welding technique for clusters

On Sat, 21 Mar 2009 12:10:37 -0700 (PDT), wrote:

On Mar 20, 6:49*pm, Bob Hoover wrote:

Of course it matters, Harry. *EVERYTHING matters!


You can say that again.

One of the things that matters is getting the finish dimensions that
you started with. I've spent hours filing and shaping a fishmouth to
get that perfect fit, only to have the end off my tube off by 1/8"
once all the warping has finished. I've learned to minimize the
warping though. You should weld the fish mouth in 4 steps. First do
each side where the mouth reaches down the side of the non-cut tube.
As the metal shrinks, it will pull the mouth tighter into the non-cut
tube. You've welded on both sides, so the warping neutralizes
itself.


make yourself a shrink warping preventer. its a good welding exercise
in itself.

when you heat up the metal to red heat and let it cool it will shrink
and unless you prevent the longeron tube from moving it will develop a
bend.

my brother in law has a simple fixture that prevents the bend (he
being a life long expert welder)

you need a little solid section that will take a threaded hole across
it for a little jack screw like the screw up part of a common old "G"
clamp.
out each side you weld some scrap tube so that you end up with a long
straight tube with the little jacking screw transversely across the
middle.

mentally place this welded up tube bit on top of a fuselage longeron
tube with the jacking screw pointing at the longeron.
ok from each end of this tube bizzo you need some arms that go out
perpendicular from each end, then downward, then back under the fuz
tube, then a little bit that goes up toward the fuz tube. at the end
of this little upward bit you place an inch or so half length of tube
so that it will cradle the fuz tube.
the tube bizzo with the little cranked arms at each end are an
interesting welding practise exercise.

now to use it you straddle the joint and clamp it very very very
lightly to the longeron you expect to warp.
when you weld the cluster and the tubes are all red hot any over
clamping will of course warp the longeron so you need just the merest
holding clamping. as the cluster cools and wants to shrink bend the
longeron the little clamp will hold the tube straight.

brother in law came up with the idea years ago and has used it ever
since on his aircraft welding. works a treat.

dont bother painting it because the flame will burn the paint off

I'll see if I can find a photo of the ones I made.

Stealth Pilot

I'll see if I can find a photo of the ones I made.

Stealth Pilot- Hide quoted text -

- Show quoted text -

Stealth,

I know exactly what you're talking about. The clamps that held Wilbur
Wright's test "air plane" and flat plate to the bicycle-wheel-thingy
of the 1901 aerodynamic experiment are made that way (on a much
smaller scale).

For those of you that think airfoils are the subject of University
wind tunnels, Reynolds Numbers, and other such ilk, you may find it
interesting to know that good 'ole Wilbur Wright made his first
aerodynamic studies by mounting them on a bike wheel attached
horizontally to another bike. The apparatus's power source was only
rated at one "Orville", but that was sufficient to determine that
Smeaton's coefficient of air pressure was flawed. The follow-up tests
were run in a wind tunnel made of pine boards.

Harry

wrote in message
...
I'll see if I can find a photo of the ones I made.

Stealth Pilot- Hide quoted text -

- Show quoted text -

Stealth,

I know exactly what you're talking about. The clamps that held Wilbur
Wright's test "air plane" and flat plate to the bicycle-wheel-thingy
of the 1901 aerodynamic experiment are made that way (on a much
smaller scale).

For those of you that think airfoils are the subject of University
wind tunnels, Reynolds Numbers, and other such ilk, you may find it
interesting to know that good 'ole Wilbur Wright made his first
aerodynamic studies by mounting them on a bike wheel attached
horizontally to another bike. The apparatus's power source was only
rated at one "Orville", but that was sufficient to determine that
Smeaton's coefficient of air pressure was flawed. The follow-up tests
were run in a wind tunnel made of pine boards.

Harry

From a sign currently posted in their bicycle shop:

"Thousands of pages have been written on the so-called science of flying,
but for the most part, the ideas set forth, like the designs for the
machines, were mere speculations and probably ninety percent were false."

Wilbur Wright

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

wrote:
... The clamps that held Wilbur
Wright's test "air plane" and flat plate to the bicycle-wheel-thingy
of the 1901 aerodynamic experiment are made that way (on a much
smaller scale).

For those of you that think airfoils are the subject of University
wind tunnels, Reynolds Numbers, and other such ilk, you may find it
interesting to know that good 'ole Wilbur Wright made his first
aerodynamic studies by mounting them on a bike wheel attached
horizontally to another bike. The apparatus's power source was only
rated at one "Orville", but that was sufficient to determine that
Smeaton's coefficient of air pressure was flawed. The follow-up tests
were run in a wind tunnel made of pine boards.

Harry

Nice post!

BrianW

On Mar 24, 2:01*pm, wrote:
On Mar 24, 2:02*am, Bob Hoover wrote:

I'm leaning toward that myself. When the tubes came out of the acid, I
rinsed them in clean tap water and then let them air-dry. I actually
watched them rust in a period of 5 minutes.

Harry

Another thought - I've seen some EMT that has been painted/coated on
the inside. The acid won't remove that. If that is the kind of EMT
you are using for practice burn out the paint and then use a wire
brush from the plumbing section to clean it out.
=======================
Leon McAtee

On Tue, 24 Mar 2009 20:12:34 -0700 (PDT),
wrote:

On Mar 24, 2:01Â*pm, wrote:
On Mar 24, 2:02Â*am, Bob Hoover wrote:

I'm leaning toward that myself. When the tubes came out of the acid, I
rinsed them in clean tap water and then let them air-dry. I actually
watched them rust in a period of 5 minutes.

Harry

Another thought - I've seen some EMT that has been painted/coated on
the inside. The acid won't remove that. If that is the kind of EMT
you are using for practice burn out the paint and then use a wire
brush from the plumbing section to clean it out.
=======================
Leon McAtee
The metalurgy of EMT is a crapshoot. It could have all kinds of
"alloys" in it, and poorly distributed - particularly if Chinese.

When building anything with EMT I acid dip and braze. Attemting to MIG
it is futile, in my opinion.

On Mar 24, 1:01*pm, wrote:
On Mar 24, 2:02*am, Bob Hoover wrote:

On Mar 23, 8:14*am, wrote:

Without seeing it I would have guessed a contaminant on your filler
rod, but if it's happening ahead of the pool it may be something on
the tubing, such as some sort of residue from the zinc.

-Bob

I'm leaning toward that myself. When the tubes came out of the acid, I
rinsed them in clean tap water and then let them air-dry. I actually
watched them rust in a period of 5 minutes. Once the tubes were dry, I
shoe-shined them with a Scotchbrite pad. They looked nice and shiny,
but I didn't do any further cleaning. I also didn't clean the filler
rod. Its copper-coated, but that doesn't seem to be doing it, or I
would have the problem all of the time.
-----------------------------------------------------------------------------------------------

Okay. At least we are singing off the same sheet of music. And to be
honest, the stuff we used, circa 1972, was salvaged from a local
lumber yard in a building erected sometime between 1945 and 1953.
They gave us (the local Scout troop) the stuff in return for hauling
it away. The EMT had held only a couple of wires, which we salvaged
and sold as copper scrap. The EMT was sliced into 12" lengths BY HAND
using Boy-Power (a Troop joke), and hack-saws having 32 tpi.

After chopping we had a fair sized BIN of tubing 'coupons' on which to
practice, plus a pretty good pile of long pieces destined for another
Project... once the boy's learned to weld tubing.

To remove the galvanizing we cheated a bit and hauled most of the
stuff to a shop in Oceanside where the guy dipped them in heaven knows
what but it required neutralizing. On the final dip the coupons
picked up a film of oil that was floated on the Mystery Fluid (which I
thin was just hot water). Bottom Line: No rusty coupons even a year
later... although we did have to de-grease the stuff before using.

One of us was a Navy Chief, several other fathers were Marine Corps
NCO's. Another was a dentist, another the Shop Teacher at our local
high school. I mention all this because nowadays, in so far as I
know, we don't even have a Scout troop; the local school district has
86'd ALL 'shop' classes due to various Fears and Budget Problems...
most of which are the Product of the same local School District
members. Our little town (Vista, California) is now a fearful place
where Political Correctness carries more weight than having a roof
that don't leak, a car that runs good, and if you want to get anything
DONE you'd damn well better be able to speak Spanish because the local
crop of youngsters willing and ABLE to tackle life's physical chores
has vanished into the reality of computer games... played on machines
they can't repair... and discussed via hunt & pecked messages because
they can't touch-type.

-Bob (who is still coming up with those Dreadful Projects... [the
current acorn is how to build a cabinet that turns an inexpensive
portable electric saw into an even less expensive Table Saw, needed to
reduce scrap lumber to longerons and sticks for ribs and a hell of a
lot of fun along the way.)

But I fed you a clanger on the tubing, Harry. But I was afraid if I
dug too deeply into the Nitty and the Gritty I'd soon find myself with
no one to talk to :-)

On Mar 24, 1:51*pm, wrote:

For those of you that think airfoils are the subject of University
wind tunnels, Reynolds Numbers, and other such ilk, you may find it
interesting to know that good 'ole Wilbur Wright made his first
aerodynamic studies by mounting them on a bike wheel attached
horizontally to another bike.
-------------------------------------------------------------------------

Roger that, Harry.

I don't know if you'll recall but you and I had an enjoyable exchange
on that topic some years ago.

I've always thought Oriville's 'How We Inveted The Airplane' one of
the best books I ever read. (I still havve a copy around here
somewhere.)

One of my dad's favorite terms for know-it-all airmen was to refer to
them as 'Orville's Flight Instructor.' This was soon reduced to:
"Another OFI... " and a shared grin.

I sure hate to see those days slipping away from me.

-Bob

On Wed, 25 Mar 2009 06:11:09 -0700 (PDT), Bob Hoover
wrote:

On Mar 24, 1:51*pm, wrote:

For those of you that think airfoils are the subject of University
wind tunnels, Reynolds Numbers, and other such ilk, you may find it
interesting to know that good 'ole Wilbur Wright made his first
aerodynamic studies by mounting them on a bike wheel attached
horizontally to another bike.
-------------------------------------------------------------------------

Roger that, Harry.

I don't know if you'll recall but you and I had an enjoyable exchange
on that topic some years ago.

I've always thought Oriville's 'How We Inveted The Airplane' one of
the best books I ever read. (I still havve a copy around here
somewhere.)

One of my dad's favorite terms for know-it-all airmen was to refer to
them as 'Orville's Flight Instructor.' This was soon reduced to:
"Another OFI... " and a shared grin.

I sure hate to see those days slipping away from me.

-Bob

been having a few people die around me lately. bit offputting. but I
steam on regardless.

I wannabe an active pilot at 99.
Stealth (just a wannabe :-) ) Pilot

Bob Hoover wrote:
On Mar 24, 1:01 pm, wrote:
On Mar 24, 2:02 am, Bob Hoover wrote:

On Mar 23, 8:14 am, wrote:
Without seeing it I would have guessed a contaminant on your filler
rod, but if it's happening ahead of the pool it may be something on
the tubing, such as some sort of residue from the zinc.
-Bob
I'm leaning toward that myself. When the tubes came out of the acid, I
rinsed them in clean tap water and then let them air-dry. I actually
watched them rust in a period of 5 minutes. Once the tubes were dry, I
shoe-shined them with a Scotchbrite pad. They looked nice and shiny,
but I didn't do any further cleaning. I also didn't clean the filler
rod. Its copper-coated, but that doesn't seem to be doing it, or I
would have the problem all of the time.
-----------------------------------------------------------------------------------------------

Okay. At least we are singing off the same sheet of music. And to be
honest, the stuff we used, circa 1972, was salvaged from a local
lumber yard in a building erected sometime between 1945 and 1953.
They gave us (the local Scout troop) the stuff in return for hauling
it away. The EMT had held only a couple of wires, which we salvaged
and sold as copper scrap. The EMT was sliced into 12" lengths BY HAND
using Boy-Power (a Troop joke), and hack-saws having 32 tpi.

After chopping we had a fair sized BIN of tubing 'coupons' on which to
practice, plus a pretty good pile of long pieces destined for another
Project... once the boy's learned to weld tubing.

To remove the galvanizing we cheated a bit and hauled most of the
stuff to a shop in Oceanside where the guy dipped them in heaven knows
what but it required neutralizing. On the final dip the coupons
picked up a film of oil that was floated on the Mystery Fluid (which I
thin was just hot water). Bottom Line: No rusty coupons even a year
later... although we did have to de-grease the stuff before using.

One of us was a Navy Chief, several other fathers were Marine Corps
NCO's. Another was a dentist, another the Shop Teacher at our local
high school. I mention all this because nowadays, in so far as I
know, we don't even have a Scout troop; the local school district has
86'd ALL 'shop' classes due to various Fears and Budget Problems...
most of which are the Product of the same local School District
members. Our little town (Vista, California) is now a fearful place
where Political Correctness carries more weight than having a roof
that don't leak, a car that runs good, and if you want to get anything
DONE you'd damn well better be able to speak Spanish because the local
crop of youngsters willing and ABLE to tackle life's physical chores
has vanished into the reality of computer games... played on machines
they can't repair... and discussed via hunt & pecked messages because
they can't touch-type.

-Bob (who is still coming up with those Dreadful Projects... [the
current acorn is how to build a cabinet that turns an inexpensive
portable electric saw into an even less expensive Table Saw, needed to
reduce scrap lumber to longerons and sticks for ribs and a hell of a
lot of fun along the way.)

But I fed you a clanger on the tubing, Harry. But I was afraid if I
dug too deeply into the Nitty and the Gritty I'd soon find myself with
no one to talk to :-)

There's no shame in finding cheap materials for test coupons.
I went and begged offcuts of muffler tube from the local shop. They
didn't ask a whole lot of money. And I placed two stubs together with
a little gap and MIG welded them up, one after another.
This gave me a false sense of security - cos it was not at all
difficult. The clean metal is such an overwhelming help!

Exhaust tube is made from ERW steel (electrical resistance welded) -
and you see the flash on the internal diameter.
I am willing to accept that ERW is now as durable as cold drawn - the
type formerly preferred for racing car space frames 'n' stuff.....


Brian Whatcott Altus OK