":8.5,"headHeight":5,"cboreDia":10,"cboreDepth":5},{"size":"M6","headDia":10,"headHeight":6,"cboreDia":11,"cboreDepth":6},{"size":"M8","headDia":13,"headHeight":8,"cboreDia":15,"cboreDepth":8},{"size":"M10","headDia":16,"headHeight":10,"cboreDia":18,"cboreDepth":10},{"size":"M12","headDia":18,"headHeight":12,"cboreDia":20,"cboreDepth":12}],"unit":"mm"},"basis":"ISO 4762 head dk/k with DIN 974-1 counterbore; the same table cad_drill_hole type 'counterbore' cuts (ops/holes.js)","sources":["iso-4762","iso-273"],"tags":["counterbore","shcs","cap screw"]},{"id":"countersink-iso-10642","kind":"fastener","tier":1,"title":"Countersink for flat-head socket screws (ISO 10642, 90°)","summary":"90° countersink, theoretical head ⌀ dk: M3 6.3, M4 8.4, M5 10.4, M6 12.6, M8 17.3, M10 20.0, M12 24.0 mm — what cad_drill_hole type 'countersink' cuts. Head height k: M3 1.9, M4 2.5, M5 3.1, M6 3.7, M8 5.0 mm; never countersink a wall thinner than k.","applies":[],"value":{"table":[{"size":"M3","dk":6.3,"k":1.86},{"size":"M4","dk":8.4,"k":2.48},{"size":"M5","dk":10.4,"k":3.1},{"size":"M6","dk":12.6,"k":3.72},{"size":"M8","dk":17.3,"k":4.96},{"size":"M10","dk":20,"k":6.2},{"size":"M12","dk":24,"k":7.44}],"unit":"mm"},"basis":"ISO 10642 theoretical dk and k at 90°; matches ops/holes.js CSK table","sources":["iso-10642"],"tags":["countersink","flat head","csk"]},{"id":"thread-engagement-by-material","kind":"rule","tier":1,"title":"Minimum thread engagement by tapped material","summary":"Tapped-hole depth as a multiple of the screw diameter: steel 1.0×d, cast iron/brass 1.5×d, aluminium 2.0×d, plastics 2.5–3.0×d (or use an insert). Add 2–3 pitches of tap-drill depth beyond the thread for a blind hole.","applies":[],"value":{"table":[{"material":"steel","engagement":1},{"material":"cast iron","engagement":1.5},{"material":"brass","engagement":1.5},{"material":"aluminium","engagement":2},{"material":"plastic","engagement":2.5}],"unit":"ratio","note":"× nominal diameter"},"basis":"Screw should fail before the internal thread strips. cad_fastener sizes a tapped joint's engagement from this table; cad_fastener_audit flags a shortfall as a floating-bolt finding.","sources":["protolabs-threads"],"tags":["thread","engagement","depth","tapped"]},{"id":"edge-distance-holes","kind":"rule","tier":1,"title":"Hole edge distance","summary":"Keep the hole centre ≥ 1.5×⌀ from any edge (≥ 2×⌀ for loaded bolts or sheet metal), and ≥ 2×⌀ between hole centres. Closer than this the ligament tears out or the punch/drill wanders.","applies":[],"value":{"min":1.5,"typical":2,"unit":"ratio","note":"centre-to-edge ÷ hole diameter"},"basis":"Ligament strength and tool wander; sheet-metal shops publish 2× as the floor. cad_fastener_audit does not check edge distance; it stays a design-time call (or the fastener rules' ≥1.5×d / ≥3×d rules of thumb, CADSF-1428).","sources":["protolabs-threads"],"tags":["edge distance","hole","spacing"]},{"id":"heat-set-inserts-metric","kind":"fastener","tier":1,"title":"Heat-set threaded inserts for plastic and 3D prints","summary":"Pilot hole ⌀ / min depth for brass heat-set inserts: M2 3.2/4.0, M2.5 3.6/5.0, M3 4.0/5.5, M4 5.6/7.5, M5 6.4/9.0, M6 8.0/12.0 mm. Boss OD ≥ 2× insert OD; for FDM print the hole 0.1–0.2 mm under and let the insert form it.","applies":["3d print","injection moulded housing"],"value":{"table":[{"size":"M2","holeDia":3.2,"depth":4,"insertOD":3.5},{"size":"M2.5","holeDia":3.6,"depth":5,"insertOD":4},{"size":"M3","holeDia":4,"depth":5.5,"insertOD":4.6},{"size":"M4","holeDia":5.6,"depth":7.5,"insertOD":6.3},{"size":"M5","holeDia":6.4,"depth":9,"insertOD":7.1},{"size":"M6","holeDia":8,"depth":12,"insertOD":8.7}],"unit":"mm"},"basis":"Supplier tapered-insert hole tables (McMaster 94180A); depth = insert length + 1 mm","sources":["cnc-cookbook-heatset"],"tags":["insert","heat-set","plastic","3d print","boss"]},{"id":"dowel-pin-holes","kind":"fastener","tier":1,"title":"Dowel pin holes (ISO 8734 m6 pins)","summary":"Press-fit side: ream to H7 in the part the pin lives in (⌀3 H7 = 3.000–3.010); slip side: F7 or a 0.02–0.05 mm oversize (⌀3.02). Sizes stocked: 2, 3, 4, 5, 6, 8, 10, 12 mm. Model as the nominal cylinder; the fit is a callout.","applies":["fixture","housing halves","mating plates"],"value":{"options":[2,3,4,5,6,8,10,12],"unit":"mm"},"basis":"ISO 8734 pins are m6 (+0.004/+0.012 on 3 mm); H7 hole gives a light press","sources":["iso-8734"],"tags":["dowel","pin","locating","fit"]},{"id":"nut-pocket-hex","kind":"fastener","tier":1,"title":"Hex nut pocket (captive nut) dimensions","summary":"ISO 4032 across-flats: M2 4, M2.5 5, M3 5.5, M4 7, M5 8, M6 10, M8 13, M10 16 mm; thickness M3 2.4, M4 3.2, M5 4.7, M6 5.2, M8 6.8 mm. Pocket = AF + 0.2 mm (0.3–0.4 for FDM), depth = thickness + 0.3 mm.","applies":["3d print","plastic housing","extrusion bracket"],"value":{"table":[{"size":"M2","af":4,"thick":1.6},{"size":"M2.5","af":5,"thick":2},{"size":"M3","af":5.5,"thick":2.4},{"size":"M4","af":7,"thick":3.2},{"size":"M5","af":8,"thick":4.7},{"size":"M6","af":10,"thick":5.2},{"size":"M8","af":13,"thick":6.8},{"size":"M10","af":16,"thick":8.4}],"unit":"mm"},"basis":"ISO 4032 style 1 s and m; clearance so the nut drops in","sources":["iso-4032"],"tags":["nut","pocket","captive","hex"]},{"id":"retaining-ring-groove-din-471","kind":"fastener","tier":1,"title":"Shaft retaining-ring groove (DIN 471)","summary":"Groove ⌀ / width for external circlips: shaft 6 → 5.7/0.8, 8 → 7.6/0.9, 10 → 9.6/1.1, 12 → 11.5/1.1, 15 → 14.3/1.1, 20 → 19.0/1.3, 25 → 23.9/1.3, 30 → 28.6/1.6 mm. The width is the ring's, not yours — do not snap it to a blade.","applies":["shaft","axle","pin"],"value":{"table":[{"shaft":6,"grooveDia":5.7,"width":0.8},{"shaft":8,"grooveDia":7.6,"width":0.9},{"shaft":10,"grooveDia":9.6,"width":1.1},{"shaft":12,"grooveDia":11.5,"width":1.1},{"shaft":15,"grooveDia":14.3,"width":1.1},{"shaft":20,"grooveDia":19,"width":1.3},{"shaft":25,"grooveDia":23.9,"width":1.3},{"shaft":30,"grooveDia":28.6,"width":1.6}],"unit":"mm"},"basis":"DIN 471 d2 and m; cad_shaft_groove cuts it","sources":["din-471"],"tags":["circlip","retaining ring","groove","shaft"]},{"id":"screw-boss-plastic","kind":"feature","tier":1,"title":"Self-tapping screw boss in moulded plastic","summary":"Boss OD = 2.0–2.5× screw ⌀, pilot hole = 0.8× thread OD (M3 thread-forming: ⌀2.5 hole, ⌀6.5–7 boss), depth ≥ 2× screw ⌀, boss wall ≤ 60 % of nominal wall at the root, 0.5° draft inside, 1 mm counterbore at the mouth to stop the top splitting.","applies":["injection moulded housing","consumer product"],"value":{"typical":2.25,"unit":"ratio","note":"boss OD ÷ screw diameter"},"basis":"Thread-forming screw supplier guidance; sink marks above 60 % wall","sources":["protolabs-threads"],"tags":["boss","screw","plastic","moulding"],"check":{"process":"injection_molding","rule":"max_rib_thickness_ratio"}},{"id":"bolt-torque-and-preload-classes","kind":"note","tier":2,"title":"Property classes and what they mean for the joint","summary":"Metric screws come 8.8 (structural default), 10.9, 12.9 (SHCS default); stainless A2-70 is ~8.8 strength. Design the clamped part so the bearing stress under the head/washer stays below yield — aluminium under an M6 12.9 needs a washer.","applies":[],"basis":"ISO 898-1 property classes; head bearing area vs part yield","sources":["protolabs-threads"],"tags":["torque","preload","class","washer"]},{"id":"washer-sizes-iso-7089","kind":"fastener","tier":1,"title":"Plain washer sizes (ISO 7089 normal series)","summary":"ID/OD/thickness: M3 3.2/7/0.5, M4 4.3/9/0.8, M5 5.3/10/1.0, M6 6.4/12/1.6, M8 8.4/16/1.6, M10 10.5/20/2.0, M12 13/24/2.5 mm. Counterbores meant to take a washer need the OD + 1 mm.","applies":[],"value":{"table":[{"size":"M3","id":3.2,"od":7,"t":0.5},{"size":"M4","id":4.3,"od":9,"t":0.8},{"size":"M5","id":5.3,"od":10,"t":1},{"size":"M6","id":6.4,"od":12,"t":1.6},{"size":"M8","id":8.4,"od":16,"t":1.6},{"size":"M10","id":10.5,"od":20,"t":2},{"size":"M12","id":13,"od":24,"t":2.5}],"unit":"mm"},"basis":"ISO 7089 normal series","sources":["iso-4032"],"tags":["washer"]},{"id":"unc-unf-tap-and-clearance","kind":"fastener","tier":1,"title":"Inch fasteners: UNC tap drills and clearance","summary":"UNC tap drill / close clearance: #4-40 0.089/0.116, #6-32 0.107/0.144, #8-32 0.136/0.172, #10-24 0.150/0.201, 1/4-20 0.201/0.257, 5/16-18 0.257/0.323, 3/8-16 0.313/0.386, 1/2-13 0.422/0.516 in. Published in inches; keep them in inches.","applies":["north america"],"value":{"table":[{"size":"#4-40","tapDrill":0.089,"clearance":0.116},{"size":"#6-32","tapDrill":0.107,"clearance":0.144},{"size":"#8-32","tapDrill":0.136,"clearance":0.172},{"size":"#10-24","tapDrill":0.15,"clearance":0.201},{"size":"1/4-20","tapDrill":0.201,"clearance":0.257},{"size":"5/16-18","tapDrill":0.257,"clearance":0.323},{"size":"3/8-16","tapDrill":0.313,"clearance":0.386},{"size":"1/2-13","tapDrill":0.422,"clearance":0.516}],"unit":"in"},"basis":"ASME B1.1 / B18.2.8 close-fit clearance","sources":["protolabs-threads"],"tags":["unc","inch","tap","clearance"]},{"id":"press-fit-pin-interference","kind":"tolerance","tier":2,"title":"Press-fit interference for steel pins in aluminium and steel","summary":"Light press (H7/m6, H7/n6): 0.005–0.02 mm interference on a 3–10 mm pin. In plastic use 0.05–0.1 mm and a lead-in chamfer. Model the hole at nominal and carry the fit as a tolerance callout.","applies":[],"value":{"min":0.005,"max":0.02,"unit":"mm"},"basis":"ISO 286 transition/interference fits for locating pins","sources":["iso-8734"],"tags":["press fit","interference","pin"]},{"id":"blind-hole-drill-point-allowance","kind":"rule","tier":1,"title":"Blind hole: drill-point and tap run-out allowance","summary":"A 118° drill leaves a cone 0.3×⌀ deep; a tap needs 2–3 pitches of unthreaded hole below the last full thread. So a blind M6 tapped 12 deep needs the tap drill 12 + 3 = 15 deep plus the 1.5 mm point — say 16.5 mm to the cone tip.","applies":[],"value":{"typical":0.3,"unit":"ratio","note":"drill-point depth ÷ diameter"},"basis":"118° point geometry; tap chamfer length","sources":["protolabs-threads"],"tags":["blind","drill point","tap","depth"]},{"id":"lead-in-chamfer","kind":"feature","tier":1,"title":"Lead-in chamfer on holes and pins","summary":"Put a 0.5 × 45° chamfer (0.3 on holes under ⌀3, 1.0 over ⌀12) at the mouth of every tapped or press-fit hole and on the end of every pin: it starts the tap square and guides the press. Cheap in every process.","applies":[],"value":{"min":0.3,"typical":0.5,"max":1,"unit":"mm"},"basis":"Tap start and pin alignment; deburr in the same operation","sources":["protolabs-threads"],"tags":["chamfer","lead-in","deburr"]},{"id":"slot-for-adjustment","kind":"feature","tier":2,"title":"Adjustment slot width and length","summary":"Slot width = clearance ⌀ (M6 → 6.6), length = 2–3× the width for ±5 mm of adjustment; add a washer under the head because a screw head bridging a slot bears on two thin lands.","applies":["bracket","mount"],"value":{"min":2,"max":3,"unit":"ratio","note":"slot length ÷ width"},"basis":"Head bearing on slot lands","sources":["iso-273"],"tags":["slot","adjustment"]},{"id":"safety-and-locking","kind":"note","tier":3,"title":"Locking a threaded joint","summary":"Vibration: nyloc (needs 2 threads past the nut), thread-locker (blind holes vent nothing), serrated flange, or wire-lock holes (⌀1.5 through the head, aerospace). Geometry only changes for wire-lock and for the extra nut height.","applies":["automotive","aerospace","machinery"],"basis":"Locking method by environment","sources":["protolabs-threads"],"tags":["locking","vibration","nyloc"]},{"id":"tap-drills-metric-fine","kind":"fastener","tier":2,"title":"Fine-pitch metric tap drills (M8x1, M10x1.25, M12x1.5)","summary":"Fine-pitch tap drill = major - pitch: M8x1 -> 7.0, M10x1.25 -> 8.75 (use 8.8), M12x1.5 -> 10.5 mm. Fine pitch gives more thread engagement per length and is common on thin-walled aluminium housings and adjustment screws.","applies":["thin wall housing","precision adjustment"],"value":{"table":[{"size":"M8x1","pitch":1,"tapDrill":7},{"size":"M10x1.25","pitch":1.25,"tapDrill":8.8},{"size":"M12x1.5","pitch":1.5,"tapDrill":10.5}],"unit":"mm"},"basis":"ISO 262 fine-pitch series; major - pitch rounded to nearest 0.05 mm drill","sources":["iso-262"],"tags":["tap","fine pitch","metric","drill"]},{"id":"clearance-tap-extended-sizes","kind":"fastener","tier":2,"title":"Extended metric sizes: M1.6, M14, M20, M24 clearance and tap drill","summary":"Clearance (medium) / tap drill: M1.6 1.8/1.25, M14 15.5/12.0, M20 22.0/17.5, M24 26.0/21.0 mm. Matches ops/holes.js CLEARANCE and TAP_DRILL tables so a modelled hole and this pack never disagree.","applies":[],"value":{"table":[{"size":"M1.6","clearance":1.8,"tapDrill":1.25},{"size":"M14","clearance":15.5,"tapDrill":12},{"size":"M20","clearance":22,"tapDrill":17.5},{"size":"M24","clearance":26,"tapDrill":21}],"unit":"mm"},"basis":"ISO 273 medium series and ISO 262 coarse tap drills; identical to the kernel's own lookup tables","sources":["iso-273","iso-262"],"tags":["clearance","tap","metric","m1.6","m14","m20","m24"]},{"id":"unf-tap-and-clearance","kind":"fastener","tier":2,"title":"Inch fasteners: UNF tap drills and clearance","summary":"UNF tap drill / close clearance: #4-48 0.0935/0.116, #6-40 0.1110/0.144, #8-36 0.1360/0.172, #10-32 0.1590/0.201, 1/4-28 0.213/0.257, 5/16-24 0.272/0.323, 3/8-24 0.332/0.386, 1/2-20 0.4531/0.516 in. Finer pitch than UNC at the same nominal diameter.","applies":["north america","precision assembly"],"value":{"table":[{"size":"#4-48","tapDrill":0.0935,"clearance":0.116},{"size":"#6-40","tapDrill":0.111,"clearance":0.144},{"size":"#8-36","tapDrill":0.136,"clearance":0.172},{"size":"#10-32","tapDrill":0.159,"clearance":0.201},{"size":"1/4-28","tapDrill":0.213,"clearance":0.257},{"size":"5/16-24","tapDrill":0.272,"clearance":0.323},{"size":"3/8-24","tapDrill":0.332,"clearance":0.386},{"size":"1/2-20","tapDrill":0.4531,"clearance":0.516}],"unit":"in"},"basis":"ASME B1.1 UNF series tap-drill and clearance columns","sources":["asme-b1-1"],"tags":["unf","tap","clearance","inch"]},{"id":"pipe-thread-tap-drills-bsp-npt","kind":"fastener","tier":3,"title":"BSP / NPT pipe thread tap drills (reference)","summary":"Tap drill by nominal pipe size: 1/8 BSP 8.8mm / NPT 11/32in, 1/4 BSP 11.8mm / NPT 7/16in, 3/8 BSP 15.2mm / NPT 9/16in, 1/2 BSP 19.0mm / NPT 45/64in, 3/4 BSP 24.3mm / NPT 15/16in. Tapered NPT needs a tapered tap; do not model a straight hole as sealing.","applies":["pneumatics","fluid fitting","piping"],"value":{"table":[{"size":"1/8","bspDrillMm":8.8,"nptDrillIn":0.344},{"size":"1/4","bspDrillMm":11.8,"nptDrillIn":0.4375},{"size":"3/8","bspDrillMm":15.2,"nptDrillIn":0.5625},{"size":"1/2","bspDrillMm":19,"nptDrillIn":0.7031},{"size":"3/4","bspDrillMm":24.3,"nptDrillIn":0.9375}]},"basis":"ISO 228-1 (BSPP) and ASME B1.20.1 (NPT) tap-drill tables; cross-reference the piping sector pack for fitting geometry","sources":["iso-228-1","asme-b1-20-1"],"tags":["bsp","npt","pipe thread","tap drill"],"detail":"BSP (ISO 228-1) is parallel and seals on a bonded washer or O-ring; NPT (ASME B1.20.1) is a 1:16 taper and seals on thread interference plus sealant. Never assume they are interchangeable: a BSP nipple in an NPT port strips or leaks. See the piping sector pack for port and fitting envelope dimensions; this entry gives only the tap-drill numbers."},{"id":"thread-forming-screws-plastite","kind":"fastener","tier":2,"title":"Thread-forming screws for plastic (Delta PT / Plastite type)","summary":"Thread-forming screw into plastic: pilot hole = 0.80x screw major diameter, boss OD = 2.0x screw major diameter. E.g. a 4mm thread-forming screw wants a 3.2mm hole in a 8mm boss. No chips are cut, so engagement can be shallower than a cut thread (1.5-2x diameter).","applies":["injection moulded housing","3d print","plastic enclosure"],"value":{"typical":0.8,"unit":"ratio","note":"pilot hole diameter / screw major diameter; boss OD = 2.0x"},"basis":"EJOT Delta PT / generic Plastite-type screw manufacturer design guides","sources":["ejot-delta-pt"],"tags":["thread-forming","self-tapping","plastite","delta pt","plastic","boss"]},{"id":"wood-screw-pilot-holes","kind":"fastener","tier":2,"title":"Wood screw pilot holes by gauge","summary":"Pilot drill by gauge, softwood/hardwood: #6 2.4/2.9mm (3/32 / 7/64 in), #8 2.9/3.5mm (7/64 / 9/64 in), #10 3.2/3.8mm (1/8 / 5/32 in). Clearance (shank) hole = screw major diameter. Hardwood always gets the larger pilot to avoid splitting.","applies":["furniture","cabinetry","enclosure to wood mount"],"value":{"table":[{"gauge":"#6","softwoodMm":2.4,"hardwoodMm":2.9},{"gauge":"#8","softwoodMm":2.9,"hardwoodMm":3.5},{"gauge":"#10","softwoodMm":3.2,"hardwoodMm":3.8}],"unit":"mm"},"basis":"Standard wood-screw pilot-hole reference chart, softwood vs. hardwood columns","sources":["wood-screw-chart"],"tags":["wood screw","pilot hole","gauge","softwood","hardwood"]},{"id":"sheet-metal-screw-pilot-holes","kind":"fastener","tier":2,"title":"Sheet-metal (self-tapping) screw pilot holes","summary":"Pilot hole for thread-forming sheet-metal screws in sheet steel/aluminium: #6 2.6mm, #8 3.2mm, #10 3.6mm, #12 4.1mm. Undersize vs. a machine-screw tap drill because the screw forms rather than cuts; verify sheet thickness supports >= 2 full threads.","applies":["sheet metal enclosure","bracket"],"value":{"table":[{"gauge":"#6","holeMm":2.6},{"gauge":"#8","holeMm":3.2},{"gauge":"#10","holeMm":3.6},{"gauge":"#12","holeMm":4.1}],"unit":"mm"},"basis":"ASME B18.6.4 thread-forming tapping-screw pilot-hole recommendations","sources":["asme-b18-6-4"],"tags":["sheet metal screw","self-tapping","pilot hole"]},{"id":"pop-rivet-hole-sizes","kind":"fastener","tier":2,"title":"Pop (blind) rivet hole sizes","summary":"Rivet hole diameter by shank size: 1/8in shank -> 3.3mm, 5/32in -> 4.1mm, 3/16in -> 4.9mm. Hole is nominally 0.1mm over the shank so the mandrel sets without binding; oversize holes lose clamp-up and shear strength.","applies":["sheet metal","enclosure seam"],"value":{"table":[{"shank":"1/8 in","holeMm":3.3},{"shank":"5/32 in","holeMm":4.1},{"shank":"3/16 in","holeMm":4.9}],"unit":"mm"},"basis":"Industrial blind-rivet hole-size chart, shank + ~0.1mm clearance","sources":["pem-catalog"],"tags":["rivet","pop rivet","blind rivet","hole"]},{"id":"rivnut-hole-sizes","kind":"fastener","tier":2,"title":"Rivet nut (rivnut) installation hole sizes","summary":"Drill hole for a blind rivet nut (steel/aluminium, standard body): M4 6.0mm, M5 7.0mm, M6 9.0mm, M8 11.0mm. Too tight and the body will not draw up; too loose and it spins under torque — hold +-0.1mm.","applies":["thin sheet","access from one side only"],"value":{"table":[{"size":"M4","holeMm":6},{"size":"M5","holeMm":7},{"size":"M6","holeMm":9},{"size":"M8","holeMm":11}],"unit":"mm"},"basis":"Bollhoff RIVKLE blind rivet nut installation drill-size table","sources":["bollhoff-rivnut"],"tags":["rivnut","rivet nut","blind fastener","insert"]},{"id":"pem-self-clinching-nut-holes","kind":"fastener","tier":2,"title":"PEM self-clinching nut / standoff hole sizes (CLS series)","summary":"Punched/drilled hole in sheet for a self-clinching nut (CLS series, cold-rolled steel): M3 4.22mm, M4 5.41mm, M5 6.35mm, M6 8.75mm. Minimum sheet thickness roughly 1.5x the fastener pitch diameter (M3 ~1.0mm, M6 ~2.0mm); thinner sheet cannot resist push-out.","applies":["sheet metal chassis","electronics enclosure"],"value":{"table":[{"size":"M3","holeMm":4.22,"minSheetMm":1},{"size":"M4","holeMm":5.41,"minSheetMm":1.5},{"size":"M5","holeMm":6.35,"minSheetMm":1.6},{"size":"M6","holeMm":8.75,"minSheetMm":2}],"unit":"mm"},"basis":"PEM (Penn Engineering) self-clinching fastener installation specification, CLS series hole sizes","sources":["pem-catalog"],"tags":["pem","self-clinching","standoff","insert","sheet metal"]},{"id":"t-slot-extrusion-hardware","kind":"fastener","tier":2,"title":"T-slot aluminium extrusion hardware (80/20-type)","summary":"T-nut and slot by extrusion series: 20 series slot 6mm takes M5 T-nuts, 30/40 series slot 8mm takes M6/M8 T-nuts. Drop-in T-nuts need the full slot width to insert; slide-in fits from the extrusion end only.","applies":["frame","enclosure rail","fixture"],"value":{"table":[{"series":"20 (2020)","slotMm":6,"tNut":"M5"},{"series":"30 (3030)","slotMm":8,"tNut":"M6"},{"series":"40 (4040)","slotMm":8,"tNut":"M8"}]},"basis":"80/20 Inc. T-slot extrusion catalogue, 10/15/20/30/40 series hardware compatibility","sources":["t-slot-8020"],"tags":["t-slot","extrusion","80-20","t-nut","frame"]},{"id":"captive-keyhole-slots","kind":"feature","tier":3,"title":"Captive slot and keyhole hanger dimensions","summary":"Keyhole slot for hang-and-drop mounting: large bore = screw head dia + 1mm clearance, narrow width = shank dia + 0.5mm, length >= 1.5x head dia for travel. Captive panel-screw slots use a land 0.5mm under the minor diameter.","applies":["panel mounting","tool-free assembly","wall mount enclosure"],"value":{"typical":1.5,"unit":"ratio","note":"slot length / screw head diameter"},"basis":"Common sheet-metal keyhole and captive-slot conventions used for hang-on-wall and panel fasteners","sources":["protolabs-threads"],"tags":["keyhole","captive slot","hanger","panel mount"]},{"id":"thumb-screws","kind":"fastener","tier":3,"title":"Thumb screws (knurled/winged, hand-operable)","summary":"Common panel thumb-screw threads M3-M6 or #6-32 to 1/4-20, knurled head OD roughly 3x the thread major diameter (M4 -> ~12mm head) so fingers get enough grip torque without tools; specify a captive/panel-mount style when the screw must not be lost.","applies":["removable panel","tool-free access cover"],"value":{"typical":3,"unit":"ratio","note":"knurled head diameter / thread major diameter"},"basis":"General panel-hardware supplier thumb-screw dimension ranges","sources":["protolabs-threads"],"tags":["thumb screw","knurled","panel","hand tighten"]},{"id":"shoulder-bolts-iso-7379","kind":"fastener","tier":2,"title":"Shoulder bolts / shoulder screws (ISO 7379)","summary":"Shoulder diameter / matching H7 bore: 6mm, 8mm, 10mm, 12mm (thread is one size smaller than the shoulder, e.g. 8mm shoulder -> M6 thread). Bore to H7 for a running or pivoting fit on the shoulder land; the threaded end always goes into a tapped hole, never a clearance hole.","applies":["pivot pin","idler","cam follower mount"],"value":{"table":[{"shoulderMm":6,"thread":"M4","boreFit":"H7"},{"shoulderMm":8,"thread":"M6","boreFit":"H7"},{"shoulderMm":10,"thread":"M8","boreFit":"H7"},{"shoulderMm":12,"thread":"M10","boreFit":"H7"}]},"basis":"ISO 7379 hexagon socket shoulder screw shoulder diameters and thread sizes","sources":["iso-7379"],"tags":["shoulder bolt","shoulder screw","pivot","h7"]},{"id":"set-screws-d-flats","kind":"fastener","tier":2,"title":"Set screws and matching shaft D-flats","summary":"Set screw size by shaft diameter (light duty): 6mm shaft -> M4, 8mm -> M5, 10mm -> M6, 12mm -> M6-M8. D-flat depth on the shaft = 0.1-0.15x shaft diameter (e.g. 8mm shaft -> 0.8-1.2mm flat) so the cup-point seats on a flat, not a point contact that marks and slips.","applies":["hub to shaft","collar","pulley"],"value":{"table":[{"shaftMm":6,"setScrew":"M4"},{"shaftMm":8,"setScrew":"M5"},{"shaftMm":10,"setScrew":"M6"},{"shaftMm":12,"setScrew":"M8"}]},"basis":"General mechanical-design set-screw sizing and D-flat depth convention","sources":["protolabs-threads"],"tags":["set screw","d-flat","shaft","collar","grub screw"]},{"id":"circlip-internal-groove-din-472","kind":"fastener","tier":2,"title":"Bore (internal) retaining-ring groove (DIN 472)","summary":"Groove dia / width for internal circlips in a bore: 10 -> 10.4/1.1, 12 -> 12.5/1.1, 16 -> 16.5/1.1, 20 -> 21.0/1.3, 25 -> 26.2/1.3, 30 -> 31.4/1.6mm. Groove is cut into the bore wall (larger than the bore), the mirror of the external DIN 471 shaft groove already in this pack.","applies":["bore","bearing bore retention","housing"],"value":{"table":[{"bore":10,"grooveDia":10.4,"width":1.1},{"bore":12,"grooveDia":12.5,"width":1.1},{"bore":16,"grooveDia":16.5,"width":1.1},{"bore":20,"grooveDia":21,"width":1.3},{"bore":25,"grooveDia":26.2,"width":1.3},{"bore":30,"grooveDia":31.4,"width":1.6}],"unit":"mm"},"basis":"DIN 472 internal retaining ring groove diameter d1 and width m","sources":["din-472"],"tags":["circlip","retaining ring","internal","bore","groove"]},{"id":"e-clips","kind":"fastener","tier":3,"title":"E-clips (E-rings)","summary":"E-clip for shaft dia 3mm needs a groove dia ~2.75mm at ~0.4mm width; 6mm shaft -> groove ~5.5mm/0.7mm; 10mm shaft -> groove ~9.2/1.15mm. Installs radially (push-on) rather than DIN 471's axial ring, so it needs radial clearance to fit a screwdriver or pliers, not axial clearance.","applies":["small shaft","light axial retention"],"value":{"table":[{"shaftMm":3,"grooveDia":2.75,"width":0.4},{"shaftMm":6,"grooveDia":5.5,"width":0.7},{"shaftMm":10,"grooveDia":9.2,"width":1.15}],"unit":"mm"},"basis":"Common E-ring (E-clip) supplier groove dimension tables","sources":["din-471"],"tags":["e-clip","e-ring","shaft retention"]},{"id":"spring-pins-roll-pins-iso-8752","kind":"fastener","tier":2,"title":"Spring pins / roll pins (ISO 8752)","summary":"Hole diameter for a slotted spring (roll) pin equals the pin's nominal size — no oversize, no reaming: a 6mm roll pin goes into a 6mm (H9-ish) drilled hole and compresses to fit. Do not treat it like a dowel pin; drilling oversize kills the retained force.","applies":["light shaft retention","hinge pin","assembly locating"],"value":{"value":"nominal","unit":"text","note":"hole = pin nominal diameter, no oversize"},"basis":"ISO 8752 spring pin nominal-size-equals-hole-size convention","sources":["iso-8752"],"tags":["roll pin","spring pin","dowel","pin"]},{"id":"taper-pins","kind":"fastener","tier":3,"title":"Taper pins","summary":"Standard taper pin taper is 1:48 (self-locking, no thread); ream the hole with the matching taper reamer to the small-end diameter marked on the pin, then drive until the large end protrudes slightly. Common small-end sizes: #0 3.7mm, #2 4.7mm, #4 6.3mm, #6 7.9mm.","applies":["shaft-to-hub locking","precision alignment"],"value":{"table":[{"size":"#0","smallEndMm":3.7},{"size":"#2","smallEndMm":4.7},{"size":"#4","smallEndMm":6.3},{"size":"#6","smallEndMm":7.9}]},"basis":"ASME B18.8.2 taper pin taper ratio and size series","sources":["asme-b18-8-2"],"tags":["taper pin","reamer","alignment"]},{"id":"cotter-pins","kind":"fastener","tier":3,"title":"Cotter (split) pins","summary":"Cotter pin diameter for a clevis/castle-nut hole: 1/16in (1.6mm) pin for M4-M5 shafts, 3/32in (2.4mm) for M6-M8, 1/8in (3.2mm) for M10-M12. Hole is a plain clearance drill at the pin's nominal diameter; the pin bends over after insertion, so it is not reusable.","applies":["castle nut retention","clevis pin retention"],"value":{"table":[{"pinIn":"1/16","shaftRange":"M4-M5"},{"pinIn":"3/32","shaftRange":"M6-M8"},{"pinIn":"1/8","shaftRange":"M10-M12"}]},"basis":"ASME B18.8.2 cotter pin size-to-application guidance","sources":["asme-b18-8-2"],"tags":["cotter pin","split pin","castle nut"]},{"id":"clevis-pins","kind":"fastener","tier":3,"title":"Clevis pins","summary":"Clevis pin diameter is a close running fit in the clevis bore, typically nominal + 0.1-0.2mm clearance (e.g. 8mm pin in an 8.1-8.2mm bore); the head end is a formed flange and the tail end takes a cotter pin or retaining ring through a cross-drilled hole near the tip.","applies":["linkage pivot","removable pivot joint"],"value":{"typical":0.15,"unit":"mm","note":"bore clearance over nominal pin diameter"},"basis":"ASME B18.8.2 clevis pin fit and retention practice","sources":["asme-b18-8-2"],"tags":["clevis pin","linkage","pivot"]},{"id":"threaded-rod","kind":"fastener","tier":3,"title":"Threaded rod (studding)","summary":"Threaded rod is sold continuously threaded, cut to length; use the same clearance-hole and nut-pocket numbers as a bolt of the same nominal size (see clearance-holes-metric, nut-pocket-hex in this pack). Common stock: M3-M20 metric, #6-32 to 1-8 UNC inch, full length 1m/3ft bars.","applies":["all-thread standoff","tie rod","levelling foot"],"value":{"options":["M3","M4","M5","M6","M8","M10","M12","M16","M20"],"unit":"text"},"basis":"General threaded-rod (studding) stocking practice; sizing follows standard bolt tables","sources":["iso-273"],"tags":["threaded rod","studding","all-thread"]},{"id":"helicoil-keensert-sizes","kind":"fastener","tier":2,"title":"Wire thread insert (Helicoil/Keensert) drill and tap sizes","summary":"Free-running (STI) insert drill/tap: M3 drill 3.3mm tap M3.5x0.6 STI; M4 drill 4.4mm tap M4.5x0.75 STI; M5 drill 5.5mm tap M5.5x0.9 STI; M6 drill 6.6mm tap M6.5x1.0 STI. The STI tap ships with the insert kit.","applies":["stripped thread repair","soft alloy tapped hole","aerospace-grade thread"],"value":{"table":[{"nominal":"M3","drillMm":3.3,"stiTap":"M3.5x0.6"},{"nominal":"M4","drillMm":4.4,"stiTap":"M4.5x0.75"},{"nominal":"M5","drillMm":5.5,"stiTap":"M5.5x0.9"},{"nominal":"M6","drillMm":6.6,"stiTap":"M6.5x1.0"}],"unit":"mm"},"basis":"Helicoil / Bollhoff wire thread insert drill and STI tap size chart","sources":["helicoil-catalog"],"tags":["helicoil","keensert","insert","sti","tap"]},{"id":"press-fit-bearing-h7-n7","kind":"tolerance","tier":2,"title":"Pressed-in bearing fits (H7 bore / N7 shaft rule)","summary":"Bearing outer race in a housing bore: H7 for a removable stationary fit, N7 for a tighter fit that resists creep under load. Inner race on a rotating shaft: k6/j6. Check the bearing maker's fit chart for the load case.","applies":["motor mount","pulley bearing bore","robotics joint"],"value":{"options":["H7","N7","k6","j6"],"unit":"text"},"basis":"Common ISO tolerance-grade convention for rolling-bearing bore and shaft fits","sources":["protolabs-threads"],"tags":["bearing","press fit","h7","n7","interference"]},{"id":"knurled-press-nuts-pcb","kind":"fastener","tier":3,"title":"Knurled press-in nuts (PCB / plastic panel)","summary":"Knurled brass press-nut for M3 needs a 4.0mm hole in FR4/thin plastic (0.3mm oversize on OD-to-hole is press-fit, not floating); flange sits flush or counterbored. Common in PCB standoff mounting where a heat-set insert is not wanted because reflow will melt the substrate area.","applies":["pcb mounting","thin plastic panel"],"value":{"typical":4,"unit":"mm","note":"M3 knurled press-nut hole diameter"},"basis":"Generic knurled press-nut supplier hole-size guidance","sources":["cnc-cookbook-heatset"],"tags":["press nut","knurled nut","pcb","insert"]},{"id":"standoffs-hex-af-lengths","kind":"fastener","tier":3,"title":"Hex standoffs — across-flats and common lengths","summary":"M3 hex standoff: 5.5mm across-flats (same AF as the M3 nut), common stock lengths 5/6/8/10/12/15/20/25/30mm, male-female or female-female thread combinations. Choose AF large enough to clear the mating screw head/washer when torquing.","applies":["pcb mounting","panel spacer"],"value":{"value":5.5,"unit":"mm","note":"M3 hex standoff across-flats"},"basis":"Standard hex standoff catalogue AF and length series","sources":["iso-4032"],"tags":["standoff","hex spacer","pcb","m3"]},{"id":"screw-head-styles-dimensions","kind":"fastener","tier":2,"title":"Screw head styles — diameter and height, M3-M8","summary":"Head dia / height by style at M3, M5, M8: pan M3 5.6/2.0, M5 9.0/3.3, M8 13.0/5.3; button (ISO 7380) M3 5.7/1.65, M5 9.5/2.7, M8 14.2/4.4; socket (ISO 4762) M3 5.5/3.0, M5 8.5/5.0, M8 13.0/8.0; flat/csk (ISO 10642) M3 6.3/1.86, M5 10.4/3.1, M8 17.3/4.96 mm.","applies":[],"value":{"table":[{"size":"M3","panDiaHt":"5.6/2.0","buttonDiaHt":"5.7/1.65","socketDiaHt":"5.5/3.0","flatDiaHt":"6.3/1.86"},{"size":"M5","panDiaHt":"9.0/3.3","buttonDiaHt":"9.5/2.7","socketDiaHt":"8.5/5.0","flatDiaHt":"10.4/3.1"},{"size":"M8","panDiaHt":"13.0/5.3","buttonDiaHt":"14.2/4.4","socketDiaHt":"13.0/8.0","flatDiaHt":"17.3/4.96"}],"unit":"mm"},"basis":"ISO 7045 (pan), ISO 7380 (button), ISO 4762 (socket cap), ISO 10642 (flat csk) head tables","sources":["iso-4762","iso-10642"],"tags":["head style","pan head","button head","socket head","flat head"]},{"id":"spring-lock-washers","kind":"fastener","tier":2,"title":"Spring (lock) washers, DIN 127","summary":"Spring washer ID/OD/thickness: M3 3.1/5.6/0.8, M4 4.1/7.1/0.9, M5 5.1/8.7/1.2, M6 6.1/10.9/1.6, M8 8.1/13.4/2.0, M10 10.2/16.4/2.2 mm. Use under a nut or bolt head where vibration risks loosening; not a substitute for a proper torque/thread-locker spec on safety-critical joints.","applies":[],"value":{"table":[{"size":"M3","id":3.1,"od":5.6,"t":0.8},{"size":"M4","id":4.1,"od":7.1,"t":0.9},{"size":"M5","id":5.1,"od":8.7,"t":1.2},{"size":"M6","id":6.1,"od":10.9,"t":1.6},{"size":"M8","id":8.1,"od":13.4,"t":2},{"size":"M10","id":10.2,"od":16.4,"t":2.2}],"unit":"mm"},"basis":"DIN 127 spring lock washer dimension table","sources":["din-127"],"tags":["spring washer","lock washer","vibration"]},{"id":"torque-table-class-8-8","kind":"fastener","tier":2,"title":"Tightening torque, property class 8.8, M3-M12","summary":"Dry, class 8.8 steel, approx. torque: M3 1.3Nm, M4 3.0Nm, M5 6.0Nm, M6 10.0Nm, M8 25.0Nm, M10 49.0Nm, M12 86.0Nm. Lubricated threads: multiply by ~0.85; always follow the specific joint's engineering spec over a generic table when one exists.","applies":[],"value":{"table":[{"size":"M3","torqueNm":1.3},{"size":"M4","torqueNm":3},{"size":"M5","torqueNm":6},{"size":"M6","torqueNm":10},{"size":"M8","torqueNm":25},{"size":"M10","torqueNm":49},{"size":"M12","torqueNm":86}],"unit":"Nm"},"basis":"ISO 898-1 property class 8.8 recommended tightening torque (approx. 75% proof load)","sources":["iso-898-1"],"tags":["torque","class 8.8","tightening","nm"]},{"id":"positional-tolerance-conventions","kind":"tolerance","tier":2,"title":"Hole-to-hole positional tolerance conventions by process","summary":"Default positional tolerance for hole patterns: +-0.1mm for CNC-milled/drilled holes, +-0.2mm for laser-cut sheet, +-0.4mm for FDM print. Tighten only where a mating part needs it; over-tolerancing raises cost without improving fit.","applies":[],"value":{"table":[{"process":"CNC milled/drilled","tolMm":0.1},{"process":"laser-cut sheet","tolMm":0.2},{"process":"FDM 3D print","tolMm":0.4}]},"basis":"ASME Y14.5 positional tolerancing practice applied to typical shop-floor process capability","sources":["asme-y14-5"],"tags":["positional tolerance","true position","cnc","laser cut"]},{"id":"counterbore-hex-bolt-iso-4017","kind":"fastener","tier":2,"title":"Counterbore for hex head bolts (ISO 4017 AF)","summary":"Counterbore diameter to clear a hex bolt head across-flats plus wrench clearance: M4 AF7 -> cbore 9mm, M6 AF10 -> cbore 13mm, M8 AF13 -> cbore 16mm, M10 AF16 -> cbore 19mm, M12 AF18 -> cbore 21mm. Depth = head height + 1mm minimum for a socket/wrench to clear the sides.","applies":[],"value":{"table":[{"size":"M4","af":7,"cboreDia":9},{"size":"M6","af":10,"cboreDia":13},{"size":"M8","af":13,"cboreDia":16},{"size":"M10","af":16,"cboreDia":19},{"size":"M12","af":18,"cboreDia":21}],"unit":"mm"},"basis":"ISO 4017 hexagon head across-flats plus standard wrench-clearance allowance","sources":["iso-4017"],"tags":["counterbore","hex bolt","hex head","af"]},{"id":"spot-face-depth","kind":"rule","tier":3,"title":"Spot-face depth for a rough or cast surface","summary":"A spot face just needs to clean up the bearing surface for a washer/head: depth 0.5-1.5mm below the as-cast/as-rolled surface is usually enough, cut to a diameter matching the washer or head OD. Do not confuse with a counterbore, which sinks the head fully flush or below.","applies":["casting","rough sheet","weldment"],"value":{"min":0.5,"max":1.5,"unit":"mm"},"basis":"General machining practice for spot-facing a fastener bearing surface","detail":"cad_fastener requires the head to bear on a face normal to the fastener axis; on a sloped or cast/curved seat it cuts a spot-face or counterbore like this one instead of leaving a proud head over an angled surface.","sources":["protolabs-threads"],"tags":["spot face","counterbore","bearing surface"]},{"id":"cad-fastener-seated-not-floating","kind":"process","tier":1,"title":"cad_fastener places it, cad_fastener_audit proves it seated","summary":"cad_fastener derives bolt length from grip + engagement (steel 1×d, aluminium 1.5-2×d, cast iron 1.25×d) using the same station table that cuts the hole; cad_fastener_audit must return zero findings for head bearing, engagement and protrusion before a bolted assembly ships.","applies":["assembly","bolted joint","fastener QA"],"basis":"V12 fastener seat audit baseline (tools/v12/fastener_audit.js, HEAD 0fae7ced): 355 fasteners measured, 112 seated, 243 not (CADSF-1422/1423/1424) — no fastener in NativeCAD output floats (CADSF-1428).","sources":[],"tags":["cad_fastener","cad_fastener_audit","bolt","bolt length","engagement","floating bolt","floating","stud","screw","nut","seated"]}]}