JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,907
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Post by JonL on Jul 5, 2020 20:06:01 GMT
I look at a lot of the engineering going on in these threads and find myself intimidated by the excellent quality and workmanship. I thought I would start this thread as a cathartic "great leveller":
What's the biggest foul up you've made whilst engineering?
I'll start you with a minor one (I've got enough to write a book...): I was once working on a classic race car with knock off wheels. As I bashed the ears of the spinner to loosen it off I didn't check the path of the hammer head and bashed one of the metal valve stems, snapping it clean off. I then had to take the wheel to the tyre fitters to get the valve changed (with my bosses shouts still ringing in my ears), get it swapped, bring it back and refit it. As I refitted it, I then did exactly the same thing again....
Come on chaps, show me you are humans and not CNC machines made flesh...
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smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
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Post by smallbrother on Jul 5, 2020 20:45:05 GMT
I once had to draw up a scheme to line a stretch of a small river in Carmarthenshire with rocks to prevent erosion.
My employer, NCB Opencast very kindly agreed to buy a book on the subject which I read from cover to cover. Did all the calcs, sized everything up and prepared the scheme.
First decent storm it all washed away.
Pointless me talking about model engineering as just about everything goes t*ts up!
Pete.
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Post by silverfox on Jul 5, 2020 21:24:16 GMT
Nobby Building a loco that no longer exists is a risky business. Through years of seeing finished locos where the Engine was excellent but the tender seemed to be a 'BMC Friday afternoon' job just so they could get it running, i decided to run both together but e tender than loco. I would urge anyone building a tender that 'doesn't exist' to do a lot of homework prior to cutting metal. My Choice of loco was the LNER B17 and when i found out that there were plans i grabbed them with both handsThe only difference is that The one i wanted to do had the shorter GE tender, BUT luck was at hand, one exists behind the B12 on the and two trips were made with copious pictures taken and the assistance!! of Martin EvaNS designs of the B12 and D16 got me started I then found out there were two locos already built Mike Sheils in Ipswich and Graeme Ainge of the NLSMEE Again lots of pics I Ten found out that like Bulleids Pacifics tenders, there seemed to be more designs and variations than locos!! No 1 error was that the front of the B12 tender bore no resemblence to the B17 so that had to be changed Then halfway through that, i noticed that the two existing models had different tender styles .... Oh which one was mine??? I then found a picture of the loco i was doing, and there was another variation!!!!! However the coping was not clear enough to even make a guess. So Version 2 remained fallow for a while. Then a copy of another B17 came to light with the same tender and was side on rather than the stadard 3/4 front view Everything became clear EXCEPT my tender looked longer that the one on the colour pic AAARRGH Last year i contacted the MRM and paid a visit to the research room THREE trolleyfulls of works drawings were made available and over 100 pictures taken. BUT there was nothing showing the extended coping on the RHS ,which did not appear on the LHS in the picture of the same loco.AND the frames were different to ME design nt by muxch but it showed!! I am now on Version Three In fact the only parts that remain from Version 1 are the Wheels,axles and axleboxes ( amended from V1 when i got plans from the GERS!!) tender sides (but now shortened by about 1.5inches... Thanks Martin!!) and the rear. Everything else has been redrawn. The good news is that on the side elevation of the tender there is a very feint outline of the heightened RHS coping BINGO.. Even the water scoop and Tender Brake standards have switched sides There is only one toolbox, not two and that is side on and not end on. Evenb the Disc holder and spare lamp brackets are different It has taken me several weeks , and more, to get it all right .Pretty certain tbAt it will be as near as possible to the original. You will note the gluge on the RH cylinder casing That will be on my loco, so in advance no snidey comments OK? lol imgur.com/a/CJdYLtc#cRGX5kLimgur.com/8pJgsRKimgur.com/rPUEsAG |
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Post by springcrocus on Jul 5, 2020 21:36:31 GMT
What's the biggest foul up you've made whilst engineering? Start a diary... 
Regards, Steve
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barlowworks
Statesman
Now finished my other projects, Britannia here I come
Posts: 874 
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Post by barlowworks on Jul 5, 2020 22:40:36 GMT
My Britannia was built for the western region and one of the modifications when built was to fit western lamp irons to take the western lamps which mount on the side not the back. Of course, when I did the four lamp irons for the back of the tender I made them all the wrong way round.
Mike
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Post by Roger on Jul 5, 2020 22:52:49 GMT
I tend to go for quantity rather than size when it comes to cockups. Snapping off a 16mm milling cutter was quite exciting though as was rapidly traversing the cross slide into the work rather than away from it on one occasion.
I repeat the same mistakes, just to make sure I get the proper amount of annoyance from them.
Mistakes are just part of the job, and nothing to worry about. I swiftly put any annoyance behind me and move on. There's no point in dwelling on what you can't change. Just learn from it.
Don't go away with the idea that someone's work is always wonderful and free from error. That person has never existed and never will. If it's good enough, I keep it. If it isn't it goes in the bin. Some work is better than others, that's just the reality of making things.
I did witness a classic cockup in a PCB factory in Russia where I was commissioning a programming machine. I think it was Marconi who were installing a bare board test machine, but they just couldn't understand why the adaptors wouldn't fit. It turns out that although Russia had copied all the integrated circuits from the West, and also the production equipment, they'd done it all in Metric units. So their chips were on a 2.5mm grid and not a 2.54mm grid. That doesn't sound like much, but over a distance it mounts up to a cockup that meant the machine was useless.
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Post by ettingtonliam on Jul 6, 2020 7:16:20 GMT
My Britannia was built for the western region and one of the modifications when built was to fit western lamp irons to take the western lamps which mount on the side not the back. Of course, when I did the four lamp irons for the back of the tender I made them all the wrong way round. Mike If thats the biggest mistake you've made, you have led a charmed life! My grandfather, a colliery enginewright, used to say 'The man that never made a mistake never made anything' When I was a contractor's site engineer working on a new power station, I had to build 4 cable chambers, one at each corner of a new bridge I'd just built. These were quite large, about 6m x3mx 3m deep, in reinforced concrete. There was only one drawing, covering all 4, but they were 'handed' with the cable cut outs in different places. When the shuttering waas stripped from one of them, I realised that I'd got the cut outs in the wrong places. I went to the site agent and 'fessed up', with a reasonable expectation of being fired, as was the practice of the day when junior staff fouled up. All he said was 'Has the clerk of Works seen it?' When I said no, he hasn't, the Agent told me to backfill it quick, before anybody does see it, by the time the cable layers come along in about 3 years time, we'll be long gone ----. |
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Post by simplyloco on Jul 6, 2020 7:40:47 GMT
When we machinists foul up it's usually on just a piece part. At the Stratford on Avon base workshop I was tasked with grooving the ends of lots of 8" dia. steel pipes to take a victualic coupling. IIRC the groove was 1/2" wide. The lathe was a huge Churchill, one end of the pipe held in the three jaw, and the other in a fixed steady. After the hundredth one or so I got bored and lazy and didn't clamp the steady shut. The tool dug in and this 8' long pipe described a few conical arcs and then flew across the shop! I was not in the way, fortunately... www.victaulic.com/products/style-877n-quickvic-installation-ready-flexible-coupling-for-potable-water-applications/ |
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timb
Statesman
Posts: 512
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Post by timb on Jul 6, 2020 8:36:23 GMT
Difficult for me to resist this.
As an electrical engineer of course we are practically perfect in every way, HOWEVER.....
A large installation of a uniquie piece of plant of our design had just been installed and commissioned over an 18 moth period. An excellent piece of kit for the flagship factory which would improve production and flexibility ten fold - worked very well. On this particular occasion the kit was being 'Opened' by the head honcho who had flown in from South Africa along with an entourage of about 150 of the top brass. The kit was working well but the main panel was getting warm and I was concerned that some of the inverter drives were going to overheat and fail. There was a built in air conditioning unit which had not kicked in so I opened the doors of the panel to let the air cool and circulate naturally thinking i wold check tha aircon later, this did the trick. Whilst waiting for the visitors one of the factory managers had a pre check walk around and asked why the doors were open, I explained what was happening but he was adamant the the doors must be kept closed. I decided that it would be a good idea to have a look at the aircon unit. Well as luck had it the plug was out, simple just plug it back in which I did.
Well the blue flash and smoke led me to believe that something was definitely amiss.
All the lights went out and the plant stopped, I don't know if I was more concerned about this or the black soot on my arm which replaced the hairs that were there, and the throbbing in my head along with muted sounds in my ears. There was a bit of a panic as the top brass had arrived and were in a presentation in the office block (thankfully on a different circuit). After the initial shock wore off I went into repair mode and started to get things back in place for a restart. Fortunately all the discrimination calculations I had done were right and only the immediate circuit breakers were tripped protecting all the kit (the main isolator was a 260A fused switch - no spares!). Thankfully the plant was up and running again within minutes - seemed like hours. The rest of the day went without issue and was a great success.
I looked at the aircon unit the following day. It was(is) a three phase unit with ability to connect in star or delta for the main fan. For those that know, it was connected in star but whoever connected it put the three phase cables to the side with the shorting bars effectively shorting the three phase together.
Not exactly model engineering but hopefully of some amusement, I am not able to go to that plant without someone reminding me of the occasion!
Tim
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barlowworks
Statesman
Now finished my other projects, Britannia here I come
Posts: 874
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Post by barlowworks on Jul 6, 2020 11:03:13 GMT
My Britannia was built for the western region and one of the modifications when built was to fit western lamp irons to take the western lamps which mount on the side not the back. Of course, when I did the four lamp irons for the back of the tender I made them all the wrong way round. Mike If thats the biggest mistake you've made, you have led a charmed life! My grandfather, a colliery enginewright, used to say 'The man that never made a mistake never made anything' When I was a contractor's site engineer working on a new power station, I had to build 4 cable chambers, one at each corner of a new bridge I'd just built. These were quite large, about 6m x3mx 3m deep, in reinforced concrete. There was only one drawing, covering all 4, but they were 'handed' with the cable cut outs in different places. When the shuttering waas stripped from one of them, I realised that I'd got the cut outs in the wrong places. I went to the site agent and 'fessed up', with a reasonable expectation of being fired, as was the practice of the day when junior staff fouled up. All he said was 'Has the clerk of Works seen it?' When I said no, he hasn't, the Agent told me to backfill it quick, before anybody does see it, by the time the cable layers come along in about 3 years time, we'll be long gone ----. That's just the one I will own up to. When I was paving I once put out some traffic lights, went through a telephone cable and hit a water feed to a shop when pinning out a kerb line, not bad for 5 pins.
Mike
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Post by ettingtonliam on Jul 6, 2020 11:04:39 GMT
Didn't happen to me (luckily) but a colleague was responsible for setting out a motorway bridge which was to be built ahead of the carriageway works, which were to be done once the bridge was up. All proceded according to plan, the bridge was up, and the earthmoving operations were approaching. At that point it was discovered that the bridge was 10m to one side of the correct position, so the central columns, instead of being in the central reservation, were in fact in the middle of one of the carriageways.
My colleague realised that something was wrong before anyone else did. He'd already got a job offer for the Middle East which he'd been considering, so he went into the office, tendered his resignation and walked out, before the shouting started. On the next available plane to Dubai.
Attempts to realign the carriageway to suit the bridge were not acceptable to the Department of Transport, so down it had to come!
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mbrown
Elder Statesman
Posts: 1,718
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Post by mbrown on Jul 6, 2020 13:46:20 GMT
The only engineering I do is model engineering - and like Roger, it's more about frequency of mistakes rather than ultimate impact. .... You wouldn't believe how often I set out to make a matched pair of some part and end up with two right hand (or left hand) ones... (well, maybe you would believe it!).
Malcolm
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Post by jon38r80 on Jul 7, 2020 11:57:48 GMT
My favourite is forgetting which way to turn the handles on my mill and wrecking a workpiece when I have almost finished it. Usualy because I have got bored or tired doing repetitive cuts. It is quite surprising how frequently this happens.
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smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
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Post by smallbrother on Jul 7, 2020 20:10:42 GMT
My favourite is forgetting which way to turn the handles on my mill and wrecking a workpiece when I have almost finished it. Usualy because I have got bored or tired doing repetitive cuts. It is quite surprising how frequently this happens. I am constantly expecting the worst to happen. I cannot relax at this game and find I can only cope with an hour or so of model engineering at a time. As soon as I drop my guard and relax I know something major will go wrong. When something turns out OK its like achieving an exhausting physical exercise for the first time. Nice, but time to relax and do something else for a while. Pete. |
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Post by andyhigham on Jul 7, 2020 20:40:47 GMT
I was re building a cooling tower control panel at a major insurance underwriters in the square mile (the one with the Lutine bell)
I had stripped out all the old components leaving just the isolation switch, the mains cables disappearing through shaped tufnol in the base into the bus bar chamber below
I was marking out for new components using my favorite Rabone 6" rule, I dropped it and it dropped through the around 1mm gap between the tufnol plates, BANG, a blinding white flash, smell of burning arm hair and the building went into darkness.
There wasn't much left of the rule and my ears were ringing for the rest of the day. The copper busbars were blackened but un damaged, the breakers reset and power restored in less than 1/2 hour
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JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,907
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Post by JonL on Jul 7, 2020 20:56:45 GMT
My favourite is forgetting which way to turn the handles on my mill and wrecking a workpiece when I have almost finished it. Usualy because I have got bored or tired doing repetitive cuts. It is quite surprising how frequently this happens. I am constantly expecting the worst to happen. I cannot relax at this game and find I can only cope with an hour or so of model engineering at a time. As soon as I drop my guard and relax I know something major will go wrong. When something turns out OK its like achieving an exhausting physical exercise for the first time. Nice, but time to relax and do something else for a while. Pete. When I find I'm starting to make silly mistakes I tend to call it a day, I'm usually getting tired and once your concentration starts to drift you might as well give up before something annoying happens... |
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Post by ettingtonliam on Jul 7, 2020 21:42:23 GMT
I was re building a cooling tower control panel at a major insurance underwriters in the square mile (the one with the Lutine bell) I had stripped out all the old components leaving just the isolation switch, the mains cables disappearing through shaped tufnol in the base into the bus bar chamber below I was marking out for new components using my favorite Rabone 6" rule, I dropped it and it dropped through the around 1mm gap between the tufnol plates, BANG, a blinding white flash, smell of burning arm hair and the building went into darkness. There wasn't much left of the rule and my ears were ringing for the rest of the day. The copper busbars were blackened but un damaged, the breakers reset and power restored in less than 1/2 hour On a much smaller scale, I was changing the power points in an old house from round pin to square pin. The house had been sort of rewired by the previous owner. He hadn't changed the power points because all his appliances were round pin, and he was too mean to change the plugs. I switched off the main power (or thought I did) by throwing the switch on the side of one of those big, old fashioned cast iron isolating switches, and set to work. Suddenly there was a blinding flash and my screwdriver shot across the room, with the end melted off it. When my eyesight came sort of back to normal, I went and looked at the isolater again. When the rewire had been done, he'd run some cables alongside the cast iron box, so close that they stopped the switch lever from opening fully. It looked like it was in the off position, but it wasn't quite, so the contacts were still closed, not open. Apparently with this sort of switch, you should hear a loud bang when the spring loaded contacts open properly, and this hadn't happened. I was lucky that day, but it was a couple of days before my eyes went back to normal, like having had an arc flash when welding. |
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timb
Statesman
Posts: 512
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Post by timb on Jul 8, 2020 8:27:14 GMT
It looked like it was in the off position, but it wasn't quite, so the contacts were still closed, not open. Apparently with this sort of switch, you should hear a loud bang when the spring loaded contacts open properly, and this hadn't happened. I was lucky that day, but it was a couple of days before my eyes went back to normal, like having had an arc flash when welding.
Lots of these isolators still in service, I am not sure of the make of the one you have but most houses used the 'Bill' type - large ally casting with a lever on the side. Fortunately the regs have outlawed these in favor of PGC or positively guided contacts that disconnect almost before the operating handle moves.
A good reason to never trust leccy, always test with a known good meter before applying fingers!
Glad you are now OK, that could have been nasty!
Tim
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Post by Shawki Shlemon on Jul 8, 2020 9:09:41 GMT
I have so many , I don't have time or even remember them to mention them here . If you make mistakes all you do is you prove you are human .
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Jul 8, 2020 11:25:30 GMT
I had a few of near electrical disasters in my career which I will own up to.
A fault had developed in an HV cable at an air force base and we needed to know where the fault was. I was the electrical engineer consulting to an insurance company who were anxious to minimise their loss. The loss could have been compounded if the Defence department had insisted upon replacement of the full length of cable. I engaged a specialist subcontractor who had a test van with fault location equipment. Working with the installation contractor we identified the circuit switch (11kV) and proceeded to remove the back panel so we could run a voltage probe onto the live connections. I was standing beside the panel when this expert went to reach into risking contact with the live connections My reaction was to shoulder him out of the way. I had seen enough photos and reports of similar incidents to know that he would most likely have been killed and I would have been badly burned.
BTW, we did find the fault, some clowns had planted a row of trees along the road verge, one hole was there with no tree just where the cable crossed the road.
Another incident occurred at home. I had switched off the circuit breaker in the house board to work on the lighting circuit. Thankfully the switchboard door squeaked when opened or shut. I was busy up in the roof when I heard my daughter come home. She must have entered the house and seen the lights didn't work. The next thing I hear is the squeak of the switchboard door. Instantly I dropped what I was doing and slithered out of the roof space to meet my daughter returning from closing the circuit breaker. Thankfully I can't recall what I said. Now I tape the circuit breaker open when working on circuits; and any work in the roof space I ensure my wife is home.
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