Why do I do it?!

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Why do I do it?!

This topic has 38 replies, 27 voices, and was last updated 30 August 2017 at 10:07 by mechman48.

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17 November 2009 at 20:37 #45229
Tony Martyr
Participant
@tonymartyr14488
A rhetorical question relating to making stupid errors, presumably when not concentrating on the job in hand.

I have just cut part of the copper of my boiler to the wrong dimension (too short of course) thus making the section a time consuming lump of scrap metal.

It was not a technically difficult job, but with careful deliberation I measured, marked out and cut the sheet to the wrong size – the only excuse I can think of is that I was listening to ‘You and Yours’ at the time which was irritating.

It is a horrible sinking feeling when you offer up the offending part and realise that gluing metal back on is not an option. The irony is that I had just done the really critical measurement and cutting of the outer boiler tube which had been a success.

I guess I’m not the only one and if it doesn’t rain tomorrow I might go an retrieve the part for somewhere at the end of the garden where it landed.

Tony
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17 November 2009 at 20:37 #4847
Tony Martyr
Participant
@tonymartyr14488
17 November 2009 at 21:18 #45233
Charlie,
Participant
@charlie18171
Hi tony,

              Know the feeling, Been there lots of times,But in my workshop there is no such

              thing as scrap,I useualy look upon my mistakes as having reduced a peice of

              metal to a more conveniant size for another job,

                                                                                                        Charlie,
17 November 2009 at 21:33 #45237
Circlip
Participant
@circlip
“Measure twice and cut once” old adage from my mentors Tony and yes, we ALWAYS remember after the event, what a wonderful teacher hindsight is.

Just ensure you restrict your “Occurances” to materials and not Soft tissue. No matter how annoying, it’s a HOBBY.

Regards Ian.
18 November 2009 at 08:53 #45247
Tony Martyr
Participant
@tonymartyr14488
Circlip you have cheered my morning!

Your first paragraph just rubs in an adage I was taught 40 years ago but your last one puts it all into perspective. Working alone in a workshop with machine tools and gas torches does make the ‘soft tissue’ vulnerable and mostly (unlike copper) irreplaceable

Tony
18 November 2009 at 10:52 #45255
Ian S C
Participant
@iansc
Oh well Tony,you’v started your next engine,you just have to find one a wee bit shorter in the boiler!I agree with you and Circlip about the soft tissue ect.IAN S C
18 November 2009 at 13:30 #45269
D.C.Clark
Participant
@d-c-clark
I don’t make mistakes. I make “test pieces”. If it doesn’t turn out right, it was a test piece. Everything made prior to the final finished product is a test piece.

I’ve never made an actual mistake in my life — made lots of test pieces, though.

David Clark in Southern Maryland, USA
18 November 2009 at 14:35 #45272
GoCreate
Participant
@gocreate
You learn from your mistakes, I am becoming very well educated, still alot of lessons to learn though.

Nigel
18 November 2009 at 17:31 #45280
chris stephens
Participant
@chrisstephens63393
Hi Tony,

Just to add to Circlip’s very wise words, The whole expression is “read the drawing three times, measure twice and cut once” The sage ones who came up with expression wouldn’t want us to make a part to perfect size, only to find it is the wrong perfect size, now would they?

It is always best to learn from other peoples mistakes first, then if you really must, learn from your own. No that should have read, make your own test pieces.

It is just a hobby, but some hobbyists make Pro’s look like Amateurs, as we shall all see at Sandown next month.

chriStephens
18 November 2009 at 17:32 #45281
Steve White
Participant
@stevewhite78094
What a great thread, it has cheered me up. Well done Tony and others!

Hands up those, that after a half a dozen attempts at making a
part, went back to the scrap box and used the one he made the first
time round? Been there, done that.

My excuse is that when the model is finished, I will go back and rectify the less than perfect bits……….

Steve
18 November 2009 at 20:02 #45293
David Clark 13
Participant
@davidclark13
Hi There

I think the idea is that you make the first part and keep making the parts until the model is complete.

Then you decide that the early parts are not up to scratch and make the the next model to a higher standard.

regards david
18 November 2009 at 20:24 #45294
David Clark 13
Participant
@davidclark13
Hi There

Read drawing three times.

Yes, read drawings three times then make the component in your head. Figure it out before you machine it.

Professional engineers do make mistakes as well.

That is why there are inspectors.

One place I worked at decided to do away with inspectors.

It was their own product so they decided inspectors were an uneccesary expence.

It was a precision product, electric motors running at speeds up to 360,000RPM.

I saw boxes of components precision ground to a tenth of a thou. Shame they were exactly ten thou undersize.

Boxes of aluminium end caps with knackered threads. They drilled out the threads, retapped for helicoils and fitted them.

Trouble was they did not reanodise the end caps. A few weeks and the end caps were covered in corrosion due to the dissimilar metals.

Same thing with designers, yes they can design with CAD but they don’t always get it right.

I say that if they did not use CAD to design it we would not need CNC machines to make it.

Perhaps someone can enlighten me?

One of my jobs was making replacement parts for the Nimrod. There were no drawings, all part designs were stored on a computer. The original was measured on a CMM Computer Measuring Machine. Nothing was flat, all surfaces were machined all over. I always thought that when they built the Nimrod., they did not make them on CNC machines so the components must have been measured from a part taken from a 25 year old Nimrod and measured.

Was I making brand new 25 year old Nimrods?

The last batch of Nimrod parts I made were done mainly on night shift but occasionally the day shift carried on with the job. I came in one night and the day shift said ” the bottom of the job wasn’t flat so I took a skim off them.

Three weeks work down the pan!

I was made redundant a day or two later so I never found out what happened to the components but the firm went bust a few months later.

Moral: even the skilled people don’t always get it right.

regards David

PS sorry if spelling is rubbish, no spell checker.
18 November 2009 at 21:00 #45297
Flying Fifer
Participant
@flyingfifer
Well, well,

I think we`ve all been there hence the cumminandy box)es!) under our benches. Strange you should mention the Nimrod, David. There was a very quiet tale circulated the MoD a few years ago that the newly manufactured wings wouldn`t fit the old fuselages. Hee Hee good old BWOS. Sees the originals were “hand made” by DeH.but the new were jig made.
18 November 2009 at 21:19 #45300
David Clark 13
Participant
@davidclark13
Hi There

Makes sense, I always thought the Nimrod rebuild would be useless.

I just remembered a typiclal error made in design. So long ago I had forgotten.

The company I worked for, must be about 35 years ago at least, made engine mounting bolts for a plane. I think the engine was in the tail. Big passenger aircraft, can’t remember the name (Comet?)
Trouble was the engines kept falling off and the jet crashed.

The management were spitting (or similar) bricks.

Luckily for us (not the passengers) the designer specified the wrong material.

Even luckier, the designer did not work for us.

I must stop going down this line of thought, I am getting happy memories.

regards David
18 November 2009 at 22:30 #45309
John Whitby
Participant
@johnwhitby39110
Certainly wasn’t the Comet David, the engines were in the wing roots, it was the airframe basis of the Nimrod!!

The only three UK commercial aircraft with rear mounted engines were the BAC 111, the DeH Trident and the Vickers VC10.

More recently, Ford did a recall notice for all the original Mondeo Estate cars, as the rear suspension mounting bolts were of the wrong specification material. My Company car went in and three weeks later the rear suspension collapsed as the replacement bolts were of the wrong material spec……
8 December 2009 at 11:27 #46008
Dunstan Eloi
Participant
@dunstaneloi23233
Hi Tony. Try boring out two cylinders to finished size onlt ot find they are too off centre to correct!!!!!!!!!!!!!!!!!!!!! Mike
8 December 2009 at 12:36 #46014
Circlip
Participant
@circlip
Of the three, the only one with engine “In” the tail” would be the Tripehound.

Can we get away from the misnomer that the D in CAD means Design?? There is a vast difference between DESIGN and DRAUGHTING.

ANY pi****k can Draught, it takes an EDUCATED pi****k to be ABLE to design.

How many starfighters if presented with a damn great insect from the planet Zog would actually STAND and fight on a one to one with a ray gun.

TCH., compewkers.

Regards Ian

Edited By Circlip on 08/12/2009 12:38:22

Edited By Circlip on 08/12/2009 12:38:40
8 December 2009 at 13:11 #46016
D.C.Clark
Participant
@d-c-clark
It was once fairly common to see the acronym CADD — Design and Drafting. There is better reason today, as modern packages have extensive design tools: finite element analysis, mass properties, motion, moments of inertia, strengths of materials, bolted structures, etc… etc…

These immensely powerful tools make it possible for the educated, but untalented, and inexperienced, designer to screw up in ways his predecessors could only dream of.

Regards,

David Clark in Southern Maryland, USA

retired NASA techie
8 December 2009 at 13:57 #46018
Tim Ostley
Participant
@timostley22330
Hi,

Remember the only difference between an amateur and a professional is that the professional gets someone else to pay for their mistakes!

On the CAD front, in spite of spending 35+ years in IT I still prefer to use a drawing board and pencil as taught many many years ago. When you actually draw a component out it really helps the thought processes on how on earth am I going to make this – I seem to get a better ‘feel’ for the component this way.

Oh well, back to work!

Tim
8 December 2009 at 18:39 #46033
Tony Martyr
Participant
@tonymartyr14488
Guys

I’m still thinking of poor Dunstan and his out of line cylinders – puts my own (cheaper) balls- ups into context.

The CAD thread that has emerged is a very deep subject.

I recommend a book written some 20 years ago called ‘To Engineer is Human’ that discusses the disassociation that can occur when a digital computer is doing complex design calculations for you and giving a totally undeserved appearance of accuracy.

I still have no answer to my original question ‘Why do I do it?’ – errors must be down to lack of attention I think.

In my work I made a study of project disasters and I noted that when interviewing the persons involved, the phase ‘I assumed…’ appeared very soon in the conversation.

A colleague who was an expert in the analysis of car crashes related a similar event in his interviews; in his case the key phrase was ‘Suddenly ……(there was a tree etc etc)

So a temporary lack of attention leads to the false assumption that I am doing the right thing until suddenly I see its gone wrong!

QED

Tony
8 December 2009 at 18:59 #46036
Martin W
Participant
@martinw
Hi All

I bet the designer of the Tacoma Narrows bridge wished he had the benefits of computer simulation available at the time. Now that’s what I call a proper c**k up. But seriously the advent of CAD has been a mixed blessing. It is often assumed that if it can be drawn it can be made!!

Tony with regard to your remarks regarding disasters and the words being proffered by the interviewees there is another classic when some person is expounding some new pet theory or another and they use well worn phrases like ‘Based on the well established ——‘ or ‘Known parameters—-‘ . At this stage one looks forward to see where the cliff is they are going to walk over as a result of a question from a perceptive member of the audience!!!

Cheers

Martin
8 December 2009 at 19:29 #46039
chris stephens
Participant
@chrisstephens63393
Hi Martin,

I don’t think even if the designer would have had computers to help him that the bridge stood much a chance. The design was fairly standard, the problem was he had not allowed for wind related problems, with the flat sides. With the best computer simulation available, it is no bl**dy good if you don’t factor in all the variables. Look at the Millennium bridge in London, clearly the designers only looked at it from an artistic point of view and completely overlooked the fact that people would actually want to walk on their piece of modern art sculpture. I hope they had to pay back their design fees.

chriStephens
9 December 2009 at 09:04 #46047
Tony Martyr
Participant
@tonymartyr14488
Martin

The book to which I refer has the Tacoma Narrows Bridge as the cover photo!

In fact it was a classic case of believing digital calculations unalloyed by experience and ‘does it look right’?

Virtual models are only as good as the algorithms they contain and in the case of the bridge there was little design knowledge of the resonance of aerofoil bridge sections.

I recently caused consternation to a group of Austrian students by using a slide rule to calculate the diameter of a pipe – they had never see such a device and were fascinated to see that my answer was arrived at by an analogue device that allowed me to see how close my chosen size was to the size larger and smaller thus giving room for judgment rather than one digital answer .

I bet most model boilers were designed using slide rules!

Tony
10 December 2009 at 20:32 #46101
Martin Cottrell
Participant
@martincottrell21329
Hi Tony,

With regard to your boiler making “cock-up”, it would appear that people in high places have read of your plight and come to your rescue.

Yesterday I heared that the chancellor has announced his new “boiler scrappage scheme”. Apparently, if you tell him of your mishap and send him your old boiler, he will give you £400 towards a nice new one! Who said politicians had no heart?!

Regards, Martin.
10 December 2009 at 21:07 #46104
AndyB
Participant
@andyb47186
Hi Tony,

My boss has an old adage that he frequently trips out when I make a mistake: “assume makes an ‘ass’ out of ‘U’ and ‘me'”…unfortunately it is his assumptions that have caused them! He’s not the sort of person to tell that to though!

I am only a rank beginner, just found out how to make the lathe spin…wonderful what those clicky bits do when you connect them to the electrickery and the motor…everything I do seems to be practice for when I do something properly!

Best of luck
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