[Amps] amp hardware

[Robert Bonner]

Sodium Hydroxide  (LYE) completely dissolves aluminum if left alone.

Acid baths will slowly eat away or etch aluminum...

I can see where Barrie would have holes getting bigger, metal getting
thinner etc using LYE..

If you have strong enough LYE, you would seriously need to neutralize it
with strong enough ACID.

We are playing on two ends of the PH scale here.  Aluminum tolerates acids
better than Alkalis'

***

The best treatments pre-painting on aluminum are ANODIZING or ALODYNE.
Anodizing can be done in many colors and can actually be a better looking
finish than paint by a long shot.  It is an electro-process.  I used to do
this back in the 1970's to our company's computer chassis.  It results in a
very strong conductive, non-corroding attractive finish that bonds with the
first .001 of the metal.

Either natural or straightlined metal reacts well.

Alodyne is a chemical treatment that the parts are dipped in.  It denatures
the aluminum and makes it good to paint or whatever. You'll see a lot of
telephone equipment done this way.  It is sort of a yellow looking coating.

Instead of painting aluminum a better treatment is POWDER COATING.  It is a
powder that is sprayed on and statically adheres to the metal.  Then baked
in an oven the surface becomes a NON-Conducting hard smooth shell finish.

If you shop around you can find commercial powder coaters near you.  It's
the total process of the 90's...  I have a small operator near me I became
buddies with.  He does all my stuff from Motorcycle chassis to equipment
racks, yard iron, railings...  You name it.  I even had a MINI-BIKE powder
coated pink for my wife to ride during her Biker Chick dance set.

Quality rack mount products are powder coated instead of painted.

Since you are sending your stuff OUT for powder coating it is much more
expensive than RATTLE CAN PAINTING...  But compared to that can of RUSTOLEUM
the finish will be much more professional.

ON all my newest works I'm sending out all metal aluminum surfaces for
POLISHING.  6061 will polish nearly to chrome and that leaves a bright,
denatured surface that looks cool.

The original "Brown Bomber" chassis were chromed.  I've gone back to this
LOOK myself as something that sets me apart from the masses.

SEMPER AMPLIO,

Crank it up and dump it in...

BOB DD

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Barrie Smith
Sent: Tuesday, April 10, 2007 11:59 AM
To: g3rzp at g3rzp.wanadoo.co.uk; Steve Flood; amps at contesting.com
Subject: Re: [Amps] amp hardware

I've used this caustice soda (sodium hydroxide) treatment on aluminum many
times, especially for front panels, with good luck.

Aside from the somewhat dangerous aspects of this prceedure, a real problem
is that if you are going to drill and tap any of the treated parts, do so
after the treatment.

If you drill and tap, and then treat the aluminum, the sodium hydroxide will
considerably enlarge the holes, and reduce the threads, to the point that
the bolts will easily strip them out.

As I often say:  "Been there, done that".

73, Barrie, W7ALW


----- Original Message ----- 
From: "Peter Chadwick" <g3rzp at g3rzp.wanadoo.co.uk>
To: "Steve Flood" <flood at ixi.net>; <amps at contesting.com>
Sent: Tuesday, April 10, 2007 7:33 AM
Subject: Re: [Amps] amp hardware


> Steve asked:
> >If I'm building up an amp (the RF compartment particularly) with aluminum
sheet and angle stock, should I be using aluminum bolts/nuts/washers to
avoid galvanic corrosion?<
> Is it going to be in the shack, or outside in a damp shed?
> If in an indoor shack, I wouldn't bother.
> Even in a damp shed, I've had no problems with aluminium and BZP (bright
zinc plated) steel hardware. For parts in a RF field, I'd use plated brass
for preference. . I've never found aluminium alloy screws too succesful,
although it may be that I'm too heavy handed - they always break before they
seem to be tight!
> It's worthwhile for a nice finish to 'soak' the aluminium for 15 minutes
or so in a strongish caustic soda bath. Do it in a well ventilated area
because of the hydrogen given off. Afterwards, ideally dip in a 20% nitric
acid bath, and if that isn't available, swab down with a cloth soaked in
vinegar - this will remove the black deposit. It helps paint to stick, too.
An alternative attractive finish is a wire brush in the electric drill. In
that case, wear goggles and gloves, and afterwards, give it a coat of clear
lacquer. Even if the aluminium isn't in view, it's good workmanship.....
> 73
> Peter G3RZP
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>


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