TIG or MIG aluminum gun

[greenblaze]

My, New to me, Miller 200 MIG is working fine now. I still have the option to buy an older Airco TIG machine, it's a late 60's- early 70's model. It's complete with cart and all else. The asking price is $925. OR would I be just as well off to buy the aluminum gun for my 200? I'm mainly going to be working with tube chassis out of D.O.M and aluminum body panels inside and out. I would like to do some Chrome Moly in the future. I've noticed alot of guys use their MIG with the right wire for this job.
Thanks for any information.
Steve

[kwrangln]

If your only going to be doing Al body pannels, then get the tig. I have both in my shop and use the tig for thin stuff, only use the spoolgun for stuff 1/4" or more.

[woody99]

With only 200 amps I don't think you will be able to weld that thick of material. It takes a lot more amperage than steel. It all depends on how thick of material you think you will be welding in the future.

[Merc69]

I have used a spool gun on .035 aluminum and welded a pile of projects.

Welding aluminum takes practice because you don't have the puddle change like welding steel. With a little practice I do not see why you could not weld your panels with a spool gun.

If you do the Tig route remember you have to have A/C to weld alum. Also understand there have been a lot of major improvements in Technology since a 60's to early 70's Tig unit was used.

[moto261]

when welding Chrome Moly you should use tig :D



:massey:

[DavidVanVorous]

When doing Alum with TIG up to 1/8" only takes about 90A cold and roughly 120-150 for 1/4. I prefer doing thick section using a preheat approach cuz it takes more A for alum due to its thermal conductivity. Preheat also yield a bit better thermal control and less warpage if done right.

The other aspect to watch is the duty cycle on the welder for continuous welding. Typically the cycle is lower on the older units yielding less than 50% of max for continuous duty.

D.

[BumpyDodge]

I'd vote for the TIG....unless you want to get into the aluminum boat building business, or repair flatbed trailers.

[desertoy]

when welding Chrome Moly you should use tig :D



:massey:


Why??

[blk87K5]

Why??

The tensile strength of the material you are welding is greater than the wire you are welding with. Theoretically, your weld would be weaker than the tubing. Reality is that MIG welding chromo is fine for what we do. MANY chassis are chromo, but only a few are Tig'ed; havent seen many welds fail yet.

Im sure you know most all of this...

[DavidVanVorous]

Why??

Off the cuff? Smaller heat affected zone, lower current, better fusion and smaller/cleaner beads proportionally... :D

D.

[desertCJ]

IMO MIG welding chrome molly with mild steel filler is actually better if we're talking about a chassis. The weld is less likely to crack and since there isn't any practical way to heat treat or stress relieve a chrome molly chassis...I just don't see the point in TIGing it with chrome molly filler rod.

[jasonmt]

The tensile strength of the material you are welding is greater than the wire you are welding with. Theoretically, your weld would be weaker than the tubing. Reality is that MIG welding chromo is fine for what we do. MANY chassis are chromo, but only a few are Tig'ed; havent seen many welds fail yet.

Im sure you know most all of this...

As GMAW and GTAW fillers are identical except for diameter and packaging basing any argument on filler choice is fallacious at best.

Theoretically a weld made on 4130 with a 70 series hardwire will have lower tensile and yield strengths but have the advantage of improved elongation behavior. As well any loss of strength in the weld area can be compensated for by the use of gussets and nodes to ensure that this reduction is compensated for. This would be true when using either GTAW or any of the GMAW processes.

As well there are a wide variety of low alloy filler materials available that have chemical and mechanical properties that are a close match for 4130 etc. such as AWS ER80S-D2 / ER90S-D2 filler material that is generally preferred for use on this material.

[greenblaze]

Thanks for all of the replies. I did go with the TIG machine. It came out of a college, the Music and Arts Dept. It looks like new. I am having to do a little reburbish work on the water tank as it was a bit corroded. I'm trying the NAPA product, Kreem. Hopefully it will be ready soon. I have gotten to weld with the stick in DC mode, and as others have said, these older machines almost start to easy. I do have to familiarize myself with all of the controls still. I'll post pictures when I can.
Thanks again.
Steve