Metal Fitters and Machinists
Fit and assemble fabricated metal parts into products, set up machining tools and production machines, and operate machining tools and machines to shape metal stock and castings.
A Thursday on the machine floor
You are a machinist and fitter in a busy workshop, with a lathe, a milling machine and three jobs due today. It is 7:30am. The first job is a replacement pump part for a dairy factory, the second is a set of bushes for a mine, and the shop's boss has just walked in with a new customer.
Choose what you would do. Then see what happens. There are often good reasons for each choice.
This is Mr Kapoor, he runs a small food plant, and his machine is down. He needs a part today. I have told him you can do it. The drawing is a bit rough, but you are good at working things out, are you not?
Start machining from the rough drawing, using your best judgement, since his plant is stopped
The part is made quickly and does not fit. The drawing was missing a key dimension, and your judgement guessed wrong. A rough drawing needs questions before cutting, not after.
Ask to see the old part, measure it, and check the key sizes with Mr Kapoor
The old part shows a thread that was not on the drawing. Mr Kapoor confirms the details, and the new part goes in the same afternoon. The questions took twenty minutes and saved a day.
Tell Mr Kapoor you will do it tomorrow once someone has fixed the drawing properly
You are careful, but Mr Kapoor's plant is shut for another day. The old part was in the room and could have answered most of your questions. Waiting for a perfect drawing was not the only way forward.
That machine guard on the lathe is a pain, it keeps getting in the way when I am measuring. I took it off for the next hour, just while I do this one. Do not tell Bernadette. It is only an hour.
Say nothing, since Tony has years of experience and it is only an hour
Nothing goes wrong this time. But a sleeve catches on a spinning chuck two weeks later when Tony does it again, and he is lucky to be unhurt. Experience does not make a guard optional.
Ask Tony to put the guard back and offer to help find a better way to measure while the machine is stopped
Tony is irritated for a minute, then sees that stopping the machine to measure is quicker than he thought. The guard stays on, and you did not need to involve the boss.
Tell Bernadette quietly, so Tony has to deal with her
Bernadette sorts it out, and the guard goes back on. But Tony feels ambushed and the workshop gets a little colder. Going to the boss is sometimes necessary, though a direct word comes first.
I made six bushes and checked the first and last. They are both right. I did not check the ones in the middle because it takes ages. They should all be the same, should they not?
Tell her the first and last are enough, because the machine is repeating the same cut
The fourth bush has a slight taper because the tool wore as it cut. It goes to the mine and sticks halfway in. Machines repeat their cuts, but they also drift.
Measure the middle ones with her, and explain why a quick check of each part saves a returned job
She checks the rest, and one is slightly off. You fix it. The lesson is good, but you did not show her a faster way to check, such as a go and no-go gauge.
Show her a go and no-go gauge, let her check all six, and write the results on the job card
The gauge takes seconds per bush, and one bush fails. Aroha learns that a quick check can be built into the process, and the mine receives six good parts.
How it went
Mr Kapoor's machine is running by evening and the mine's bushes are on the truck. Machinists turn drawings into real parts, and the work lives in tiny measurements, careful questions and honesty about errors. Does the idea of making things that fit perfectly sound satisfying to you?
This is a simplified, fictional situation to help you explore. It is not professional instruction or a test of your ability.
Case study: The shaft that was a fraction too big
A fictional case set in a fictional machine shop making and repairing parts for mines, farms and food factories.
The situation
Dimitra was a turner at Copperfield Engineering, machining a replacement shaft for a gearbox at a quarry. The quarry had been shut down for three days waiting for it, and the manager, Rhys, rang each morning. On the last pass she measured the shaft and found it was a fraction over size at one end. It would still go into the housing if it was hammered.
What they did
Dimitra put the shaft down and measured it again with a second instrument. It really was over size. She told Rhys that the shaft would be another three hours, and why. She set the machine again and took a finer cut, then measured at several points along the shaft. She tested the fit with the bearing before wrapping it for delivery.
How it turned out
The shaft went to the quarry that afternoon and slid in with a gentle push. Rhys said it was the first time all week that something had gone right. Dimitra wrote a note on the job card about the machine's drift so the next operator could allow for it.
What would you do?
- Why might a part that goes in with a hammer cause trouble later?
- How would you handle a customer who is losing money while they wait?
- Do you like the idea of working to a measurement thinner than a hair?