Workshop Mistakes (True Confessions)

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!

My first factory job on leaving school was operating a shaper. It faced the back of a large mill a few feet away. There were 3 of us using shapers on the same type of components. I copied the others in winding down the vertical feed while the machine was going but one occasion I over did it with the tool jammed against the rear of the work and stalled the machine with the motor slipping its 3 drive belts to the gearbox. Before I could switch off, there was an almighty bang with bits of busted tool flying out. Fortunately most of the shrapnel hit the back of the mill, causing its operator to come and have a look. Not broken much since - one learns to be a bit more cautious, especially when having to buy ones own replacements. Can only recall breaking the small nose part off of one of my centre drills many years ago and in recent years taking a chance with work in a machine vise not secured to the drill table. Drill (3/16) jammed, shattered and work + vise off drill table down on bench. I had been holding the handle but humans are puny against machinery. All now bolted down on any machine before switching on.

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

My old mate Barrie Bushell was showing his newly completed Minnie to his then elderly relative Harry Bushell who had a workshop near Thursford  in Norfolk in here he built threshing drums and repaired Traction engines. Being somewhat in awe of the old timer whose engineering skills were legendary Barrie admitted to having made a few mistakes. Harry’s reply was “they never see what you chuck under the bench boy”

Stayed with me that tale.

regards Martin

Edited By Martin Kyte on 09/03/2023 23:05:32

My commonest, recurring error is to ever so carefully and methodically, machine some detail to exactly, but completely the wrong dimension. And it's always in the irrecoverable direction, like the diameter register on a chuck backplate being exactly 0.100(0)" too small. I still don't know how to avoid such f-ups: I suppose sometimes it's failing to count handwheel turns correctly, sometimes mental arithmetic failure, sometimes just having tunnel vision, and a lack of awareness that things could be going well, but have been wrong from the start.

And then there's just plain stupidity. I had a tall, narrow-based component standing up on a Jones and Shipman 1400 surface grinder, intending to take a tiny lick off the top. It was the inner part of an Albrecht chuck, so valuable. I had arranged support blocks to try to stabilise the set-up, and knew it looked a bit risky, however... I was bending down, to get a closer look, to see whether the surface had cleaned up enough, when there was an almighty bang. Yes, you guessed it, the wheel had shatterd, driving the work into the mag chuck, leaving an unsightly dent, embedding grinding wheel particles into the workpiece and bending it out of shape. Proper, kite-marked safety glasses are a Good Thing!

Kiwi Bloke's elaboration of Murphy's law: the probability of irrecoverable error is in direct proportion to the importance of the job, multiplied by the care taken.

(edits: more f-ups...)

Edited By Kiwi Bloke on 10/03/2023 00:29:41

Edited By Kiwi Bloke on 10/03/2023 00:31:34

My milling instructor said,"check with a 6 inch rule as well as a micrometer"

He came from Inspection in the ercting shop where he used a 24" rule to check

It wasn't unknown for somethikng to be exact to a thou, but an ninch out!

Howard

I wonder how many of us rough components down initially. I find I never get the exact to the thou but out to the 1/10” syndrome that way whereas I occasionally do when going direct to size. There are methodical ways to avoid errors but I for one am prone to taking short cuts.

regards Martin

I dont think of them as mistakes, more as additions to my scrap box, which gets bigger by the day.

I am sure we can all relate to massive cock ups, but remember, those that do not make mistakes, do not learn or make anything.

It's amazing what we can make when sat in a chair, the reality is a little different.

Keep making those mistakes folks, in the knowledge that you are now wiser than you were before.

Edited By Howi on 10/03/2023 10:34:32

Two mistakes on the same part first was cutting the port face 1/16" to low which I could work around then to add to my woes two weeks later I cut the inlet steam ports 1/32" to wide(picked up the wrong milling cutter without double checking. Kicking myself was not good enough punishment.

Being a beginner is no excuse as I have been working with wood making models where items need to be the correct size.

I spent an afternoon making a floor pan with all the grooves, panels and folded edges. Matched the template, and looked great until I held it in the hole. It was upside down.

I've been told that templates and marking it and the part with up/down/inside/etc and using different colour markers for which way a fold goes is a waste of time. It isn't...

The above is nice and may be a justification for making mistakes.

Many do not learn from their mistakes. You do not have to make mistakes to learn something.

Yes, we all make mistakes. Sometimes you can be proud of them. Occasionally they can be really useful.

JA

I make many mistakes. The most annoying are those where I have measured twice or more times, but STILL get the hole in the wrong place - owing to flawed logic or stupidity.

I once drilled a load of holes into brick to fix skirting boards, and only noticed halfway through that I had accidentally fitted a metal HSS drill into the chuck instead of a masonry drill ! The HSS drill did quite well, and I only noticed my mistake when I noticed that it was glowing dull red !!!

A good general tip is to allow your subconscious time to think about whatever you are doing. Never be afraid to have a break to let your subconscious work. A cup of tea has more benefits than just a drink of hot liquid.

If tired and fed up with something, or something is not going well, don't rush it: leave it and come back to it the next day.

Most stupid thing I've ever done to a car was to screw-jack it up just enough to crawl underneath and undo what was obviously the sump plug whilst doing an oil-change. Not familiar with the vehicle, I actually drained the gearbox, which protested loudly after about 30 miles. Made a noise like sheet metal being shredded. Got way with it though - refilling the box kept the car going until rust did for it.

Later, I had the same car on the same jack changing brake pads when it rolled off the jack! No warning, and despite bricks under the wheels. The jack had sunk lopsided into the tarmac, tilted, and crunch! No damage done, but it reminded me I'd crawled under the same arrangement whilst changing the oil. Since then I've been much more careful, never going under a car supported only by a jack.

Won't make that mistake again - I'm too old to crawl under cars now...

Dave

Many years ago we had a genuine Czec made Skoda car, not the rear engine one. One evening I did an oil change and was waiting for the draining to be complete, then the wife shouted time we should be going out, I forgot to put the oil in, we went about 5 miles and could smell hot oil, a quick about turn, I filled up the engine with oil. The car went for another two or three years before it failed its MOT amazing. John

After spending the first year of my apprenticeship full time at college soon after my return to work I was given a job that required a 1" diameter reamed hole in brass. Obviously reaming the hole was one of the last operations after a considerable amount of machining in the lathe. For some reason we only had a hand reamer so I set it up with a centre in the tailstock and set to. In those days I was less than 10 stones wringing wet and soon tired of the manual effort. However, the lathe was the type with a permanently running motor and a clutch, so I set the tap wrench against the compound slide and with the lathe set to the slowest speed began to nudge the clutch and feed the reamer through with the tailstock. All was going splendidly until I obviously got past the initial taper of the reamer and it began to take more off, when there was an awful crunching noise as the reamer stuck in the job and the tap wrench and back half of the reamer fell into the tray!!!

The foreman was known to be a "bit of a bar steward" who could even be a bit punchy (it was 1975 by the way) so I was absolutely terrified when I went to tell him. To my absolute amazement as I explained what happened he just said "well you obviously left too much reaming allowance so you won't do that again will you?". And I have never done it again thankfully.

Speaking of the aforementioned first year at college there was one pupil in our group who was so inept the senior lecturer took him to one side and asked him if he really wanted to continue or perhaps he might consider an alternative career. Early on he completely destroyed an Adcock Shipley horizontal mill so badly I never saw it work again. The mill had a joystick with fast traverse functions (that seemed like a space ship in 1974), he drove a 3" slab mill into the vice so hard that it even bent the overhead arm casting. The final straw was when making an adjustable V-block with the V on top of a 1" ACME thread with a total length of about 6" he decided to try and grind the top face by simply sitting the end face of the thread on the magnetic chuck, despite us having been instructed never to do such a thing. Inevitably it was flung across the whole width of the workshop to land in the tray of another pupils lathe, shattered the wheel and damaged the surface grinder into the bargain. I sometimes wonder what became of him when we returned to our employers?

Edited By Phil Lingham on 10/03/2023 17:34:12

Phil, he most probably got quickly promoted to foreman, at least that’s what happened to all the merchant bankers that I worked with, the more hopeless they were the higher they got.

A large casting, having been extensively machined had the word ‘scrape’ written on it with chalk to wait for a fork-lift to take it away. However some wag rubbed out the’e’ meaning it was taken out the back of the factory and dumped with other unwanted metal to wait for the scrap-man. The next few weeks saw an increasing number of ‘progress chasers’ wandering in confused circles complete with clipboards.

it was found and chalk was banned!

Just remembered a marking out/machining ballsup with a loco project. Used a second hand long rule to mark out the frames, starting with the 1" line instead of the zero end of the rule because it looked dodgy and wasn't sure about how accurate it would be, if used. All went well, checked and started drilling. However, I somehow missed the darned great big hole to be made for the exhaust steam to be piped out of the outside cylinders to the smoke box and to the blast pipe. Didn't notice until after 2 large holes had been made 1" apart! Ah well, just bolt on a patch plate to hide it. If it was good enough for the GWR to patch their old cracked frames then it's good enough for me!

The type of mistake that frustrated me the most is where I have to mill on project from both sides at angles and became sloppy(impatient one should never be) and milled it wrong in the twist of things.