IE, "The nut that holds the handwheel".

Don't assume it is only self-taught beginners who drop clangers. I was told very early on that a good tradesman is not one who never makes a mistake, but is one who knows how to fix his mistakes. (Or at least hide them. Which means he probably won't post them on the internet for all to see!)

Here's one: Very early on in my chequered career I had the job in a car assembly plant toolroom in Zimbabwe to machine up some quite a few dozens of cast iron trolley wheels to run on an overhead track to carry car bodies along the production line from hangers. They were rough castings about 6" diameter, flanged like a train wheel and had to be machined all over and bored with a recess to take a big 4" or so diameter ball bearing. So I machined them all up over a week or so, then gave them to one of the African apprentices to press the bearings in. But somehow I had managed to bore them all a thou or two too tight so when they were done, the bearings would not turn, they had closed up with the pressing in. So we had to press all the bearings back out again, set each and every wheel up true in the four jaw chuck painstakingly, and skim about two thou out of each bearing recess then reassemble.

Never did tell the foreman. He just thought i was painfully slow at getting the job finished. As an old Glaswegian tradesman out of the shipyards once told me "Just act dumb and you will always get by". (In that particular case I did not have to act too hard!)

Here is what I am talking about, hiding your mistakes. The ball on the end of the handle on my lever tailstock was SUPPOSED to be just a perfect sphere with a flat on it where the handle screwed in. But in my faffing about, I set up my jury rigged ball turning tool about 75 thou too far toward the end of the blank, resulting in the bit left sticking out where it joins the handle as seen in the above pic. It looked pretty ugly with a V groove in it from the turning tool and flaring out. So rather than scrap the job and start all over again, I simply turned the most of it down parallel as seen and blended the small remaining V groove in with a file. Until it all looked like that is how it was supposed to have been in the first place.

It was good enough to fool most of the people most of the time and made it onto the front of MEW so can't have looked too bad! Looks quite the part with a lick of paint, which covers many sins. Sometimes you get lucky.

Yes, when I get to thinking, I could write a book…

I was working in a shop that made geological exploration sondes. I had to machine a flat on a cylindrical diameter that was part of a longish complex component called a caliper body. I'd already set it up on a Bridgeport, in a dividing head with tailstock support to drill, then ream or tap, a number of holes in angular relationship to each other and the flat, which was the last feature to machine. I think the piece already had several hours of machining time done on it.

I used plastic tape to wrap the divvy head chuck end of the part to protect the existing finish.

When the endmill hit the cylindrical diameter to cut the flat, the workpiece rotated in the chuck, gashing teethmarks in the end face of the diameter and bending the slender protruding end diameter. Obviously I should've foreseen it, but my mind was more on the holes when deciding on the setup.

It was only because of the clock-and-mallet skills of the chargehand (an otherwise quite unpleasant man disliked by most of the machinists) that the bent bit could be rectified within a few tenths, the teethmarks machined out without loss of function, and I managed to keep my job.

That was 1976. I can only talk about it now because I've lived it down in my own mind since, and seen others, who should also have known better, make hugely more expensive mistakes.

My guess is that it happens to most engineers. They always say that anyone who never made a mistake never did owt that mattered.

Edited By Mick B1 on 09/03/2023 13:36:51

Many many mistakes both at work and in the home workshop, but one of the most amusing to the rest of the workforce was when I was asked to measure up and order some stickers to go on some electrical switchgear control boxes saying " Danger equipment fed from two separate sources" or some such. Never having ordered anything like this before I measured very carefully and as the boxes were quite small decided that 100mm x 150mm would be most appropriate,ordered 1000, filled out the supplied form and forwarded to the department that printed our signs. A week or so later came the message " theres a truck in the loading bay with stuff for you, where would you like it put, as soon as the forklift is free we'll shift it for you". Puzzled, went to the loading bay to find several very large heavy boxes waiting for me, on opening found 1000 huge signs 1m x1.5 , turns out the form carefully filled out was clearly in cm not mm! Boss took it remarkably well, the boxes were carefully hidden and were still there as a constant reminder when the firm closed down a few years later, every so often a huge sign would appear stuck across my locker or draped across one of the machines, Still get reminded of it forty years on!

Edited By Dave Wootton on 09/03/2023 13:54:16

Edited By Dave Wootton on 09/03/2023 13:55:28

Mine are far too many, and too embarrassing to enumerate. One place I worked backed onto the canal. Rumour has it that barges would go aground on bits machined in error and chucked out the window to avoid the foreman's wrath.

Hi, yes I've made many silly mistakes, both at home and at work. The last one I remember making in my final day job, was cutting up material which only enough was ordered each time on one customers items which were made on a four to six week periods, depending how quick they would wear the previous ones out. Cutting up the material, which was 25mm dia. EN8, meant putting aside four uncut lengths four each of four fabs, as their lengths were cut at the end of each fab. I then had to cut 40 short lengths and eight long lengths, but! eight lengths had to have three short lengths and one long length cut, however, I must have got a bit carried away cutting the short lengths first, but I realised just in time that I wouldn't have enough material to get the four longer lengths. The next but! was, what was left over was not long enough to complete the number of short lengths, and butt welding any bits together was unacceptable, however, I was lucky enough to find some odd off cuts in the stock shed that would complete the job, but. yes there was a third one, two or three of them were about 20mm shy, however, this is where fortune shined on me, as all the short lengths had to have a short section bent to a right angle at one end, which can be seen in the photo below. This sort section is where all these short lengths were welded to each of the four uncut lengths and this bent section could tolerate the odd shortcomings here, and so the mistake could be to some degree hidden by not putting them all on the same fab. Needless to say I had to deliver them to the customer the day after the were finished and no comments or complaints were made from them.

Regards Nick.

Edited By Nicholas Farr on 09/03/2023 15:55:40

Best I can remember at sea was the entire engine room staff trying to get a cylinder head off the main engine. Swarming round frantically, the main hoist pulling at it, chainblocks, hammers, iron bars sweating, aggression, desperation

I only watched for a couple of minutes then made myself scarce

It took a while until someone noticed it had been welded on

Not me but a work collegue, tasked with milling a flat on the telescope of a brand new Theodolite. ( Maybe £3000 worth) It was duly strapped down on the mill table and the shell end mill starting to cut when it caught and threw the the Theodolite out onto the floor. Frantic check of theodolite and then reset on the mill and double clamped. Then succesfully machined Much touch up needed but ended up OK. He kept his job!

The 'mistakes' coin has another side:

Back in the 1970s, I did a few seasons on a 'Model Engineering Course' at West Ham College. It was an evening course, from memory a mere £10 per academic year.

During the day the well equipped workshop was the domain of day-release students on various vocational courses. They had to machine a succession of exercises for which they were issued with ready-cut blanks, mostly mild steel, from the stores. If they made a machining error, they discarded the blank and went to the stores for a new one!

Mild steel sold by the various Model Engineer suppliers usually came in 13" lengths and, including post & packing, wasn't cheap. So, when we 'Model Engineers' were admitted to the workshop each college night, the first port of call was to the swarf trays of the lathes and milling machines to see what windfalls might be waiting there. Not 13" lengths but beggars can't be choosers!

Eventually there came 'the cuts' and non-vocational courses were discontinued.

Best regards,

Swarf, Mostly!

Only this week I had made a number of widely different dia. parts to be Loctited together to save turning down each end of a very large dia. bar. Upon gluing up a small dia. piece to a thin large dia. part, I realised that I had muddled up the various parts! That sort of thing and mis-reading drawings are more my 'speciality'of balls-ups rather than busting cutters.

One only learns by making errors.

John