[spclark]

Thickish-skinned newbie here.

Got an itch to build frame for something (not life-supporting) out of 3/16" 6061 angle.

Done some stick maybe 50 years ago, oxy-fuel a little after that, otherwise nothin'. Acquired a Forney #322 140MP last fall, added #85653 spool gun, 130 cu ft 100% Argon, pound of 0.030" 4043, gloves, AD mask, apron, MIG pliers, respirator, fire extinguisher...

Standing now at foot of learning curve, trying to grasp what I ought to be doing differently to avoid what I'm seeing in first attempts; too much heat? Too fast feed?

Know I need to practice, but practice w/o knowing what to change is wasteful of both material and time.

Al-1,2,3.jpg (72.46 KiB) Viewed 953 times

Comments, suggestions welcomed.

[MinnesotaDave]

Opinion, 140 amps is very small for the thickness you want to weld.

Aluminum mig is a spray arc transfer.
Adjust until you hear the fine humming of spray instead of the crackle of short circuit transfer.

Short one minute video:

https://m.youtube.com/watch?v=IHkbh0oKv_g

[spclark]

OK so no 'bacon-frying' sound, it's a hiss I want to aim for.

Amperage needed isn't so much for penetration but to generate spray so penetration comes from the resulting heat once spray's deposited?

Stick-out ought to be more than what I'd been using? Initial trials were @ ~ 3/8".

Good thing it's the weekend.

[tweake]

i just got my spool gun up and running yesterday.

imho the metal is to thick for that machine. you might sneak it in with a bit of a pre heat.
however you will be hitting the duty cycle of the machine.

the pics show cold welds. i suspect you need to increase the voltage and possibly the wire speed.
i have 180 amp mig and i'm almost maxing out the wire feed speed with 0.030 wire on 1/8" material.

you have aluminum mig tips? if not go up a couple of sizes and make sure you have heaps, you will chew through a lot of tips.

[spclark]

imho the metal is too thick for that machine. you might sneak it in with a bit of a pre heat.

Wondered about the pre-heat stuff. Have propane torch handy, could use that. Risking contamination?

however you will be hitting the duty cycle of the machine.

No big deal. Joints I'm doing are no longer than maybe 2-1/2" / 30cm. Not production stuff.

the pics show cold welds. i suspect you need to increase the voltage and possibly the wire speed.
i have 180 amp mig and i'm almost maxing out the wire feed speed with 0.030 wire on 1/8" material.

And here I was thinking I was using too much heat, too fast feed? Burned through one corner in first attempt in fact.
If I slowed down, would things have improved any? With that burn-thru I thought I had to move faster, get in then out before metal fell apart.

you have aluminum mig tips? if not go up a couple of sizes and make sure you have heaps, you will chew through a lot of tips.

No, just short copper. Wasn't aware there are tips made for Al; these actually made from Al or are they just sized
differently? Copper will work with larger bore, say 0.035" for 0.030" wire? Or should I go even bigger?

Or find tips for Aluminum, which'd work best?

I'm gonna section / etch those joints tomorrow, see what kind of penetration I might have gotten. Good practice anyway, good feedback.

[tweake]

for aluminum you need aluminum rated tips. they are cooper tips, not made from aluminum. typically they have an A after the number ie 0.8A (0.030A). the reason is the aluminum mig wire heats up and expands, it then sticks in the tip and you bird nest the roll of wire. if the A type is not available, then use 2 sizes up. eg for 0.8mm(0.030") aluminum then use 1mm (0.040") tips.

one of the big problems with aluminum is heat soaking the part. if you go to slow the part over heats and you will suddenly blow through.
to reduce over heating of the work you need to keep travel speed fairly high. small parts are the hardest as it will over heat the quickest.
the really good migs have a hot start. so it runs hotter at the start, when the work is cold, then backs of the amps as the work heats up.

[spclark]

Right... recall reading about the oversize bore tips to overcome the expansion aluminum wire will do when heated.

So far I'm using 0.030" 4043 wire in a spool gun, the 0.030" tips seem to be adequate as I'm not doing any long seams. Can source 0.035" locally if need be.

That blow thru I mentioned was on my first attempt. I'm working to build a 12" square frame of 3/16" x 1-1/4" 6061 L stock. Corners are mitered so there's lots of metal adjacent to each seam, with a vertical component in the corners. Probably not the easiest way to get into this craft.

That one pic I posted with the inside corner showing to my eye looks closest to what I see being done by folks more skilled at this than I can claim. I'll be sectioning that tomorrow, I want to see what kind of penetration I got in that weld.

Then practice practice practice.

Maybe I should have bought into an AC-capable TIG machine? Dunno. Budget was good with this Forney 140MP but from what I'm hearing it may be a little bit under-spec for what I want to do.

[tweake]

for short runs standard size will work.
my spool gun is 2nd hand and thats what they had on it. it would work fine for a few inches then jam. with bigger tips no jams so far.
edit: when it jams it bird-nests, but also can burn back to the tip and toast that.

you have jumped in the deep end thats for sure.

[cj737]

Too long of a CWD will also cause crappy, cold welds and blow through. A Push angle for ally MIG works better when possible.

Whatever the highest settings are on your box, use those for 3/16” ally. You’re short already on volts and amps with that box. A few hot tacks can help put some heat into your part before running a bead. A preheat with propane won’t contaminate anything, but scrub the part with a stainless brush immediately afterwards to clean and break up the oxide layer.

[spclark]

Suggestions all welcome, thanks!

Taking it seriously, I’ve downsized my project’s specs to fit better with equipment capability.

I tend to overbuild stuff so picked 3/16” L-stock at the get-go, before deciding I wanted to weld it up rather than bolt it together. Solid reasons to re-spec for 1/8” wall, still 1-1/4” wide L 6061. Should be plenty strong enough with maybe more cross-bracing than I’d planned for.