Talk:Unified Thread Standard

message: Added these in based on the sources in the external links, cross-checked against some other web sites: ,, and .
There's some discrepancies in the drill size for a 1-64 thread, source cite both #53 and #54.  #53 is most common.
Pstemari (talk) 20:38, 1 September 2008 (UTC)
replies: text: For metric threads, yes. For non-metric threads such as UTS threads (the subject of this article), no, it's not normal, but it is usually OK, as long as (1) the user understands and applies the concepts properly and (2) the requirements (per drawing, DPD, or informal need) allow it. The goal is a hole of a size that falls within a certain range, regardless of whose system of units is used to measure it. For example, for a 1/4-28 thread, both 5.5 mm and 5.6 mm drills make good tap drills for virtually any purposes, even though 7/32" is the principal tap drill. The idea is explained more at List of drill and tap sizes § Rules of thumb, and then worked examples are given at List of drill and tap sizes § Examples. The only thing that would stop someone from using a metric tap drill for a UTS thread is that by the book, if you are meeting a thread size callout to the letter, you technically should only use the tap drills named in the ASME/ANSI UTS standard tables. But in real life, on most products, if you use a 10 mm (.393") drill in place of either a 25/64" (.391") or a letter X (.397") when creating a 7/16-20 threaded hole, no one will ever have any reason to know, find out, or care. Physically, the differences between those 3 features (one made with each drill) are so small that to posit a context in which they are not negligible takes a lot of contrivance or rarity. By the way, the number drill series and letter drill series are imperial/customary series, not metric series (don't know whether this was realized). Cheers, — ¾-10 23:04, 19 March 2015 (UTC)
thread_title: Tap Drill Sizes

message: Unifed Thread Standard is not going away. It won't go away intill the US switches totaly over to metrics. Even after that it will be another 50 to 75 years untill UTS bolts and taps are stoped being produced. ISO and UTS are not interchangeable due to the smaller id on the minior dimater on the internal threads. This means that as long as there are machines in the world that are old we will still be using UTS. The 50 to 75 years for thoes machines to come totaly out of service.
- ctempleton3
:In other words its a matter of time, but a long time? Hyacinth 18:11, 8 Mar 2005 (UTC)
thread_title: Switch

message: How do you call these threads colloquially? An ISO metric thread is called 'metric', but how do you call non-metric threads? -- Hokanomono ✉ 15:57, 2 May 2007 (UTC)
replies: text: "Imperial," "English" or "inch." Or they are just referred to directly such as: "quarter-twenty" or “ten-thirty two.”--gargoyle888 19:46, 2 May 2007 (UTC)
replies: text: I don't think that UNF or UNC can be 'Imperial'.  In the UK Imperial standards are those defined in the Weights and Measures Act of 1824.  The Inch and Gallon are Imperial measurements, but no-one would call a Whitworth thread 'Imperial'.  Although BSP pipe threads, society microscope thread, and the standard brass thread were all defined in the Imperial era.  But for UNF/UNC I thought there had been some earlier war that had caused a rift across the atlantic - it is unlikely that an American Engineer would think his measures Imperial. I've only ever heard them called "Inch" threads, or (less than accurately) "standard".Brunnian (talk) 19:25, 5 August 2009 (UTC)
replies: text: In the United States these are often referred to as standard threads or SAE threads.  Jayscore (talk) 18:03, 31 December 2009 (UTC)
thread_title:  Colloquial name? 

message: It is very true that there are various terms that are loosely used although not technically accurate, and there is an annoying lack of a compelling, simple, technically accurate blanket term that would enjoy widespread dominance in laypersons' usage. For example, "imperial" is often sloppily used as a blanket term, including in the U.S., even though from a technical perspective there are many important distinctions between true Imperial and American units of measure. "Customary units" is a term sometimes heard, but not on the shop floor as much as in writing. "English" is very often used generally, including in the U.S. on the shop floor, even though from a technical perspective there are important differences between American and British units. As Jayscore also mentions above, it is not uncommon to hear people (in the U.S. at least) use the term "SAE" to mean only "inch as opposed to metric", even though that usage is really unfortunate for how technically ignorant it is. But I believe that it is the reason why so many people mistakenly think that "SAE" stands for "Society of American Engineers" whereas it actually (used to) stand for "Society of Automotive Engineers" (it is no longer acronymous). People in the U.S. also often use the terms "U.S. standard (USS)", "American Standard", and just plain "standard" or "regular" to mean "inch-based as opposed to metric". Those are all unfortunate, sloppy usages. "USS" is way outdated (it was over half a century ago that the joint U.S.-U.K.-Commonwealth Unified Thread Standard superseded it). "American Standard" is outdated for similar reasons (and also happens to be an unfortunately chosen brand name for restroom fixtures). Using terms such as "standard", "regular", and "conventional" are always poor ways to handle retronymy, because they become increasingly ridiculous  misnomers once the "new" way has been around for a really long time (hello metric system) and has halfway displaced the old way toward becoming the standard, conventional, or default way (hello U.S. use of metric). To summarize, the reason that there is no good, simple answer to this "colloquial name?" question is that the general public wallows in nomenclatural confusion and technical ignorance, and natural language reigns over controlled vocabulary. Probably the best colloquial blanket terms for nonmetric units in general that are both technically accurate and socially acceptable (i.e., even idiots will not balk upon hearing them) are "nonmetric" or "non-SI". And for the threads that this article is about, "inch-based thread standards" would work for laypeople, and "UNC" and "UNF" are probably the terms that shop-floor metalworkers would recognize most readily. But, as Gargoyle888 said above, usually the number itself is all they need to hear: "ten-thirty-two", "quarter-twenty", "half-twenty", "three-quarter-ten".  — ¾-10 22:10, 31 December 2009 (UTC)
thread_title: The whole answer(s)

message: I wonder why D and D1 in the diagram on this article are swapped compared to the otherwise (except for insignificant artistic details) identical diagram on the ISO metric screw thread article. I had thought, in both screw threads, the major diameter is the nominal diameter D, i.e. the one after which the thread is named. It would make more sense to me if D were the nominal diameter in both diagrams. Is this just a typo on Unified_Thread_Diagram.gif? I would have thought, the exact same diagram can be used to explain the Unified Thread Standard and ISO metric screw thread, and that both differ merely in their choices of major diameter and pitch values. Anyone here who has the UTS standard at hand to check? Markus Kuhn (talk) 20:36, 4 January 2008 (UTC)
thread_title:  ''D'' versus ''D''<sub>1</sub> in diagram 

message: Image improvement request: WP:GL/IMPROVE#Screw_thread_profile Markus Kuhn (talk) 20:41, 4 January 2008 (UTC)
thread_title: Vectorizing diagram

message: My machinists and my fastener suppliers have told me that 1-12UNF is an old standard, and 1-14UNF is the new standard for 1" fine thread.
I don't have access to the ANSI documents, so I can't reference those, however, these sites do reflect the change: , , 
Khawki02 (talk) 19:32, 15 December 2009 (UTC)
replies: text: Quite right. I double checked it with my Machinery's handbook and fixed it on the page. Wizard191 (talk) 13:36, 16 December 2009 (UTC)
thread_title: 1-14 UNF

message: The edit to include metric values included only one real value: "5.5"; the rest were just "mm". This is not a constructive edit. Seeing how this article is about customary units, I don't see the use in include metric equivalents, especially if there is only one. Instead, I added a note to the top of the table that references the Drill bit sizes article, for those interested in the exact metric conversion. Wizard191 (talk) 15:10, 30 August 2010 (UTC)
replies: text: More interesting than exact conversions of the imperial sizes would be knowing which of the common metric drill sizes are appropriate for a given size of UNC tap. This would be useful information for those of us who live in metric countries but from time to time have to deal with stuff designed in america. 151.229.191.223 (talk) 15:31, 16 June 2014 (UTC)
replies: text:  That info ("which of the common metric drill sizes are appropriate for a given size of UNC tap") is indeed quite useful, as is the reverse here in the U.S. ("which of the common inch-based drill sizes are appropriate for a given size of metric tap"). I plan to eventually add them all to List of drill and tap sizes, but I don't know when I will get time to do it. This ties into a discussion at that talk page, Talk:List of drill and tap sizes > Errors in M6 and others. — ¾-10 02:31, 17 June 2014 (UTC)

text: Update: I added the rules of thumb to that article today (List of drill and tap sizes > Rules of thumb), which helps anyone looking for this info (by giving them the general case, from which they can figure out the instances). Someday when I have hours of free time to spend and not prioritized to another also-worthy activity, I will insert  into existing table rows, showing the specific instances for each size thread. — ¾-10 14:52, 19 June 2014 (UTC)
thread_title:  Inclusion of metric equivalent 

message: This useful article is too limited. It lacks obvious links to comparable information about other aspects of screw dimensions (screw heads and tips), nuts, and washers. Please add good links to such information.-96.237.79.6 (talk) 11:59, 28 September 2010 (UTC)
replies: text: See washer (hardware), nut (hardware), and list of screw drives. Wizard191 (talk) 17:52, 28 September 2010 (UTC)
thread_title:  screw nut washer dimensions 

message: Isn't the Dmaj in the drawing actually the radius of the screw. Or in other words, should the drawing use Dmaj/2 for that dimension in the drawing?  — Preceding unsigned comment added by Kentamanos (talk • contribs) 03:33, 31 August 2011 (UTC)
replies: text: The drawing isn't wrong, it's just "jargony" in the sense that it's made for viewers who will take the intent as understood. The dot-dash line is a conventional way of representing the centerline of the cylinder, and each DIA's dimension line continues past it, rather than terminating in a second arrowhead right at centerline. If the latter were done, then "over two" (/2) would agree with it, but if doing "over two" then the dimension line would need to be changed. Even though it is correct as drawn, perhaps your suggested way is better for a general-audience encyclopedia. If anyone gets time to modify, that would be fine. — ¾-10 23:52, 2 September 2011 (UTC)
thread_title:  D<sub>maj</sub> in SVG Drawing 

message: the table of screw sizes says major diamter but writes the minor diamters.  — Preceding unsigned comment added by 188.120.137.254 (talk) 17:33, 12 January 2013 (UTC)
replies: text: Nope, the table is correct—the left-hand column lists major (not minor) diameter, and the columns on the right list the tap drill sizes. — ¾-10 19:58, 12 January 2013 (UTC)
thread_title:  Important mistake 

message: Is there a UNO thread?  Lamps and lamp shades identified as "UNO" or "Uno" are commonplace.  Does "UNO" refer to the fine thread on the outside of the bulb socket near the glass?  PeterEasthope (talk) 23:47, 6 January 2014 (UTC)
replies: text: Most traditional bulb thread sizes are "ES" (Edison Screw) and the diameter in millimetres.  See https://en.wikipedia.org/wiki/Edison_screw  Darkman101 (talk) 02:48, 9 December 2015 (UTC)

text: UNO thread on a lamp socket or lamp shade refers to the thread on the outside shell of a lamp socket and the inside thread of the shade fitter of the lamp shade. UNO sockets allow threading a lmmp shade directly on to the lamp socket.  — Preceding unsigned comment added by Joe-tuttle (talk • contribs) 18:01, 2 January 2017 (UTC)
thread_title:  UNO thread? 

message: Hi, the article should mention the gauge system referred to by the numbers #0 .. #12. I don't have a copy of ASME/ANSI B1.1 at hand. It would cite the gauge, which would have existed before the thread standard. Regards, ... PeterEasthope (talk) 19:11, 5 August 2020 (UTC)
thread_title:  Gauge numbers 

message: Does anyone know the origin of the formula: Major diameter = Screw # × 0.013 in + 0.060 in. How were the values of 0.013" and 0.060" determined? The only information I was able to find online regarding this is this forum where the question is posed and not answered and this site which claims that strength of the screw is doubled as the # increases, however, when calculating strength based on tensile stress area this claim is incorrect; the ratio ranges from 1.1 to 1.5. Thanks in advance. Acolosi22 (talk) 19:03, 7 March 2023 (UTC)
thread_title:  Origin of # Formula