Workshop Mistakes (True Confessions)

[Kiwi BlokeParticipant @kiwibloke62605]

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

[Howard LewisParticipant @howardlewis46836]

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

[Martin KyteParticipant @martinkyte99762]

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

[larry phelan 1Participant @larryphelan1]

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

[HowiParticipant @howi]

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

[DalboyParticipant @dalboy]

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.

[Nick WheelerParticipant @nickwheeler]

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…

[JAParticipant @ja]

Posted by Howi on 10/03/2023 10:33:58:

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

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

[John Doe 2Participant @johndoe2]

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.

[SillyOldDufferModerator @sillyoldduffer]

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

[john fletcher 1Participant @johnfletcher1]

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

[Phil LinghamParticipant @phillingham79132]

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

[BazParticipant @baz89810]

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.

[SteveWParticipant @stevew54046]

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!

[DMBParticipant @dmb]

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!

[Chris MateParticipant @chrismate31303]

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.

[HopperParticipant @hopper]

Just had one in the shed this morning. Wiring a tail-light onto a motorbike I used a male and female bullet connector, those horrible crimp on ones from the auto parts store. I hate the look of those squashed plastic connectors so decided to put a bit of heat shrink over the plastic sleeve on the female fitting to hide it. Hit it with the heat gun and promptly shrunk the heat shrink tube AND the plastic surrounding the metal fitting inside. So bad that the male fitting would not go in, even after a bit of "rework" with a screwdriver to open the plastic up a bit. Cut the whole mess off and did it again, without heat shrink.

So I won't do that again and must order some more proper solder-on fittings or the crimp on ones that use the special pliers and then you slip the sleeve on afterwards.

[SillyOldDufferModerator @sillyoldduffer]

Tidy versus untidy? In theory, I vote tidy, but in practice I let disorder prevail. Something about my memory makes it quicker for me to pick up parts and tools from a clutter, rather than 'waste time' keeping everything in it's proper place. Now I'm older, the system doesn't work half as well, probably because my short-term memory is iffy.

I started the thread with a cast-iron tale of woe, which is still causing trouble. Demoralised, I returned to fix the job and found the workshop in total disorder. Items in the work area included a sink plunger, broken umbrella, a scattering of used emery paper, random twist drills, the spilled contents of a collapsed scrap-box and much, much more. And everything was and is covered in smeary black graphite. Two hours cleaning and tidying have barely made a dent in it.

I think I either need an Apprentice, who I can bully into keeping the place tidy, or one of those terrifying foremen of yesteryear, a vicious b*st*d who eats lazy sods for breakfast.

Oh, and early yesterday morning, I was out in a snowfall trying to clean off orange dust stuck to my double-glazing. And there's a big orange circle in the middle of my patio too. I knew angle-grinding cast-iron was messy, and still underestimated it. Good job I'm already divorced…

Dave

[HopperParticipant @hopper]

Aye, good job. Or you soon would be, by the sound of it!

[SamsarandaParticipant @samsaranda]

Dave, when grinding cast iron the orange dust has a propensity to bond with the glass of double glazing if it’s is still hot when it hits the glass, don’t ask how I know, I am still married, only just after peppering the windows of the conservatory. Dave W

[John Doe 2Participant @johndoe2]

Oh yes, reminds me of another…..

Removing the old galvanised steel water pipework in the bathroom of my first house, before re-plumbing the whole place.

Often with pipes in a fixed installation – especially near a corner – you cannot get a hacksaw in there, (or any other sort of pipe cutter), and even if you can, hand sawing pipe with a hacksaw is very difficult because the teeth jam on the pipe walls. So I used my angle grinder……..(This was years before somebody invented the multitool).

I cut through the pipes no bother and proceeded to instal new copper water and central heating pipe throughout the house, aided by my new pipe bender tool. Fantastic, except that there seemed to be some grey/black mould on the bathroom tiles, which would not wipe off. Oh dear, it was tiny blobs of zinc, (I assume), that had heated to red-hot during the angle grinding, and then fused into the glaze of the bathroom tiles.

OK, I was inexperienced then, but about 5 years later, I did almost exactly the same thing in the bathroom of the next house – this time, the zinc blobs landed on and fused all over the base of the white basin stand. I had to go and buy and instal another brand new porcelain basin stand !

PS, yes, don't jack cars on "domestic" tarmac without some sort of plate under the jack or axle stand, and always use axle stands, never just a jack.

[duncan webster 1Participant @duncanwebster1]

Posted by Samsaranda on 11/03/2023 10:12:40:

Dave, when grinding cast iron the orange dust has a propensity to bond with the glass of double glazing if it’s is still hot when it hits the glass, don’t ask how I know, I am still married, only just after peppering the windows of the conservatory. Dave W

I'm still maintaining that I've no idea what those little black bits stuck to the kitchen window are. Using a Stanley knife blade as a scraper helps, but nothing gets rid of it totally

[John Doe 2Participant @johndoe2]

Acid; e.g. sulphuric or hydrochloric, should dissolve the metal but not touch the glass – most acids are stored in glass bottles.

However, the logistics of applying strong acid – without it dripping onto and damaging the plastic or metal window frame, or yourself – would be challenging……..

I think double glazed glass panels can be removed from the frame by gently prising off the internal plastic beads.

 

Note: I have not personally attempted either suggestion, so proceed at your own risk !

 

Edited By John Doe 2 on 15/03/2023 10:40:17

[Mike HurleyParticipant @mikehurley60381]

Posted by Samsaranda on 11/03/2023 10:12:40:

Dave, when grinding cast iron the orange dust has a propensity to bond with the glass of double glazing if it’s is still hot when it hits the glass, don’t ask how I know, I am still married, only just after peppering the windows of the conservatory. Dave W

Been there, done that, tried to blame atmospheric pollution – that didn't wash! Put self in dog-house.

[Nigel Graham 2Participant @nigelgraham2]

My biggest mistakes are two-fold and mutually supportive:

– No proper drawings, or even fair sketches first.

– A tendency to over-think and so over-complicate the problem hence the resulting metalwork;

both leading to a lot of rework later.

.

I can vouch for swarf loving to colonise its surroundings far and wide. It would explain the orangey-brown rash on the PVC still of my back door.

. Measure once. So I do. Measure twice. So I do. Cut once… Oh Dear! Start again….

.

Even the experienced (and supposedly skilled) professionals can be caught…

Among the stock at my club's workshop many years ago was a large hexagon of thin steel sheet, donated by a member who'd scrounged it from his works scrap-bin. In fact it was scrap only because when he remarked to the workshop manager that he could not cut the requisite number of hexagons from the supplied sheet, he was firmly told to look at the drawing again…. of an octagon.

In one of my employments the company, making its own products to its own design, proudly bought a CNC Milling-machine with among work lined up for it, a complex part carved out of a big slab of aluminium-alloy plate. All would have been well had someone first ascertained the part-width + cutter allowance against the machine's wee bit smaller travel specifications in the catalogue. The drawing-office re-designed the part a slightly bigger wee bit smaller.

'

I do though recall a retired gentleman, properly time-served and educated, formerly a senior engineering-manager in the nuclear-power industry. He had come back to work part-time, now for a specialist, bespoke electronics manufacturer, where his role was making small but often intricate metal components with a lot of hand-work in them. One day he told me of sometimes in his managerial days having to stand next to very skilled machinists working on large, extremely high-grade components; to give them moral support and read the dials and micrometers with them. It was not that the part was too difficult for them, but they knew it was functionally critical and worth many thousands of pounds, and were too frightened to be all alone in making its finishing cuts.

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