On 17/10/2014 01:32, Lostgallifreyan wrote:

I usually get round that lack of knowledge by using a good hard edge on the
inside of the bend and also one on the outside, then hammer gently on the
outer bar held right onto the bend to press it against the immer supporting
bar (or vice edge, whatever I can make fit). It's a bit tedious, but can
result in very nice clean and sharp angles at 90° regardless of metal used.
Penalty for error is usually no worse than a slight thinning at the crease.
I've considered trying to build a DIY tool based on a good quality hinge, but
never done it.

Some lightweight alloys I have used have cracked on a sharp edge. Often
I just use sheet steel a blowtorch, flux and braze it together. A LOT
easier than bending without the right kit.

Andy

AndyW wrote in
:

Some lightweight alloys I have used have cracked on a sharp edge.

Yep, I gate those. If that happens I either chuck it or use it where it
won't get bent. Most thin Al sheet is very ductile though, if anything, too
much so, hard to make clean edged holes in without good tools.

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.

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? :-)

On Sun, 19 Oct 2014, gareth wrote:

"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? :-)


Well I was thinking of the time when there'd be endless IF transformers at
the hamfests and the like, I remember buying a bunch of them for nothing
much in the seventies.

But now that you mention it, you could take those metal-cased eletrolytics
that have dried up, and build modules in them. I know I have a bunch of
thsoe around, and chances are good they aren't in good shape now.

Michael

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!

Michael Black wrote in
xample.org:

For larger boxes, computer power supplies offer up nice boxes. Cover any
side with the wrong holes with circuit board

You do like some rough-and-ready boxes! Normally I hate them, but one
very nice exception is old rack units. There are things so cheap on eBay (and
audio junk wherever it might be had) that is valued far lower than the box
it's in is worth. In this case a blank panel bought on eBay can make an
awesome case. One of my computers is based in one. ITX, 1.2GHz, should be fan
cooleed, but I made it totally silent, rack only 18cm front to back, 1U. All
kinds of very high quality work can be based on old rack units, whose
original innards may well be chosen for some otherwise expensive, rare and
exotic spares too.

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.