Decisions, Decisions!!!

[fun4now]

dvi

here is a link to the dvi about $400 more than the mm175


http://www.andale.com/store?sid=1773...=&parentCatId=


good luck

if you chose to buy on line i have bought from this site twice and been real happy with service and speed 2-3days and he took my CC# and order over the phone so i didnt have to put it on the computer

[Alex]

Gordo,
Don't know much about the DVI's (other than what I've read here) but I've heard nothing but good things about the MM175's.

Brad-man,
Build the Challenger, there's already too many Mustangs out there and those guys up in Dallas are buyin' up what's left to build "Ellenores". I'm not a Dodge dude but the Challengers have always intrigued me.

Be cool,
Alex

also a 50 year-old bad back weldor (too many motorcycle and oil field accidents).

[Andy249]

Another long post!

Gordo,

You are dead on with your interpretation of the warping factor, the more the heat hangs around the more warping you will get. You can limit this kind of thing with strongbacks (tacked on stiffeners that are removed after the project has cooled) but you will find that pent up stresses will be there regardless, even if strongbacks aren't used you will find that there is some locked up residual stress anyway. Not that this really matters when it comes to sheet metal or panel work on a car anyway!! We aren't talking about needing the same structural integrity as a bridge! Welding is much of a what you can get away with game as much as it is for decent weld appearance and integrity. Forget about getting 100% perfect welds all the time, fact is you are allowed different weld defects in different amounts no matter how critical the job is!!

To make a blanket statement that one welding process creates a smaller heat affected zone than another is pretty narrow minded in my opinion. Fact is every weld zone has a HAZ and the only way to eliminate it is through post heat treatment through normalisation after the job is completed! There are so many variables such as gas type, electrode polarity, travel speed and welder competency that has an affect on all aspects of weld integrity.

Welding differing thicknesses is really about being smart about where you direct your heat, obviously to get sufficient fusion to the thicker material you will run at an elevated amperage compared to that of what you would normally run on the thinner material. I aim the heat at the thicker section and watch the edges of the puddle to ensure I am wetting across to the thinner material.

Don't forget about what sort of finish you are applying to your weld after it is made, why spend the time with a TIG (unless your application specifically calls for it) making a nice bead if all you are going to do is rip it off with a grinder afterwards? In this case, run a quick bead with the MIG, grind it and keep progressing with the job!

In my case I purchased my MIG first, it is quicker to fab with (thereby keeping you progressing along nicely), and more forgiving with joint preparation and cleanliness. Next up I purchased the pulsed TIG (absolutely AWESOME feature) and when I get a little more dosh the plasma may be the go.

[fun4now]

plasma is a bit much

plasma cutters wile verry nice and comming way down in price they realy are a bit much for a car restoration.although i will no dought use mine when i start to restore my 51 chev i would not have bought a plasma cutter to do it i got mine to do artsy fartsy stuff with, the kind of cut's you cant make ant other way with any speed or reepetability. if you do dicide to get a plasma cutter for body pannels the lil spec125C would do great for that i use mine on 14 and 16 gage all the time with great results (see atached pic) only complaint i have is the price of the consumables. it runs on 110V and has its own compressor so it is supper portable just bring an extention cord and you can go anywhere

[Alex]

Hey Andy249,
I hope that crack about the HAZ wasn't pointed at me. Like I said "I'm sure anyone who has done tig welding will tell you that the Heat Affected Zone (HAZ) will always be smaller (compared to GMAW) when using the GTAW process." I, personally, have never done any tig welding. When I'm concerned about warping, I'll throw down a few tacks, have a brew, throw down a few tacks, have a brew. Well, you get the idea.

Be cool,
Alex

[fun4now]

Alex

When I'm concerned about warping, I'll throw down a few tacks, have a brew, throw down a few tacks, have a brew. Well, you get the idea.

sounds like i fine way to avoid haz.

[Brad-Man]

Just to reiterate - MIG is only for thick aluminum, which I don't think is any part of car restoration - more like utility boxes for trucks and even chassis for trailers. For sheet aluminum < 3/8ths you will need TIG, which is why I wouldn't go the 210, unless you will have a need for > 1/4" one pass welding on steel.

[Blown S-10]

MIG is only for thick aluminum, For sheet aluminum < 3/8ths you will need TIG

incorrect. i have successfully welded .125 6061 with my humble mig, but it was somewhat difficult. i'm sure a larger machine would make easy work of it.

[Alex]

1/8 inch aluminum

I, too, have welded 0.125" 6061-T4 successfully (fillets and flat) with 4043 wire. I didn't think it was that big a deal.

Alex

[Brad-Man]

OK, I believe ya'll!

Every source I've been at/read says that for intakes and such, TIG is the key though.

As with anything else in welding, experience will tell.

I'm lucky that I have a friend that has an SD180 he just got. He has an '82 ZXT and I have an '83!

[Blown S-10]

Every source I've been at/read saiys that for intakes and such, TIG is the key though.

i guess mig could be used for an intake, but i wouldn't try it. it would look pretty ugly, wouldn't want that on my truck. so yes, tig is where its at for most stuff that needs to look good. but mig would befine on some things.

when i go to wallmart. they have aluminum carts there for the employees to use. these carts are mig welded, about 1" square tube. and the welds are just fine for this, tig would take to long.

[dyn88]

ever try to make a water tight start stop with mig, steel ar aluminum, ti is the only way to go for critical fabrications.

[Andy249]

Alex,

Crack about the HAZ?! You weren't trying to be punny were you?

Well I've done a heap of research on the subject and I think I could safely say that GTAW as a whole does NOT have a smaller HAZ than GMAW. For steel and stainless steel GTAW for instance, nine times out of ten you are running DC electrode negative, therefore 2/3rds of the heat is in the job compared to MIG welding which is typically done with DC electrode positive which means that 2/3rds of the heat generated is at the tip of the electrode. The less heat the material has to absorb, the smaller your HAZ will be.

Although an ultra sharp GTAW electrode can get to some pretty low amperages and allow you to weld very thin sheet, you have still elevated the temperature of the steel at the arc to above its melting point. Wherever this happens you will always get a HAZ. Oxy cutting and plasma cutting also leave a HAZ, which depending on the application that the material is going into, may need to be removed to prevent premature cracking later on down the track. The HAZ is actually parent metal that has undergone grain growth because of the temperature it has been elevated to during the weld process. Cracking may or may not occur depending on the alloy composition, how quick the quench was after the heat was removed etc. (remember, the quench effect may have been achieved by the cooler material around the joint acting as a heat sink and sapping the heat away quickly!)

The size of the HAZ is directly influenced by the total heat input in the welded area. Like I said in my last post, polarity, travel speed, welder competency, gas type, flux type, amperage etc. etc. all have an affect on how great or small the HAZ will be, remembering though, the HAZ is only one part of the weld that may or may not have an affect on the weld integrity.

MIG can be used to weld ally that is below 3/8" thick, but it won't do it well. Ideally all aluminium welding should be done in spray transfer to ensure decent wetting of the weld toes and good penetration. This is where pulsed MIG is excellent, it enables spray transfer, but doesn't overheat the job because of the funky switching to the lower background current.

I use TIG on all of my fuel and water tanks for the fact that most of it is corner to corner work so TIG definately has a place in my workshop. MIG is so much quicker though when it comes to fabrication, and the appearance isn't to bad either! Horses for courses guys, that is what it comes down to!

[Gordo]

Decision Update

Well, I did it! I just ordered:

- A MM210
- Protective cover/bag
- Miller Big Window Elite - Stars & Stripes
- Tillman 9230 welding jacket
- 10 extra tips of .030 and .023

$1,500 delivered from IOC. I really wanted to buy locally, but the prices just weren't even in the same ballpark... and then the taxes on top of it. Oh well, I'll pickup the cylinder, gas and wire local.


Two more quick questions though:

1) I've been told that .023 non-flux wire works well for auto-body (quarters and such). What do I need (in terms of parts) to use .023 wire in a MM210? I picked up the .023 tips, but do I need different liners, a different drive roll, etc?

2) What would be the best sheilding gas for the bodywork? Standard 98/2 Argon/O?

--Thanks

[Brad-Man]

At a minimum a drive roll. You can probably do w/o a different liner, but they're only ~$20 so why not?

You will need C25 for sheet metal, and any chassis welding you do.