Talk:2880: Sheet Bend

Why is this called a "sheet" bend? SystemParadox (talk) 21:17, 12 January 2024 (UTC)

I don't know the full answer but it's a sailing thing: the 'sheet' is the rope you pull in or let out to control the position of the sail. I guess bend describes the category of knot. 172.70.90.48 21:23, 12 January 2024 (UTC)

NO NO NO. The sheet is the sail. JohnB (talk) 21:36, 12 January 2024 (UTC)

It is the rope - Sheet (sailing). "In sailing, a sheet is a line (rope, cable or chain) used to control the movable corner(s) (clews) of a sail." 172.71.242.5 21:56, 12 January 2024 (UTC)

Huh. Dueling Wikipedia articles. The Sheet_bend article has a definition section that says the term "sheet bend" derives from its use bending ropes to sails (sheets). But the Sheet_(sailing) article says a sheet is a line used to control the movable corner(s) of a sail. JohnB (talk) 23:08, 12 January 2024 (UTC)

The sheet bend is named for its ability to to secure a sail, or sheet. You fold over the corner of the sail and that's one of your "ropes". The sheet bend is generally used as a knot for tying a large, inflexible rope (or rope-like object) to a smaller, more flexible rope.172.69.70.22 22:30, 12 January 2024 (UTC)

I would take the Ashley Book of Knots as authoritative. Sheet Bend is the first knot in the book, and is always (in modern terms) rope-to-rope, not to sail. It is one of the basic knots. https://en.wikipedia.org/wiki/The_Ashley_Book_of_Knots https://en.wikipedia.org/wiki/Sheet_bend

-- PRR (talk) 04:04, 13 January 2024 (please sign your comments with ~~~~)

But what dispute are you taking TABoK's authority on? Two things can have the same name in different contexts (or namespaces). And does Ashley use anything other than ropes exclusively in the whole book? 108.162.241.170 14:42, 14 January 2024 (UTC)

I added a link to the wikipedia entry, it explains the name. Barmar (talk) 21:25, 12 January 2024 (UTC)

Presumably the "different loads" title text is a pun between electrical load and mechanical stress on the knot? Jim-at-home (talk) 21:56, 12 January 2024 (UTC)

A sail is never, and was never, properly called a "sheet", since at least the 13th century. The Wikipedia explanation of the name is misleading. According to https://www.etymonline.com/word/sheet, it's "shortened from Old English sceatline "sheet-line," from sceata "lower part of sail," originally "piece of cloth," from same Proto-Germanic source as sheet (n.1)." Jlearman (talk) 17:44, 13 January 2024 (UTC)

When I took a sailing class as a kid they used the word “sheet”, I think it was the lines connected to the sails used for adjusting them? 108.162.245.82 19:46, 13 January 2024 (UTC)

“silver being joined to silver and gold being joined to gold within the insulating white cable” is not the conventional way to join cables. Unless you are joining one cable to itself (like a Möbius strip), you have two cables with insulation. And usually you use non-cursed connectors, where you first remove the insulation at the end of the cable and then crimp or solder the conductors to metal parts of the connector; or solder the conductors and then add a different type of insulation for protection; or use screw terminals;... Only with insulation displacement connectors you keep using all the insulation of the two cables. And finally, conductors are usually copper or aluminum, and very rarely silver and gold. --162.158.94.141 08:45, 13 January 2024 (UTC)

I think the gold and silver is just color coded for the reader. Not that they are meant to indicate that the conductors are made from this material. Apart from that you comment sounds like you know what you are talking about. So please improve the explanation if you can. --Kynde (talk) 10:58, 13 January 2024 (UTC)

I changed it to gold- and silver-colored. It was obvious to me that it was the colours used in the comic that were being referenced, but fixed for the avoidance of doubt. The join being made within the one cable was clearly an error though. 172.70.85.161 22:13, 13 January 2024 (UTC)

cables often have the signal parts copper-colored (described gold atm) and they are obviously copper, and the outer ground more the color of steel or something, not sure what metal it is, but it’s easy to solder like copper or silver is, not aluminum which is very hard to solder. usually gold and silver are used at the contacts of a connector, not inside a wire, i don’t know who would ever make that mistake. 108.162.245.83 19:49, 13 January 2024 (UTC)

"more the color of steel or something, not sure what metal it is, but it’s easy to solder like copper or silver" Traditionally tinned copper. Tinned not just for identification, or easier soldering, but because early rubber insulation actively rotted copper and tinning slowed the damage. Many sorts of damage, why much copper today is silvery. PRR (talk) 04:16, 14 January 2024 (UTC)

Not wishing to spoil it, but the series finale of a certain radio comedy reveals... ah well, that's the spoiler (in the article, if you read that far down... rather than just listen to it if you haven't heard about it already but now think you like the premise). 172.69.79.188 21:01, 13 January 2024 (UTC)

Okay I looked at the wikipedia article and the knot depicted in the comic looks like a right handed one. I still don't know why it's called right handed, or why the left handed one is insecure.198.41.236.207 11:46, 13 January 2024 (UTC)

It's not. Ropes and heavier ropes (called cables) are commonly made by twisting smaller ropes together, the twist direction (terminologically the 'lay' of the rope, (s-laid or z-laid)) is the main thing (that I know about) that can make chirality (handedness) of knots important to their strength. Electrical cables and wires aren't usually expected to have any tensile strength, and their tensile components aren't usually twisted in a way that would affect their strength. (Sorry for all the parentheticals.) 108.162.241.130 14:56, 14 January 2024 (UTC)

A note I nearly added in the bit about short-circuits (or, as I added, 'un'circuiting) is that the electrical behaviour of the knot is different according to which 'end' slips. If the left-side cable 'slips through' enough, then its gold and silver bits of sheath could contact (would short-circuit any current driven at that side). If the right-side cable slips out, it is in no danger of doing so for a right-driven current (it would just disconnect). That ignores the cross-talking that could occur (on one conducting line at a time, so may not matter if there's no external ground-return element, except as far as not being a proper connection any more), or both ends slipping (where one of the LHS sheaths might shuffle into a position to bridge the two RHS sheaths). But, as tied, the LHS silver (being bent in and out of the page around its crossing counterpart wire) seems unlikely to be pressed against both gold and silver, should it trivially untwine/slip through. Actual studies with actual knots might be useful. I thought I had a spare length of unterminated Cat5, nearby, but apparently (k)not... that, with some coloured permanent marker-pen marks made upon it, would probably have made a decent analogue for visual analysis of failure conditions. Maybe I'll de-plug an old cable (I've got a number of damaged USB cables I could chop, but their being thinner would change the scale and dynamics of the knot, meaning I might as well just use a scrap of twisted-pair internally-sheathed strands). – But I thought you'd like my mind's-eye analysis of the knot behaviour, before I get around to trying anything practical to this end. 141.101.99.7 17:08, 13 January 2024 (UTC) (<- ex Cub-/Boy-/Venture-Scout, but never got any Knot Untying badge... that brief stint with escapology aside... ;) )

This comic contained material familiar to a hobby engineer that was cast critically and derogatorily (e.g. “sheety” bend) throughout the explanation. I edited a lot of it. I’ve seen this happen repeatedly in other explanations. I don’t edit most of them. 172.71.150.155 18:41, 13 January 2024 (UTC)

"this is a scenario commonly encountered by hobby engineers from the last millenium" "commonly"? Can any hobbyist engineers from the last millennium attest? Also, this sounds ageist - is it ageist? 172.70.86.166 21:56, 13 January 2024 (UTC)

Well, I definitely did electrics/electronics pre-millenium. I'm not at all unhappy with the idea with the possibility of an occasional 'bodge job' connection having happened (e.g. tying a cable in a simple knot, in suitable cases, to add mechanical resistance to any further tendency for a cable to be tugged out of a grommit-hole and the core conducting wires being tugged out of whatever terminal/patch-block they need to be connected to - or, more likely, pulling the core copper strands beyond their tensile limits).

Although (while I respected the idea of this being based upon a repair-bodge), I don't see this as a "this wire was damaged, this is how the two ends are reconnected", but rather as a deliberate cable termination method (like adding moulded plugs/etc) which could then be mated end-to-end with another similarly terminated cable. (Like using a gender-changer 'double-socket' between two phono-ended lengths of cable, or using a BNC T-connector just to join two lengths of networking cable but without the need for the extra connector and adding intrinsic tensile resistance - though actually not as much as the BNC 'bayonet' version already does...)

If I was writing this from scratch, I'd actually remove all the 'repair' aspect of it, TBH. It looks more like a deliberate patch-type cable (1x2core) manufactured to be directly and hermaphroditically compatible with any other such cable, tied together without the need for tools (screwdrivers, crimpers, punch-downs, etc) and untied as and when required (at least as easily as any similar rope-knot can be undone, which isn't always a given if mishandled and overtightened).

I'd also be looking at various knots and working out which (if any) could support more than two contact-patches/sleavings per cable, for three-core or more-core connections between any two such cables. The geometry of the knots would define roughly where (and how long) the external contact-sleaves would need to be (presumably identical for both cables) such that they made appropriate connections between the two halves (cross-overs could be allowed, but that'd have to be down to the IEEE specifications of how to detect/interpret RX/TX assymetry at the end devices, etc). But then I'd also be writing a vastly more complicated alternate explanation. Perhaps just remove the bodge-job implications, someone? Clearly it's not an end-user bodge. Though it could be a manufacturer/industry bodge (such as using an 8P8C connector for essentially 6P4C purposes). 172.69.79.138 00:53, 14 January 2024 (UTC)

I use the reader app in inverted color mode, so I could not for the life of me figure out what all the discussion about silver and gold was about. Also, can I just comment on how the conductive sleeves are magically flexible? I wonder if they are braided. Even then, this would severely limit how tight the knot could be pulled. 162.158.154.238 13:26, 14 January 2024 (UTC)