Looking for a non-magnetic, strong, easily glued material

[Anonymous]

Posted by Donald MacDonald 1 on 28/04/2022 12:59:46:

…assuming that you lot have better things to do than to read my PhD…

Correct, but I'll make a deal, you read mine and I'll read yours. Mine is mostly mathematics, associated with pulse compression radar signal design and Fourier transform processing.

It's magnanimous to fed us the constraints that you feel are sufficient, but if you're having to ask these questions I wonder how you know what is sufficient? Can you put some numbers on the requirements?

The sheet of 1050 is almost pure aluminium. Consequently it is very soft and horrible to work, by machine or hand, like warm fudge. It's basically useless except for low stress sheet metalwork, which is why it is only available in sheet form.

Andrew

PS: A copy of my Ph.D. is available for reading in the Cambridge University library, where is yours?

Edited By Andrew Johnston on 28/04/2022 21:06:35

[Donald MacDonald 1Participant @donaldmacdonald1]

@Andrew Johnston
Good. So I think can both agree that we both have better things to do than boost our Egos by reading anybody's entirely unrelated PhD theses just to prove some point on a forum.

Yes, we also agree that although cheap and widely available that 1050 Aluminium is a broadly horrible engineering material. Knowledge of the point was precisely the reason for my starting this thread. Only because time was against me did I buy some more 1mm thick sheet.

@Bill Pudney Yes, assuming that the 1050 works adequately magnetically, I shall keep searching for a small piece of Grade "2024 T3" "7075 T651". But first I also have the Nylon 6 to experiment with, which should arrive shortly.

If anyone happens to know of a model-making friendly supplier of such grades of Aluminium [1mm sheet, small samples, fast delivery] please let me know

And if I find a good supplier myself I shall let you folks know.

Don

[BazParticipant @baz89810]

PS: A copy of my Ph.D. is available for reading in the Cambridge University library, where is yours?

Edited By Andrew Johnston on 28/04/2022 21:06:35

Mr McDonald seems to have forgotten to answer Andrews question, just a gentle reminder for him.

[Tim StevensParticipant @timstevens64731]

When anyone asks me 'Where can I get it' but they do not say where they are, I wonder if they have really thought through their question. It always helps to stand in the shoes of the other bloke, and tell him what he needs to know – even if he might possibly already know it. Or her, of course.

Tim

[Donald MacDonald 1Participant @donaldmacdonald1]

Posted by Baz on 29/04/2022 11:36:10:

PS: A copy of my Ph.D. is available for reading in the Cambridge University library, where is yours?

Edited By Andrew Johnston on 28/04/2022 21:06:35

Mr McDonald seems to have forgotten to answer Andrews question, just a gentle reminder for him.

Baz, I can't see any genuinely relevant questions, and I'm not going to get into a war of words. Sorry.

Tim, I am on mainland UK. Given that I am not very mobile, I don't intend to leave the house if I can avoid it in any case but deliveries work well.

[BazParticipant @baz89810]

The relevant question is that you claim to have a PhD, Andrew told us about his and stated it can be read in Cambridge University library and asked where yours was, it is not a war of words it is a simple question, please let us all know about it and where we can read it.

[Jon LawesParticipant @jonlawes51698]

It's all got a bit silly. I think we need to remember we are all here because we support an enjoyable, inclusive hobby.

[SillyOldDufferModerator @sillyoldduffer]

I've failed to meet Requirement ' G. Needs to be available… fast! (ideally within 24 hours)'!

Have to say, when searching for an engineering material, it's not good to limit choices with purchasing considerations and colour restrictions.

However, on the face of it, an Austenic Stainless steels comes close to meeting Donald's needs. Unfortunately, he rejects Carbon Fibre, suggesting he's doing something very special because Carbon fibre magnetically outperforms most Austenic Stainless Steels.

It would help to know if the sheet's purpose is to protect a permanent (or electro-) magnet from dirt and dings, or to allow a magnetic field to reach a sensitive detector. The attenuation caused in the first situation can be overcome by using a more powerful magnet. The second case is more difficult. Having to join the dots in Donald's partial requirement is unhelpful: I guess the unstated need is to protect a big magnet rather than a sensor because electric fields haven't been mentioned – yet! Could be wrong.

Anyway, if 'A. Completely non-magnetic' really is important, then Donald needs a particular grade of Stainless and it needs to be worked carefully. Not 316, or 316L, but 316LN. 316LN is formulated to minimise it's magnetic effect, and to be less susceptable to having it's magnetic properties trashed by cold-working, flame-cutting, or welding. It's not just the material, it may be import to use it properly. (A few other grades like 304LN, 305, or 310 would perform as well as 316LN.)

But I suspect Donald's requirement may be carelessly worded and ordinary 316L is fine. If so that's a good thing because 'almost non-magnetic' stainless steels are easier to find and use than 'Completely non-magnetic'.

Not throwing rocks at Donald, the point is Requirement Writing is difficult! Sadly, what's crystal clear in the mind of the writer is often morphed by the written word and the reader trying to decode it into an ambiguous, contradictory muddle. Some advice on Requirement Writing, here and here. Note the second link kicks off by saying: 'It has become clear that enormous numbers of engineering design errors originate in the requirements document.' Too true!

In formulating requirements I recommend:

• Giving as much information about goals as possible. (Writing requirements when the goal is secret is exceptionally difficult because the writer has to get everything right. He cannot rely on the reader to second guess what he's after. If the writer doesn't get it spot on, the reader loses confidence in him.)
• Ideally, requirements should concentrate on what things have to do, not how they should do it. Avoid steering towards particular technical answers.
• Always use the word 'must' or 'should'.
• Aggressively self-criticise 'Must' requirements before release because they severely cramp the solution, often in unexpected ways.
• Word 'Must' requirements to get clear yes/no answers. Reword the requirement if 'yes but' or 'no but' answers are acceptanble: it's either badly worded or is a 'should' requirement.
• 'Should' requirements are only desirable and should be weighted to indicate their relative importance. The requirement must be worded such that the response is measurable.
• Numbers should be used wherever possible.
• Avoid unquantifiable words like reasonable, easy, fast, quality, good, strong. They don't help!
• Don't use show-stopper words like 'completely' unless absolutely essential. Many projects fail because over tight requirements carelessly commit them to expensive, unattainable, or time-wasting solutions.
• Get someone else to review the draft and don't take offence when one's pride and joy comes back plastered in red-ink!

Dave

[Donald MacDonald 1Participant @donaldmacdonald1]

Posted by Jon Lawes on 29/04/2022 14:07:51:

It's all got a bit silly. I think we need to remember we are all here because we support an enjoyable, inclusive hobby.

The voice of sanity.

HONESTLY!

Don

[Michael GilliganParticipant @michaelgilligan61133]

Just a thought [almost sure to be rejected but here goes] …

The thin glass sheets which are used as screen-protectors are hard, non-magnetic, and easily glued with LOCA UV-curing adhesive.

MichaelG.

[John Smith 47Participant @johnsmith47]

Woohoo – hello People!

I saw my name being mentioned…. so I thought I'd drop in.

I have to tell you people, that this thread is absolutely HILARIOUS.

I don't know if you gents are being serious or whether it is deliberate self-parody but this thread is absolutely heaving with self-parody.

Poor you Don – now you know what I went through. The wolves won't let go until you publish every single detail of your life & your project… At which point expect to be told that your living in the wrong house and doing the wrong project!

How you people have time to write all this Lord knows, but I hope everyone is enjoying themselves… or is it "oneself", I forget grammar never was my strong suit.

Good luck!

J

PS Don, you have no right to any opinion on which hobby model engineering materials to use on until you have done at least a degree in mathematics, radar signalling and Fourier transform processing algorithms, and obviously you need to have read several papers on how to write an engineering specification before daring to seek any such advice.

But if your PhD is on "Comparing and contrasting the social anthropology of washer-women with online forums of highly educated gentlemen with too much time on their hands, based on the the competitive power dynamics of male specimens of the common Chimpanzee" then you've come to the right place.

Wait, I have just the book for your PhD: "Chimpanzee Politics" by Frans de Waal. I'm told it used to be on the list of required reading for US White House interns.
https://www.amazon.com/Chimpanzee-Politics-Power-among-Apes/dp/0801886562
It's an excellent read, BTW. Highly recommended.

I'm going to scuttle away now before Armageddon kicks in!

Have fun chaps! Byeeeee… xx

 

Edited By John Smith 47 on 29/04/2022 16:52:30

[Robert ButlerParticipant @robertbutler92161]

Posted by John Smith 47 on 29/04/2022 16:50:02:

Woohoo – hello People!

I saw my name being mentioned…. so I thought I'd drop in.

Edited By John Smith 47 on 29/04/2022 16:52:30

Where?

Robert Butler

[SteambuffParticipant @steambuff]

Posted by Robert Butler on 29/04/2022 17:17:08:

Posted by John Smith 47 on 29/04/2022 16:50:02:

Woohoo – hello People!

I saw my name being mentioned…. so I thought I'd drop in.

Edited By John Smith 47 on 29/04/2022 16:52:30

Where?

Robert Butler

Looks as if the Mod's removed it !!!!

[Ramon WilsonParticipant @ramonwilson3]

I would have thought you guys would have woken up by now – there's basic time wasting and there's advanced time wasting and then there's some bloody serious time wasting

Donald's PhD subject possibly – he certainly appears to be a master at it

But then what would I know – I've never been educated – in some eyes

Tug

[DrDaveParticipant @drdave]

At the risk of going back on topic…. Lasaero.com list both 2024-T3 and 7075-T6 in 0.040” thickness. 2024 is out of stock, but would not really suit: they only do Alclad, which has a thin coating of pure ally both sides, so it fails the scuffing requirement. They do have 4’ x 2’ sheets of 7075-T6 showing as in stock at £45, and they are based in the UK.

[SamsarandaParticipant @samsaranda]

I used to work for a seal-less pump manufacturer we manufactured our own magnetic drives, they used stainless steels of varying specifications to meet the product conditions, some of which were highly abrasive or corrosive, the magnetic drive operated through the stainless steels with no problems, my choice for this application would be the appropriate stainless steel. Dave W

[HopperParticipant @hopper]

Only 2001 views and 39 posts on this thread so far? Donald and John are slipping. Ooops. 40 now.

Edited By Hopper on 30/04/2022 01:15:36

[Donald MacDonald 1Participant @donaldmacdonald1]

Posted by Samsaranda on 29/04/2022 19:10:00:

I used to work for a seal-less pump manufacturer we manufactured our own magnetic drives, they used stainless steels of varying specifications to meet the product conditions, some of which were highly abrasive or corrosive, the magnetic drive operated through the stainless steels with no problems, my choice for this application would be the appropriate stainless steel. Dave W

Dave W – yes, this is an excellent call.

I have now run some tests on magnetic prototyping software and it seems that the key metric is (magnetic) Relative Permeability and it turns out that "non-magnetic" stainless steel (e.g. 316L), 1050 Aluminium and Nylon all have a magnetic Relative Permeability of very close 1. And for this reason magnetically speaking when in 'permanent' magnetic fields there is little to choose between them.

Meanwhile I have already now got my hands on both some 1050 Aluminium and some 316L Stainless Steel, but not the Nylon 6. Given how much physically stronger the 316L is compared to 1050, I have started experimenting with the 316L first.

And so far the 316L is working… beautifully. I think we have a winner!

So bad luck to the pedants & detractors… and a big thank you to those of you how have been helpful. 

I think we're done here.

Cheers

Don

PS Once it arrives, I shall also experiment with the Nylon 6 as that may prove to be useful too.

Edited By Donald MacDonald 1 on 30/04/2022 02:56:51

[John Smith 47Participant @johnsmith47]

Congrats Don!

KBO, eh?!

J

[10ba12baParticipant @10ba12ba]

The Johnny / Dr.Donny show grinds to a halt?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by 10ba12ba on 30/04/2022 04:48:04:

The Johnny / Dr.Donny show grinds to a halt?

.

Or has it become a double-act ?

”I think we have a winner!” has a familiar ring to it

MichaelG.

[HopperParticipant @hopper]

It's not the only thing that has a familiar ring to it.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Baz on 29/04/2022 11:36:10:

PS: A copy of my Ph.D. is available for reading in the Cambridge University library, where is yours?

Edited By Andrew Johnston on 28/04/2022 21:06:35

Mr McDonald seems to have forgotten to answer Andrews question, just a gentle reminder for him.

.

I’m sure there must be more, so this is probably a case of mistaken identity … but I did find reference to one Ph.D. thesis by Donald MacDonald : **LINK**

https://researchr.org/publication/ethos-6428

Unfortunately, the actual content is not there … so perhaps it was ‘Secret’

MichaelG.

[HuubParticipant @huub]

Posted by Donald MacDonald 1 on 30/04/2022 02:46:16:

I have now run some tests on magnetic prototyping software and it seems that the key metric is (magnetic) Relative Permeability and it turns out that "non-magnetic" stainless steel (e.g. 316L), 1050 Aluminium and Nylon all have a magnetic Relative Permeability of very close 1. And for this reason magnetically speaking when in 'permanent' magnetic fields there is little to choose between them.

And so far the 316L is working… beautifully. I think we have a winner!

Thank you for sharing. I use POM for my magnetic holders and didn't expect any metal would be "magnetically" comparable.

[HopperParticipant @hopper]

Posted by Michael Gilligan on 30/04/2022 07:20:16:

Posted by Baz on 29/04/2022 11:36:10:

PS: A copy of my Ph.D. is available for reading in the Cambridge University library, where is yours?

Edited By Andrew Johnston on 28/04/2022 21:06:35

Mr McDonald seems to have forgotten to answer Andrews question, just a gentle reminder for him.

.

I’m sure there must be more, so this is probably a case of mistaken identity … but I did find reference to one Ph.D. thesis by Donald MacDonald : **LINK**

https://researchr.org/publication/ethos-6428

Unfortunately, the actual content is not there … so perhaps it was ‘Secret’

MichaelG.

Topic: "Unsupervised neural networks for visualisation of data"

That's got to be it. Describes several threads to a tee.

[Author]

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