On Thu, 03 Feb 2005 18:11:42 -0600, DougC wrote:

Aluminum can be "hand-machined", if you have a Dremel and buy some
smaller steel bits--the ones they sell for "wood and plastic use only"?
I found recently that those work pretty well on 6061-T6 aluminum, but
you must work very slowly cutting just a bit at a time and keep a firm
grip on the Dremel or it will chatter and chew up your workpiece. You
could use quarter-inch-thick Aluminum sheet and slowly, carefully mill
out even the big tube base holes, I'd bet. ....

My father used to machine 1/4 inch aluminum with a router. He'd
make a wooden template for the router, and take his time, but
get beautiful results. I've always been too afraid to try it,
myself.

Sescom will do punched lightweight aluminum chassis to order,
and can anodize them afterwards. They're beautiful, but you'll
need to build an internal framework of various angle stock to
bear the weight of transformers and such, and to carry the load
to the sides past the flimsy (for tube amps) corners. Maybe worth
the trouble and cost for some projects.

Once you've seen a punched panel anodized through the holes
you may fall in love with flimsy chassis. Or maybe not.

Good fortune,

Chris Hornbeck

"Chris Hornbeck"

Sescom will do punched lightweight aluminum chassis to order,
and can anodize them afterwards. They're beautiful, but you'll
need to build an internal framework of various angle stock to
bear the weight of transformers and such, and to carry the load
to the sides past the flimsy (for tube amps) corners. Maybe worth
the trouble and cost for some projects.

Once you've seen a punched panel anodized through the holes
you may fall in love with flimsy chassis. Or maybe not.



** Beware - anodised aluminium is an INSULATOR !!!

Any areas to be used for grounding will need to be SCRAPED bare first - a
real PITA.




............... Phil

Phil Allison wrote:

"Chris Hornbeck"

Sescom will do punched lightweight aluminum chassis to order,
and can anodize them afterwards. They're beautiful, but you'll
need to build an internal framework of various angle stock to
bear the weight of transformers and such, and to carry the load
to the sides past the flimsy (for tube amps) corners. Maybe worth
the trouble and cost for some projects.

Once you've seen a punched panel anodized through the holes
you may fall in love with flimsy chassis. Or maybe not.



** Beware - anodised aluminium is an INSULATOR !!!

Any areas to be used for grounding will need to be SCRAPED bare first - a
real PITA.

.............. Phil

One of the summer jobs I had while still in high school was running the
anodizing machine at DeHavilland Aircraft near Toronto. The drop off wing fuel
tanks for the Vampire (DH110) jet fighter aircraft which first flew in Sept of
1943 were all anodized in a large tank of Chromic Acid. The whole thing was
powered by a motor /generator set up. When first turned on the DC current to
the bath was very high but as time progressed the voltage had to be increased
to maintain the current. Eventually the wing tank was finished & lifted out for
rinsing in water, then dried. As Phil has noted, anodizing results in a very
thick layer of high resistance on the surface of the Aluminum (Aluminium).

That was my summer in 1949 while my pals were carrying bricks & cutting grass.

Cheers, John Stewart

in article , John Stewart at
wrote on 2/4/05 8:44 AM:

Phil Allison wrote:

"Chris Hornbeck"

Sescom will do punched lightweight aluminum chassis to order,
and can anodize them afterwards. They're beautiful, but you'll
need to build an internal framework of various angle stock to
bear the weight of transformers and such, and to carry the load
to the sides past the flimsy (for tube amps) corners. Maybe worth
the trouble and cost for some projects.

Once you've seen a punched panel anodized through the holes
you may fall in love with flimsy chassis. Or maybe not.



** Beware - anodised aluminium is an INSULATOR !!!

Any areas to be used for grounding will need to be SCRAPED bare first - a
real PITA.

.............. Phil

One of the summer jobs I had while still in high school was running the
anodizing machine at DeHavilland Aircraft near Toronto. The drop off wing fuel
tanks for the Vampire (DH110) jet fighter aircraft which first flew in Sept of
1943 were all anodized in a large tank of Chromic Acid. The whole thing was
powered by a motor /generator set up. When first turned on the DC current to
the bath was very high but as time progressed the voltage had to be increased
to maintain the current. Eventually the wing tank was finished & lifted out
for
rinsing in water, then dried. As Phil has noted, anodizing results in a very
thick layer of high resistance on the surface of the Aluminum (Aluminium).

That was my summer in 1949 while my pals were carrying bricks & cutting grass.

Cheers, John Stewart

Isn't hexavalent chromium an incredible carcinogen?

Jon

"John Stewart"
Phil Allison wrote:

** Beware - anodised aluminium is an INSULATOR !!!

Any areas to be used for grounding will need to be SCRAPED bare first -
a
real PITA.

One of the summer jobs I had while still in high school was running the
anodizing machine at DeHavilland Aircraft near Toronto. The drop off wing
fuel
tanks for the Vampire (DH110) jet fighter aircraft which first flew in
Sept of
1943 were all anodized in a large tank of Chromic Acid. The whole thing
was
powered by a motor /generator set up. When first turned on the DC current
to
the bath was very high but as time progressed the voltage had to be
increased
to maintain the current. Eventually the wing tank was finished & lifted
out for
rinsing in water, then dried. As Phil has noted, anodizing results in a
very
thick layer of high resistance on the surface of the Aluminum (Aluminium).



** That is one hell of a coincidence JS !!!!

One of my customers, here to pick up his EV 'Entertainer' yesterday, was
telling me how he worked at Hawker DeHavilland's facility at Bankstown in
Sydney - on Vampires !!!

The front fuselage was made of plywood and covered in fabric - which as a
lad he painted with many coats of silver paint to help make it look like
alloy !!





................ Phil

Phil Allison wrote:

"John Stewart"
Phil Allison wrote:

** Beware - anodised aluminium is an INSULATOR !!!

Any areas to be used for grounding will need to be SCRAPED bare first -
a
real PITA.

One of the summer jobs I had while still in high school was running the
anodizing machine at DeHavilland Aircraft near Toronto. The drop off wing
fuel
tanks for the Vampire (DH110) jet fighter aircraft which first flew in
Sept of
1943 were all anodized in a large tank of Chromic Acid. The whole thing
was
powered by a motor /generator set up. When first turned on the DC current
to
the bath was very high but as time progressed the voltage had to be
increased
to maintain the current. Eventually the wing tank was finished & lifted
out for
rinsing in water, then dried. As Phil has noted, anodizing results in a
very
thick layer of high resistance on the surface of the Aluminum (Aluminium).


** That is one hell of a coincidence JS !!!!

One of my customers, here to pick up his EV 'Entertainer' yesterday, was
telling me how he worked at Hawker DeHavilland's facility at Bankstown in
Sydney - on Vampires !!!

The front fuselage was made of plywood and covered in fabric - which as a
lad he painted with many coats of silver paint to help make it look like
alloy !!

............... Phil

Tried to send you a photo at your posted email address of a Vampire aircraft
acting like a huge blowtorch, but no luck. So I have posted it at ABSE & ABPR
where I hope you are able to copy. Attached message follows.
Cheers, JLS

----------------------------------------------------------------------------

Phil- Here is a photo you could show your customer. These aircraft
would often start in this fashion after failing to start on one or
two of the initial tries. Unburned fuel would settle in the engine &
we would have to as a group tip the tailplane down to the ground.
Then most but not all of the fuel would run out on the ground. What
remained on ignition often resulted in a huge blow torch, so I had a
camera at the ready this time.

This photo was taken at Chatham AFB in New Bruswick in the summer of
1951.

Cheers, John

Phil Allison wrote:

"John Stewart"
Phil Allison wrote:

** Beware - anodised aluminium is an INSULATOR !!!

Any areas to be used for grounding will need to be SCRAPED bare first -
a
real PITA.

One of the summer jobs I had while still in high school was running the
anodizing machine at DeHavilland Aircraft near Toronto. The drop off wing
fuel
tanks for the Vampire (DH110) jet fighter aircraft which first flew in
Sept of
1943 were all anodized in a large tank of Chromic Acid. The whole thing
was
powered by a motor /generator set up. When first turned on the DC current
to
the bath was very high but as time progressed the voltage had to be
increased
to maintain the current. Eventually the wing tank was finished & lifted
out for
rinsing in water, then dried. As Phil has noted, anodizing results in a
very
thick layer of high resistance on the surface of the Aluminum (Aluminium).


** That is one hell of a coincidence JS !!!!

One of my customers, here to pick up his EV 'Entertainer' yesterday, was
telling me how he worked at Hawker DeHavilland's facility at Bankstown in
Sydney - on Vampires !!!

The front fuselage was made of plywood and covered in fabric - which as a
lad he painted with many coats of silver paint to help make it look like
alloy !!

............... Phil

The nose of the aircraft contained a DF (Direction Finding radio) which was
considered a piece of super-mega-secret apparatus in the beginning. There was an
explosive charge in the nose that would destroy the radio should the aircraft
crash in enemy territory.

By the time we were working on these aircraft several radios had been destroyed
by a simple hard landing of the aircraft. Imagine how surprised the pilot was
when the nose of his aircraft would explode on landing. One of the jobs
specified in the maintenance contract at DeHavilland Canada was the removal of
this nasty little gadget.

The triggering device was a one inch diameter steel ball that would fly forward
when you hit the deck to hard. That closed the contacts & the charge would
explode.
The steel ball looked like a giant ball bearing.

These balls also looked like the balls in a pin-ball machine. I took some with
me to a local restaurant where the owner had a pin-ball set up to make money.
The owners son often played the pin-ball & would push it around the floor trying
to get the balls going where he wanted them. I waited a couple of minutes &
dropped a few of my steel balls on the floor under the pin-ball machine, then
told the kid he had busted his father's machine. He picked up the balls from the
floor & desperately tried to find a hole on the underside where he could fit
them back in, but no luck!!

Cheers, John Stewart