Aviation Sheetmetal Work

To All:

Guy calls, wants to buy my metal brake & sheet metal tools. Left
unsaid is WHY someone you don't even know would call you up out of the
blue and want to buy some tools which, in a couple of cases belonged
to my grandfather, my dad, and my brother.

The WHY? Because I've been diagnosed with cancer. With multiple
myeloma.

But I can't sell my tools, firstly because they're already promised to
my son. But more importantly because I'd just have to buy all new
stuff WHEN I LICK THIS DAMNED CANCER!

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Okay, so it really isn't something that's worth the trouble to tell
all you guys about it. But I did mention it to a couple of friends.
One of them said he could understand the guy's point of view. Not
about the cancer but about buying the tools. Way back when, one
reason he bought a set of plans for the Fly Baby was because he didn't
have any metal-working experience at all, whereas the Fly Baby was
advertised as an ALL WOOD design.

You already know the punch-line, right? :-)
(There's no such thing as an 'All Wood' design. EVERY homebuilt, be it
wood, composite or metal, requires some skill in those other areas as
well.)

Buying a book on BASIC aviation metal-smithing isn't a lot of help
because they start-out pretty far along the learning curve. And if
you're out there by yourself -- no local Chapter to rely on -- you may
have a hell of a time learning how to bend tin.

So don't. Bend tin. Or roof flashing... or whatever else you're
using as your basic How-To material. Bend CARDBOARD instead. No, not
corrugated cardboard; something like a cereal box. You can draw the
part on the cardboard then bend it in your vise. Once you've mastered
the basic idea you can drop by the Borg and pick up some galvanized
sheet metal, roof flashing or what-have-you and TRANSFER your skills
to real metal. (The biggest difference is in the CUTTING and how you
DRESS the edges.)

You probably won't believe it but a good bench vise, one with
auxiliary jaws (ie, smooth metal jaws that fit over the regular jaws)
can handle about 90% of the bending chores in the typical "all wood"
design.

Need to make a LONGER bend? Then go back to the Borg and pick up a
piece of ANGLE IRON (or even TWO pieces if one isn't long enough).
Drill some counter-sunk holes in the angle iron and fasten it to the
edge of your work bench. Use... something.. another piece of angle
iron or just a piece of flat steel... to CLAMP the metal you want to
bend, to the angle iron you've bolted to the work bench. Now BEND the
metal by GENTLY tapping on it with a mallet. Thin metal, you need to
go over it a dozen times or more; thicker metal, you'll need to go
over it a LOT more times... mebbe a hundred. The idea here is to
DISTRIBUTE the energy of the hammer's blow so as not to WRINKLE the
metal. To do that you have to learn how to overlap your blows,
working your way over the metal again and again, SLOWLY folding it
over the angle iron 'edge' you've fastened to your workbench.

You won't believe it but you can produce a flanged wing-spar in forty-
thou 2024-T3 that is JUST AS GOOD as anything made with a metal
brake. What's the secret? Practice.

In the same vein, buying a lot of metal-working tools doesn't mean
you'll be turning out usable parts. Before that can happen you'll
have to learn how to USE those tools. A work bench with a metal edge
IS a 'metal brake' ('Brake' is an archaic term for vise or clamp.) So
instead of day-dreaming about a 48" metal brake from Harbor Freight
that you'll probably never buy anyway, why not pick up a piece of
angle iron and start LEARNING how to do metal-work. Seriously; it
doesn't cost very much and once you learn to 'hammer-fold' a piece of
metal, you'll never forget it -- You will have acquired a LIFE-TIME
skill. Which is better than coming down with a dose of cancer any
day :-)

-R.S.Hoover

PS -- I haven't mentioned spring-back or a lot of other stuff you'll
have to learn before you can can bend your Fly Baby hinges in your
vise. When you get that far along, ask. There's lots of good tin-
benders in this Newsgroup who'll be more than happy to help you.

wrote:
... buying a lot of metal-working tools doesn't mean
you'll be turning out usable parts. ... So
instead of day-dreaming about a 48" metal brake from Harbor Freight
that you'll probably never buy anyway, why not pick up a piece of
angle iron and start LEARNING how to do metal-work....

-R.S.Hoover


There is another outcome possible at Harbor Freight - other than the
day-dream ending. Like me, you may BUY a tool.
I am thinking of the tube bender I bought. I KNEW that the usual tube
bender that features a ram pushing a forming tool against a pipe while
two side rollers hold it in place - is a disaster - it is about
guaranteed to collapse the wall unless the tube is loaded with sand,
ice, eutectic - whatever. So I bought the BETTER type tube bender on
sale. This has a roller that pulls the tube round a die - this
provides the motivation to stretch the tube wall on the outside, rather
than ripple the tube wall on the inside of the turn.

So fine: I bought it, and I bought a tube drilling jig, to make those
nicely fitted tube joints at 90deg, 45 deg etc....and plenty of other
things too.

What's wrong with that? I haven't used these tools at all. Not once.
And now I covet a machine lathe too (there could hardly be a more
bargain deal for $400 after all). Trouble is, Momma would have
conniptions if I put it in my study, and I would not dream of putting a
machine lathe in an unheated workshop where the ways might attract a
layer of rust.
That would about break my heart.....

Brian W

On Feb 15, 7:55*am, Brian Whatcott wrote:
I bought a tube drilling jig, to make those
nicely fitted tube joints at 90deg, 45 deg etc....and plenty of other
things too.
-----------------------------------------------------------------------------------------

Funny(?) Story:
Until Harbor Freight came along I've seen tube-drilling jigs in use
perhaps half a dozen times in my life. All but one of those times was
at the shop of a sub-contractor and the tube-drilling jig was usually
home-made. AFTER Harbor Freight came along I've guess I've seen a
dozen or more of the HF tool, always rigged to a DRILL PRESS.

The funny part of this tale is that, until the Harbor Freight drill-
jig came along, the drill-jig was ALWAYS fastened to one corner of a
WORK TABLE, providing room to support the tubing, which on the first
cut, could be up to twenty feet long. Power was provided by a 1/2"
drill-motor.

Personally, I've got four or five round files from 3/8th to 3/4", all
that's needed to put a fish-mouth on a piece of tubing that is going
to be welded. (You can cut a large fish-mouth with a file of smaller
diameter.)

The tricky bit in hand-filing a fish-mouth is HOLDING the tubing so
that the fish-mouth is perfectly aligned with the fish-mouth on the
OPPOSITE end of the tube. The holders are hunks of MAPLE, drilled to
match the diameter of the tube. This allows the piece of tubing to be
held in a vise and adjusted so as to facilitate the filing, which is
always done two-handed with the file perfectly level (or nearly so).
A machinist's protractor is used to verify the position of the
tubing. Snips or an angle-head grinder is used to notch the fish-
mount, reducing the amount of filing needed. A short piece of tubing
matching the size of the fish-mouth is used as a gauge.

As-received tubing is usually oily. The oil is removed to ensure the
clamps can get a grip. When the clamps can no longer get a grip you
can 'tighten' them by pressing them against a disk sander for a
moment. You may also add rosin to the tubing groove.

The sides of most fuselages fabricated from welded steel tubing are
identical, allowing you to cut TWO pieces. The longerons are
typically supported on two to four saw-horses and the side pieces (ie,
vertical & diagonal tubes) are tack-welded as soon as the tube(s) are
cut. The pieces for the top & bottom may not be symmetrical so that
tacking only one at a time (ie, either the top or the bottom) is
usually the most practical method. Once all of the structural member
for the fuselage have been fitted and tack-welded, you will probably
find it more convenient to support the fuselage in a rotisserie,
allowing you to ROLL the fuselage as you finish-weld the tacked
joints. Using only the tools described here it takes 35 to 40 man-
hours to put the typical fuselage on its gear. Then comes all the
fiddley bits; tabs for fasteners; fuel tank supports, controls and so
forth... which can take an additional 100 hours or more (!!).

Oddly enough, when you see an ad for an AIRCRAFT WELDER, odds are
they don't want someone who only experience is fuselage structures.
What they usually want is someone experienced (usually certified) in
welding aluminum, monel and so forth. (As a point of interest, the
last time I checked [1970's] there were more than a hundred
certificates that applied to AVIATION/AERO-SPACE welding. If you
have a lot of experience (and the certificates to go with it) some
companies will hire you as a 'weldor under instruction' giving you 90
days (or whatever) to gain the experience needed to pass the
certification test needed for their particular application.

Of course, that was then. Nowadays you'll find it kinda hard to
compete with a fully certified Chinese weldor pulling down $17 per
week... (They save so much on LABOR they can afford to have the
parts FLOWN from China to the USA)

On larger diameter tubing having a heavier wall, an angle-head
GRINDER is usually more convenient than filing, especially if you have
that program (WINTUBE ?) that prints out a pattern of the cut after
you enter the diameter of the tubing, the angle of it's intersection,
and the diameter of the tube it's supposed to mate with. (This is
very handy for fabricating roll-cages and the like for vehicles that
operate off pavement.)
-----------------------------------------------------------------------------------

I would not dream of putting a
machine lathe in an unheated workshop where the ways might attract a
layer of rust.
-----------------------------------------------------------------------------------------

So buy a Flit gun and 5 gallons of kerosene. After using the lathe,
pump up the Flit gun and give the lathe a light coating of kerosene,
then cover it with a piece of canvas that is NOT allowed to touch any
unpainted surface.

-Bob

PS -- Can't find a Flit gun? Then use one of those refillable aerosol
cans... or use an air-brush.

wrote:

I would not dream of putting a
machine lathe in an unheated workshop where the ways might attract a
layer of rust.
-----------------------------------------------------------------------------------------

So buy a Flit gun and 5 gallons of kerosene. After using the lathe,
pump up the Flit gun and give the lathe a light coating of kerosene,
then cover it with a piece of canvas that is NOT allowed to touch any
unpainted surface.

-Bob

PS -- Can't find a Flit gun? Then use one of those refillable aerosol
cans... or use an air-brush.


Flit-gun? THAT takes me back! I will admit to considering a 10 oz duck
cover and a 40 watt lamp under it.... Say kerosene and I think WD-40
of course - but I keep reminding myself - a corrosion preventative that
sets waxy, like BoeShield T-6 aerosol would be better.

Which reminds me: in the long, long-ago there was an auto chassis
treatment (back when cars had chassis). The kit was a bottle of wax
dissolved in a solvent and a Flit-gun. Worked like a champ.

(I later verified you can dissolve grated candlewax in most any
petrochemical like kerosene, gasoline, diesel oil, lamp oil whatever, if
you first WARMED the oil.)

Brian W

"Brian Whatcott" wrote in message
...
wrote:

I would not dream of putting a
machine lathe in an unheated workshop where the ways might attract a
layer of rust.
-----------------------------------------------------------------------------------------

So buy a Flit gun and 5 gallons of kerosene. After using the lathe,
pump up the Flit gun and give the lathe a light coating of kerosene,
then cover it with a piece of canvas that is NOT allowed to touch any
unpainted surface.

-Bob

PS -- Can't find a Flit gun? Then use one of those refillable aerosol
cans... or use an air-brush.


Flit-gun? THAT takes me back! I will admit to considering a 10 oz duck
cover and a 40 watt lamp under it.... Say kerosene and I think WD-40 of
course - but I keep reminding myself - a corrosion preventative that sets
waxy, like BoeShield T-6 aerosol would be better.

Which reminds me: in the long, long-ago there was an auto chassis
treatment (back when cars had chassis). The kit was a bottle of wax
dissolved in a solvent and a Flit-gun. Worked like a champ.

(I later verified you can dissolve grated candlewax in most any
petrochemical like kerosene, gasoline, diesel oil, lamp oil whatever, if
you first WARMED the oil.)

Brian W

You might also try LPS-3, if I recall correctly--or was it LPS-2. In any
case, I believe that the one that gets waxy is also fairly popular for
spraying in pick-up truck beds before istalling a bed-liner.

Peter

Peter Dohm wrote:
"Brian Whatcott" wrote in message
...
wrote:

I would not dream of putting a
machine lathe in an unheated workshop where the ways might attract a
layer of rust.
-----------------------------------------------------------------------------------------

So buy a Flit gun and 5 gallons of kerosene. After using the lathe,
pump up the Flit gun and give the lathe a light coating of kerosene,
then cover it with a piece of canvas that is NOT allowed to touch any
unpainted surface.

-Bob

PS -- Can't find a Flit gun? Then use one of those refillable aerosol
cans... or use an air-brush.

Flit-gun? THAT takes me back! I will admit to considering a 10 oz duck
cover and a 40 watt lamp under it.... Say kerosene and I think WD-40 of
course - but I keep reminding myself - a corrosion preventative that sets
waxy, like BoeShield T-6 aerosol would be better.

Which reminds me: in the long, long-ago there was an auto chassis
treatment (back when cars had chassis). The kit was a bottle of wax
dissolved in a solvent and a Flit-gun. Worked like a champ.

(I later verified you can dissolve grated candlewax in most any
petrochemical like kerosene, gasoline, diesel oil, lamp oil whatever, if
you first WARMED the oil.)

Brian W

You might also try LPS-3, if I recall correctly--or was it LPS-2. In any
case, I believe that the one that gets waxy is also fairly popular for
spraying in pick-up truck beds before istalling a bed-liner.

Peter



That's LPS-3. But I can't find it anywhere locally.

"Brian Whatcott" wrote in message
...
wrote:

I would not dream of putting a
machine lathe in an unheated workshop where the ways might attract a
layer of rust.
-----------------------------------------------------------------------------------------

So buy a Flit gun and 5 gallons of kerosene. After using the lathe,
pump up the Flit gun and give the lathe a light coating of kerosene,
then cover it with a piece of canvas that is NOT allowed to touch any
unpainted surface.

-Bob



Which reminds me: in the long, long-ago there was an auto chassis
treatment (back when cars had chassis). The kit was a bottle of wax
dissolved in a solvent and a Flit-gun. Worked like a champ.

(I later verified you can dissolve grated candlewax in most any
petrochemical like kerosene, gasoline, diesel oil, lamp oil whatever, if
you first WARMED the oil.)

Brian W


Back in the middle of the last century, we doped dry-flies in - hold on for
this one -- Ronsonol lighter fluid with parafin household wax dissolved
in it . Hey, it worked.

Flash

On Feb 15, 8:05*pm, "Flash" wrote:

Back in the middle of the last century, we doped dry-flies in *- hold on for
this one -- * Ronsonol lighter fluid with parafin household wax dissolved
in it . *Hey, it worked.
-------------------------------------------------------------------------------------------

Ronsonol... and other 'lighter fluids' are in fact, naphtha, available
in quarts, gallons and 5-gal containers from a competent painter's
supply house.

Old-time sailors use a number of formulas containing paraffin wax
dissolved in naphtha and mixed with BOILED LINSEED OIL. The mixture
was painted on to CANVAS then allowed to dry in sunlight. The result
was known as OIL-SKINS. This was usually the top-most cover of any
battened-down hatch, the foul-weather gear you wore, covers for boats
on davits, and so forth.

Among airmen, a modern-day equivalent would be Johnson's 'Jonwax 50.'
This will waterproof a sewn canvas propeller cover, cockpit cover,
etc. But if you can't afford the Jonwax (or more likely, can't locate
a source), it's always handy to have the 'old fashioned' formulas as a
back-up.

If you have trouble finding real canvas ( for a water-proof cover you
want 100% cotton or flax [ie, linen] ) try the heaviest grade of 100%
cotton 'muslin' from your local fabric shop. And if that doesn't
serve, order the largest 'tool cover' you can find in the Harbor
Freight catalog. Most such covers are made from #8 canvas (ie light-
weight stuff; lighter than the fabric in a pair of Levis).

-R.S.Hoover

PS - Covers of various kinds are a fact of aviation-life. If each
flight returns to its point of origin then you would of course have
some provision for the temporary storage of such covers. But on a
cross-country flight that includes any RON's ( ie remain-over-night )
you should make some provision for carrying such covers with you,
unless you are willing to bet the flight will NOT encounter any
problems that would require you to RON for SEVERAL nights, especially
during foul weather.
Indeed, your cross-country flight-planning usually carries such
preparations a step further; to the inclusion of adequate survival
gear for each of the plane's occupants. It should go without saying
that the WEIGHT of such gear, plus the previously mentioned covers,
must be taken into account, along with suitable STOWAGE. - rsh

On Feb 15, 4:34*pm, Brian Whatcott wrote:
. . . a corrosion preventative that
sets waxy, like BoeShield T-6 aerosol would be better.

Veeduber had it right. With the kerosene, you take the canvas off, use
the lathe, sweep up the chips and cover it again. With the waxy stuff,
you must remove it from any working surfaces before you can use the
lathe. It's formulated to be difficult to remove. You'll end up not
using the lathe for small jobs.

Rich S.

wrote:
On Feb 15, 4:34 pm, Brian Whatcott wrote:
. . . a corrosion preventative that
sets waxy, like BoeShield T-6 aerosol would be better.

Veeduber had it right. With the kerosene, you take the canvas off, use
the lathe, sweep up the chips and cover it again. With the waxy stuff,
you must remove it from any working surfaces before you can use the
lathe. It's formulated to be difficult to remove. You'll end up not
using the lathe for small jobs.

Rich S.

I understand this objection. But I have an objection to WD-40 or
straight kerosene. It evaporates. Then here comes the FeO2

(At least, that's what I have in mind - I would be pleased to hear I'm
wrong on this one...)

Brian W