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Aluminium working techniques


#1

Hi everyone,

a friend of mine gave me a bagful of aluminium things, strange
extruded objects, spare bits from an aluminium factory. I was asking
myself if it would be possible to cold work them, such as use them
as practice pieces for hand engraving, chasing… Does anybody have
some experience in this? Such as: which tools to use? How to anneal
it (if it’s needed)? and so on.

thanx for any

italian newbie davide


#2

I have been told not to work on aluminum and sterling in the same
workplace or with the same tools. Can anyone comment on this?

Mary A.


#3

Davide

My recent experience has led me to believe it’s great practice
material, but if you really want a nice piece, don’t use it.

Yes, it will take a stamping / chasing nicely(, ONCE?). I don’t know
about annealing.

Yes, you can repousse(, ONCE?). (Annealing, see above.) I have these
lovely pieces that were cut out with a circle cutter, then stamped,
then domed. I’m either going to set them in a bezel cup, or drill
them & connect with jump rings.

I spend most of today cutting out a design in 20g aluminum sheet
(some kind of commercial surface layer that keeps it shiny - even if
you dome it). At first it cut like a dream, but aluminum will dull a
saw blade faster than you’d believe. The dust is so light that it
WILL get in your eyes; not like silver where it falls away in a
well-behaved manner. And the stuff is DIRTY! I had to wash the
grey-black patina off my hands often.

But it cuts easily without having to be annealed, it’s very
compliant when drilling, and once riveted to the copper underlay it
will look FABULOUS. As a large piece, it won’t be too heavy to wear.

For engraving, I would think it would be great practice material.
But since the surface oxidizes so easily, it’s not suitable for a
presentation piece. I would guess it would be more useful in learning
to handle the graver than in learning to handle the metal. It doesn’t
give enough resistance.

In fact, for any cold working, it will help you learn about
technique and your tools. But it will not inform you about how to
accomodate silver, copper or gold.

HTH, and looking for more input,
Kelley


#4

Hi Guys,

I know I took a class in college that reactive metals taught. They
told us it had something to do with the aluminum dust and it being
highly flammable if you were to get it on your silver pieces and use
a torch. They are really nice there and know just about everything
there is to know about about aluminum and titanium. Contact them I’m
sure they will be glad to help.

Linda Reboh
www.YourCosmicCreations.com


#5
I spend most of today cutting out a design in 20g aluminum sheet
(some kind of commercial surface layer that keeps it shiny - even
if you dome it). At first it cut like a dream, but aluminum will
dull a saw blade faster than you'd believe. 

One thing about aluminum, it likes to gall to cutters. Tiny chunks
will weld themselves in place. I’ve done some machining of aluminum,
and generally a cutting lubricant is very important with it. The
favourite seems to be turpentine. As for annealing, it is my
understanding that aluminum suffers from a serious hot-short
problem. If you try to heat treat without very specialized equipment,
you can expect it to crack.

Also, bear in mind that aluminum oxidizes very rapidly. It maintains
a thin layer of aluminum oxide on the surface, and this is in itself
very hard and very abrasive. Common grinding wheels are made from
it. Of interest, if you place a small drop of mercury it will form an
amalgam with the aluminum, preventing the aluminum from covering
itself with oxide. The whole piece of aluminum will turn to aluminum
oxide dust very rapidly.

Paul Anderson


#6
I have been told not to work on aluminum and sterling in the same
workplace or with the same tools. Can anyone comment on this? 

Some metals one might work on would, even in small quantities,
contaminate silver. and example is pewter, which is mostly tin. Small
bits on your silver, if still there when next you heat the silver to
anneal or solder, will deeply etch nasty scars or even holes right
through the silver. Lead alloys (like tin/lead solders, etc) are even
worse. But aluminum does not alloy with or mix with silver, so even a
bit of molten aluminum on the silver shouldn’t have a negative
effect. Mixing tools, etc, would of course mean your filings and
dust would not have as much silver in it as you expect when you send
it for refining, but aluminum is one white metal which probably CAN
be used on the same workbench without risk of disaster. That’s not
true with a number of others. Brass, for example, on the silver would
also etch/melt in much easier than expected (silver solder is, after
all, essentially silver mixed with brass)

In a similar vein, we’re usually told when working with platinum, to
use seperate tools and workspace if possible from when working with
gold, silver, or other lower melting metals. The dangers are indeed
there, but to be honest, with some care, you can avoid the problems.
It IS important to keep your heating/soldering surfaces clean of
other metals or bits of solder, etc. That’s where the most dangerous
risks exist. And cleaning your files, especially, is a good idea,
since a file gets used with enough force on the cutting edges that
bits of the metal already stuck in the file teeth can sometimes get
forced into the metal your filing. Not common or a major problem, but
possible, and an avoidable risk.

In general, at least in my experience, the dire statements of risk
tend to be somewhat over stated. It’s real enough sometimes (but not
really with aluminum, for the reasons already stated, it doesn’t mix
with precious metals even when melted), but with decent attention,
you can safely work with multiple metals on the same bench, with the
same tools. I think in the last 35 years or so that i’ve been working
with metals, I can probably count on one hand the number of times
I’ve had a problem with this sort of contamination, and I’m not all
THAT careful either. After all, a basic rule of soldering is that
your metal should be clean first. Just doing that attentively avoids
the majority of situations you can get in trouble.

I think I’d probably be safe in saying that if you’re working in
pewter, then perhaps you need to be more careful than usual. Tin and
lead are unusually damaging to precious metals. And if you’re working
with platinum you need to be more attentive too, and with more than
just avoiding other metals. But those tend to be special cases.

Hope that helps.
Peter Rowe


#7

Hi there

You can cold work aluminium but you do need to anneal it. You need
to be careful because if you overheat it then it becomes brittle, but
there is a trick to this - get a bar of soap and rub it on a bit of
AL. Heat the AL evenly and when the soap mark turns black you have
reached the annealing temperature. When I do this I have let it cool
naturally to good effect, no idea if quenching is a good thing or
not.

Other than that, work it like a soft copper.

Chris
collarsandcuffs.co.uk


#8

Mary,

Low melting point metals will make nasty pits in sterling and gold if
heated to typical soldering temperatures. Lead is the classic example
but tin (pewter), bismuth, and aluminium work just as well. There are
others, these 4 come to mind since I use them all. Just keep track of
your metal hygiene… and for sure use separate files.

Jeff
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#9

Hi Davide,

To anneal aluminium wipe it with a bar of household soap and then
heat carefully with a large soft flame until the soap mark goes
black, then quench (I think). You won’t see it glow etc, so you have
to be careful not to be tempted to “heat a little bit more” etc:
it’ll just slump.


#10

Because I wasn’t sure what would happen, I went to my garage and used
a separate bench pin & blades to pierce the aluminum. Washed my hands
often & before I used silver. Anyway, the item turned our really
nice. But none of it went into my usual workspace. With respect to
connecting the aluminum to the copper backing (hey there, I’ve made a
battery!), I used 20g silver wire as the rivets. You only see it when
you look at the back of the pendant, and wonder what those little
white dots are.

Here’s what it looks like: [1st photo]
http://homepage.mac.com/wise_lady/DragonWerx/PhotoAlbum5.html