"Gregg" wrote in message
news:8rFMd.555$rB6.134@edtnps91...
Behold, Tim Williams scribed on tube chassis:

snippage

Steel is stronger, cheaper and all the other things that usually go with
it (like solderability).

Exactly!

Steel can encourage the "ground it anywhere" technique - what we want to
try and avoid :-o

Oh Greggggg...
Just 'coz one can stick a pencil in his eye & poke it out, does it mean that
we should stick to real soft crayons?
Sure, it's possible to go very wrong with steel, but one can go just as
wrong with aluminum, if not worse. Most production gear relies on steel
chassis, and even uses those chassis for ground systems (when you're going
to mass-produce something, you can spend some R&D time figuring out just
*where* on the chassis the grounding points should be, and do what so many
manufacturers do (err... did.) - punch out little lugs at the precise points
where the ground points are. requires a bit of thought, but hey - try
bettering that ground scheme, & you'll, most likely, find out that you
can't.
And hey, you could think of the steel as an electromagnetic shield, if you
wish. If the chokes /transformers are stood off by as little as 1/8 of an
inch (something which is not often done in cheap gear, economic reasons),
you can avoid the nasties you get with transformer cores *touching* the
steel, if steel hardware is used (which is, strangely, not always the case),
you could avoid creeping electrolysis, which makes aluminum chassisage weird
& generate intermittent problems. That white powdery stuff is a good
insulator, you know...
There's all kinds of stuff in favor of steel, even if you forget cost &
resistance to fatigue (Tim the child-pilot could tell you about metal
fatigue in aluminum plane parts, and how thousands of rivets have to be
drilled out & re-riveted when old planes are brought back up to being
flight-worthy... The special primers needed to prevent corrosion & make any
paint stick.
This, of course, is all moot for folks like us, who can't afford chassis
punches, modify the layout 20 times, and have crap for tools (I use a
carbide-tipped table saw to cut & do basic horizontal milling on aluminum
plate, and use a regular plunge router to cut clean holes & as a substitute
for a vertical mill (neither recommended - even if you're good, you'll hurt
yourself eventually - I did, more than once). The stuff cuts nicely,
there's always a good supply of plate from both metal salvage & dumpsters,
small square stock could be used for joining plates together (look at any
one-off chunk of early lab gear - gorgeously done chassis without any use of
metal breaks), etc., etc.
Of course, I always stuck with steel for guitar amps, which have a totally
different set of requirements. Nothing beats a welded steel chassis
there...

Behold, shiva scribed on tube chassis:


"Gregg" wrote in message
news:8rFMd.555$rB6.134@edtnps91...
Behold, Tim Williams scribed on tube chassis:

snippage

Steel is stronger, cheaper and all the other things that usually go
with it (like solderability).

Exactly!

Steel can encourage the "ground it anywhere" technique - what we want
to try and avoid :-o

Oh Greggggg...
Just 'coz one can stick a pencil in his eye & poke it out, does it mean
that we should stick to real soft crayons?

LOL!

I can easily name a dozen folks between here, abse and rar+p who need them
crayons! :-p


snip

Of course, I always stuck with steel for guitar amps, which have a
totally
different set of requirements.

*thaht* one will not get an arguement from me ;-)

--
Gregg "t3h g33k"
http://geek.scorpiorising.ca
*Ratings are for transistors, tubes have guidelines*

"Patrick Turner" wrote in message
...
snip
I just spray paint some gear, and that's good enough for a one off where
somebody wants a black item.

Patrick Turner.

Hi Patrick -
Try this as a cheap & quick alternative to powdercoating (I'm not patient
enough to go out & buy a new can of spray paint - my latest chassis is,
thus, a hideous refrigerator white...):
use "epoxy" spray enamel, almost any will do, but stuff like "motorcycle
case paint" is really easy to spray & has tons of pigment.
After ~20 mins, put the chassis in *your kitchen stove*, set it at 180F,
leave the door cracked about 1 inch, and let the whole thing sit there for
an hour or so. Take out *carefully, hopefully with some screws or wires
you've used to suspend the chassis while spraying*, the paint will still be
(possibly) tacky. quench with cold water under the kitchen tap. You'll be
*amazed* at the hardness & adhesion of the paint. I first discovered this
after using motorcycle "Case Black" on a bike, which I laid down (on
pavement) & slid about 100 ft. Right on the sidecover which was painted &
baked. The paint was not even ground through!
Baked enamel used to be a standard before powder coating, and, while a bit
messier & more wasteful, the finish is equally durable & requires no
rub-out. If you have a spray gun, automotive stuff like Starthane (I'm
talking 10 yrs back, when i still did cars - there are probably better
products out now) & hardner, Emron, which is older, a bit tougher, but
nowhere as 'purty (both toxic as hell - a charcoal mask helps, but painting
has caused me much more brain damage than all the recreational chemistry,
which filled my "misspent" youth... The cans tell you to use "full body
respirator suits"... I never owned one.) are the way to fly. Get out of
thhe kitchen if you bake those...
Anyhow, try baking - you'll be impressed. Oh, and yoou can get etching
primers in spray cans, too - it looks like you're spraying nothing, but,
especially on Aluminum, they're a must (some spray paints, like "case
black", already contain something similar, so just aluminum cleaner & water
wash is plenty (if you want to be real cheap, heavily diluted Crystal Drano,
followed by a detergent /water wash give you both cleaning & surface
etching, just make sure it's, like a teaspoon per gallon, and take out the
chassis as soon as all of it is "fizzing", or you'll have too much slime &
too little chassis left... Drano's a bad-ass base, use heavy rubber gloves,
and a bucket of clean water to rinse anything which lands on your skin.
Have fun. Oh, there's a cool self-anodizing site, can't remember the
addy, but it's a no-bull approach, using commonly available stuff, 'except
for the anodizing salts, which are pretty cheap & come in more colors than
you can shake a stick at.
-dim

"Ronald" wrote in message
...

schreef in bericht
oups.com...
Aluminum doesn't rust and is easy to drill, but solder doesn't stick to
aluminum and chassis can be flimsey.

Ever thought of copper ?

Copper is ridiculously soft, heavy, and generally a disaster to machine
(you've got to be pretty slick & use correct cutting tools). Copper
*plated* steel chassis used to be fairly common in early production gear,
though. Yep, mainly to make it easy to solder to. Later, it seems everyone
switched to nickel plating (most steel chassis are nickel dipped or plated,
and it's a pain in the butt to get them looking perfect after something like
a 'lytic has burst & ate through the plating. small copper sub-chassis,
though, are great for lil' stuff...
-dim

"Gregg" wrote in message
news:tAbNd.14165$tU6.7694@edtnps91...
Behold, shiva scribed on tube chassis:


"Gregg" wrote in message
news:8rFMd.555$rB6.134@edtnps91...
Behold, Tim Williams scribed on tube chassis:

snippage

Steel is stronger, cheaper and all the other things that usually go
with it (like solderability).

Exactly!

Steel can encourage the "ground it anywhere" technique - what we want
to try and avoid :-o

Oh Greggggg...
Just 'coz one can stick a pencil in his eye & poke it out, does it mean
that we should stick to real soft crayons?

LOL!

I can easily name a dozen folks between here, abse and rar+p who need them
crayons! :-p


snip

My GF lets me use sharp & dangerous tools... Perhaps she's grown tired of
me... sad grin
-dim