Technical and engineering drawing.

[Steve GarnettParticipant @stevegarnett62550]

Posted by Tony Pratt 1 on 19/04/2011 22:15:17:

Hi Sam, doesn’t look like any one knows the answer to your trick/puzzle judging by the lack of responses.

 

That’s hardly fair – he asked us not to say! And anyway, by Sam’s rules apparently we all know…

 

If you want a clue though, ask yourself what the two inner squares really represent… bearing in mind that there are no hidden lines in the drawing!

Edited By Steve Garnett on 19/04/2011 22:32:28

[Harold Hall 1Participant @haroldhall1]

Making one of my occasional visits to
the forum I have hit on this thread and felt I would like to add a
few comments on two aspects of the discussion.

Whilst I do not disagree with Terry’s
initial suggestion but do not see how the magazine can
separate reading drawings totally from drawing drawings, as he
mentions he would base his article on interpreting drawings drawn to
BS308. My reservations are based on just how many contributors are
conversant with that standard, my self included. In my case, the last
time I worked producing engineering drawings was 57 years ago as was
the last time I worked for a mechanical engineering company.

Also, having spent a few years as
editor of MEW, I am fully aware of the impossibility of redrawing
contributors drawings, both for practical and financial reasons, so
that they comply. Contributors will therefore need help to comply
fully, or at least largely, with the standard so that Terry’s article
on reading them stands a chance of achieving its aim.

Secondly, I calculate that the number
of contributors to the subject amount to approximately 0.2% of MEW’s
readership and does not therefore alone make an overriding case in
favour of the original idea. In any case, not all of the contributors
appear to see the need for the item. The editor must therefore be
allowed to balance this very small number against the feedback he
receives by other means.

Of course, at this stage I have not
found it possible to read every contribution in depth so if I have
missed something my apologies.

Harold Hall

[adyParticipant @ady]

Got it!

 

[Steve GarnettParticipant @stevegarnett62550]

ady, you are close, but not there yet. You haven’t worked out the significance of NO hidden lines… and your cat looks depressed.

 

Harold, I suspect (well I hope…) that a more accurate way of assessing the vote in favour or against this would be to look at the proportionality of the voting here, rather than the absolute numbers.

[Sam StonesParticipant @samstones42903]

Some of you guys are working late, but it’s nice to get up in a morning and find so many postings.

 

Sam

Melbourne time = 08:15

[TerrydParticipant @terryd72465]

Posted by Richard Parsons on 19/04/2011 18:13:13:

……………..We were to have been taught Technical Drawing at my grammer school. Lesson 1 was how to sharpen our pencils and draw lines. It was OK. Lesson 2 was ‘incoherent’ and lesson 3, the teacher was ‘indisposed’ so ‘indisposed’ he had to be helped off the premises. So it was back to the confounded Gardening lessons which I hated. The only fun I had burying things, spades, trowels, hoes, the instructor’s hat, etc. I once nearly buried the instructor. After that they never let me near the manure barrow again.

 

 

Hi Richard,

 

Your comments really made me chuckle. I went to a very Trad Grammar School myself (founded 1562, and no I wasn’t there then) . We also had quite a few ‘indisposed’ teachers at one time or another. They used to have to visit the staff room for one reason or another – mostly ‘another’.

 

Funny thing is I’ve never been able to stomach gin since, curious!

 

Best regards

 

Terry

[NJHParticipant @njh]

Harold

 

Thank you – that puts it into perspective for me. I’m fairly neutral about an article on drawings and rather against a series of articles but, if thats what folk want then I won’t beef about it. There seems to be an overwhelming desire on this thread for this product and an arguement that somehow a post here is of more value than the result of a survey of the readership.

Your assessment that the posts here represent 0.2 % of the readership goes against that assumption. There have been over 3000 views of the thread BUT contributions from less than 40 posters – how do the “viewers only” feel and why is there a reluctance to join in the debate?

I’m a bit surprised at the enthusiasm from some of the “for” brigade – the quality of the work and depth of knowledge they demonstrate must surely mean that they already have considerable understanding of technical drawings.

So, if acceptance of articles is to be driven ( as I guess it quite rightly should be) by readers opinions, then let that be from a wider field than just this one.

One very good idea however is that it should be possible for surveys to be carried out on line.

In the end though the magazines exist to make money and the editor’s job is to ensure that the content is popular and sells the product. He must be allowed to use his judgement to ensure that is the case.

 

Regards

 

Norman

Edited By NJH on 19/04/2011 23:42:21

Edited By NJH on 19/04/2011 23:43:09

[Bill PudneyParticipant @billpudney37759]

Hi David,

About a survey. Those of us up here in Australasia get the magazines some weeks or months after publication in the UK. As a result the closing date for returning surveys is usually long gone. So can you either

 

1/ Have a later closing date to suit responses from overseas

 

or

 

2/ Have an online poll

 

cheers

Bill Pudney

in sunny Adelaide

[Sam StonesParticipant @samstones42903]

Geoff, Thanks for your comment. Bob Sheppard (from Harper Green Secondary Modern School, in Farnworth c.1946) holds a very important place in my memory.

Tony, I think you’re right. Where are all the responses to the test?

Yes, I think you’re right too Steve. It must be too simple a test.

I have another anecdote for those of you who are enjoying Terry’s thread. I must preface mine by saying that Melburnians have an expression about exposing ones posterior in Burke Street, so here goes.

In the late 50’s, it became necessary to redesign the outer casing of a toilet cistern. At that time, the casing and lid were being compression moulded from a composite of pitch and other reinforcing materials. The `new’ material was the much more modern thermoplastics polypropylene (PP), and had become commercial around 1957. Unlike the pitch compound, PP could be injection moulded. The specification also included that the existing innards of polyethylene ball valve and syphon, and various metal fittings were to remain.

The cistern casing was designed for both `high’ level and `low’ level operation, and for greater adaptability, was identical left to right. It was necessary with this `new’ material to provide parallel wall thickness by local thickening the five inlet/overflow/outlet positions, thus forming `bosses’ on the ends and underneath.

The next task was to design and detail the tooling (injection moulds). Eventually, I had produced about half a dozen sheets of tool drawings for the cistern’s lower half. These drawings, having passed through the checkers hands a couple of times, and gained approval at various other levels, were sent off to a German toolmaker. Two injection moulding machines were duly ordered and installed, and after about 6 months the cistern and cistern lid moulds arrived.

“Have a look at this!” It was the chief draughtsman.

One of the end bosses was missing! But how could that have happened?

It turned out that on the GA and also in detail, (having sectioned the mould through various planes to show the feed arrangement, water circuits, air ejection, etc. etc.), I had inadvertently omitted to show that the cistern was actually symmetrical about the vertical centre line. The toolmakers had gone ahead and worked exactly to my drawing.

Eventually, the problem was rectified, but by this time I had (coincidentally), taken on a new position with a major raw-material supplier. This company supplied PP, the very supplier of the grade being used for the cistern!!!?

Guess what? The bl . . y cistern followed me there with another problem. But that’s yet another story.

They say things come back to haunt you. But surely not twice. A couple of evenings ago, my wife and I were watching a very early `On the Buses’ episode. Bus driver, Stan Butler was replacing their old toilet cistern with a modern low-level version, and as usual, he was getting into all sorts of bother.

You’ve guessed it!

He was installing the very same cistern which I designed (and helped to screw-up), all those years ago.

 

AND, the point is, besides following my story, have you understood some of my deliberately placed design engineering jargon? If not, then Terry’s objective gains more validity.

 

Best regards to all,

 

Sam

 

 

Edited By Sam Stones on 20/04/2011 05:33:50

Edited By Sam Stones on 20/04/2011 05:35:29

[David Clark 13Participant @davidclark13]

Hi There

I never put a closing date on the survey.

If there is one it has been added by someone else.

Last time, I waited for all the surveys to came back and

gave out the prizes a couple of weeks after they stopped arriving.

No more were received.

regards David

[David Clark 13Participant @davidclark13]

Hi There

I think more readers of MEW need it than readers of ME.

Most ME readers have been reading for many years and have gained a lot of knowledge.

regards david

[Gordon WParticipant @gordonw]

Graham, just read your earlier post, I would be happy to proof-read ,or act as checker for drawings. But as been pointed out already, there will still be mistakes, or what people see as mistakes. I still have some old BS308’s. I was a contract draffy ( self employed) for years, long before employment rights etc. If you were no good at the job it was “don’t bother coming tomorrow” Every company I worked for had their own methods and standards, If I was doing a drawing for , maybe a small co., I would use my own standards, mainly all views and sections clearly labeled. BS308 is for guidance ,but still the best basics. CAD has produced some dreadful results, mainly because anyone can use it, and knowledge of what is happening is not required.

[Geoff SheppardParticipant @geoffsheppard46476]

Sam

 

The little problem you set us and the mention of spatial awareness jogged my memory and took me back quite a few years. A colleague Development Engineer was having a problem with an engine component, so laid hands on one and examined it thoroughly. He soon worked out what the problem was and devised a design change which he thought would fix it. The task was to now convince the project’s Chief Designer (VERY important in the hierarchy) that a) there was a problem and b) his solution would fix it, so he marches along to the great man bearing the offending object. After carefully explaining chapter and verse he was astonished when the designer said that he couldn’t really appreciate the problem without the drawing in front of him. This despite the fact that all was plain to see. It is all too easy to get mesmerised by the theoretical and lose sight of the real world.

 

By the way, your challenge really had me delving into the memory bank. This sort of ‘teaser’ was very popular in the Training Drawing Office, with students trying to out-do each other with more and more obscure examples.

 

Geoff

[Steve GarnettParticipant @stevegarnett62550]

Posted by Sam Stones on 20/04/2011 05:32:27:

Tony, I think you’re right. Where are all the responses to the test?

Yes, I think you’re right too Steve. It must be too simple a test.

 

Well, ady’s response was interesting. If technical drawing of this nature allowed perspective, and ady had added just one more dotted line, he’d have been correct.

 

And the answer would have been the same if it had been either side, the underneath or the back view you’d asked for!

Edited By Steve Garnett on 20/04/2011 10:58:51

[adyParticipant @ady]

Well, ady’s response was interesting. If technical drawing of this
nature allowed perspective, and ady had added just one more dotted
line, he’d have been correct.

 

I never got less than 90% at techie drawing…used to show the teacher his mistakes…

Taught myself to build CAD gearboxes in my head from haynes manuals at one point, many years ago.

Finished the Merchant navy perspective test(add a line to complete the boxy type shape) when you weren’t actually supposed to get to the end of the 40 odd questions in 2 minutes.

 

This is my first techie drawing answer since 1976.

 

I’m hoping the middle box doesn’t represent a spoof engraving and is part of something visually amazing, like a donut.

 

(My answer was actually a “right back at ya” test to see if anyone could see what I was getting at.

well spotted)

Edited By ady on 20/04/2011 12:09:39

[The Merry MillerParticipant @themerrymiller]

I would like to recommend to any modeller who aspires to greatness in the interpretation of engineering drawings to get hold of a copy of the following hardbacked book.

 

“Interpreting Engineering Drawings -metric edition”

by Cecil H Jensen & Raymond D Hines.

 

Readily available on Amazon.

 

It’s an American book but very pertinent to our own scheme of things with an incredible amount of detail and data.

I bought a copy for my son when he was studying hoping he might discover some latent engineering genes in his body, but no, the fool went into banking!

[Geoff SheppardParticipant @geoffsheppard46476]

How about a verbal description of the figure shown in Sam’s puzzle?:-

 

“A solid object formed by slicing a cube of side x diagonally from top to bottom. Superimposed on the resulting sloping face is a section of a second, smaller cube, similarly sliced, the two arranged sloping face to sloping face.”

 

I’m sure that someone can make a better job of it than that.

 

Geoff

[Geoff SheppardParticipant @geoffsheppard46476]

How about a verbal description of the figure shown in Sam’s puzzle?:-

 

“A solid object formed by slicing a cube of side x diagonally from top to bottom. Superimposed on the resulting sloping face is a section of a second, smaller cube, similarly sliced, the two arranged sloping face to sloping face.”

 

I’m sure that someone can make a better job of it than that.

 

Geoff

[adyParticipant @ady]

and if ady had added just one more dotted line, he’d have been correct.

 

I reckon that if I removed the top right hand dotted line then it could be right, the curvature of the donuts could meet at the top right hand corner of the inner box, merging seamlessly along the line which is deleted.

Edited By ady on 20/04/2011 14:14:07

[TerrydParticipant @terryd72465]

Posted by ady on 20/04/2011 14:04:22:

and if ady had added just one more dotted line, he’d have been correct.

 

I reckon that if I removed the top right hand dotted line then it would be correct.

 

 

Hi Ady,

 

Actually there should be no dotted lines. As Sam said in his original post, there is no hidden detail on the drawings and dotted lines are used to show such detail.

 

Best regards

 

Terry

[David Clark 13Participant @davidclark13]

Hi there

Readily availble but not very cheap.

£50 or £60 at least for an up to date edition.

regards David

 

[The Merry MillerParticipant @themerrymiller]

Hi David,

 

You may have been looking at the Jensen & Helsel editions at that price.

The version I have is from 1979 (Jensen & Hines) and is still very pertinent in todays times believe me.

 

Used later versions are available from a couple of quid, not all in hardback.

[Steve GarnettParticipant @stevegarnett62550]

Posted by Terryd on 20/04/2011 14:22:53:

 

Actually there should be no dotted lines. As Sam said in his original post, there is no hidden detail on the drawings and dotted lines are used to show such detail.

 

Terry is absolutely correct, of course. And that’s why I said previously that ady’s dotted lines would only be correct if he added one, and perspective was allowed, because they could represent the outside edges of a cube – which we could legitimately establish from the plan and front view, although that’s not the only option, as Geoff has pointed out. But of course perspective isn’t allowed, so I repeat – what do those two inner squares actually represent on the plan and front views?

Edited By Steve Garnett on 20/04/2011 17:49:14

[Les Jones 1Participant @lesjones1]

Hi all,

I’m prepared to admit that I haven’t worked out the answer.

Les.

[Steve GarnettParticipant @stevegarnett62550]

I’m getting bored with this now, so I’ll tell you my take on it – and that’s basically that there isn’t enough information to give you a single definitive answer to the side view. I think there may be two possibilities only, though. One is the diagonal cut, as Geoff mentions (with or without inner cube) – and the implication of this is that the central square isn’t necessarily a square at all, but a rectangle, and it’s just drawn on the cut as such – but then it won’t show from the side. The other is, of course, that it’s a cube with two squares drawn on it as shown, and from the side, once again, no inner square will be visible.

 

With other options for the diagonal plane (such as curves) you run into problems with needing the rectangle to move position between the plan and front views, so they’re out. All other options appear to require detail lines on either the plan or the front view, so they’re out too.

 

Have I missed any other possibilities that don’t involve hidden detail? 

Edited By Steve Garnett on 20/04/2011 18:48:06

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