Welding and Materials

[Aussie Mike]

The pic of mine was after a quick scrub with a wire brush. The soot looks nasty but comes off easy. Welding aluminium also makes a lot of smoke too. Definitly a job to be done in a well ventilated workshop.

I usually keep to a fairly sheltered spot when welding as I'm a bit cheap and try to keep my shielding gas uses to a minimum. When I'm finished I open up the doors and turn a fan on to clear the air. I'll often wair my spray painting respirator under my welding helmet as well.

Cheers

[Dominik]

hi Nick,

okay: I try another one.
when working with stainless (welding as well), never use tools that have been used with mild steel.
stainless will attract the rust from mild steel and start to corrode.

after welding stainless clean the heat affected zone generously at least with distilled water or better yet with a suitable cleaning agent.

otherwise you will get rust close to where you welded and not only at the weld!

dominik

[BeasleyRB]

Re: Mig Aluminum - Try to watch out for that crater at the end of the weld. Cracks start in craters as the weld pool cools and the material shrinks. Also, the welds should be at worst flat, better if a little convex (higher in the center). Use the right filler material for the base metal both for strength and appearance. Miller and Lincoln both have a lot of published materials on Mig and Tig aluminum welding. Buy your welding equipment and supplies from a welding supply distributor as opposed to Lowes or some tool company. You can negotiate for as good a price (or better) AND get all the consulting and welding hints you need.

[stangden]

Mike, Wish you were in my backyard. That is some beautiful work. Not many in my area good with alum.
stangden (Dennis)

[Aussie Mike]

Truth be known I'm not that good with aluminium. I'm getting better results with practice but I'm no where near what the professional welders can do.

I must say it's very satisfying when you do a good weld on any material.

Practice, practice, practice.

Cheers

[63mercury]

I've welded in the factory for over 15 years and the secret to good welda of ANY kind is practice,practice and more practice. I've done very little aluminum welding, mostly while in the reserves ( Air Force) but I love my 120v mig unit for body work and my old 225 Lincoln for heavier stuff. just my .02 worth.

[ponvire09]

My latest welding project, a mailbox for the wife. I purchased a set of scroll benders from Harbor Freight last month to bend the scroll pieces and twist the flat bar. All of the pieces were welded using an old Sears Mig welder I just bought. The mig machine worked great after I purchased Lincoln wire, the original owner had been using some really cheap wire that wouldnt even burn...another great deal on a broken welder

This picture is just before we installed the box.

Keith

[mickmate]

I've also found a big difference between wire brands, especially on aluminum MIG. The polarity has to be set correctly for flux core or it won't burn properly or at all.

[boxhead]

I am wondering if anyone knows of a printable flow chart that shows amperage versus material thickness and argon flow rates for TIG welding?
I have found a Miller online chart, but really want something I can print off, laminate and hang off my welding trolly.

Cheers for any help.

[Rick Parker]

I believe the aluminum boodies are & were gas welded.
Several years ago I watched a fellow gas weld aluminum mufflers for RC Control Planes at the manufacturing plant in the outskirts of Sacramento. It was a work of art to see the aluminum just reach the point were it began to flow and see him dab the aluminum filler rod in the puddle.

[COBRANIP]

Boxhead:
Miller makes a nice quick reference calculater; It is a sleve with a card inside that you slide up and down to identify material type, thickness, etc.: (Miller TIG welding Calculator 171086):

Miller TIG Welding Calculator 171086

Good luck,

John

[lovehamr]

I bought a Lincoln 216 a few months back to replace a smaller flux only unit that was stolen. I bought it at that time because they were running a special where you could get $100 back or you could get a spool gun. Of course I went for the spool gun. With the small aluminum stuff that I've done so far I'd have had much better luck with a TIG but that would be $$$$ and this is way better than what I had before anyway. I found out the hard way about moving fast as the first couple of scraps that I tried to weld just turned into molten AL and dripped on the floor. Luckily not my feet! My Lincoln also has a reference chart for power, metal gauge, wire speed/thickness, etc. on the inside of the cover. I've found that to be quite convenient so far.

Steve

[mickmate]

I just got Eastwoods 175 MIG with a spool. I just repaired some 16 Ga ally body work with it and had minimal distortion. It really shouldn't weld anything that thin but a copper backing block is the trick there, that and the right push angle. I would have preferred to TIG that thickness but I'm sure it would have wrinkled up like Grandma.

[G-Pete]

Originally Posted by COBRANIP

Boxhead:
Miller makes a nice quick reference calculater; It is a sleve with a card inside that you slide up and down to identify material type, thickness, etc.: (Miller TIG welding Calculator 171086):
Miller TIG Welding Calculator 171086
Good luck,
John

John,
Miller direct charges only $1.50 --- besides that Miller has the calculator online for free...

Miller - TIG Welding Calculator

[120mm]

I'm relatively new to the forum, and notice this section doesn't get much play.

I used to be an A&P mechanic and have welded up a few aircraft tube steel frames out of 4130 chromoly using Oxy-Acetylene out of a micro-torch. I'm wondering if anyone out there is scratch building Cobra frames using this or everyone is just using TIG/MIG.

I'm also looking for reliable drawings for the Cobra frame, or a modern adaptation that would work.

[xb-60]

Originally Posted by 120mm

....or a modern adaptation that would work.

Could try an AP semi-monocoque:

http://www.absolutepace.com/images/brochure_pace427.pdf

Cheers,
Glen

[Dominik]

Welcome 120mm!

I built a handful of chassis based on the Cobra Restorers drawings. They are actually not that bad. I did improve on a few measurements, based on a CSX 4000 chassis which I measured here in South Africa. I can't recall the changes because I built the last one years ago. The scuttle hoop is critical.

Mickmate build a usable chassis from CR prints and might be able to assist.

There are plenty of modern adaptions around, and it's a matter of preference I suppose.
I drew up a chassis from a SA built version, done by a local race car builder, whose car handled extremely well. I managed the same lap times with a 302 and 290hp as the local 300+ hp 911s.

What I mean is, plenty of chassis that behave 90% well if the suspension is thought through nicely. The other 10% I leave to the professionals :-)

[alfy65]

I used the CR drawings but modified to portion of rear frame to be a little different for the jag rear end...seems ok so far...scuttle tube had to be lowered about an inch or so to fit the body that I used...trial and error..lol.... used a tig for all steel, stainless and aluminum...

[120mm]

So, the "scuttle tube" or "scuttle hoop" is the lateral curved tubing behind and/or in front of the cockpit that lends the body support and shape?

Looking at various build photos, I don't see how it is essential, strength-wise, to the chassis. So would it be possible to leave these off until the body is selected and fitted?

Sorry if that's a dumb question. I've welded up a few Piper Cub fuselages and they have a central core for strength and an outer framework for shape. Am wondering if these are similar structures. With those, I tacked everything together first to make it easier to "try and fit" the rest of the structure, then finish welded using skip welding to keep warpage down.

[alfy65]

Supports the cowl, dash ,door hinges front coil over uprights and adds ridgety to the frame..I put in a bolt in backbone over transmission to add some strength.. no reason not to set a body in place and tack in support tubes..I think my gallery might show you some frame pics that might help.