AndyW wrote in
:

I just use sheet steel a blowtorch, flux and braze it together. A LOT
easier than bending without the right kit.


I've never done that. Could be a good way to waterproof a box though. In
another radio group someone mentioned that only welds would really seal a box
(in a marine environment, specifically), but a braze goes a long way. I have
brazed. just not used it this way.. Also I haven't thought about galvanic
corrosion with brazed steel before either. I suspect a very good painting
might be in order.

On 17/10/2014 09:43, Lostgallifreyan wrote:
AndyW wrote in
:

I just use sheet steel a blowtorch, flux and braze it together. A LOT
easier than bending without the right kit.


I've never done that. Could be a good way to waterproof a box though. In
another radio group someone mentioned that only welds would really seal a box
(in a marine environment, specifically), but a braze goes a long way. I have
brazed. just not used it this way.. Also I haven't thought about galvanic
corrosion with brazed steel before either. I suspect a very good painting
might be in order.

A lot of modern paints will last forever in the elements as long as the
user repaints any nicks and dings.
I usually braze up a box and clean it with brake cleaner to get rid of
the flux and grease then bung on some paint. Never really had a problem.

Brazing is a lot simpler than welding or bending.

Andy

AndyW wrote in
:

A lot of modern paints will last forever in the elements as long as the
user repaints any nicks and dings.


I like hammerite.. I think it even has some prevention of galvanic corrosion
even if it gets damaged a bit. There are also paintable zinc-based layers
specifically to extent the life of steel. I guess the impossible thing tio
grant is totally maintenance free seals, but many methods likely don't need
much more than one reworking per decade. I just wouldn't trust my estimate on
milage in sea spray.

Brian Reay wrote in news:63445296435368038.386267no.sp-
:

I've not looked into a source of this tape but it would seem to be an
easily technique, if a suitable tape can be
obtained.


Definitely! If you can find out what is is, where to get it to try it, and
the temperature and duration needed for the ovenm, please post what you find.
Point taken about aluminium, but I used to collect scrap metal in a city at
one time, and noticed that anything that got thrown out was usually a tad
less than exotic. Mostly very ductile. When I want anythign better I
invariably have to pay for it, and then I know what I'm getting. eBay's not
bad for loose bits.

Brian Reay wrote in news:1207878279435369714.592439no.sp-
:

The ideal finish is anodise and dye (at least I'm pretty sure it is
anodise, perhaps another treatment, certainly dye). A very good finish and
durable. I don't think it is practical at home, partly due to the pre-
treatments. You often see this on commercial alloy products, which have a
very thin, silky, finish. Things like Karibiners used in climbing.

Sulphuric acid and electrolysis... I considered it... But anodising is best
left to those weho specialise in it. I already have acetone, MEK,
isoproponal, ferric chloride, in flasks and cans in my home. I decided not to
temp fate by adding lots of strong acid to the collection.

As far as aluminium's finish goes, why not just leave it bare? Not so pretty,
but it won't change much over a decade or two because all anodising is, is an
acceleration of the natural oxide layer formation (with dye fixed into any
porosity to make it look better). Once that layer is there, being the second
hardest natural mineral known, it just sits there unless something can break
through the thin layer by compressing the soft metal underneath.

One thing I have seen is old TV aerials in advanced corrosion so indications
of worst case real conditions can be known from those. They tend to thin, but
less so in recent years, less acid rain about.. Where they do fail is in
galvanic corrosion where cheap ferromagnetic steel bolts were used on them.
Most clean lengths of bare Al seem to last a very long time despite looking
very frail.

On 19/10/14 08:33, Lostgallifreyan wrote:
Brian Reay wrote in news:63445296435368038.386267no.sp-
:

I've not looked into a source of this tape but it would seem to be an
easily technique, if a suitable tape can be
obtained.


Definitely! If you can find out what is is, where to get it to try it, and
the temperature and duration needed for the ovenm, please post what you find.
Point taken about aluminium, but I used to collect scrap metal in a city at
one time, and noticed that anything that got thrown out was usually a tad
less than exotic. Mostly very ductile. When I want anythign better I
invariably have to pay for it, and then I know what I'm getting. eBay's not
bad for loose bits.


I'd not even looked for it until just now. But a quite 'google' produced
this:

http://www.hexcel.com/products/indus...adhesives-main

It refers to 'film', which I assume is the tape I was thinking of.

As for sources, that may be an issue. Many of these specialist
chemically type things are so-and-so's to get hold of if you are not
in the industry. I still have some contacts who can sometimes point me
at suppliers willing to help.

I tend to buy boxes, a lot of my projects are more for the technology
than 'looks' so diecast boxes are de-riquer in most cases, especially
for RF projects where you can have several modules in isolated boxes etc.

73
Brian

On Sun, 19 Oct 2014, Brian Reay wrote:

On 19/10/14 08:33, Lostgallifreyan wrote:
Brian Reay wrote in news:63445296435368038.386267no.sp-
:

I've not looked into a source of this tape but it would seem to be an
easily technique, if a suitable tape can be
obtained.


Definitely! If you can find out what is is, where to get it to try it, and
the temperature and duration needed for the ovenm, please post what you
find.
Point taken about aluminium, but I used to collect scrap metal in a city at
one time, and noticed that anything that got thrown out was usually a tad
less than exotic. Mostly very ductile. When I want anythign better I
invariably have to pay for it, and then I know what I'm getting. eBay's not
bad for loose bits.


I'd not even looked for it until just now. But a quite 'google' produced
this:

http://www.hexcel.com/products/indus...adhesives-main

It refers to 'film', which I assume is the tape I was thinking of.

As for sources, that may be an issue. Many of these specialist chemically
type things are so-and-so's to get hold of if you are not
in the industry. I still have some contacts who can sometimes point me
at suppliers willing to help.

I tend to buy boxes, a lot of my projects are more for the technology than
'looks' so diecast boxes are de-riquer in most cases, especially for RF
projects where you can have several modules in isolated boxes etc.

When looks don't count, you can get away with all kinds of things.

I've seen people build up modules in old IF transformer, though now that
source has mostly dried up. Real old IF transformers have a lot of space,
AA5 type transformers more for a couple of stages.

Cans that food comes in has been used as chassis in some famous projects,
but slap a piece of circuit board across the top, and you've got a
shielded box to build a module into.

I've played with making more traditional boxes out of cut up tin cans,
that works but didn't seem worth the effort.

Module boxes can be made out of copper circuit board, but getting them
nice requires some effort.

For larger boxes, computer power supplies offer up nice boxes. Cover any
side with the wrong holes with circuit board (well it could be aluminum,
but I have more circuit board lying around than sheet aluminum. Those are
really pretty common, I'm not finding new enough computers on the sidewalk
to bother bringing home, but I may strip out the power supply, to use as a
power supply or for the box.

I see lots of satellite and cable boxes, thsoe can useful for larger
projects, though sometimes one has to come up with a new front panel.
Sometimes the power supplies are separate inside the box, so you can reuse
that as is.

Michael

"Michael Black" wrote in message
xample.org...
I've seen people build up modules in old IF transformer, though now that
source has mostly dried up.

As have the capacitors from the defunct rig that provided them? :-)

Brian Reay wrote in :

http://www.hexcel.com/products/indus...adhesives-main


Thanks. I'll do a bit of hunting and see if I can get it.

By the way, nothing wrong with a painted diecast box, I really like them.
Very cheap, and thet stay looking better than many 'project boxes' look right
off the shelf. For isolated (separately screened), but interlocking boxes,
Maplin sell (or used to sell) some extruded box sections that dovetail onto
each other. The end plates are that nasty ductile aluminium I mentioned, but
they can be easily used as templates for something better.

Michael Black wrote in
xample.org:

Module boxes can be made out of copper circuit board, but getting them
nice requires some effort.


I came close to solving that, a small cheap Proxxon circular saw with a
carbide blade. The edge was awesome, so clean the FR4 was almost polished,
but it's extremely dangerous because the blade binds against the FR4, so this
method is ONLY safe to trim small flexible strips. But as a finish after
using a hacksaw to do the grunt work, it would work. A hollow-sided carbide
blade would be great, but I've never seen one, and dread to think what it
would cost!