I would liketo build a new frame for my jeep CJ-7 and want something
that will not rust, ever. Would 2" X 4" X 1/4" wall aluminum tubing be
strong enough. How would that compare in strength to 2" X 4" X 1/8"
wall steel which is what aftermarket frames are made from?

"mark" wrote in message
...
I would liketo build a new frame for my jeep CJ-7 and want something
that will not rust, ever. Would 2" X 4" X 1/4" wall aluminum tubing be
strong enough. How would that compare in strength to 2" X 4" X 1/8"
wall steel which is what aftermarket frames are made from?

The aluminum would be roughly 2/3 as strong. More importantly to handling,
it would be 2/3 as stiff. Whether that's enough, someone else would have to
answer.

To get an advantage out of aluminum's low density you would have to use
different sectional depths or shapes. Since you're using the same section (2
x 4) with greater thickness, you're facing the specific
strength/stiffness/weight relationships of steel vs. aluminum. The rule of
thumb is that aluminum weighs 1/3 as much, is 1/3 as stiff, and is 1/3 as
strong.

However, the strength varies with the alloy, both of the aluminum and the
steel. You can compare weight and stiffness easily, because they're the
same, pretty much, for all alloys you're likely to encounter. But as someone
will probably point out, you could alter that strength ratio by quite a bit
by choosing specific alloys.

All in all, though, I think you'll wind up with a flexi-flyer that doesn't
have adequate stiffness. It's a lot cheaper to go all out in protecting the
steel. For example, epoxy-based, zinc-loaded primer.

--
Ed Huntress

The problem with ant paint is the inside is not protected, my other
choices would be 1/8" wall stainless or just steel and have it hot
dipped galvanized.

On Feb 17, 7:04*pm, "Ed Huntress" wrote:
"mark" wrote in message

...

I would liketo build a new frame for my jeep CJ-7 and want something
that will not rust, ever. Would 2" X 4" X 1/4" wall aluminum tubing be
strong enough. How would that compare in strength to *2" X 4" X 1/8"
wall steel which is what aftermarket frames are made from?

The aluminum would be roughly 2/3 as strong. More importantly to handling,
it would be 2/3 as stiff. Whether that's enough, someone else would have to
answer.

To get an advantage out of aluminum's low density you would have to use
different sectional depths or shapes. Since you're using the same section (2
x 4) with greater thickness, you're facing the specific
strength/stiffness/weight relationships of steel vs. aluminum. The rule of
thumb is that aluminum weighs 1/3 as much, is 1/3 as stiff, and is 1/3 as
strong.

However, the strength varies with the alloy, both of the aluminum and the
steel. You can compare weight and stiffness easily, because they're the
same, pretty much, for all alloys you're likely to encounter. But as someone
will probably point out, you could alter that strength ratio by quite a bit
by choosing specific alloys.

All in all, though, I think you'll wind up with a flexi-flyer that doesn't
have adequate stiffness. It's a lot cheaper to go all out in protecting the
steel. For example, epoxy-based, zinc-loaded primer.

--
Ed Huntress

On Feb 17, 6:04 pm, "Ed Huntress" wrote:
"mark" wrote in message

...

I would liketo build a new frame for my jeep CJ-7 and want something
that will not rust, ever. Would 2" X 4" X 1/4" wall aluminum tubing be
strong enough. How would that compare in strength to 2" X 4" X 1/8"
wall steel which is what aftermarket frames are made from?

The aluminum would be roughly 2/3 as strong. More importantly to handling,
it would be 2/3 as stiff. Whether that's enough, someone else would have to
answer.

To get an advantage out of aluminum's low density you would have to use
different sectional depths or shapes. Since you're using the same section (2
x 4) with greater thickness, you're facing the specific
strength/stiffness/weight relationships of steel vs. aluminum. The rule of
thumb is that aluminum weighs 1/3 as much, is 1/3 as stiff, and is 1/3 as
strong.

However, the strength varies with the alloy, both of the aluminum and the
steel. You can compare weight and stiffness easily, because they're the
same, pretty much, for all alloys you're likely to encounter. But as someone
will probably point out, you could alter that strength ratio by quite a bit
by choosing specific alloys.

All in all, though, I think you'll wind up with a flexi-flyer that doesn't
have adequate stiffness. It's a lot cheaper to go all out in protecting the
steel. For example, epoxy-based, zinc-loaded primer.

--
Ed Huntress


Perhaps you could build the frame from steel in bolt-together sections
which you could get galvanized, followed with a contrasting epoxy
paint. Thus you can see where the paint has chipped off and touch it
up before the onset of rust.

Lacking galvanizing you can flame spray the sand blasted frame with
metallic zinc, using a specialized oxy-acetylene flame spray torch.
Followed by painting. Check if there is such a service in your area.

I would not use aluminum for the reasons Ed gave, but also, aluminum
is not fatigue failure proof as carbon steel is. Depending on the
amount of usage, you may find that certain frame joints and attachment
points experience pre-mature cracking.

That said some AUDI's have aluminum frames but they spend big $$$ to
conduct finite element stress analysis to keep stress concentrations
to a rock bottom minimum. Certain heat treated aluminum alloys can
carry an amazing amount of stress, 12,000 to 15,000 psi IIRC, with a
fatigue life of 50,000,000 cycles,but the stress concentrations negate
this.

Wolfgang

"mark" wrote in message
news:a9978e0f-cf6c-4b53-9d60-
...
The problem with ant paint is the inside is not protected, my other
choices would be 1/8" wall stainless or just steel and have it hot
dipped galvanized.

Can you have an entire Jeep frame hot-dip galvanized? I've never seen
anything bigger than about the size of a toaster oven done that way. But
maybe the frames come in pieces?

The solution for inside treatments used by homebuilt airframe builders is
linseed oil, which seems to work OK. I've also heard of pouring in zinc
chromate primer, through a drilled hole, and then letting it out. Then there
is another aircraft solution, which is to pull a vacuum in the tubes, after
they've been interconnected with drilled holes, and installing a vacuum gage
in one of the tubes to keep an eye on it (but that's mostly to detect
cracks, although it also detects the integrity of the air seal). That sounds
like overkill to me.

The Excalibur car people used to fill the square tubes they used for frames
with expand-in-place foam. Supposedly it works quite well. They initially
used a urea-formaldehyde foam, but that pulled away from the metal with age.
Polyurethane foam-in-place has been recommended.

--
Ed Huntress

On Feb 17, 6:48*pm, "Ed Huntress" wrote:


Can you have an entire Jeep frame hot-dip galvanized? I've never seen
anything bigger than about the size of a toaster oven done that way. But
maybe the frames come in pieces?


Ed Huntress

Yes, you can. Replacement frames for Land Rovers are available hot-
dip galvanized, and I believe those are done here. Look hard enough
and you might find hot-dipped Jeep frames as well.

As to an amuminum frame, I might be a bit concerned about reactions
where it meets steel pieces.

John Martin

"John Martin" wrote in message
...
On Feb 17, 6:48 pm, "Ed Huntress" wrote:


Can you have an entire Jeep frame hot-dip galvanized? I've never seen
anything bigger than about the size of a toaster oven done that way. But
maybe the frames come in pieces?


Ed Huntress

Yes, you can. Replacement frames for Land Rovers are available hot-
dip galvanized, and I believe those are done here. Look hard enough
and you might find hot-dipped Jeep frames as well.

As to an amuminum frame, I might be a bit concerned about reactions
where it meets steel pieces.

John Martin

Aha! I see on the Web that someone says it cost only $200 to get his
Chevelle wagon frame acid-dipped and hot-dip galvanized. I had no idea it
would be that cheap.

http://einstyn.com/einstyn-hardtop-02.htm

It looks like a good way to go, except that the insides of the tubes still
have to be treated.

--
Ed Huntress

http://www.4wd.com/productdetails.as...4&partID=10626
For the aftermarket galvanized frame at $2350

Considering that the aftermarket frames are mandrel bent in both
directions (read LARGE setup cost for the first one!), you would need to
cut and weld the aluminum frame. IIRC there are 6 bends per side so 6
cut and weld joints in aluminum. Assuming you use something like
6061-T6, the weld areas will eventually age harden to about 6061-T4. To
get a reasonable compromise between cost and strength and stiffness, you
would need to go to a 2"x5" or 3"x5" aluminum rail. Other posters have
mentioned the fatigue issues, I think I'd be more worried about weld
strength, HAZ areas, and the lower yield strength near the welds. THEN
you get to worry about fatigue.

The frame dimensions are commonly available, it's just a matter of
deciding on cut and weld vs mandrel bent.

mark wrote:
I would liketo build a new frame for my jeep CJ-7 and want something
that will not rust, ever. Would 2" X 4" X 1/4" wall aluminum tubing be
strong enough. How would that compare in strength to 2" X 4" X 1/8"
wall steel which is what aftermarket frames are made from?

mark wrote:
I would liketo build a new frame for my jeep CJ-7 and want something
that will not rust, ever. Would 2" X 4" X 1/4" wall aluminum tubing be
strong enough. How would that compare in strength to 2" X 4" X 1/8"
wall steel which is what aftermarket frames are made from?

It'll break. It's one of the reliable characteristics of aluminum. It
flexes, work hardens, and comes apart.

Stick to steel. It welds, flexes, and lasts, far better than aluminum
tube will.

The aluminum frames for cars that are out there, definately are not
just cobbled together out of tube. Serious stress analyisis, mondo heat
treating ovens, carefull process control all the way. Not a home remedy.



Cheers
Trevor Jones

"Ed Huntress" wrote in message
...

"John Martin" wrote in message
...
On Feb 17, 6:48 pm, "Ed Huntress" wrote:


Can you have an entire Jeep frame hot-dip galvanized? I've never seen
anything bigger than about the size of a toaster oven done that way. But
maybe the frames come in pieces?


Ed Huntress

Yes, you can. Replacement frames for Land Rovers are available hot-
dip galvanized, and I believe those are done here. Look hard enough
and you might find hot-dipped Jeep frames as well.

As to an amuminum frame, I might be a bit concerned about reactions
where it meets steel pieces.

John Martin

Aha! I see on the Web that someone says it cost only $200 to get his
Chevelle wagon frame acid-dipped and hot-dip galvanized. I had no idea it
would be that cheap.

http://einstyn.com/einstyn-hardtop-02.htm

It looks like a good way to go, except that the insides of the tubes still
have to be treated.

--
Ed Huntress



many years ago i visited a hot dip place in long island city, near the
noguchi museum and mark di suvero's studio. i was amazed they let me walk
all throughout the shop. checking out their huge vats of pickle, etc.
there was a big vat of molten zinc, it was flush with the floor, no
protective barriers around it at all. i was astounded (not just at that vat
of molten zinc but that they'd let me walk right up next to it!) the vat
was (in my memory) about 5 or 6 feet wide and about 12 or 15 feet long, no
idea really how deep, i only guessed it must be about as deep as the acid
tanks, 4 or 5 feet deep. that must've been one very HEAVY thing huh?! was
way cool. they're out of business now. a shame.

b.w.

"Ed Huntress" wrote in message
...




many years ago i visited a hot dip place in long island city, near the
noguchi museum and mark di suvero's studio. i was amazed they let me walk
all throughout the shop. checking out their huge vats of pickle, etc.
there was a big vat of molten zinc, it was flush with the floor, no
protective barriers around it at all. i was astounded (not just at that
vat of molten zinc but that they'd let me walk right up next to it!) the
vat was (in my memory) about 5 or 6 feet wide and about 12 or 15 feet
long, no idea really how deep, i only guessed it must be about as deep as
the acid tanks, 4 or 5 feet deep. that must've been one very HEAVY thing
huh?! was way cool. they're out of business now. a shame.

b.w.


oh, and they had stacks of stuff that they'd already done. was very pretty,
that crystaline pattern of the hot dip. the way i remember it they were
dipping street corner traffic signal poles, so i bet the tank that i
remember was even longer than 15 feet.

"William Wixon" wrote in message
...

"Ed Huntress" wrote in message
...

"John Martin" wrote in message
...
On Feb 17, 6:48 pm, "Ed Huntress" wrote:


Can you have an entire Jeep frame hot-dip galvanized? I've never seen
anything bigger than about the size of a toaster oven done that way.
But
maybe the frames come in pieces?


Ed Huntress

Yes, you can. Replacement frames for Land Rovers are available hot-
dip galvanized, and I believe those are done here. Look hard enough
and you might find hot-dipped Jeep frames as well.

As to an amuminum frame, I might be a bit concerned about reactions
where it meets steel pieces.

John Martin

Aha! I see on the Web that someone says it cost only $200 to get his
Chevelle wagon frame acid-dipped and hot-dip galvanized. I had no idea it
would be that cheap.

http://einstyn.com/einstyn-hardtop-02.htm

It looks like a good way to go, except that the insides of the tubes
still have to be treated.

--
Ed Huntress



many years ago i visited a hot dip place in long island city, near the
noguchi museum and mark di suvero's studio. i was amazed they let me walk
all throughout the shop. checking out their huge vats of pickle, etc.
there was a big vat of molten zinc, it was flush with the floor, no
protective barriers around it at all. i was astounded (not just at that
vat of molten zinc but that they'd let me walk right up next to it!) the
vat was (in my memory) about 5 or 6 feet wide and about 12 or 15 feet
long, no idea really how deep, i only guessed it must be about as deep as
the acid tanks, 4 or 5 feet deep. that must've been one very HEAVY thing
huh?! was way cool. they're out of business now. a shame.

I wonder what that much zinc *weighs*. I'm not about to calculate it. g

Looking around the Web I saw one that's 54 feet long and ten feet wide,
supposedly the biggest in the US, for doing truck trailer frames.

--
Ed Huntress

Ed Huntress wrote:
"John Martin" wrote in message
...
On Feb 17, 6:48 pm, "Ed Huntress" wrote:


Can you have an entire Jeep frame hot-dip galvanized? I've never seen
anything bigger than about the size of a toaster oven done that way. But
maybe the frames come in pieces?



Ed Huntress


Yes, you can. Replacement frames for Land Rovers are available hot-
dip galvanized, and I believe those are done here. Look hard enough
and you might find hot-dipped Jeep frames as well.


As to an amuminum frame, I might be a bit concerned about reactions
where it meets steel pieces.


John Martin


Aha! I see on the Web that someone says it cost only $200 to get his
Chevelle wagon frame acid-dipped and hot-dip galvanized. I had no idea it
would be that cheap.

http://einstyn.com/einstyn-hardtop-02.htm

It looks like a good way to go, except that the insides of the tubes still
have to be treated.

--
Ed Huntress




You mentioned some of the complicated aircraft solutions.

But he simple one is to simple seal the tubes.
Once the oxygen inside the tube is "used up" it won't rust any more...

What's that Lassie? You say that Ed Huntress fell down the old
rec.crafts.metalworking mine and will die if we don't mount a rescue
by Sun, 17 Feb 2008 18:48:00 -0500:

Can you have an entire Jeep frame hot-dip galvanized? I've never seen
anything bigger than about the size of a toaster oven done that way. But
maybe the frames come in pieces?

Yes you can. I think the catalog is called Quadratec.
They have frames for CJ5 and CJ7, and one of the many options is hot
dipped galv. That should do it, unless you cut into it.

They can even include a 2" receiver in the rear crossmember.


found the link: http://www.quadratec.com/

and here is a link to the one of the frames:
http://www.quadratec.com/products/56011_08D_T.htm
The HDG comes with a 10 year rust through warranty
Dan
--

Dan

"RoyJ" wrote in message
...
http://www.4wd.com/productdetails.as...4&partID=10626
snip---

Assuming you use something like 6061-T6, the weld areas will eventually
age harden to about 6061-T4.

Not likely unless the entire frame is solution annealed first.

Harold

Ed Huntress wrote:
"John Martin" wrote in message
...
On Feb 17, 6:48 pm, "Ed Huntress" wrote:


Can you have an entire Jeep frame hot-dip galvanized? I've never seen
anything bigger than about the size of a toaster oven done that way. But
maybe the frames come in pieces?




Ed Huntress



Yes, you can. Replacement frames for Land Rovers are available hot-
dip galvanized, and I believe those are done here. Look hard enough
and you might find hot-dipped Jeep frames as well.



As to an amuminum frame, I might be a bit concerned about reactions
where it meets steel pieces.



John Martin


Aha! I see on the Web that someone says it cost only $200 to get his
Chevelle wagon frame acid-dipped and hot-dip galvanized. I had no idea it
would be that cheap.

http://einstyn.com/einstyn-hardtop-02.htm

It looks like a good way to go, except that the insides of the tubes still
have to be treated.

Hollow tube frames can be done also if you know what you're doing. A guy
near me has Marcos steel tube chassis done inside and out, he said it
did take a few goes to get it right and he has the dipper trained to do
the job right. Someone else I know had a simple hollow tube chassis done
and said he could lift it by himself when it went in but not when it
came out as the tubing hadn't been drained properly, costly as you pay
by the weight of zinc typically.

--
Ed Huntress

On Mon, 18 Feb 2008 09:14:27 GMT, "Harold and Susan Vordos"
wrote:


"RoyJ" wrote in message
...
http://www.4wd.com/productdetails.as...4&partID=10626
snip---

Assuming you use something like 6061-T6, the weld areas will eventually
age harden to about 6061-T4.

Not likely unless the entire frame is solution annealed first.

Harold

Actually, any 6061T6 weldment WILL eventually age to T4.
However, aluminum is NOT the material of choice for a jeep frame. ANY
deflection in aluminum is a cumulative stress, and the frame WILL
eventually fale from flexing.

Go with steel, hot dipped, or perhaps stainless.
Acid dipped and then hot dip galvanized will coat inside and outside.
I'd sand blast first, particularly the weldments, to be sure the zink
will get a good adhesion to the steel.

--
Posted via a free Usenet account from http://www.teranews.com