Hi

Two questions about aluminium sheet approx 1mm thick.

Can I cut it using my table saw with a TCT blade and/or will doing so blunt
the blade rapidly?

Can I get a polishing mop to fit a 115mm angle grinder, so I can mirror
finish it?

Dave

David Lang wrote:
Two questions about aluminium sheet approx 1mm thick.

Can I cut it using my table saw with a TCT blade and/or will doing so blunt
the blade rapidly?

No, it won't blunt the blade. You will have to be very careful of
feed rate and support, though, or you'll get wobbly edges, to say
the least.


Can I get a polishing mop to fit a 115mm angle grinder, so I can mirror
finish it?

I doubt that'll mirror finish it - maybe make lots of polishing
marks in it. Use flour grade wet'n dry (if need be) with plenty
of wayer with a drop of hairy lipsquid, then brasso on a clean
cotton cloth by hand.

"Chris Bacon" wrote in message
...
David Lang wrote:
Two questions about aluminium sheet approx 1mm thick.

Can I cut it using my table saw with a TCT blade and/or will doing so blunt
the blade rapidly?

No, it won't blunt the blade. You will have to be very careful of
feed rate and support, though, or you'll get wobbly edges, to say
the least.


Can I get a polishing mop to fit a 115mm angle grinder, so I can mirror
finish it?

I doubt that'll mirror finish it - maybe make lots of polishing
marks in it. Use flour grade wet'n dry (if need be) with plenty
of wayer with a drop of hairy lipsquid, then brasso on a clean
cotton cloth by hand.

I thought paraffin was the fluid for working aluminium?

Roger

Roger R wrote:
"Chris Bacon" wrote...
David Lang wrote:
Can I get a polishing mop to fit a 115mm angle grinder, so I can mirror
finish it?

I doubt that'll mirror finish it - maybe make lots of polishing
marks in it. Use flour grade wet'n dry (if need be) with plenty
of wayer with a drop of hairy lipsquid, then brasso on a clean
cotton cloth by hand.

I thought paraffin was the fluid for working aluminium?

I meant Brasso for polishing - it's a very good start. I'm sure
there are other suitable polishes...

Hi Chris
No, it won't blunt the blade. You will have to be very careful of
feed rate and support, though, or you'll get wobbly edges, to say
the least.

Thanks - I'll watch those points - I have enough wobbly edges as it is!

I doubt that'll mirror finish it - maybe make lots of polishing
marks in it. Use flour grade wet'n dry (if need be) with plenty
of wayer with a drop of hairy lipsquid, then brasso on a clean
cotton cloth by hand.

I was trying to avoid the 'by hand' method. I saw on The Caravan Show the
other night someone mirror finishing aluminium with what looked like an
angle grinder, but the pad was at right angles, The pad appeared to be
discs of cloth stitched together.

Dave

On Thu, 09 Jun 2005 21:48:38 GMT, "David Lang"
wrote:

Can I cut it using my table saw with a TCT blade and/or will doing so blunt
the blade rapidly?

I really wouldn't do this - there's a kickback risk. If you get the
right sort of sawblade (negative tooth rake) then it's easy and safe.
You won't "blunt the blade".

It will be incredibly noisy though, especially on a saw that's less than
perfectly rigid!

You'll also want something like a Dreadnought file (a coarse-toothed
curved tooth rasp) for working the edges. Aluminium benefits from new,
sharp coarse files and rubbing the teeth with chalk before beginning.
The teeth tend to "pin up" with aluminium, so the rasp stays cleaner.

Can I get a polishing mop to fit a 115mm angle grinder, so I can mirror
finish it?

No, the angle grinder is much too fast.

There are useful nylon bristled abrasive-loaded rotary brushes you can
get to use in a hand drill. These are excellent for copper, but
aluminium is just a bit too soft - you can too easy put obvious swirl
marks in with them.

I suggest a range of hand Garryflex blocks instead (also made for
Roebuck), rubber blocks full of abrasive grit in a range of grades.
Aluminium is soft enough that doing it by hand doesn't take long, even
for large pieces. Make sure you use the coarsest first and don't go
finer until you've got the last of the scratches out. A mirror finish is
easy and only takes moments, a good unscratched mirror finish takes more
care and effort.

Either keep separate sets of blocks for ferrous and non-ferrous metals,
or rub then clean when swapping over - otherwise you get black smears.

Look after your aluminium when you're working on it (masking tape etc.
do avoid scratching where you're working). It's easier to not put big
scratches on than to take them off later. Emery or wire wool will shift
them, if you have to.

--
Cats have nine lives, which is why they rarely post to Usenet.

In article ,
David Lang wrote:
Two questions about aluminium sheet approx 1mm thick.

Can I cut it using my table saw with a TCT blade and/or will doing so
blunt the blade rapidly?

Easier to get an accurate cut with decent tinsnips? Or if well supported a
jigsaw with suitable blade?

I'd be very worried about a table saw 'grabbing' and throwing things every
which way.

Can I get a polishing mop to fit a 115mm angle grinder, so I can mirror
finish it?

Most polishers run at a low speed to avoid burning the polisher and paste.

I'd try a random orbit sander with a lambs wool bonnet.

--
*Just remember...if the world didn't suck, we'd all fall off.

Dave Plowman London SW
To e-mail, change noise into sound.

David Lang wrote:
(polishing)
I was trying to avoid the 'by hand' method. I saw on The Caravan Show the
other night someone mirror finishing aluminium with what looked like an
angle grinder, but the pad was at right angles, The pad appeared to be
discs of cloth stitched together.

That's a rag buffing wheel, I have no idea what it's mounted on - note
that your grangle winder whizzes around at at least 10,000 RPM, so it
will be a bit tasty on aluminium. What about a car polisher? You can
get a thing called a "Power Devil car polisher" if it's no good or
breaks, take it back!

In article ,
"David Lang" says...
snip
Can I get a polishing mop to fit a 115mm angle grinder, so I can mirror
finish it?

Grinders run much too fast for polishing.

In article , says...
David Lang wrote:
Two questions about aluminium sheet approx 1mm thick.

Can I cut it using my table saw with a TCT blade and/or will doing so blunt
the blade rapidly?

No, it won't blunt the blade. You will have to be very careful of
feed rate and support, though, or you'll get wobbly edges, to say
the least.

Sandwich it between two pieces of ply, mdf, chipboard, whatever you
have. Clamp or screw the sandwich together. It will then cut fine for
you

Paul Mc Cann

"David Lang" wrote in message
o.uk...
Hi

Two questions about aluminium sheet approx 1mm thick.

Can I cut it using my table saw with a TCT blade and/or will doing so
blunt
the blade rapidly?

Can I get a polishing mop to fit a 115mm angle grinder, so I can mirror
finish it?

Dave


read this a while back and thought it was interesting

http://www.popsci.com/popsci/how2/ar...693558,00.html

"when aluminum rusts, it forms aluminum oxide, an entirely different
animal. In crystal form, aluminum oxide is called corundum, sapphire or ruby
(depending on the color), and it is among the hardest substances known. If
you wanted to design a strong, scratchproof coating to put on a metal, few
things other than diamond would be better than aluminum oxide."

So you are really going to be polishing the oxide or corundum, the trick is
not to do anything that will cut/scratch through the coating I guess

Paul

Paul ( Skiing8 ) wrote:

"when aluminum rusts, it forms aluminum oxide, an entirely different
animal. In crystal form, aluminum oxide is called corundum, sapphire or ruby
(depending on the color), and it is among the hardest substances known. If
you wanted to design a strong, scratchproof coating to put on a metal, few
things other than diamond would be better than aluminum oxide."

So you are really going to be polishing the oxide or corundum, the trick is
not to do anything that will cut/scratch through the coating I guess

'e wants to polish the *metal* to a mirrer finis

Huge wrote:
Chris Bacon writes:
(polishing aluminium)

You can't.

Want to bet? A quick Google will show many interesting things...


The moment the metal is exposed to the air, it forms a coat of oxide.

Hm. Yet there's plenty of polished aluminium about. How *do* they
do it ?

On 10/06/2005 12:35 Chris Bacon gurgled:

David Lang wrote:
(polishing)
I was trying to avoid the 'by hand' method. I saw on The Caravan Show the
other night someone mirror finishing aluminium with what looked like an
angle grinder, but the pad was at right angles, The pad appeared to be
discs of cloth stitched together.

That's a rag buffing wheel, I have no idea what it's mounted on - note
that your grangle winder whizzes around at at least 10,000 RPM, so it
will be a bit tasty on aluminium. What about a car polisher? You can
get a thing called a "Power Devil car polisher" if it's no good or
breaks, take it back!

Solvol Autosol is the stuff for polishing aluminium used with a 3" felt
wheel (Black and Decker make one) that fits your leccy drill using the
same arbour as a grinding wheel. You may need to finish with a bit of
Solvol Autosol on a cloth to remove any polishing marks but it is easy.

Used to get a chrome-like finish on engine castings when I was a biker.

Parish

Huge wrote:
Chris Bacon writes:
Hm. Yet there's plenty of polished aluminium about. How *do* they
do it ?

You're looking at a coat of aluminium oxide. The fact that it's a nice
optically flat one due to the metal beneath being flat also is irrelevant. It
is simply impossible to have a bare coat of aluminium metal in air.

So aluminium oxidises in air, and you can't polish it. Other
metals also oxidise in air, so are you saying it's impossible
to polish them? If not, why not?

"David Lang" wrote in message
.uk...
Hi Chris
No, it won't blunt the blade. You will have to be very careful of
feed rate and support, though, or you'll get wobbly edges, to say
the least.

Thanks - I'll watch those points - I have enough wobbly edges as it is!

I doubt that'll mirror finish it - maybe make lots of polishing
marks in it. Use flour grade wet'n dry (if need be) with plenty
of wayer with a drop of hairy lipsquid, then brasso on a clean
cotton cloth by hand.

I was trying to avoid the 'by hand' method. I saw on The Caravan Show the
other night someone mirror finishing aluminium with what looked like an
angle grinder, but the pad was at right angles, The pad appeared to be
discs of cloth stitched together.

Probably a stitched polishing mop, available from professional polishing
suppliers, but I doubt the ones I know would fit on an angle grinder.

Colin Bignell

In article ,
(Huge) writes:
Chris Bacon writes:

Hm. Yet there's plenty of polished aluminium about. How *do* they
do it ?

You're looking at a coat of aluminium oxide.

Aluminium oxide is transparent -- clear as glass.
It's also incredibly hard (not far off diamonds), although
the layer which forms is really too thin to provide much
protection. It can be deliberately thickened by anodising,
which makes the surface harder. It's a damn good electrical
insulator too, which is a bad thing when trying to connect
aluminium conductors.

--
Andrew Gabriel

On Fri, 10 Jun 2005 15:01:51 +0100, Parish wrote:

Solvol Autosol is the stuff for polishing aluminium u

Autosol is a chrome polish, so it's a very hard abrasive. It'll work on
aluminium, but it's a lot more effort than you need. Using a coarser and
softer polish will get you there much more quickly.

Don't use Brasso. Unless you clean it carefully afterwards, you can get
discolouring, because of the ammonia in it.

On 10 Jun 2005 13:43:32 GMT, (Huge) wrote:

The moment the metal is exposed to the air, it forms a coat of oxide.

Not in practical terms. Aluminium takes hours or days to form an
appreciable oxide coat, and even then it's pretty negligible. Ti in
contrast is far more reactive and you can watch the oxide film form in
seconds. If your aluminium has an oxide coat that you can mechanically
notice, it got there by anodising, either deliberately or as a
side-effect of heat treatment or pickling.

And "aluminium oxide" covers a range of materials, where the mechanics
depend on the crystallography, not just the chemistry. Comparing the
stuff found on a sheet of aluminium metal to corundum is ridiculous.
And it will never be "ruby" or "sapphire" unless you start doping it.

Andy Dingley wrote:
(about polishing aluminium)
Don't use Brasso.

Rubbish, total ablls, Brasso is a good polish for aluminium (also
Perspex, etc). Google "brasso aluminium".

Unless you clean it carefully afterwards, you can get discolouring,
because of the ammonia in it.

Well, duh.

Andy Dingley wrote:
Huge wrote:
The moment the metal is exposed to the air, it forms a coat of oxide.

Not in practical terms. Aluminium takes hours or days to form an
appreciable oxide coat

Well done.

Chris Bacon wrote:

Rubbish, total ablls, Brasso is a good polish for aluminium (also
Perspex, etc). Google "brasso aluminium".

While it will work on aluminium (as long as you wash it afterwards to
avoid discolouration), it is not in any way a good polish for perspex -
it will leave a very cloudy surface. Try it.


--
Grunff

Grunff wrote:
(Brasso)
While it will work on aluminium (as long as you wash it afterwards to
avoid discolouration), it is not in any way a good polish for perspex -
it will leave a very cloudy surface. Try it.

I have tried it, on 1/2" Perspex. It works well. A better result is had
using Perspex polish No. 2 afterward. Perspex polish No. 1 is very
gritty (some yrs ago, perhaps No. 1 & No. 2 are the wrong way around).
Perhaps you were thinking of something other than "Perspex"? Brasso is
also good on resin castings.

N.B. if you polish aluminium off properly, or even polish reasonably
frequently with Brasso there's no problem with "discolouration".

"Andy Dingley" wrote in message
...
On Fri, 10 Jun 2005 15:01:51 +0100, Parish wrote:

Solvol Autosol is the stuff for polishing aluminium u

Autosol is a chrome polish, so it's a very hard abrasive. It'll work on
aluminium, but it's a lot more effort than you need. Using a coarser and
softer polish will get you there much more quickly.

Don't use Brasso. Unless you clean it carefully afterwards, you can get
discolouring, because of the ammonia in it.

Oh - is THAT what does it! I should have realised ... Brasso is certainly
not effective in polishing Al but I don't know what is in a
household/workshop situation.

Mary

In article ,
Grunff wrote:
While it will work on aluminium (as long as you wash it afterwards to
avoid discolouration), it is not in any way a good polish for perspex -
it will leave a very cloudy surface. Try it.

Eh? Have they changed the formulation? It certainly used to work ok.

--
*Taxation WITH representation ain't much fun, either.

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 10 Jun 2005 17:44:35 +0100, Chris Bacon
wrote:

Don't use Brasso.

Rubbish, total ablls, Brasso is a good polish for aluminium (also
Perspex, etc). Google "brasso aluminium".

Brasso is a soft tripoli in a liquid medium. Tripoli is an appropriate
polishing medium for soft metals like aluminium and is pretty good for
some harder plastics too. It won't make a dent in chrome though, hence
the existence of Solvol Autosol. However the choice of liquid for Brasso
is chosen for cuprous metals, and it's not a good choice for aluminium
of plastics.

In particular, it's hard to polish plastics with a liquid medium and a
standard mop. You're much better off with a paste medium. A hard mop is
too likely to burn the surface on plastics, unless you arrange a lapping
machine.

Unless you clean it carefully afterwards, you can get discolouring,
because of the ammonia in it.

Well, duh.

As you know everything about everything, perhaps you'd like to explain
to us _why_ Brasso uses ammonia, and why this is an irrelevance (and
potentially a harmfully discolouring one) for aluminium.

Paul ( Skiing8 ) wrote:

"David Lang" wrote in message
o.uk...

Hi

Two questions about aluminium sheet approx 1mm thick.

Can I cut it using my table saw with a TCT blade and/or will doing so

blunt

the blade rapidly?

Can I get a polishing mop to fit a 115mm angle grinder, so I can mirror
finish it?

Dave



read this a while back and thought it was interesting

http://www.popsci.com/popsci/how2/ar...693558,00.html

"when aluminum rusts, it forms aluminum oxide, an entirely different
animal. In crystal form, aluminum oxide is called corundum, sapphire or ruby
(depending on the color), and it is among the hardest substances known. If
you wanted to design a strong, scratchproof coating to put on a metal, few
things other than diamond would be better than aluminum oxide."

So you are really going to be polishing the oxide or corundum, the trick is
not to do anything that will cut/scratch through the coating I guess

Paul


Actually about a day after you polish it, a new oxide layer forms. Its a
bit of a watse of time really.

Chris Bacon wrote:

Huge wrote:

Chris Bacon writes:
(polishing aluminium)

You can't.


Want to bet? A quick Google will show many interesting things...


The moment the metal is exposed to the air, it forms a coat of oxide.


Hm. Yet there's plenty of polished aluminium about. How *do* they
do it ?

The short amnswer is the oxide is so thin that it doesn't impede
reflection.

However its not scratchproof at all.

Huge wrote:

Chris Bacon writes:

Paul ( Skiing8 ) wrote:


"when aluminum rusts, it forms aluminum oxide, an entirely different
animal. In crystal form, aluminum oxide is called corundum, sapphire or ruby
(depending on the color), and it is among the hardest substances known. If
you wanted to design a strong, scratchproof coating to put on a metal, few
things other than diamond would be better than aluminum oxide."

So you are really going to be polishing the oxide or corundum, the trick is
not to do anything that will cut/scratch through the coating I guess

'e wants to polish the *metal* to a mirrer finis


You can't.

The moment the metal is exposed to the air, it forms a coat of oxide.

I agree!

All pure and semi pure forms of aluminium suffer the same fate. It is
only the exotic alloys that can remain reflective.

I worked in the aerospace industry for nearly 30 years and the only mil
jet that was polished was the lightning and for the life of me, I can't
remember what polish was used. It was never like a mirror, but it did
make a big difference to its appearance though.

Dave

In article ,
Andy Dingley wrote:
As you know everything about everything, perhaps you'd like to explain
to us _why_ Brasso uses ammonia, and why this is an irrelevance (and
potentially a harmfully discolouring one) for aluminium.

It used to have some form of alcohol base? as I've seen 'unfortunates'
drinking it. Although this was in Balham. They drink anything here.

--
*Many people quit looking for work when they find a job *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Huge wrote:
The moment the metal is exposed to the air, it forms a coat of oxide.

Not in practical terms. Aluminium takes hours or days to form an
appreciable oxide coat, and even then it's pretty negligible.

Damn. My 'A' level chemistry master was lying. I wonder why?

'Twas my understanding it oxidised very quickly which is why it's
difficult to weld or solder.

--
*A day without sunshine is like... night.

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:

While it will work on aluminium (as long as you wash it afterwards to
avoid discolouration), it is not in any way a good polish for perspex -
it will leave a very cloudy surface. Try it.


Eh? Have they changed the formulation? It certainly used to work ok.


You mean on perspex? Dunno if they've changed the formulation, but I
tried to polish out some scratches on a piece of clear perspex a few
years ago and ended up with a very cloudy surface.


--
Grunff