Stair 2, Stair 3, and so on are named by moving in a clockwise direction on the first floor or presumably the egress level , with stairs keeping the same names on all other levels. Other stairs that may not come down to the first floor are numbered next. Elevator 1 is closest to the building entrance with largest capacity; then continue the numbering moving clockwise within elevator banks. Shaft 1 same principle as with elevators, starting with shaft closest to biggest entry.

Specific information about the door is contained in a "door schedule. Unlike doors, which are individually named, windows are organized by "type. Furniture, fixtures, and equipment: See more on fonts below. The organization of information begins with the floor plan. From this drawing, we reference sections, elevations, interior elevations, large-scale plans, and plan details. Avoid redundancy by keeping notations in a single location e. The idea of a mock-up set see week 8 helps.

Cross-reference other drawings where such information is helpful, but be somewhat selective, avoiding obvious cross-references as in: As mentioned previously, identify each drawing and each sheet with a unique identifier.

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The cross-referencing can continue, if necessary, with additional details keyed in from the "detail" itself. Terms and abbreviations PDF pp. Spell out words whenever possible. In general, do not abbreviate any word of 5 letters or less, except where useful for formatting schedules. Some abbreviations refer to multiple words. This is OK where the variations occur in different disciplines, but not OK if it is likely to cause confusion within a single discipline.

In the latter case, spell it out. Soon this evolved into the "check mark" sign with accompanying number that tells the reader a max roughness value RMS, microinches or micrometres for the machined finish, to be measured with a profilometer. FAO finish all over A note telling the manufacturer that all surfaces of the part are to be machined as opposed to leaving any surfaces as-cast or as-forged.

Not an obsolete usage, but not seen as commonly as it was decades ago; not least because parts that once would have been spot-faced castings are now likelier to be contoured from billet with CNC milling. But more importantly, best engineering practice today, reflecting design for manufacturability and avoidance of spurious cost drivers, is either to specify specific, quantifiable requirements for surfaces with specific needs such as RMS roughness measurements in microinches or micrometres, plus any plating or painting needs , or to leave finish out of the part definition and thus at the manufacturer's discretion because it is not important to fit, function, or criticality.

This same spirit is behind the shift in military standards from writing requirements about methods to writing them instead about performance, with the method to reach that goal being up to the ingenuity of the designer. It typically tells you what sort of geometric condition e. Rationales for drawing changes that are noted in the rev block often use these abbreviations for brevity e.

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FL flag note , flagnote A note that is called out in specific spots in the field of the drawing. It is numbered with a stylized flag symbol surrounding the number. A general note applies generally and is not called out with flags. A flagnote is a note that is called out in specific spots in the field of the drawing. It is numbered with a stylized flag symbol surrounding the number or sometimes a delta symbol.

Thus "fasten using FN7" refers to a fastener that is "find number" 7 in the list. FoS feature of size A type of physical feature on a part. An FoS is a feature that can have size associated with it, usually involving the opposition of two surfaces e. Features of size FoSs in reality always have actual sizes and forms that differ from their theoretical size and form; the purpose of tolerancing is to define whether the difference is acceptable or not. FS far side The drawing notations " near side " and "far side" tell the reader which side of the part a feature is on, in occasional contexts where that fact is not communicated using the rules of projection alone.

Contexts of usage are rather limited. One example is hole locations; "3X AND 3X FAR SIDE" defines symmetrical groups of 3 holes on both sides of a part 6 total , without having to redefine equivalent hole center coordinates on two separate views, one for each group. This is not only a convenience for the designer but also a method of error prevention, because it provides a way to avoid forking geometric definition that ideally should be kept unforked to prevent discrepancies.

For example, the groups defined above cannot accidentally become asymmetrically discrepant in a future revision by the revisor failing to revise both groups equally because their definition is unified in only one place.


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Another example is part marking locations. An area for part identification marking can be circled on a top view but assigned to either the top or bottom of the part simply with a "near side" or "far side" notation—which obviates adding any otherwise-unneeded bottom view to the field of the drawing. The "W" comes from the element symbol for tungsten , W, which comes from the German Wolfram. Part of the motivation behind the choice of words "in accordance with" is that they do not allege that any particular activity is explicitly specified by standard XYZ.

But this is a subtle connotative distinction, and "per" and "IAW" are denotatively equivalent. ID inner diameter; identity, identification number IED Insufficient Edge Distance Drilled holes commonly have a required minimum edge distance, if the inspection finds that the edge distance is below minimum, then commonly reported as having an IED condition.

They are thus subjected to higher inspection sampling levels. KSI , ksi kilopounds per square inch, that is, thousands of pounds per square inch KSI or ksi , also abbreviated KPSI or kpsi, is a common non- SI measurement scale for ultimate tensile strength , that is, the number of units of tensile force that a material can endure per unit of cross-sectional area before breaking. All information missing from the drawing is to be pulled from a 3D model of the part or assembly.

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LH left-hand Referring to handedness , such as the helix handedness of screw threads or the mirror-image handedness of a symmetrical pair of parts. Means that a feature of size FoS is at the limit of its size tolerance in the direction that leaves the least material left on the part. Thus an internal feature of size e. Drawings may be printed plotted from the model for reference use, but the model remains the governing legal instrument. Means that a feature of size FoS is at the limit of its size tolerance in the direction that leaves the most material left on the part.

There is only one correct casing for the symbol, cap-M-cap-P-small-a, which, like any SI unit of measurement symbol, properly should be preserved even when surrounding text is styled in all caps which latter is a frequently employed tradition in engineering drawing. But it is not uncommon to see "MPA" through carelessness. Users are not confused regardless.

Standard hardware sometimes uses the MS- prefix in the catalog numbers. Standard hardware for aerospace work sometimes uses the NAS- prefix in the catalog numbers. See also AN- and MS-. NCM nonconforming material s This abbreviation is used in a machine shop when recording nonconformances out of tolerance, etc. For example, "An NCM tag was tied to the scrap part. Helps to analyze system weaknesses such as worn-out equipment, operators in need of more training, or risky practices. NEC not elsewhere classified; National Electrical Code In the sense of "not elsewhere classified", the abbreviation is well-known within certain fields, but not others; to avoid confusion, spell out.

The National Electrical Code is a standard for electrical work. See also HT TR. NS National Special; near side 1. National Special, a screw thread series; see Unified Thread Standard. An extensible series, covering various special threads. The drawing notations "near side" and " far side " tell the reader which side of the part a feature is on, in occasional contexts where that fact is not communicated using the rules of projection alone.

See " far side " for examples. Compare to CDA , the entity that currently has design authority over the part design definition. OHL over high limit This abbreviation is used in a machine shop when recording nonconformances. It is the intersection point of lines that may not meet on the finished part, such as the tangent lines of a curve or the theoretical sharp corner TSC that edge-breaking and deburring will remove. PSI pounds per square inch A unit of measurement for pressure. Flats and reversals falling within the dimensional tolerance zone are tolerated unless "CR" controlled radius is explicitly specified.

The dimension may also be surrounded by parentheses to signify a reference dimension. When a dimension is defined in one view but also mentioned again in another view, it will be given as reference in the second case. This rule prevents the mistake of defining it in two different ways accidentally; the "main" non-reference mention is the only one that counts as a feature definition and thus as a part acceptance criterion. See also basic dimensions, which are similar in some respects. REV revision Engineering drawings and material or process specifications are often revised; the usual revision control convention is to label the versions A, B, C, D, etc.

Revisions beyond "Z" start the alphabet over again with doubling, e. They thus accompany the drawing as part of the TDP. In recent years the revision control of engineering drawings has even been standardized by ASME, in their standard Y RH right-hand Referring to handedness , such as the helix handedness of screw threads or the mirror-image handedness of a symmetrical pair of parts. RHR roughness height reading See surface roughness.

RMS root mean square RMS in general is a statistical technique to define a representative value for a group of data points. With regard to surface roughness, it means that the heights of the individual microscopic peaks and valleys shall be averaged together via RMS to yield a measurement of roughness. See also herein f as a finish mark. Can apply to bar stock or to parts in-process.

Room temperature is sometimes abbreviated "RT" within tables of specs for finishing operations plating, painting, etc. In other words, the event when a draft becomes a completed, official document. RTV room-temperature vulcanizing ; return to vendor 1. RTV sealants, a way to seal joints. Return to vendor, send parts back to a vendor for rework or refund because they are nonconforming. RZ , Rz roughness, mean depth See surface roughness. In other words, distances may be given from intersection points where lines intersect, regardless of edge breaks or fillets.

But in some cases it clarifies the definition. SHSS socket head set screw A set screw with a socket head usually implying a hex socket, driven with a hex key. Stainless steel, see also CRES. SST stainless steel A somewhat unusual abbreviation; spell out for clarity.

Drawing revision versioning information is not always included in the title block because it often appears in a separate revisions block. TDP technical data package The complete package of information that defines a part, of which the drawing itself is often only a subset.

It also includes engineering orders drawing change notices , 3D model datasets, data tables, memoranda, and any special conditions called out by the purchase order or the companies' terms-and-conditions documents. For example, THRU may be stated in a hole dimension if the hole's end condition is not clear from graphical representation of the workpiece. Sometimes used on hole dimensions for clarity to denote that the hole extends through multiple open space features as it goes through the whole workpiece.

TYP [2] Typical Other features share the same characteristic. For example, if the drawing shows 8 holes on a bolt circle, and just one is dimensioned, with "TYP" or " TYP " following the dimension label, it means that that hole is typical of all 8 holes; in other words, it means that the other 7 holes are that size also. The latest revisions of Y This helps avoid any ambiguity or uncertainty. TYP or Typical was describe in Mil-Std-8, the directing body prior to adoption of the dimension tolerance interpretation Y Its last revision was C in , but can still be found in many older aircraft drawings.

Others include scrap and rework. ULL under low limit This abbreviation is used in a machine shop when recording nonconformances. For applications requiring maximum fatigue resistance amid chronic vibration such as in aircraft.

Engineering drawing abbreviations and symbols - Wikipedia

UNO unless noted otherwise A fairly well-known abbreviation, but to avoid confusion, spell out. It is an extensible series, covering various special threads. The unified numbering system is a vaguely named standard for naming alloys by principal element percentages.

UON unless otherwise noted A little-used thus not well recognized abbreviation. To avoid confusion, spell out. UOS unless otherwise specified A fairly well-known abbreviation, but to avoid confusion, spell out. Standard threads became the National series e.

Terms and abbreviations

Steel, it was once the largest steel company on earth, often an approved supplier , and not infrequently a sole source ; hence its mention on drawings. The older symbol for this was a small script italic f see herein f. WI wrought iron Both the material and the abbreviation are obsolete, or nearly so. Spell out the words if this material is to be mentioned at all in modern drawings.

This example signifies eight places. There should be no whitespace between the numeral and the letter X. Note on character encoding: X — Calls out the drawing standard that this drawing is following. American Society of Mechanical Engineers. Retrieved from " https: Engineering Lists of abbreviations.


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Views Read Edit View history. This page was last edited on 24 November , at By using this site, you agree to the Terms of Use and Privacy Policy. A dimension that establishes a distance away from the finished floor. American Iron and Steel Institute. Standards in materials science and engineering maintained by SAE International and widely used in the aerospace manufacturing industries.