Checklist Before Releasing a Drawing (Drafting, GD&T, Manufacturability, Jig Design)

Whole drawing

Does the title block show the projection symbol (third-angle or first-angle projection)?There have been cases where a first-angle drawing without the symbol was assumed to be third-angle and the part was made reversed.^[1][2][3]
Are the part name, drawing number, scale, material, quantity, creator and date, checker, and approver in the title block?A missing material or quantity leads to ordering mistakes, and a missing drawing number leads to control mistakes.^[2][3]
Are the dimension units millimeters (no centimeters or inches mixed in)?JIS mechanical drawings assume mm. Drawings with the wrong unit, or with inch-based CAD settings mixed in, do occur.^[1]
Was it drawn in CAD that supports JIS (not in slide software or the like)?Depending on the software, the aspect ratio or scale may not match the entered dimensions, and overseas CAD may be set to first-angle projection or inches.^[1]
Does the front view carry the most shape information and sit in a stable orientation? Is the center line of shaft parts horizontal?If a face with little information is made the front, shape and dimensions are scattered across several views.^[2]
Is the number of projected views the minimum that defines the shape (no unnecessary views and none missing)?Too many views make dimensions redundant, and too few leave the shape undefined.^[2][4]

Lines and shapes

Is there a clear difference in thickness between visible outlines (thick lines) and dimension lines and center lines (thin lines)?If all line thicknesses are the same, it is hard to tell shape lines from dimension lines.^[5][6]
Do all round holes, threaded holes, and cylindrical parts have center lines in both the front and side views?Without a center line, the center of the hole and the starting point of the position dimensions cannot be read.^[5]
Does the cutting-plane line of a section have arrows and a letter, and is the same letter written on the section view?If the viewing direction is unclear, the shape is read backwards.^[7]
In section views, are shafts, bolts, pins, and keys not cut lengthwise and hatched?Cutting them does not aid understanding, and the boundaries between parts become hard to see.^[7][8]
Is everything other than your own part (adjacent parts, tools, jigs, alternate positions of moving parts) drawn with phantom lines (thin double-dot chain lines)?If drawn with visible outlines, those shapes are read as something to be machined.^[6][9]
Are thread crests thick lines and roots thin lines, with the root circle in the end view drawn as 3/4 of a circle?If the crest and root lines are reversed, male and female threads or large and small diameters are misread.^[10][5]

Dimensions

Are all dimensions needed for machining given as numbers (nothing that has to be measured off the drawing)?A drawing is not meant to be scaled, and dimensions go wrong with scale differences and print shrinkage or stretch.^[11][5]
Did you walk through the machining from the state of the stock, in order, to see which face is the datum and where how many mm are machined, and confirm the dimensions are sufficient?Checking against the machining sequence makes it easy to find missing dimensions and dimensions that require calculation.^[5]
Is the same dimension written in two places? Are the overall length and all partial dimensions given with tolerances?Redundancy causes mismatches from missed corrections and contradictory tolerances.^[1][12][5]
Does the machinist avoid having to add or subtract? Where necessary, did you add reference dimensions (in parentheses)?Making people calculate is a source of errors. However, dimensions that contradict under general tolerances should be made reference dimensions.^[1][12]
Are the dimensions of one feature gathered in one view, with no dimensions on hidden lines?When dimensions are split across several views, comparing them takes more effort, and dimensions on dashed lines are hard to read.^[1][11]
Are dimensions given from the datum surfaces for machining, assembly and measurement? Are symmetric parts dimensioned symmetrically about the centerline?Dimensions that are not tied to a datum cause positioning errors and assembly mix-ups.^[5][1][13]
Do repeated holes carry a quantity, as in "4-φ5.5"?Without a quantity, the number of holes is judged from what is visible in the view, and holes get missed.^[14][5]
Are arcs and circles over 180° dimensioned with φ, and arcs of 180° or less with R?Using the wrong symbol leads to mixing up diameter and radius.^[15]

Tolerance

Is the general tolerance (e.g., a JIS B 0405 class) shown in the title block?Without a general tolerance, there is no basis for accepting or rejecting dimensions that carry no tolerance.^[16][2][17]
Are tight tolerances applied only to the dimensions that matter for function?The machining cost of holding a tolerance is added for each dimension that has one.^[18][1]
Is a dimension that must not deviate in one direction given a ± bilateral tolerance?If it varies toward the narrow side, the parts will not assemble.^[1]
Does the fit suit the function (moving, locating, fixing, disassembly) and come from the recommended hole-basis combinations?An excessive fit is expensive, and an interference fit at a point that gets disassembled can no longer be taken apart.^[19][20]
In the tolerance class symbols, is the hole uppercase (H7) and the shaft lowercase (g6)?Uppercase and lowercase letters give deviations in completely opposite directions.^[21][5]
Are the deviations and fit symbols large enough to read even with dirt and creases?Shop drawings get oily and folded, and small characters get misread.^[22]

Geometric tolerancing (GD&T)

Have form and position relations that affect function, such as parallelism, perpendicularity and coaxiality, been specified with geometric tolerances?Size tolerances alone do not control form or position, so a slanted or bent part can still pass.^[23][24][25]
Are datums specified for orientation, location and run-out tolerances, and do the datum surfaces have accuracy suited to a datum?Without datums the meaning of the tolerance is undefined, and a rough datum surface makes measurements scatter.^[26][25][27]
Is the datum precedence (from the left of the frame) in order of importance for assembly and function?If the order changes, the measurement result changes even for the same part.^[28][25]
Are the leader arrow and the datum triangle placed as intended (in line with the dimension line = center; offset = surface)?Just how the arrow is placed decides whether the axis or the surface is controlled.^[29][30][31]
Is φ added where a cylindrical tolerance zone is needed, as for straightness, perpendicularity and position of an axis?Without φ, the tolerance zone becomes two parallel planes in one direction.^[28][32]
Are the dimensions that define position, profile and angularity written as TEDs (in a box)?Chaining toleranced dimensions accumulates the tolerances and leaves the datum position undefined.^[33][25]
Have you stated and confirmed which standard the drawing follows (ISO/JIS or ASME)?In ASME, a size tolerance also controls form (Rule #1), so the same indication is interpreted differently.^[23][25][34]
Is Ⓜ used for mating features and Ⓛ for securing remaining wall thickness?With Ⓜ, a larger hole allows more positional shift, which works against wall thickness.^[35][36]
For threaded or press-fit holes that carry a bolt or pin, did you consider whether the position tolerance needs a projected tolerance zone?Hole tilt becomes a large positional error at the tip of the protruding part and interferes with the mating part.^[37][38]

Surface

Does the surface texture indication give a parameter symbol (Ra, Rz, etc.) and a value?Without the parameter, the same number means something different.^[39][40]
Do the general indication (near the title block) and the individual indications conflict? Are the individual indications listed in parentheses?If the relation between the general and individual indications is ambiguous, it is unclear which surfaces must be better.^[39][41]
Are you confusing the old JIS Rz (ten-point mean roughness) with the current Rz (maximum height)?The 2001 revision changed the meaning of the parameter.^[42][39]
Is a lay direction symbol given only for surfaces where lay direction matters for function?Without an indication, the machinist chooses the direction to suit the process.^[43][39]

Manufacturability

Are corner chamfers and the no-burr requirement specified together in a note (e.g., "Unspecified corners C0.3 MAX")?Burrs cause jamming into locating surfaces and injuries.^[41][44][45]
Do inside corners of pockets and steps have a radius at least as large as the tool radius?With a rotating tool the inside corner is always rounded, and a square inside corner cannot be machined as drawn.^[46][41]
Did you consider whether a relief groove is needed at the root of a stepped shaft or at the end of a thread?The tool radius and the incomplete thread remain, and the mating part cannot seat fully.^[47]
Do press-fit and locating holes have an entry chamfer that makes insertion easy?Without a chamfer, parts catch during insertion, causing galling and scratches.^[48][49]
Is the hole layout arranged so that several holes can be located at once?Holes laid out along an outline arc each need their own locating, which is costly.^[14]
Are there walls or features too thin to machine?Protolabs' machining guidelines recommend a feature thickness of at least 0.51 mm.^[46]
For molded parts, do faces parallel to the mold-opening direction have draft, and is the wall thickness roughly uniform?Without draft the part drags on release, and uneven wall thickness causes warpage, sink marks and short shots.^[50][51]

Assembly

For the two parts to be fastened, is one hole a clearance hole and the other a threaded hole?If both are threaded, the parts cannot be assembled.^[1][5]
Is there any interference in the hole phase between mating flanges, or in the assembly and disassembly sequence?Ignoring phase causes problems such as holes that do not line up or tools that cannot get in.^[1]
Does assembly avoid two places starting to engage at the same time (is there a height difference)?Engaging two points at once cannot be assembled.^[48][52]
Is there a way to remove a press-fitted part (such as a push-out hole)?A worn locating pin and the like cannot be replaced.^[48][52]

Features

Did you give the pitch for fine threads and LH for left-hand threads?Omitting the pitch means coarse thread.^[10][47]
Does the gear carry a data table (module, pressure angle, number of teeth, profile shift coefficient, accuracy, etc.)?Tooth specifications are defined by the data table, not by the drawn shape.^[53][41]
Does the spring carry a data table that specifies the relation between force and dimensions?Springs are designed and made to specified forces or dimensions, so the shape alone does not define the specification.^[54]
Is the basic weld symbol placed on the correct side of the reference line (arrow side or other side)?Putting it on the wrong side gets the opposite face welded.^[55][56]

Fixtures

Do the faces and holes the workpiece rests on in the fixture match the drawing datums (and their precedence) and the origins of the dimensions?Locating on faces other than the drawing's adds the error between those faces to the machining result.^[57][58][59]
Is locating done with 3-2-1 (3 points on the bottom face, 2 on the side, 1 on the end)? Is a plane supported by four or more fixed pins?Too many fixed supports leave one point floating, and the part's attitude changes every time it is placed.^[60][57]
When locating with two holes, is the second pin a diamond pin and is it relieved in the right direction?With two round pins, variation in the hole spacing either prevents the part from going on or forces it on.^[52][57]
Are the locating pins spaced as far apart as possible?With narrow spacing, the same hole-to-pin clearance gives a larger angular error.^[61][57]
Is the layout such that cutting force (thrust, torque) is taken by locators and pins, not by clamps?If there is no datum in the direction of the force, the workpiece moves, leading to damage and accidents.^[62][57]
Is there a support or auxiliary support under each point the clamp presses, so the workpiece is not distorted?Pressing an unsupported spot deflects it, and it springs back on release, so accuracy is lost.^[63][57]
Is the structure one where chips, burrs and debris do not get trapped on datum surfaces (raised datum, corner relief, pin tip shape)?Trapped debris reduces locating accuracy and speeds up wear.^[64][44][45]
Are wearing parts such as locating pins and bushings hardened and made replaceable?Both pins and holes wear with use, and accuracy drops.^[52][65][57]
Is the workpiece easy to load and unload (chamfered guides, finger holes, clamps that stay out of the way)?A fixture that is hard to load and unload lengthens work time, and the part gets bumped and scratched.^[49][57]
Is the structure mistake-proof, so the part cannot be set backwards or in the wrong position?Machining after a wrong setup produces defective parts.^[57]
Where a long pin goes into a bushing or hole, is there an air-relief groove or relief hole?If air cannot escape, the pin is hard to insert and hard to pull out.^[65]

📚Sources

Items without a mark are those on which two or more sources from different publishers agree. The wording is Kezuriba's own summary.