Welding Tips and Tricks

I'm in the process of replacing my fluxcore machine and am exploring all my options (multiprocess ac/dc, seperate mig and tig machines, etc.). I've looked far and wide for answers to my questions and all I've found so far are opinions, nothing concrete and scientific. I'm in the process of restoring a 1983 Jeep CJ5, and I also want to build a BBQ table out of aluminum for my Big Green Egg, make new steps for the patio, build a patio table, etc. regular household stuff.
So, my questions are:
1. patching the rusted sheet metal on the jeep, why would I use TIG vs MIG or MIG vs TIG? Is one better than the other for 18 ga steel? or a combination of both?
2. Is it possible to TIG aluminum with a DC only machine?
3. What are the Pros and Cons of AC TIG aluminum vs Spool gun MIG?

Thanks for your help,
Onelick

1. patching the rusted sheet metal on the jeep, why would I use TIG vs MIG or MIG vs TIG? Is one better than the other for 18 ga steel? or a combination of both?

I believe there is no "better" really. Both can do the job well, but you need advanced skills with either process to weld 18 gauge and not warp it, OR you need advanced sheet metal/body work skills to be able to use a hammer and a dolly to deal with the warp, and maybe both skills will be required. Some folks will like TIG because it has so much more precise control and application of the heat, but it takes two hands to weld with TIG, which is a challenge for some people who don't have the requisite hand eye coordination. TIG is also way slower for most people. MIG is less precise but you can work with tack welds, and stitch welds to control heat, and you can use your off hand to hold parts while you tack.

2. Is it possible to TIG aluminum with a DC only machine?

Technically, yes, if you use 100% helium for shielding gas. BUT you will not be happy with the results and helium is very expensive nowadays. For all intents and purposes you really should use an AC/DC TIG to weld aluminum.

3. What are the Pros and Cons of AC TIG aluminum vs Spool gun MIG?

About the same answer as the first question. Both techniques work well. For aesthetics most people lean towards TIG, but MIG is used almost exclusively in production environments and robotics applications Jody has a great video on this subject.

https://www.youtube.com/watch?v=tNmj-R8tIJw

Onelick wrote:I'm in the process of replacing my fluxcore machine and am exploring all my options (multiprocess ac/dc, seperate mig and tig machines, etc.). I've looked far and wide for answers to my questions and all I've found so far are opinions, nothing concrete and scientific. I'm in the process of restoring a 1983 Jeep CJ5, and I also want to build a BBQ table out of aluminum for my Big Green Egg, make new steps for the patio, build a patio table, etc. regular household stuff.
So, my questions are:
1. patching the rusted sheet metal on the jeep, why would I use TIG vs MIG or MIG vs TIG? Is one better than the other for 18 ga steel? or a combination of both?
2. Is it possible to TIG aluminum with a DC only machine?
3. What are the Pros and Cons of AC TIG aluminum vs Spool gun MIG?

Thanks for your help,
Onelick

1. TIG offers much more control because the heat input can be completely independent of the filler metal deposition, and vice-versa. With MIG, generally speaking, the the heat-input is directly tied to the filler metal deposition via the WFS-Amperage inter-dependency. Both can be implemented with great success. There is no substitute for user knowledge and experience.

2. Yes, but you need Helium. If you haven't checked helium prices recently, just as a rough estimate, each refill end ups being the monthly payment for a small car.

3. Same as #1. As a corollary, most MIGs do not have a hot-start for aluminum, which produces a cold-start even if the end of the weld ends up melting away from you. (The better Inverter MIGs do have hot-start AND crater-fill functions, so all is not lost, but there is a pretty penny to pay for those capabilities.) Not so with AC TIG because again you can control the heat input and filler metal deposition separately. Also Spoolgun aluminum mig generally needs to occur in spray-transfer, which limits it to roughly 1/8" and thicker. It can be used for lower thicknesses, but the spatter generated is horrible.

Oh an as an addendum to my answer, pulse MIG really changes everything with regard to aluminum MIG welding. It becomes as aesthetically pleasing as TIG welding with the correct pulse enabled MIG welding equipment. https://www.millerwelds.com/resources/a ... heet-metal

1. TIG tack, MIG finish.
2. Not worth it. Hassle to get an extra bottle, results sort of suck because you lack the cleaning action of AC.
3. For your BBQ, Spool Gun it. You'll finish in 1/5 the amount of time and the results will be more consistent as a new Ally weldor.

Thanks for all the replies. The replies to my second question ruled out a multiprocess DC only machine.
So what I'm down to is either the Miller Multimatic 220, ESAB Rebel 205 for the all in one machines.
Or 2 separate macines, one ac/dc tig and one mig.

The Miller 220 amperage for TIG goes down to 20 amps verses 5 amps for the ESAB. Will the 20 amps make tacking the 18 gauge a difficult process? Will I be blowing holes through the sheet metal? Am I over thinking it?

Thanks for the help,
Onelick

It doesn't so much depend on the minimum amps regarding the concerns about blowing holes in very thin material, but more so the hot-start amperage/time duration programmed into the unit. That being said, I think it will be completely fine for 18ga and even thinner.

I've used a couple multimatic 220s. In fact I have my friends set up at my house right now. I've only bottomed out the machine twice, one was when welding razor blades and the other was when welding uphill along the edge of a piece of 1/16 sheet aluminum. For tacking 18 gauge steel you'll be more than fine generally the rule is 1 amp per thousandth of steel, so you'd only run into problems trying to weld things around .020 or thinner.

Thanks for all the replies and help. I've been to my local Praxair, AirGas, and a local independent shop. I looked into separate TIG and MIG machines, and multiprocess machines. I've settled on the Miller Multimatic 220. It will be in the local independent shop the middle of next week.

Thanks for the help.
Onelick