Talk:Screw

Coatings

Six different tanks for blackening? I only counted 4.

The discussion is oversimplified as it does not deal with typical protective coating processes such as anodizing for aluminum; ozide treatments for brass; passivation for stainless steels; conversion coatings (phosphate and oil), or mechanical plating, or galvanizing and electroplating of zinc, cadmium, nickel, and copper-nickel-chrome for steels.

On a side note

Based on all of the above I started the following discussion which might be of interest to those here: Wikipedia_talk:WikiProject_Metalworking#Heading_.28metalworking.29_and_upsetting.

Distinction between bolt and screw

I think this has become somewhat confused due, not to stupidity by anyone, but rather differing language and terminology on each side of the Atlantic. If I order a bolt in the UK it will come with a length of plain, unthreaded shank, every time. If I order a screw or machine screw it will come fully threaded, every time. Also, machine screws come in far larger diameters than the article currently suggests, and may have either hex, cap or Torx heads, not usually Philips or Pozi. Worse, a set screw may in fact be just an ordinary (machine) screw, and not headless, to be used as a grub screw. All this is regardless of what the various standards say. Considering that probably 99% of end users do not have access to the likes of ISO standards due to their cost, it is hardly surprising! In any case it seems that the terminology was in use long before ISO existed. Considering that BSI probably preceded every other standards body, early versions may be instructive. Sadly as I am retired I no longer have access to the standards library at work so can't look them up to see how things were once named. Most of my experience is with fastenings of either 8.8 grade or the similar old BS grade S or higher, i.e. high tensile, so I don't know much about the naming conventions for the mild steel varieties commonly available in DIY stores, except to note that all I have seen were fully threaded and in common usage should be screws.

I have only made one small edit, to note that a set screw is often known as a grub screw. That is fairly clear and distinct, and adds no confusion. It also agrees with the set screw article. I am not going to touch the main body of the article for fear of damaging a lot of good work that has been done my many people, and I don't see a clear way of fixing things that will not offend many. Changes would be needed in nearly every section. We would also need to take into account common usage other than in the UK, although we should be aware that standardised threads, a key requirement to allow mechanical engineering to fully develop, were first introduced in the UK by Josiah Whitworth a long time ago, and strictly speaking, whatever terminology he used should have been retained. I suspect that everyone has drifted well away from that in different directions. Anyway, it is not about being nationalistic, just hoping to get some form of consensus that will be fully understood by as many bolt users as possible, everywhere. We are not there yet.

Please discuss freely, and if I am wrong, say so.

Tiger99 (talk) 13:36, 9 March 2020 (UTC)

Any generic product that exists for a long enough time will develop confounding terminology, the problem for Wikipedia is that the guy at the fastener shop mostly understands what you are asking for, so they never see the need to try and more precisely define things. To me a bolt can have a fully threaded shank, screws are pointed and are used in soft materials or for sheet metal, machine screws are under 5/16" are always fully threaded.

I have also heard bolts fasten to nuts and screws fasten to threaded objects, to me it seems ridiculous to change the name of an object based on it's intended use when the applications are so similar and the object is unchanged.

Creating an article that addresses all this seems like a very large challenge, I suspect you would find many conflicting sources. Toasted Meter (talk) 16:56, 9 March 2020 (UTC)

• "If I order a bolt in the UK it will come with a length of plain, unthreaded shank, every time."

Not always. [1] [2] It's just not consistent.

Also note that many suppliers sell "set screws", but they use this for fully-threaded hex bolts, with full size heads. [3] When 'set screw' (as you seem to be using it above) has a long history as a screw with a reduced size head, for use as a clamp screw in shaft collars with limited clearance to the sides.

Also see bolt (fastener). Andy Dingley (talk) 17:05, 9 March 2020 (UTC)

Lag Screw

https://www.youtube.com/watch?v=M99gtHeCBb4 says their Lag screws were hammered in until the last few turns. Can anyone confirm? Wizzy…☎ 16:58, 27 April 2020 (UTC)

It might make sense if you don't have powered fastening tools, it would take a long time to drive it by hand. Toasted Meter (talk) 19:54, 27 April 2020 (UTC)

As a quick and simple way to install a crossbar high on a pole where it's mostly loaded in shear and not subject to significant withdrawal force, it's fine. The proper way is to pre-drill an appropriate hole and to turn it with a wrench. Hammering reduces the gripping power all but the last few threads. One might use a hammer to seat the lag in the hole, but no engineer would endorse hammering one most of the way in if it's a critical application. In this case, up in the air with limited scope for leverage, quick and simple wins. Acroterion (talk) 01:11, 28 April 2020 (UTC)

Good for one screw

I am pretty sure that's a different kind of screw.

https://picclick.com/SILVER-DOLLAR-HOTEL-Large-Brothel-Token-Denver-Colo-224200044859.html#&gid=1&pid=1 — Preceding unsigned comment added by 188.80.214.144 (talk) 18:32, 19 October 2020 (UTC)

Conflicting metric terminology

Here, in the Screw#ISO metric screw thread section it says: "If the thread does not use the normal coarse pitch (e.g. 1.25 mm in the case of M8), then the pitch in millimeters is also appended with a multiplication sign (e.g. "M8×1" if the screw thread has an outer diameter of 8 mm and advances by 1 mm per 360° rotation)."

However in the article ISO metric screw thread#Designation it says "A metric ISO screw thread is designated by the letter M followed by the value of the nominal diameter D (the maximum thread diameter) and the pitch P, both expressed in millimetres and separated by the hyphen sign, - (e.g., M8-1.25). If the pitch is the normally used "coarse" pitch listed in ISO 261 or ISO 262, it can be omitted (e.g., M8). [...] A common error or colloquialism is to use the 'x' or '/' when describing the pitch, so "M8x1.0" or "M8/1" might be seen where "M8-1.0" would be the clearer text to use. Similarly a 30mm bolt with this pitch might be written as "M8x1x30", where "M8-1.0x30 could be used." (Hmm. Also there really is a missing quote in that article.)

Clearly one of those is wrong (I would assume this one, and that hyphen is the correct way.) 82.24.247.127 (talk) 11:22, 20 May 2021 (UTC)