caveman tech II - rebuilding your cowl top from scrap

Hi guys.
This was an experimental project I am happy to share with you guys.
Hopefully it will help others to have fun in the shop,
instead of spending a bunch of money on poorly fitting patch panels.

Please be aware that this is not a show car,
so some of the techniques may seem a little crude.
Here is the link to its build-up so far if your interested...
http://www.jalopyjournal.com/forum/showthread.php?t=286059

One of my favorite parts of this project is all the metal was scrap, real scrap from the shop,
and the tools were very simple, a hammer, a grinder/discs, welder, a torch and a press.
The press used was an older 5000lb press,
but even a bottlejack in a steel channel frame would probably do the job!

The bummer is the molds take alot of time to make,
and once used are heavy useless pieces of scrap again!

Maybe some of you will set aside your bead roller after this tech!

++++++++++++++++++++++++++++++++++++++++++++++

The problem was a severely rusted 40 cowl...

This gaping hole was the first thing most people saw when they checked out the project,
really made me seem more crazy for wanting to build it!


I had looked for months for a decent donor piece.
Came really close on a HAMB deal, but fell through.

One night I drove my nicer 40 and realized that the cowl top isn't a gradual curve,
but more of a sharp center bend which is almost flat to the outer part.
The windshield has a curve up to it but nothing to crazy.


So after making some measurements and a really rough template,
(I used the hood to make the V rather than the actual cowl, alot easier.)
Used some of this 1/4" steel scrap we have lying around to make a mold.

A plasma cutter was used to do the cutting,
although a torch would be ok too.
Using a piece of angle iron ensures a straight cut...


I was happy with the cut on the male side.
Only a little grinding to true it up.


The female side had a couple dips on the curve,
so had to fill it with some weld to make it right.


After a little grinding,
got the two pieces to match as close as possible before dinner...


Then got another piece of the 1/4" scrap and made 2 backing plates.

At this point I was a little hesitant.
The stock hood lip has 3 steps,
which would mean making 3 steps on the mold, or 6 curved pieces.
It took long enough to make the first step piece so decided to use plan B.

Matched the 2 halves and drilled a bunch of 5/16 locator bolt pins so it would press tight.


Using a piece of galvanized sheet scrap,
I did a test run to see how it would come out.

I was pretty satisfied with the definition.
And this was with no clamps or anything, just tightening the bolts.

The curve seemed good enough.
The tricky part is the curve gets tighter when the center is bent
(bringing the ends down)

It was hard to sleep that night,
really wanted to see if it would work with a thicker gauge...
TP

 

got any pics?

 

I might have to continue this in the morning, its pretty late here.
But here's a little bit...

+++++++++++++

I wasn't able to get a new piece of sheetmetal after work,
so I scoured the shop for some sheetmetal scrap.
Nothing.
But then I remembered the back half of the 40!

The flat floor part is probably 18 gauge.
Way thicker than the original but all I had.
So figured worth a try...

Cut out a donor chunk...
Actually I oiled it up before it was buttoned up,
hoping that it might press better.

And me and my friend Pigpen(LUKE) used the neighbors 5000lb press to squeeze it out,
in the dark of course!
That mold is HEAVY, it was good he was around.

It seemed hopeless actually thought the mold would shear the piece at the curve,
the sheetmetal was pretty thick,
it wouldn't squeeze down all the way.

So figured replacing the 5/16 bolt pins with 1/4 bolt pins would give it a little slop,
and wow it worked!
I think it took 5 or 6 presses, each like 4 inches apart or so,
to squeeze it.

We were expecting failure but got this...


We were so stoked,
well I was so relieved really.
Was thinking of all the wasted time if it didn't work!

So before Pig left, we pressed another one...

just a thin one too add to the bigger piece.

TP

 

very cool... awesome job... that 40 is gonna rock

 

Would it not be possible to press all three ribs into the panel by reusing the same press?

 

hats off to you i dig the cave tech articles

 

Excuse the delay there...ya know sleep and work!

Anyway where were we...

Ok then trim the pieces to match the original cowl step..

IMPORTANT
I had bent both pieces on the center point over a piece of tube.
And matched the angle as close as possible to my green 40.
This sharpened the V of the reveal alot,
but the 2 pieces also match at different points than when they were flat.
This is important because attaching the 2 pre-bent will make it stiff and hold the bend.
(and make it not look buckled too.)

Than little tacks, moving around the clamps to make sure its always flat...



Than finish welded...

A line must be drawn to hammer the leading edge lip down,
I like this trick alot...


And using a flat steel table, this anvil jig-stand, and my trusty long hammer...


The leading edge is tapped down.
I was lucky to get such close measurements.



After that the windshield bottom was cut to fit,
then hammered against a long 2x6 to mimick the gradual roll-up to the windshield bottom.

I have a plan for the rubber seal, so wasn't to worried about that seal lip just yet..


TP

 

Not without either modifying the mold or ruining the piece.
The mold would need to be trimmed to not destroy the previous step.
Also the press would probably need to be alot stronger,
especially for the thickness of the sheet I was using.

I like welding and cutting better anyway!

TP

 

BRILLIANT!!

I love those old school sheetmetal clamps, or whatever those are??

 

yea i was wondering what the name of those were, I have several,but would like to find more. I believe they may be used for aviation sheet metal work.

 

You are the ruler of the cavemen. Great work man.

 

Awesome! Now just redo all the rest of the sheet metal and you will just about have it done.

 

Some of you heard this story but...
Basically those clamps are inherited from my dead grandfather "papa".
He gave me alot of his tools when he realized my interest.
He was a lifer in the NAVY,
and at the end of his time there,
and actually as a civilian after "retirement"
worked in this section that built miniatures of the navy ships, battleships, submarines etc.
They used them for radar and sonar tests,
replicating accidents for investigations,
and alot are for show in certain public areas around san diego's bases.
This was before fiberglass was common so they were all sheetmetal, steel, brass, aluminum etc.

I will get the name tonight for ya!

TP

 

Holy shit!That first pic looked like something they brought up from the Titanic!Lookin' good ferther down,keep on plugin'

 

Yeah sometimes I think what the heck did I get myself into!

+++

Ok the hard part is figuring out how much of the patch panel to use.
I ended up using all the panel that went from the peak flat to the beginning of the curve down,
right outside of the windshield wipers.
This was actually more than I had originally planned (before doing the piece)
but alot smaller than the pressed piece too.

I was lucky cause the outer cowl area was useable (to me anyway).

After some trimming and using the special clamps (my camera had died...)
The piece was tacked in.

I was extremely satisfied with the outcome!
Although the "step" corners match,
It doesn't match the original "step" pattern exactly,
so it'll be obvious to a restorer that it was replaced, (if the hood is off!)
but man its a big difference than that gaping rust hole.

The big change is the omittal of the cowl vent.
I'd been thinking about hammering a hole before the panel installation, when it was easy,
but decided against it.
The reason is the engine.
The distributor is right beneath the cowl vent,
so NOT having one is easier than
designing one that is shallow, and will not drip water..

If you follow that RED arrow, the shop has a new wall hanger!



However this was just the beginning...

TP

 

Hey CHAVEZ got GEICO!

 

impressive!!

 

ditto.....

Neat and simple tech that works....

Cheers,

Drewfus

 

Yep, now I see 'um. Couldn't see them last night but now I likewhat I see. Looks fantastic.

Pete

 

Great Ideas, thanks for sharing.

 

Look for "Toggle Clamps".

 

My hats off to you !!!!!!!!!

 

Very nice, it is always nice to see alternative ways of shaping metal. Thanks for sharing.

 

My mistake was making this cardboard template.

actually it wasn't a mistake,
its just that since the cowl came out OK,
the template proved I needed to see this through!

I've always liked the solid center bar on convertible 40's.
Instead of a bolt-on chrome or stainless piece, its an extension of the cowl sheetmetal.
(no pic!)

Copying the curves of the stock rear window,
whipped out some crude 3/8's roughcuts.


And after way to much grinding,
got a decent mold made...


Of course I realized that maybe it woulda been smarter or quicker to make only one half of the curve,
then just press 2 pieces and cut them to fit,
instead of hoping that my measurements will fit a 11 5/8" windshield heighth!

Using a piece of scrap from the original piece of scrap,
pressed out the first piece...

Using the same 5000lb press, in 3 different spots on the mold,
the first press was kinda soft.

-I had used 4" channel which flexed too much for the thicker than normal 18 sheetmetal

-I was a little lazy with the fit of the center bars.
They had bowed out when tacked, and instead of fixing it, didn't.

It took a little pounding to get the first one sharp.

I had figured it would be stronger and cleaner looking if 2 pieces were joined back to back.
So got another chunk of scrap.


Than matched them up and did a rough cut on the lip.

Although there were a couple press marks,
the parts looked pretty good.
They still would need alot of tweaking to fit right...

TP

 

really nice work!

 

this is very cool! very neat ideas. I was gonna say those clamps rock.

 

The whole job looks great.Thanks for sharing

 

Ok.

The piece looks right, but needs to follow the V of the windshield.
Not hard on the front piece.

The vice was all it needed.


THan some tapping on the anvil stand.


The inside piece was a little trickier.
It needed some dimpling on a piece of wood,
than the vice.



There ya go...

The roofline was marked.


Than cut...

first.

 

This is the inside...



So a little fitting,
than the bottom is marked.


and the outer piece is fitted with the clamps.
MG]

Using the only non-caveman tool I've got!

set on 65...

the piece is welded in.



making sure the insides of both parts were clean,
used the trusty clamps, fit the inner piece.




Since there was not much to weld too,
and I wanted to use something that would seep into the crack of the 2 pieces,
The good ole welding torch and brazing rod were brought out...

I missed this old thing, and the smell of the flux!

The brazing rod is an excellent way to attach the dirty body to the steel,
even upside-down!

little tacks up the middle too...

And the top of the top..


TP

 

and there ya go!


It really cleaned up that rusty old body.

Now just need to do the seal-lip around the window.
TP