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Machining drawing notes

By Fred Vierheller, senior mechanical engineer, Certified SOLIDWORKS Professional · Updated November 4, 2026

19 copy-ready notes for machining, hole and thread callouts, in English and Spanish. Copy a note, replace the [bracketed] example values, and check the "Watch for" line before you release the drawing.

Values in [brackets] are examples; replace them with your own. Notes marked Verify values rely on common practice; confirm them with your supplier or design engineer. These notes are examples, not an engineering approval of your drawing.

MCH-01 Tapped hole (inch)MCH-02 Tapped hole (metric)MCH-03 Thread depth definitionMCH-04 Thread gaugingMCH-05 Metric thread with limits (internal)MCH-06 Metric thread with limits (external)MCH-07 Plated threadsMCH-08 CounterboreMCH-09 CountersinkMCH-10 SpotfaceMCH-11 MaskingMCH-12 Inside corner radiiMCH-13 Threaded insertsMCH-14 Heat treatment (through hardening)MCH-15 Case hardeningMCH-16 Stress relief before finish machiningMCH-17 KnurlMCH-18 Center holesMCH-19 Tool marks on critical surfaces

MCH-01

Tapped hole (inch)

Checked
EN
[1/4-20 UNC-2B] ↧ [.50] MIN FULL THREAD, Ø[.201] ↧ [.62]
ES
[1/4-20 UNC-2B] ↧ [.50] MÍN. DE ROSCA COMPLETA, BROCA Ø[.201] ↧ [.62]

Use: blind tapped holes. Through holes: [1/4-20 UNC-2B] THRU.

Watch for: no thread class; only the drill depth given; thread depth deeper than the drill.

Basis: ASME B1.1 (Unified threads); #7 (.201) is the standard 75% tap drill for 1/4-20. checked

MCH-02

Tapped hole (metric)

Checked
EN
[M6x1-6H] ↧ [12] MIN FULL THREAD, Ø[5] ↧ [15]
ES
[M6x1-6H] ↧ [12] MÍN. DE ROSCA COMPLETA, BROCA Ø[5] ↧ [15]

Use: metric blind tapped holes.

Watch for: "M6" with no pitch on a drawing that also uses fine pitches; "M6-1.0 6H" (write M6x1-6H).

Basis: ISO 261 / ISO 965-1 (metric threads and tolerances). checked

MCH-03

Thread depth definition

Verify values
EN
THREAD DEPTHS ARE MINIMUM FULL THREAD.
ES
LAS PROFUNDIDADES DE ROSCA SON DE ROSCA COMPLETA MÍNIMA.

Use: drawings with many tapped holes, to avoid repeating "MIN FULL THREAD".

Basis: convention. verify

MCH-04

Thread gauging

Verify values
EN
INCH THREADS PER ASME B1.1, GAGE PER ASME B1.3, SYSTEM [21]. METRIC THREADS PER ISO 965-1, GAGE PER ISO 1502.
ES
ROSCAS EN PULGADAS SEGÚN ASME B1.1, CALIBRAR SEGÚN ASME B1.3, SISTEMA [21]. ROSCAS MÉTRICAS SEGÚN ISO 965-1, CALIBRAR SEGÚN ISO 1502.

Use: production parts where thread acceptance matters (aerospace, pressure, safety).

Watch for: the gauging system decides how strictly threads are inspected; choose it with Quality.

Basis: ASME B1.3 gauging systems 21/22/23; which one applies by default: verify

MCH-05

Metric thread with limits (internal)

Checked
EN
[M8x1-6H] MINOR Ø[6.917–7.153] PITCH Ø[7.350–7.500]
ES
[M8x1-6H] Ø MENOR [6.917–7.153] Ø DE PASO [7.350–7.500]

Use: when the inspector needs the limits on the print (no thread tables at the supplier).

Watch for: writing diameters as "M7.153"; mislabeled pitch (a "M5-.6" line that lists M5x0.8 values); pitches that are not standard for that diameter.

Basis: ISO 965-1 limits; values for M8x1-6H match ISO tables. checked

MCH-06

Metric thread with limits (external)

Checked
EN
[M8x1-4g6g] MAJOR Ø[7.794–7.974] PITCH Ø[7.253–7.324]
ES
[M8x1-4g6g] Ø MAYOR [7.794–7.974] Ø DE PASO [7.253–7.324]

Use: precision external threads.

Watch for: 4g6g is tighter than the common 6g; use it only when the fit needs it.

Basis: ISO 965-1. checked

MCH-07

Plated threads

Checked
EN
THREADS: CLASS [2A] BEFORE PLATING; [3A] GAGE AFTER PLATING. or MASK THREADS.
ES
ROSCAS: CLASE [2A] ANTES DEL RECUBRIMIENTO; … / ENMASCARAR ROSCAS.

Use: plated external threads.

Watch for: class 3A threads plated with no allowance left — they won't gauge.

Basis: ASME B1.1 allowance on 2A (none on 3A). checked

MCH-08

Counterbore

Checked
EN
Ø[.257] THRU, ⌴ Ø[.438] ↧ [.250]
ES
Ø[.257] PASANTE, CAJA Ø[.438] ↧ [.250]

Use: socket head cap screws (example: 1/4).

Watch for: no depth; callout placed on the view where the counterbore isn't visible.

Basis: Y14.5-2018 symbols. checked

MCH-09

Countersink

Checked
EN
Ø[.266] THRU, ⌵ Ø[.516] X [82]°
ES
Ø[.266] PASANTE, AVELLANADO Ø[.516] X [82]°

Use: flat head screws. 82° for inch screws, 90° for metric.

Watch for: no angle; 90° countersink for an inch screw.

Basis: Y14.5-2018 symbols; screw head angles from ASME B18.3 / ISO 10642. checked (sizes are examples)

MCH-10

Spotface

Checked
EN
⌴ SF Ø[.750] ↧ [.03] or SF Ø[.750] TO CLEAN UP, [.25] MIN MATERIAL REMAINING
ES
REFRENTADO Ø[.750] ↧ [.03] / REFRENTADO Ø[.750] HASTA LIMPIAR, [.25] MÍN. DE MATERIAL RESTANTE

Use: rough or cast surfaces under a screw head or washer.

Basis: Y14.5-2018 (spotface symbol). checked

MCH-11

Masking

Verify values
EN
MASK [THREADS AND Ø.500 BORE] FROM [FINISH].
ES
ENMASCARAR [ROSCAS Y BARRENO Ø.500] DURANTE EL [ACABADO].

Use: any plated, anodized or painted part with threads, bores, grounding or datum faces.

Watch for: "MASK ALL THREADS" when a datum face also has to stay bare.

Basis: convention. verify

MCH-12

Inside corner radii

Verify values
EN
INSIDE CORNER RADII R[.030] MAX UNLESS NOTED.
ES
RADIOS DE ESQUINAS INTERIORES R[.030] MÁX. A MENOS QUE SE INDIQUE.

Use: milled pockets. Pick a radius a standard end mill can cut.

Watch for: sharp inside corners on a milled pocket (EDM or a shop-chosen radius).

Basis: convention. verify

MCH-13

Threaded inserts

Verify values
EN
INSTALL [HELICAL COIL INSERT, P/N ___], [1.5D] LENGTH, IN HOLES MARKED [△6]. TAP PER INSERT MANUFACTURER (STI).
ES
INSTALAR [INSERTO HELICOIDAL, N/P ___] EN LOS BARRENOS MARCADOS [△6]. MACHUELEAR SEGÚN EL FABRICANTE (STI).

Use: threads in aluminum, magnesium or plastic that see repeated assembly.

Watch for: "THREADED HOLES TO UTILIZE INSERTS WHERE GEOMETRY ALLOWS" — the shop can't know which holes or which insert.

Basis: convention. verify

MCH-14

Heat treatment (through hardening)

Checked
EN
HEAT TREAT TO [40–45] HRC PER AMS 2759/1. HARDNESS TEST PER ASTM E18. DIMENSIONS APPLY AFTER HEAT TREATMENT.
ES
TRATAMIENTO TÉRMICO A [40–45] HRC SEGÚN AMS 2759/1. PRUEBA DE DUREZA SEGÚN ASTM E18. LAS DIMENSIONES APLICAN DESPUÉS DEL TRATAMIENTO.

Use: hardened carbon and low-alloy steel parts.

Watch for: "RC 43-48" (write 43–48 HRC); no test location; dimensions before/after not stated.

Basis: AMS 2759/1 (steel parts heat treatment) and ASTM E18 (Rockwell). checked. Values are examples.

MCH-15

Case hardening

Verify values
EN
CARBURIZE AND HARDEN: EFFECTIVE CASE DEPTH [.020–.030] TO 50 HRC, SURFACE [58–62] HRC. AREAS MARKED [△7] TO REMAIN SOFT.
ES
CEMENTAR Y TEMPLAR: PROFUNDIDAD DE CAPA EFECTIVA [.020–.030] A 50 HRC, SUPERFICIE [58–62] HRC. LAS ZONAS MARCADAS [△7] QUEDAN SUAVES.

Use: gears, shafts, wear surfaces.

Basis: effective case depth to 50 HRC per SAE J423 practice. verify

MCH-16

Stress relief before finish machining

Verify values
EN
STRESS RELIEVE AFTER ROUGH MACHINING, BEFORE FINISH MACHINING.
ES
RELEVAR ESFUERZOS DESPUÉS DEL DESBASTE Y ANTES DEL ACABADO.

Use: thin or long parts that move after heavy material removal, weldments that get machined.

Basis: convention; give the cycle or spec for critical parts. verify

MCH-17

Knurl

Checked
EN
[DIAMOND] KNURL, [96] DIAMETRAL PITCH, RAISED, PER ASME B94.6.
ES
MOLETEADO [DIAMANTE], PASO DIAMETRAL [96], EN RELIEVE, SEGÚN ASME B94.6.

Use: grips and press-fit knurls (give the diameter after knurling for press fits).

Basis: ASME B94.6 (knurling). checked

MCH-18

Center holes

Verify values
EN
CENTER HOLES [PERMITTED / NOT PERMITTED] ON FINISHED PART.
ES
BARRENOS DE CENTRO [PERMITIDOS / NO PERMITIDOS] EN LA PIEZA TERMINADA.

Use: turned shafts.

Basis: convention. verify

MCH-19

Tool marks on critical surfaces

Verify values
EN
NO CHATTER, TOOL MARKS OR SCRATCHES ON SURFACES MARKED [△8].
ES
SIN VIBRACIÓN, MARCAS DE HERRAMIENTA NI RAYONES EN LAS SUPERFICIES MARCADAS [△8].

Use: seal faces, bearing seats, cosmetic faces. Add a surface texture symbol too.

Basis: convention. verify

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