Yes very few 13A plugs can handle 13A continuously. A good manufacturer checks the performance, but even then they are at the mercy of the contact resistance in the socket.
Yes very few 13A plugs can handle 13A continuously. A good manufacturer checks the performance, but even then they are at the mercy of the contact resistance in the socket.
Beautiful. ;-)
Well, we can all make mistakes and if it was a lesson learned ...
(That must have been interesting?)
And in theory, so you (we) should.
Sounds like fun.
;-(
I think it's because they don't think and / or realise that something that looks 'solid' is often very flexible, even something as substantial as a cylinder head or pipe flange.
Yup. There is quite a science in fastness and I'd hate to think (as you say) how many things (typically vehicles) are going around with them incorrectly set? A classic example of where uneducated people sometimes get to play with such things are wheel nuts (both the drivers and the tyre fitters).
I think it all comes under the saying 'You can manage what you can measure' and whilst I'm sure an experienced engineer can get a fastener torque pretty close by 'feel', especially on those fasteners that are not 'critical', the only way you can truly know what torque are applying is to use the tight tool for the job. Even with that there is room for error, like if the figures are given with the fastener used dry and the fitter uses an anti-seize grease or thread locker, without making suitable compensation.
Cheers, T i m
And these days with lead free solder mandated, its not a great way to do anything.
Every way to terminate a flexible wire to a solid post or whatever has problems. Crimps and IDC connections are prone to water ingress and corrosion, solder joints to stress concentrations and resultant metal fatigue.
There is no 'best' way. Just the balancing of a lot of factors and te whole solution needs to consist in all case not just of the joint itself, but the means by which its shortcomings are addressed. E.g. gel filled crimps, or sleeved and supported solder joints.
And I have seen cable end tinning used in a (Datacomms / mobile radio) production environment myself (for several years) with workers on a flow-line tinning the ends of a stranded cable in a 'Tinning pot' pre the cable being screwed into a terminal connector. These were typically transformer winding 'ends' and where a cable form would join a PCB (where the PCB or connected item may need to be easily replaced in the future).
Of course.
And how many strands didn't make it into the crimp etc.
I will often make a joint in 3 stages. First crimp (where possible) to provide the 'mechanical connection. Then I'll solder to support the crimp (electrically and mechanically and to minimise corrosion) and then heat shrink to further help support the cable / connector interface and 'seal' the insulation to the connector.
Ok.
Quite. ;-)
Cheers, T i m
I was taught (i.e. told) to do this when I was about 15. Well worth while for something like a BSA C10 head with, IIRC, 8 bolts. The opposite - if that's the right word - is also true: slacken off a bit at a time. This has the same advantage of not allowing distortion with the added benefit of not undoing n-1 fasters and finding that the last one (isn't it always?) is stuck. Because there's been, say, 1 flat on each, if one is stuck it's simple to redo the others and possibly still use the device. Another thing worth doing - found out the hard way many years ago - is always back-turn self-tappers in plastic or any screw in wood when replacing them. Often the screw is so aggressive that a random start will remove what's left of the thread.
I learned to do so from the Haynes Workshop manual for the Fiat 850 (engine) I rebuilt when I was 15. ;-)
I'd say it's probably not a bad idea on anything retained by 'a few' bolts. I just feel more comfortable first just nipping up all the nuts in a criss-cross order and then fully tightening them similarly. Even with 4 wheel nuts. ;-)
Hehe, yes, it's that often the case.
Yup, good tip. And the same applies to things that have to be removed in sequence. There is no point undoing something that *will* require a new gasket if you can't get it clear, or do whatever needs doing next if you can't also remove another component.
Yup, in fact I did that yesterday (4 self tappers retaining a plastic cover over the start / run caps on a compressor) but I think someone had been there before. I allowed them to find the previous threads but
2 of the 4 I could feel weren't going to nip up but were tight enough to fall out. The clue that might be the case was the plastic still trapped on two of the screw heads. ;-(Now, if it were mine or I wasn't in a rush I would have checked to see if the holes were blind and / or if it was safe to take them deeper and then find some longer or possibly slightly thicker screws and replace all 4.
The other thing you see is people over tightening things like waterproof covers with rubber gaskets underneath where you want to try to minimise the distortion to ensure the seal remains consistent. Instead you see the 4 corners pulled down hard and great big gaps at the middle of the long edges. ;-(
I wonder if 'mechanical feel / empathy' is something you can actually learn?
Oh, the other thing is destroying something useable to fix something else when the straight solution is available and not expensive. It's a bit like say stripping one classic car to restore another ... when it's possible that someone else along the line will want to rebuild the donor. ;-(
Don't get me wrong, I can see the financial and practical merits (I've done it myself) but I don't really like doing so (unless the thing you are taking the parts from is never going to be useable again, like taking the engine out of an otherwise unsalvageable body shell). [1]
Cheers, T i m
[1] We built our kitcar mainly out of one Mk2 Escort Saloon that had been 'lightly' rolled and therefore unlikely to ever be repaired. That said, now you see what price a rusted out Mk2 shell is going for ... ;-(En el artículo , PeterC escribió:
Agreed. Not just self-tappers, but any screw or bolt. Turn anticlockwise slowly until you feel/hear the click, then start turning from there.
Sounds like something someone not familiar with doing up nuts and bolts might do, if done routinely?
I think I might have done it under extreme circumstances (a particularly big or bizarre / plastic thread) but certainly not with the regularity I do with re-fitting self-tappers into (worst case) plastic or thin / soft materials.
Cheers, T i m
Try doing the same thing by pushing a screw into the bundle of sticks and note what happens, report back and let us know.
Don't need to mate as 50 years of doing what I have and seeing it done the same way on a production line is all I need.
However, for your (miss)point to be valid you would have stand on the the sticks, not 'push a screw into them' to make anything like a valid comparison.
The point is, anything tightly bundled (so all parts already in contact) aren't going to be free to move as far when held together (eg, with solder) than they would when left 'free', even when that binding agent isn't as hard as the material itself.
Trap that 'bound bundle' in a confined space and clamp sufficiently and the outcome can only be 'better' than doing so without the extra binding.
It's *only* when the individual strands aren't in close proximity before being tinned and / or the clamping force not sufficient do you get any problems, over an above what would have been there already.
Anyway, I'll carry on doing what I've done (as it works), as and when I feel it is appropriate thanks. ;-)
Cheers, T i m
Seriously, when did you last wire a plug when the wire completely filled the hole in the pin? Unless the wire completely fills the hole your jubilee clip analogy is wrong.
As long as the wire is smaller than the hole the strands will spread when compressed. Solder stops immediate spreading but does nothing to stop delayed spreading.
Tim
That's right. Solder is used because it doesn't stick wires together or to anything else. Stands to reason.
I mean circuit boards have components that gradually work their way out of the board and walk away . Eny Fule Kno That.
Yesterday (well nearly and after I'd doubled it over ). The thing is it doesn't have to fill the hole, it just has to not be allowed back past the screw itself. eg, The available 'void' for the strands shrinks as you do up the screw. However, with fine stranded wire and some cheap screw terminals, it is possible for loose strands to get lost up the sides of the screw and therefore lower the current carrying capacity of the cable at that point. Also more chance of cutting through the strands that do get trapped (because there are now less of them).
Well, not really. The point is that the strands are twisted pre tinning, helping to (mechanically) bind them together. Think of the whipping on the end of a rope.
See above.
See above, unless your understanding of how it works can affect how I've had it working for ~50 years? ;-)
When I get rid of some dead equipment I generally cut the mains lead off and if the plug is moulded on, leave it like that but if it's a re-wireable plug, I remove the wire manually, making it ready to re-use next time. I have a clear storage box full of such leads, plugs, trailing sockets etc.
So, when I remove a plug that I have previously fitted (I can tell from the layout of the wiring, the accuracy of the insulation trim back and the tinning of the conductors (where suitable)), I make a mental note, just how tight the screws still are. I'll leave you to guess what I have found so far. I would certainly notice a burnt wire!
FWIW I designed, built and ran a mobile disco for about 7 years and
*every* plug on all the kit was fitted by me, many of which (because of the low current concerned) used thinner cables and so I tinned the conductors. In spite of them being handled nearly once a week and bounced about in the van, not once did I have an issue (with screw terminals or any connector wiring for that matter).Now, YMMV but I can only tell you how I experience it. ;-)
Cheers, T i m
p.s. If I'm doing anything 'detailed' with anyone who know me, they will generally give it to me to do because they know I'll do a neater job than them. That could partly be because of my dexterity compared with them, my experience with the tools and that I probably pay greater attention to the details than them and will *always* start again if I'm not happy it's the best it can be. 'Thattle do' isn't really in my vocabulary, especially re things like that. Whilst it generally works out for the best, it does take more time (for me).
It was a tremendous experience, which I had never anticipated. I finished my apprenticeship at a small garage near Maidstone and wondered what to do next. Someone said, they're looking to hire guest workers in Germany. So I wrote to Ford-Werke (in German, using what little of the language I knew at the time), they invited me to Cologne and paid for my petrol and provided free accommodation in a Ford hostel. I did the interview, and two weeks later they offered me a job. The Prototypenbau was about as far removed from the little garage in terms of working practices as it was possible to get. It was almost as clean as a laboratory for a start. Safety was paramount. Before moving under a vehicle on a hoist a foreman had to check that it was safe etc etc. Even the tiniest drop of oil spilled on the floor had to be wiped away immediately. I got paid very well indeed compared to Maidstone. Later I had studied enough spoken and written German to move on to the salaried staff as a technical translator, never got my hands dirty again -- except when wiring plugs -- and was paid a lot more!
MM
If I had my time over again I would restore classic cars for a living. Have you SEEN the price of these nowadays if in concours condition?!! I had several old cars, some pre-war, even before I was legally old enough to drive. Look at what you have to fork out now, even for a pre-war Austin Seven.
MM
Yes, malleable (in the sense of rubber etc.) gaskets are rather 'delicate' in this way. I also found out that using any form of grease on a gasket can cause leakage, or at least more so than with just a dry gasket. Possibly the grease is compressed in voids and stops the gasket being fully deformed. The exception might be a /very/ thin coating (wipe on - wipe off) of silicone grease in plumbing.
I seem to have it 'naturally', but that's more likely to come from p'ing about with stuff from a very early age. I once removed and replaced the head from an old car, open-ended spanners, torqued up from memory of undoing. Got it to work, checked with a torque wrench, all moved a minute amount ecept for one that went one flat - failure!
Not usually necessary with metal, but the spring-loaded top of a 376 carb., under the tank, definitely? I used some Turbo Ultra wood screws. Removed one and a load of wood came out with it - that was turned to engage!
Hmm, I guess given the right facilities it could be ok. I say that because I have already done my share of repairing rusted monocoque and can't say I really enjoy it.
Yup, a feeling made worse with the knowledge I cut up and gave to the scrap man a reasonable (by today's standards, worth nothing at the time) Mk1 Escort 2 door shell when building the kitcar and sold my 2 Morris Minor vans and Mums 4 door saloon for next to nothing.
Maybe people in the know are just fed up with all this 'automatic' stuff you get on cars these days and want to take back some control and actually driving the things themselves again. ;-)
I really do think we are being isolated and insulated from the outside world more and more and modern cars are a classic example of that. It's as if people want to be sitting in their lounge but able to go from A to B? It may be something one might appreciate when you get older, don't actually enjoy mechanics / driving or have to regularly drive long distances.
On that though, I think my Mrs is a better bike rider than car driver (and she's admitted the same) and I think that's because when on a motorbike you are very much aware of your surroundings and have to focus more on the actual process than you do in a car, making you more involved (the reverse of modern 'automatic everything' cars).
Cheers, T i m
En el artículo , PeterC escribió:
I find it helps prevent cross-threading, especially if the bolt or nut is a bit reluctant and you're not sure if it's just stiff due to crap on the threads (e.g. on a car) or the beginning of a crossed thread.
It also works for spark plugs - something you really don't want to cross the threads on.
Could be. Again, I am often obsessive with the cleanliness of such mating surfaces and will remove location dowels and put the item on some fine wet and dry on a sheet of plate glass to remove an high spots and burrs. If I can do that to both surfaces all the better and I don't think I've ever had anything treated like that leak afterwards. It goes from that to using (red) Hermetite (and new gasket) when the surfaces are less than ideal.
I know some people use the silicone 'Instant Gasket' and I have once or twice but I find it too messy for general use. I have sheets of gasket paper and would rather make my own than use Instant gasket because I prefer the idea of something 'stable' in the joint.
Same with me then possibly. That said, both my Dad and his Dad were d-i-y craftsmen (carpenters) and many people of my age (and background) also had to get involved in stuff, simply because there wasn't an affordable alternative? My Dad had company cars so he never got involved in their upkeep (outside the routine checks) but as I generally 'found' my vehicles (people offered them to be broken / cheap) I gained an interest in getting them going as well (along with electrical items etc) for my own use.
Hehe. I think that would count as a big pass! (considering). ;-)
Cheers, T i m
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