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Why do I do it?!
| Tony Martyr | 17/11/2009 20:37:04 |
 226 forum posts 45 photos | 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 |
| Charlie, | 17/11/2009 21:18:25 |
| 76 forum posts 1 photos | 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, |
| Circlip | 17/11/2009 21:33:56 |
| 1723 forum posts | "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. |
| Tony Martyr | 18/11/2009 08:53:50 |
226 forum posts 45 photos | 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 |
| Ian S C | 18/11/2009 10:52:55 |
 7468 forum posts 230 photos | 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 |
| D.C.Clark | 18/11/2009 13:30:58 |
| 16 forum posts 8 photos | 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 |
| GoCreate | 18/11/2009 14:35:44 |
 387 forum posts 119 photos | You learn from your mistakes, I am becoming very well educated, still alot of lessons to learn though.
Nigel |
| chris stephens | 18/11/2009 17:31:26 |
| 1049 forum posts 1 photos | 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 |
| Steve White | 18/11/2009 17:32:45 |
| 11 forum posts 2 photos | 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 |
| David Clark 1 | 18/11/2009 20:02:29 |
 3357 forum posts 112 photos 10 articles | 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
|
| David Clark 1 | 18/11/2009 20:24:25 |
3357 forum posts 112 photos 10 articles | 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. |
| Flying Fifer | 18/11/2009 21:00:57 |
| 180 forum posts | 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. |
| David Clark 1 | 18/11/2009 21:19:12 |
3357 forum posts 112 photos 10 articles | 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
|
| John Whitby | 18/11/2009 22:30:43 |
| 5 forum posts | 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...... |
| Dunstan Eloi | 08/12/2009 11:27:48 |
| 5 forum posts | Hi Tony. Try boring out two cylinders to finished size onlt ot find they are too off centre to correct!!!!!!!!!!!!!!!!!!!!! Mike |
| Circlip | 08/12/2009 12:36:12 |
| 1723 forum posts | 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 |
| D.C.Clark | 08/12/2009 13:11:18 |
| 16 forum posts 8 photos | 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 |
| Tim Ostley | 08/12/2009 13:57:42 |
| 17 forum posts 2 photos | 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 |
| Tony Martyr | 08/12/2009 18:39:23 |
226 forum posts 45 photos | 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 |
| Martin W | 08/12/2009 18:59:29 |
| 940 forum posts 30 photos | 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 |
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All Forum Topics > Beginners questions > Why do I do it?!