Bending aluminium
 

I want to make up some bent aluminium components.

The items will be 'U" shape brackets.

I intend to start with aluminium strip that's about 250mm long and 50mm
wide and then bend the last 50mm at each end to stand up at 90 deg.

The thing I don't know is how thick can the strip be and still be
sensibly bent without special tools ? For my purposes, the thicker the
better as it needs to have holes tapped in it, but I still need to bend
the stuff.

I don't know exactly what grade it's going to be as it's just the ali
strip I get from my ironmonger.

As far as bending is concerned, I usually use an old Workmate with
angle iron as jaw protectors/strengtheners. I mark the bend point,
clamp it up, place a hardwood block against it and belt it with the
hammer ( 2kg ish ).

So my question is really three questions

What's the thickest 50mm wide strip that I'm likely to successfully
bend this way ?

Is there a better way of doing it without buying special tools ? I
assume that hot bending isn't appropriate for ali, neither is any form
of heat softening or hardening a practical proposition.

If all else fails, how much might I have to pay to get four items like
that made for me in 6mm thick strip ?

In an earlier contribution to this discussion,
wrote:

I want to make up some bent aluminium components.

The items will be 'U" shape brackets.

I intend to start with aluminium strip that's about 250mm long and
50mm wide and then bend the last 50mm at each end to stand up at 90
deg.

The thing I don't know is how thick can the strip be and still be
sensibly bent without special tools ? For my purposes, the thicker the
better as it needs to have holes tapped in it, but I still need to
bend the stuff.

I don't know exactly what grade it's going to be as it's just the ali
strip I get from my ironmonger.

As far as bending is concerned, I usually use an old Workmate with
angle iron as jaw protectors/strengtheners. I mark the bend point,
clamp it up, place a hardwood block against it and belt it with the
hammer ( 2kg ish ).

So my question is really three questions

What's the thickest 50mm wide strip that I'm likely to successfully
bend this way ?

Is there a better way of doing it without buying special tools ? I
assume that hot bending isn't appropriate for ali, neither is any form
of heat softening or hardening a practical proposition.

If all else fails, how much might I have to pay to get four items
like that made for me in 6mm thick strip ?

Forget trying to bend 6mm thick aluminium - 2-3 mm is the best you are
likely to achieve. Forget trying to do it with a Workmate too - you need a
decent metal-working vice.

Rather than trying to cut threads in thin sheet - which won't work, anyway -
why not use threaded inserts such as Rivnuts [See
http://www.nfauto.co.uk/rivnut.htm - but note that you don't need their
expensive tool to attach them to sheet metal - you can DIY with a fully
threaded bolt, a nut and a washer!]

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In article .com,
Roly wrote:
I want to make up some bent aluminium components.

The items will be 'U" shape brackets.

I intend to start with aluminium strip that's about 250mm long and 50mm
wide and then bend the last 50mm at each end to stand up at 90 deg.

You might find you can get 'U' section ally near enough for what you need.
And at 50mm wide, it wouldn't cost a fortune for offcuts. George King
Metals in Colliers Wood would be my first call if you're anywhere close -
they sell by weight and of course a cutting charge.

The thing I don't know is how thick can the strip be and still be
sensibly bent without special tools ? For my purposes, the thicker the
better as it needs to have holes tapped in it, but I still need to bend
the stuff.

I don't know exactly what grade it's going to be as it's just the ali
strip I get from my ironmonger.

As far as bending is concerned, I usually use an old Workmate with
angle iron as jaw protectors/strengtheners. I mark the bend point,
clamp it up, place a hardwood block against it and belt it with the
hammer ( 2kg ish ).

So my question is really three questions

What's the thickest 50mm wide strip that I'm likely to successfully
bend this way ?

Is there a better way of doing it without buying special tools ? I
assume that hot bending isn't appropriate for ali, neither is any form
of heat softening or hardening a practical proposition.

Annealing ally is easy. Wipe it with soap - the sort you clean your face
with - and heat it 'till the soap turns black. Then quench in water.

If all else fails, how much might I have to pay to get four items like
that made for me in 6mm thick strip ?

I'd first try to find suitable U section extruded. It's a delight to work
with. I use it for making up things that have to fit in a 19" bay, etc,
and it comes in various heights. I've not needed anything 250mm high, but
with a bit of luck...

--
*Frankly, scallop, I don't give a clam

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

4mm would do, 6mm would be better. There's no significant load on the
threads, the threaded part just hold another minor part in place.

Inserts would stick out the other side and I need the front & back to
be flat so that it can slide into alternative fixing positions - where
it's fastened by a bolt through a hole into something more solid.

I don't have a heavy enough bench for a decent vice.

I do have a tool for setting threaded inserts. I don't much like it as
the inserts don't always bite very well and sometimes work loose enough
to rotate in their hole. The tool looks much like the one you linked
to. I get better results by doing what I previously used to do. Cinch
nuts, a ball bearing and a hammer !

Dave Plowman said -
You might find you can get 'U' section ally near enough for what you
need.

I rather doubt it.

The width needs to fit an existing part and it's not a convenient round
figure either. Extrusions always seem to be whole inch or cm multiples.

That's why I reckon I'll need to make something the right size.

Thanks to the two of you for the info about annealing and hardening.

I can remember doing that as a kid when I used to make model aircraft
undercarts, but had long forgotten the details.

But the aluminium I used to use was an alloy that's much stiffer than
the aluminium I usually find in shops.

Is there an easy ( and cheap ) source of an alloy that's more suitable
than bog-standard soft ali ?

On Mon, 04 Apr 2005 00:37:02 +0100, The Natural Philosopher
wrote:

Heating and fast cooling re-hardens.

Not on aluminium (or most non-ferrous metals, for that matter).

Annealing of aluminium or copper is a different process from steel.
For steel you're trying to change the crystal structure of the metal,
either by heating it to a temperature where the desired structure is
stable, then freezing it in place (hardening) or by slowly reducing it
in temperature so that it can re-align to the structure that's stable
at low temperatures (annealing).

For aluminium (and pure unalloyed metals in general), you're just
shaking the dislocations out of the crystal lattice and putting it
back the way it was.

"The Natural Philosopher" wrote in message
...
wrote:
....
Is there a better way of doing it without buying special tools ? I
assume that hot bending isn't appropriate for ali, neither is any form
of heat softening or hardening a practical proposition.


Actually, they are. Heating and slow cooling anneals. Heating and fast
cooling re-hardens....

It does, however, normally require a temperature controlled oven to do it
in. For example, the annealing information I have for one fairly common
free-machining age-hardening alloy is to hold at 410C for 2-3 hours, reduce
at 10C per hour down to 260C, then air cool. Age hardening, for T4 temper is
soak at 510C for 3 hours, then water quench. Hardening for optimum strength
(T8 temper) requires 510C for an adequate time to heat the piece through,
water quench, cold working to shape, then holding at 160C for 15 hours
before air cooling.

Colin Bignell

"The Natural Philosopher" wrote in message
...

I
assume that hot bending isn't appropriate for ali, neither is any form
of heat softening or hardening a practical proposition.


Actually, they are. Heating and slow cooling anneals. Heating and fast
cooling re-hardens.

NONONO! Not with Al!

Mary

In article . com,
Roly wrote:
You might find you can get 'U' section ally near enough for what you
need.

I rather doubt it.

The width needs to fit an existing part and it's not a convenient round
figure either. Extrusions always seem to be whole inch or cm multiples.

That's why I reckon I'll need to make something the right size.

Ah - right. Your original post suggested the size wasn't critical.

--
*I used up all my sick days so I called in dead

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

In article ,
Andy Dingley writes:

For aluminium (and pure unalloyed metals in general), you're just
shaking the dislocations out of the crystal lattice and putting it
back the way it was.

I think you're describing work hardening.
Annealing (heating) is the opposite, breaking the lattice up into
small crystal domains with lots of dislocation boundaries so it
bends more easily (at the more dislocation boundaries).

--
Andrew Gabriel

wrote in message
oups.com...
I want to make up some bent aluminium components.

The items will be 'U" shape brackets.

I intend to start with aluminium strip that's about 250mm long and 50mm
wide and then bend the last 50mm at each end to stand up at 90 deg.

The thing I don't know is how thick can the strip be and still be
sensibly bent without special tools ? For my purposes, the thicker the
better as it needs to have holes tapped in it, but I still need to bend
the stuff.

I don't know exactly what grade it's going to be as it's just the ali
strip I get from my ironmonger.

As far as bending is concerned, I usually use an old Workmate with
angle iron as jaw protectors/strengtheners. I mark the bend point,
clamp it up, place a hardwood block against it and belt it with the
hammer ( 2kg ish ).

So my question is really three questions

What's the thickest 50mm wide strip that I'm likely to successfully
bend this way ?

Is there a better way of doing it without buying special tools ? I
assume that hot bending isn't appropriate for ali, neither is any form
of heat softening or hardening a practical proposition.

If all else fails, how much might I have to pay to get four items like
that made for me in 6mm thick strip ?


Dave Plowmans method for Annealing is the way to go.

"Annealing ally is easy. Wipe it with soap - the sort you clean your face
with - and heat it 'till the soap turns black. Then quench in water."

Baz

Mary Fisher wrote:

"The Natural Philosopher" wrote in message
...

I
assume that hot bending isn't appropriate for ali, neither is any form
of heat softening or hardening a practical proposition.


Actually, they are. Heating and slow cooling anneals. Heating and fast
cooling re-hardens.


NONONO! Not with Al!


Yes, with Al.


Mary

Baz wrote:

wrote in message
oups.com...

I want to make up some bent aluminium components.

The items will be 'U" shape brackets.

I intend to start with aluminium strip that's about 250mm long and 50mm
wide and then bend the last 50mm at each end to stand up at 90 deg.

The thing I don't know is how thick can the strip be and still be
sensibly bent without special tools ? For my purposes, the thicker the
better as it needs to have holes tapped in it, but I still need to bend
the stuff.

I don't know exactly what grade it's going to be as it's just the ali
strip I get from my ironmonger.

As far as bending is concerned, I usually use an old Workmate with
angle iron as jaw protectors/strengtheners. I mark the bend point,
clamp it up, place a hardwood block against it and belt it with the
hammer ( 2kg ish ).

So my question is really three questions

What's the thickest 50mm wide strip that I'm likely to successfully
bend this way ?

Is there a better way of doing it without buying special tools ? I
assume that hot bending isn't appropriate for ali, neither is any form
of heat softening or hardening a practical proposition.

If all else fails, how much might I have to pay to get four items like
that made for me in 6mm thick strip ?



Dave Plowmans method for Annealing is the way to go.

"Annealing ally is easy. Wipe it with soap - the sort you clean your face
with - and heat it 'till the soap turns black. Then quench in water."


That's the one!

Baz

On Mon, 4 Apr 2005 10:21:55 +0000 (UTC),
(Andrew Gabriel) wrote:

In article ,
Andy Dingley writes:

For aluminium (and pure unalloyed metals in general), you're just
shaking the dislocations out of the crystal lattice and putting it
back the way it was.

I think you're describing work hardening.

No, I'm actually describing the annealing process in unalloyed copper
(because it's simpler). I'm describing the thermal process applied to
reverse work hardening.

Aluminium is a bit more complex, and so yes I am being somewhat
inaccurate here. It's complicated by being an alloy (nearly all of
the time) and also because dislocations are inherently more mobile in
aluminium than they are in copper. Where dislocations become trapped
in aluminium is due to the alloying elements and the domain boundaries
they give rise to, not just to dislocations trapping themselves, as
they do in copper.

What I describe does go on in aluminium, it's just not the only, or
even the most significant process. In pure alumium that's purely
work-hardened then it may be. The other annealing process in aluminium
(as you mention it) is to do with dislocations that are trapped on
these boundaries, or by changing the conditions at these boundaries
themselves. This is the hardening that's caused by heat treatment or
aging of the aluminium alloys.

Annealing (heating) is the opposite, breaking the lattice up into
small crystal domains with lots of dislocation boundaries so it
bends more easily (at the more dislocation boundaries).

On Mon, 04 Apr 2005 11:30:47 +0100, The Natural Philosopher
wrote:

Actually, they are. Heating and slow cooling anneals. Heating and fast
cooling re-hardens.

NONONO! Not with Al!

Yes, with Al.


Baz wrote (and you followed up):
"Annealing ally is easy. Wipe it with soap - the sort you clean your face
with - and heat it 'till the soap turns black. Then quench in water."


That's the one!


So which is it ? Does heating and quenching harden aluminium or
soften it ?


The answer is of course both. There _are_ quenching processes for
aluminium that strengthen it, and coincidentally make it less ductile.
They're not useful "hardening" processes though.

If your bike frame is in 6065-T6 alloy, then that "T6" refers to just
such a process.


But for all practical home workshop processes, any heating of
aluminium anneals, normalises and softens it - whether you quench it
afterwards or not.

"Mary Fisher" wrote in message
. net...

"The Natural Philosopher" wrote in message
...

I
assume that hot bending isn't appropriate for ali, neither is any form
of heat softening or hardening a practical proposition.


Actually, they are. Heating and slow cooling anneals. Heating and fast
cooling re-hardens.

NONONO! Not with Al!

Yes, given the right alloy, equipment and procedures, (see my other post).
It is not, however, a home project. Even with a professional metal workshop,
I send the stuff away to a specialist heat treatment company.

Colin Bignell

"Baz" wrote in message
...
....
Dave Plowmans method for Annealing is the way to go.

"Annealing ally is easy. Wipe it with soap - the sort you clean your face
with - and heat it 'till the soap turns black. Then quench in water."

However, if you want to put a thread in annealed aluminium, use a three-lobe
displacement tap, not a convential tap that cuts the threads. Three-lobe
taps work harden the material locally, making the thread stronger than if
you cut it.

Colin Bignell

In article .com,
wrote:

As far as bending is concerned, I usually use an old Workmate
with angle iron as jaw protectors/strengtheners. I mark the bend
point, clamp it up, place a hardwood block against it and belt it
with the hammer ( 2kg ish ).
[snip]
What's the thickest 50mm wide strip that I'm likely to
successfully bend this way ?

The Radiospares 3mm 'bending grade' soft aluminium
sheet would bend ok, but with a small amount of
crystallisation on the outer of the bend. Trouble
is, a thread in soft aluminium would not be very
strong. Perhaps consider using self tappers.

--
Tony Williams.

On 3 Apr 2005 14:19:52 -0700, wrote:

I want to make up some bent aluminium components.

The items will be 'U" shape brackets.

I intend to start with aluminium strip that's about 250mm long and 50mm
wide and then bend the last 50mm at each end to stand up at 90 deg.

The thing I don't know is how thick can the strip be and still be
sensibly bent without special tools ? For my purposes, the thicker the
better as it needs to have holes tapped in it, but I still need to bend
the stuff.

I don't know exactly what grade it's going to be as it's just the ali
strip I get from my ironmonger.

As far as bending is concerned, I usually use an old Workmate with
angle iron as jaw protectors/strengtheners. I mark the bend point,
clamp it up, place a hardwood block against it and belt it with the
hammer ( 2kg ish ).

So my question is really three questions

What's the thickest 50mm wide strip that I'm likely to successfully
bend this way ?

Is there a better way of doing it without buying special tools ? I
assume that hot bending isn't appropriate for ali, neither is any form
of heat softening or hardening a practical proposition.

If all else fails, how much might I have to pay to get four items like
that made for me in 6mm thick strip ?

Hi,

Try clamping between two bits of thick angle, you may well need to
grind the inside edge out a bit on one. Also some blocks of wood to
hold them at 45 deg to clamping force IYSWIM:

clamp block angle block clamp
------| | | |----

If there is a local fabricators with a press try taking a sketch
along, it might be well worth paying to have it made up.

cheers,
Pete.