What welder shall I buy

[fannanxx]

I am planning to buy a welding machine to use it for light work. I am building a house with lots of steel works so I will be welding bearing plates of 5/8" and 3/4" to square tubes and wide flang beams. I will also use it to manufacture my own steel connectors for roofing and other structural connections.

Suggestions about reasonably priced machine are appreciated.

 

[Metalguy]

If you're welding outside and wind-shielding isn't practical, buy a good DC stick welder. You will need stick if you cannot/don't want to remove paint and rust (use 6010 electrodes, esp. if the steel is very rusty/dirty). For fairly clean welding, either 6013 or 7014 will work well on thinner steel.

If you're welding clean steel inside or are well wind-shielded, buy a good MIG welder and use CO2 gas. Get a good size 220 volt machine--Esab, Miller, Lincoln or Hobart.

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[ornerynorsk]

First of all, 5/8 and 3/4 plate are not "light welding" unless you're in a shipyard. As Metalguy mentioned, SMAW might be the best way to go. I personally like 7018 rods for "general" work, but then I take the time to clean off most of the crud before welding. 6011's and 6013's are what farmers use to patch their junk together to make it through one more season, but if your material is A36 and the like, it's a moot point.

Do you have a local shop that could do submerged arc for your steelwork? That's really the way to go. Then you have to decide if weld in place is more convenient than fabricate offsite.

 

[vesselfab]

submerged arc is hard by hand. wire is stiff and pushes the gun away.

if you are a pretty good welder, flux-core is easier and cleaner.

kobelco dwa-50 wire 0.045 or 0.065" diamer weld has good deposition rate and is fine for structural work.

stick is good but has lots of buckshot and harder to clean, but does weld through the light rust. E7018 is good rod but is less forgiving than 6011.

stay away from the home toy wire machines. not enough duty cycle if you are going to "get after it" and lay metal down

 

[racookpe1978]

I don't weld anything thicker than 1/2" for my wrought iron work, so your thick plates are a bit past my experience personally. (At work ... well that's a different story. But at work, the professional welders are doing their thing, and I'm only QA and safety and paperwork and job orders and work permits and fire permits ...))

For my uses, a 240 volt Miller or Hobart MIG with CO2-Ar mixed gas is perfect: Very good penetration at the higher power settings, dialed down to a "1" setting I can join thin gage sheet metal or gratings. Almost nothing to clean up (no BB's and no slag) and you can weld indoors (garage or basement) with little issues other than a fan or filter. My steel is usually "new" - I prime and paint afterwords, so there is no rust issues with any type rod.

Outdoors? With a cardboard or wood shield, I've not had problems with the MIG.

I do have a Miller "little blue box" that is TIG and stick (SMAW) capable, and have used both successfully. MIG is faster than either, and I feel I have the best control and best looking welds with the MIG.

Stick cannot be beat when I'm up a ladder or on scaffolding though: Just a single cable to pull up (instead of the whole machine plus the gas bottle and gas line extension) and you use stick one-handed if access is poor or you're working overhead. Durty, smoky, flame-producing, lacks of spatter and lots of slag to chip off. Start & stop opertioon as you change weld rods slows stick down.

if you have a real small SMAW machine, you still can't get good penetration; so get to a weld shop - NOT a Sears, Home Depot, Lowes, or Ace Hardware. NOT a "Orchard Supply Hardware", or cheap import place.

 

[CRG]

Take a few classes at from the local community college, welding school, supplier, etc and learn the basics of Ox/Act cutting, plasma cutting, SMAW and GMAW. Decide if you will ever want to use GMAW spay transfer or just short circuit. Try out some different machines at welding supply houses. After which, you should have a good idea of what you want.

 

[mfgenggear]

fannanxx

besides all of the very very good suggestions

I would prefer a stick welder for the 1/2" & thicker.
more hassle than MIG but easier for me for penetration.

make sure to clean & prep your edges.
do some practice test welds & then do destruct test
to validate your welds.

being it's bearing loads.

 

[racookpe1978]

By the way, when I teach a brand new welder, I start with a 3 inch wide x 1/8 or 1/4 thick piece of waste steel bar.

then have him (her) print their name with the weld rod (or MIG stick), then go to their signature with the weld rod/MIG gun.

Then, when they're confident with controlling the flame/arc/sparks/light/welding helmet/etc, then I have them begin with a butt-weld of that same piece of plate, then (later) go to fillet welding. Seems to work for them.

 

[fannanxx]

Thanks for very well advise.

 

[rmw]

RACook,

When do you have them (him/her) get under the work and do it overhead (with the buckshot going down the collar?

rmw

 

[racookpe1978]

Day (or night) 3.

First, ya gotta convince them this is a "cool" and "neat" thing to be doing. 8<)

THEN, ya discourage them with the pain and agony. (Been there, done that, burned the ugly green jacket.)

 

[lawayosh]

House? What does your local Building Department have to say about it? Where? In the U.S. structural welding is (and should be) pretty tightly regulated by building and welding codes, AWS D1.1 for example, and usually requires welders to be qualified by testing with inspection of fabrication by an AWS certified or governmental agency licensed welding inspector.

Even with this, the Los Angeles and San Francisco earthquakes caused plenty of damage to steel structures.

Yosh