Rubbish Engineers!

[Drains]

Had a 1" thick, 2' sq plate in from a supplier today, pre drilled and tapped with various holes.

Two of the outer set of holes were wrong and I had to get the plate onto the mill and slot the holes.

Both inner pcd's were 2mm out. (which we can cope with)

The central hole for the register plate (on a hydraulic pump) was 5mm too small. (BUGGER!)

I can't believe that a professional machine shop can get so many 20mm (!) holes in the wrong places, and sod up a 150mm register hole, so badly!

The opinion in the shop is that 90% of our suppliers will make mistakes in machining, on a regular basis. Hands on inspection (at their works) will improve the situation, but if you leave it, quality will always drop.

Do other people have this problem? Are there no good machinists left? Does every idiot rely on cad/cam and think they can leave their brains at home and expect the machines to sort everything out.

Have all the good shops gone out of business, leaving all the rubbish behind?

I don't know.....

 

[rusty69bus]

i often find that generally people leave their brains at home and expect others to sort everything out.

 

[snowcat]

Had a 1" thick, 2' sq plate in from a supplier today, pre drilled and tapped with various holes.

Two of the outer set of holes were wrong and I had to get the plate onto the mill and slot the holes.

Both inner pcd's were 2mm out. (which we can cope with)

The central hole for the register plate (on a hydraulic pump) was 5mm too small. (BUGGER!)

I can't believe that a professional machine shop can get so many 20mm (!) holes in the wrong places, and sod up a 150mm register hole, so badly!

The opinion in the shop is that 90% of our suppliers will make mistakes in machining, on a regular basis. Hands on inspection (at their works) will improve the situation, but if you leave it, quality will always drop.

Do other people have this problem? Are there no good machinists left? Does every idiot rely on cad/cam and think they can leave their brains at home and expect the machines to sort everything out.

Have all the good shops gone out of business, leaving all the rubbish behind?

I don't know.....

sorry about that si, Il try and get the holes right next time

 

[Robotstar5]

Our engineer designs and has manufacturered new machines / tooling which work fine, but when they wear / break he cannot find info so we have to dismantle and reverse engineer drawings to have spares made which all costs production downtime.

 

[Hitch]

Depends on the maching.... something like that, id probably mark out by hand, especially if it were a one off. Youve obviously supplied a drawing or pattern, but did you specify a tolerance?

We dont work to a specific tolerance, but most of us use our descretion- if its a beam for a builder, 5mm oversize wouldnt matter...

If its a part for a peice of a machinery, 1 or 2mm...

The centre hole, i wouldnt be suprised if it were flame cut? But a good bloke on a oxyfuel profiler should be able to do to 1mm without too much hassle.

 

[MrFluffy]

A machine shop would cut out the centre hole undersized and finish bore it to tolerance with a boring head or jig borer surely? If no tolerance is specified on a print to a machine shop, and they made a hole to +2.00mm Im not sure Id want to go back
For the rest of the holes, even if they couldnt fit it on the cnc, presumably they have a dro on the mill or radial arm drill, program in set of co-ordinates, move and drill?

Did you reject the job, or just grumble and fix it yourselves? if the latter, theyre quids in while they keep sending you stuff the yts lad has made...

 

[snowcat]

I sometimes cock up when converting Metric to Imperial, luckily people who know me give me everything in inches........I hate working in metric

Your right tho fluff, any shop worth its salt should be drilling with DROs, how can you go wrong????

 

[Drains]

The drawing had tolerances, and they were nowhere near 5mm, which is how far off one of the holes was.

I think in this event the 20mm holes were marked out - badly. I can't imagine they used a DRO - too far wrong. How they cut the 150mm hole I don't know, but on the mill would be the obvious. I imagine I shall do it properly in the next day or two...

One problem with where I am working is there is no system of inspection of bought in items. It is the laxest place i've ever worked (which is nice in some ways - not a clock card in sight) , most of the lads are graduate engineers (spit), who are given no supervision nor educated in the basics, largely because the people who run the place don't know the basics - of engineering or management (although they are top-line development engineers, sort of)

I've been working there for 6-odd months, but on a building/maintenance role. This is the first job where i've been involved in engineering - in this case fitting up the first in a series of test rigs for a massive (massive!) wind turbine hydraulic power development.

So today, I had to ASK for a general assembly drawing (which was rubbish), a parts list (which was incomplete), and all the components to be brought together in one place so I could inspect them, and not keep asking what on earth I am meant to be fitting up.

So this plate was sitting on a pallet waiting for me to look at it. TBH, it was easier for me to re-work it, and get paid for the day, than spit out the dummy and go home, and charge them slightly less than I would have otherwise. As I charge by the hour it's actually in my interests to do re-work. I would rather not though, as I'm too busy, thankyou.


Oh, and here's another one for you... I was asked to bed the motor down (2.15 tonnes) onto Tico machine mounting material, because they are having issues with sound from their test rigs. I've refused, because in my book, a motor- flexible coupling- hydraulic pump assembly should be rigid as, and lined up bang on, so the flex coupling is doing (virtually) nothing.

If I mount the motor on Tico it will be impossibe for me to accurately align the shafts, as every time I tighten a mounting bolt the Tico will compress and my lovingly measured DTI and feeler gauge readings will be thrown out.

I went and had a look at their "noisy" rig. Good God! The shafts were totally out of alignment, as they were relying on the allowable tolerances on the coupling to stop everything from exploding. I could see the misalignment at a glance! I could almost have forgiven them if i'd had to measure it, but no, the bloody thing was winking at me. And they wonder why their rigs are noisy. Jeeze.

Rant over.

 

[Hitch]

The bad bit, if everyone had a brain, inspection departments would be out of work.
Our place has no specific inspection department, but it is very very rare anything comes back. Like i said previously, down to the individuals discretion.

For example, i have been pressing up some stairtreads today, i have the drawings, i can tell that the back is the most important measurement, as a cumalative error, it could be as much as 20mm out at the top of the finished product.

So i work from that, get that within 0.25 of a mm, and the other two dont really matter to the nearest 2mm.
Having worked in a place with inspection departments aswell, they would make you press up channels for a trailer for example, to the nearest 0.5mm. If it was 0.6mm oversize, it was rejected. We all know that 1mm is adequate tolerance for a trailer chassis rail.
The term 'fit for purpose' springs to mind.

 

[MrFluffy]

Ah but thats all in the pricing isnt it? if the sheet calls for 0.005mm on a shaft, or a fold within 0.5mm accuracy, you price for the extra work of setup and inspection, bit to cover off a bit of the certification of your measuring kit against standards etc.
Then, if someone sends you a print with 0.005mm tolerance on it,and moans about the price you can always say "well if it doesnt have to be that tight, I can save you some money if you specify what it really should be" you are the hero du jour, and the engineer who designed the print gets a small real world lesson in fits and costings
The real problem is that most cad software defaults to say 0.01mm tolerance, and nobody can be bothered to change the tolerance to what it really should be.

Ask if you can realign the noisy jig to prove your point. Noisy grumblely rework on the plate is useful, cant see who's actually doing real stuff unless its noticed

 

[snowcat]

A Friend of mine is involved now with a local firm, who Boeing sub a fair chunk of work to, He has the opposite problem, only making jigs fixtures etc (mostly for impact testing stuff),He, is an all round welder type fabricator and no engineer, the problem being they expect these fixtures to have Micron tolerances, although there only made of off the shelf M/S and maybe welded galore, Heat distortion and fit for purpose are not words they seem to have heard.......

 

[runnach]

Many of the good ol days machine shops are well gone Simon, there are still some companies I visit who do have inspection dept, as these companies do precision machining and metalwork, a few of the others I visit will operate inspection via the foreman or manager, who is most cases was on the tools at one time or other. Then there are the companies who solely rely on the trades person doing the work to be within close tolerance of the job in hand. Using cad/cam is only as good as the person inputting the data and, setting up the machine/s.

I feel cost is a factor to many companies like the one where you are currently, go for the cheapest quote, sort any probs out later. Poor thinking in my eyes, I'd rather spend reasonable top dollar knowing in return a quality accurate piece of kit. Does ISO9000 still exist?

With my fabrication apprentices marking out work, I see many pulling out pens for marking out with a rule, a no no for me, I give them sound training and nowledge in using vernier hight gauge, once they have this knowledge, calipers are a dawdle for inspecting completed work. But I guess I still tend to lean towards old school and how it should be done methods.

Cheers........

 

[Hitch]

My way of thinking, providing the job has sensible tolerances, there shouldnt be anything wrong with self inspection. If the person doing the job is incapable of self inspection, they are in my eyes, incapabale of doing the job in hand.

I did precision pressbrake work for a while, had one job inparticular, you could get it very very close, but if the inspection department rejected it, accidentally hit it on the doorframe on the way out, the tun on your heel, and retest it. Pass.

 

[runnach]

My way of thinking, providing the job has sensible tolerances, there shouldnt be anything wrong with self inspection. If the person doing the job is incapable of self inspection, they are in my eyes, incapabale of doing the job in hand.

I did precision pressbrake work for a while, had one job inparticular, you could get it very very close, but if the inspection department rejected it, accidentally hit it on the doorframe on the way out, the tun on your heel, and retest it. Pass.

Indeed inspectors can be fickle fella's at times. I have dealt with a few over the years where I would cringe if he was the next inspector available!

Although I agree with what you say on self inspection, however as an old tradesman once said to me "the man who has not made a mistake has made fook all" he was spot on. We can all have our bad days, hence the reason for quality departments, who I suppose can have their bad days too!

 

[Hitch]

But i think, part of being good at your job is knowing when you have done wrong, and noting how to avoid it in future.
Nobodys perfect, we all amke mistakes, but knowing when and why is an important part.

 

[runnach]

But i think, part of being good at your job is knowing when you have done wrong, and noting how to avoid it in future.
Nobodys perfect, we all amke mistakes, but knowing when and why is an important part.

Exactly my point Hitch, of course we should be capable of doing the task in hand, then there are times where the exceptional, tasking, head bursting job drawing is laid in front of you to manu, you do your best to manu a correct fabrication/machining component to spec. In Simon's case, it appears that either some one has had a bad day (silly error)? Or can't be ersed?

Now if there is a quality inspection system in place, any out with tolerance can be caught before it meets the customer, this is where you find the the where and whys of where you made an error.

Same for welding, I have seen many guys dip (me included) after a weld test! Down to a bad day on a weld you do every day!

Cheers........

 

[MrFluffy]

A Friend of mine is involved now with a local firm, who Boeing sub a fair chunk of work to, He has the opposite problem, only making jigs fixtures etc (mostly for impact testing stuff),He, is an all round welder type fabricator and no engineer, the problem being they expect these fixtures to have Micron tolerances, although there only made of off the shelf M/S and maybe welded galore, Heat distortion and fit for purpose are not words they seem to have heard.......

Maybe boeing expect the fixture to be finish machined to size after all the welding ops have taken place. The designers are probably wandering round the boeing plant wondering how the hell the subby company can bring their quote in so cheap "but it says +0.1mm on those weldments right on the print"
I worked a job once making shuttering for prc pillars on a designer building. The print called for 0.1mm tolerance on alignment but all the other blokes pitching for it on site said "pah doesnt need to be that tight" and made up their forms and chucked em on after getting the tender on price. Inspection rejected them all, and we got the rectification-remake job (which we'd priced up 4* everyone else because of the tolerance) and got it all in spec.
Turned out that the design needed the alignment to that tolerance to conform to its load bearing specs... We wont mention the pillar we took back out to recast and found a load of rubble in the centre, concrete wagon must have been a bit short that day and someone would rather go home than wait for another it seems...

Self inspection only works when the person running the parts is honest. For people who care its all management can do to dissaude you from thrashing yourself with a cat o nine bowden cables and Im sure you fall into that self motivated self steering mould hitch, but joe down the road might not be in engineering for the love of it, and doesnt really care what sort of work he turns out. Filling a pillar with bricks to get him home 20 mins earlier might be like water off a ducks back as a result...

 

[snowcat]

One of the fixtures in question was around 30' long, how the hell they expected it to be to a micron god knows, the trouble is the engineers have these 60grand wizzy bang gauges that they can pick up from an 0 point and then measure down to pretty much anything they want, and because they can they expect us mortals with tapes to be able to work the same, yet and heres the crux of it pay peanuts for the job...

Mind you on the flip side me mate is proper cavalier sometimes in his approach, his works fine but Christ is paperwork is shocking, and it also came to light on this very job that hes carried no public liability for 8 years.....Not the way to impress blue chip company's really