Identifying Light Alloy

[Martin Dilly 2Participant @martindilly2]

I've acquired a couple of sheets 5mm x about 4 feet square of light alloy left over from a water-cutting job producing letters for a shop sign.

I'd like to sell this as it's taking up workshop space but have no idea how to describe it. It's a bit 'puddingy' when drilled or milled, so probably isn't anything high tensile. Any suggestions please as to what it might be (or indeed offers to buy!)?

[Martin Dilly 2Participant @martindilly2]

[not done it yetParticipant @notdoneityet]

An indication of location might help. Metric thickness and imperial dimensions could put you anywhere on the globe?

[Anonymous]

The two most common aluminium products are 1050A and 6082, unless you're into proper engineering. As far as I'm aware 1050A is only available as sheet; it's pretty much pure aluminium and is great for sheet metalwork as it bends without cracking. It's horrid stuff to machine, warm fudge would be easier. It would seem an odd choice for letters, if bending wasn't needed. On the other hand 6082 is available in a variety of hardnesses and tempers in sheet and bar form. It machines very nicely, although it is prone to built up edges on tools.

Andrew

[Alan Waddington 2Participant @alanwaddington2]

‘Very light’ Are you sure it’s not Dibond composite ally sheet. Very common in the sign industry 👍

[Neil WyattModerator @neilwyatt]

If it's puddingly, it's probably the near pure aluminium.

Neil

[Martin Dilly 2Participant @martindilly2]

Thanks for the suggestions, gents. I'm in the Croydon-Bromley area, in case an orderly queue wants to form to buy a couple of sheets of this. I'm pretty sure it's not Dibond, as it's consistent through the thickness and has no obvious surface treatment.

Is there any way, apart from paying a fortune for metallurgical analysis, that I can make an educated guess about what I've got? It produces more of a clunk than a ping when you drop a piece!

[SillyOldDufferModerator @sillyoldduffer]

Posted by Martin Dilly 2 on 09/01/2020 10:44:23:

…

Is there any way, apart from paying a fortune for metallurgical analysis, that I can make an educated guess about what I've got? It produces more of a clunk than a ping when you drop a piece!

It's unlikely to be Titanium, Magnesium, or Zinc. Aluminium reacts with Sodium Hydroxide (Caustic Soda) to make Hydrogen. Done in a test tube the hydrogen can be ignited with a characteristic 'pop' explosion. If you have a drop of Mercury, Aluminium is eaten by it, producing a characteristic efflorescence.

These simple chemical tests will only confirm it's an Aluminium Alloy. You could get close to identifying which particular alloy (and there are dozens of them) by measuring the sheet's density. Done by comparing the sheet's accurate weight with the weight or volume of water displaced when immersed. See 'Eureka'.

Seems an awful fuss for an ebay sale though. I don't suppose anyone in Aerospace will buy it!. If it were mine I'd just describe it as Aluminium sheet surplus from signage. If confident about telling the difference I' might go so far as to describe it as soft or hard. (This is easy to do by comparison, tricky if you only have experience of one type!) You can say what you like as long as the description isn't misleading.

Dave

[not done it yetParticipant @notdoneityet]

Not too difficult in calculating the volume if the sheets are square and of uniform thickness?

[Anonymous]

The difference in density between 1050A and 6082 is 0.37%.

Andrew

[JasonBModerator @jasonb]

Pop down your local scrappy and get them to point their Alloy Analyzer gun at it, you could also sell it to them.

[egaParticipant @ega]

Eureka:

A propos but OT, I happened to notice the other day that the lathes.co.uk site entry for Selig Sonnenthal Lathes has a picture of the cutter backing-off device which has been discussed here some time ago.

http://www.lathes.co.uk/seligsonnenthal/page2.html

[Author]

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