I have both, a 120v Lincoln SP125 MIG with gas, and a 240vLincoln 200 power MIG. The 120v machine is rated for 3/16 steel, but there's no way I would ever weld anything more than 3/32 with it.
Having said that, under "ideal" conditions like welding on a corner, then I would trust it because I've been welding for many years and you can tell when you get good penetration by the shape and look of the weld bead. The problem that happens with these small machines, is that inexperienced welders will go out and buy these and think they can build bridges with it. Flux cored machines IMO are not worth the box they came in.
My 200 amp machine does everything I need it to do, but it has it's limitations I would trust it up to 5/16" steel but that's about it. Anything thicker, then stick welding is the way to go because it will have the best penetration. I also have a Hobart 250 TIG machine with stick capabilities, but I haven't burned one stick in the past 15 years.
If I could only own one welding machine, I would choose a 240v MIG around 250amp with the highest duty cycle.

"I made a comment that a 120v machine, which is typically in the 125 amp range is meant for sheet metal by both amperage and duty cycle. Can it be used for thicker materials? As someone mentioned, yes it is possible if you know how. Preheat is fine, but if you don't understand joint prep, welding technique and machine settings, you are not getting a good weld. A 9 second car built with a 120v/125 amp MIG is not one I'd want to take a pass in thank you. Not unless I've built it myself, and I've spent many many hours behind 120v to 575v machines.  If I'm going to build a frame for a car with only 120v, it has to be TIG. I know the new Miller 120v/140a runs up to 140 amps but that's still on the light side, especially for fillet welds, single pass IMO. 

Besides, why not spend another couple hundred bucks to get the machine you *should* be using? Playing the preheat game will cost you more in the short run and your time...well, I value mine"

 

 

Agree! I have a 90 Amp 110V MIG set up with .023 wire for the light duty sheet metal stuff and a 185 Amp 220V Miller set up with a heavy duty Hobart gun with .035 wire for the big stuff. I also have two arc welders that don't get much use, a cheap Eastwood TIG, and even a vintage spot weld machine, along with the 'oldest school' oxy/acetylene torches which I occasionally use for brazing cast iron manifolds - Mostly heating stubborn fasteners. The right machine for the right job!

My buddy that built the 9 sec race car with a 110 MIG, raced that car for many years with no frame/structural issues. The car left hard and straight probably thousands of times, just proving he knew what he was doing. I wouldn't, but he did! I was over at his shop a few times while he was building it and it was painful to watch how slow the process went, waiting for the small machine to catch it's breath. I offered up my 220V Miller to finish it off, but he only had 110V in the shop and didn't want to move the project. Is it ideal? Nope! It sure takes way more patience than I would ever have to offer! Keep in mind, this was all over 20 years ago- his machine was 120 Amp and he had to use the 10% duty cycle at the high setting - lots of down time! One time when I was there, after tacking the 4 link brackets in place, he preheated them at the axle and frame before fully welding them in. I'm not sure if he did everything that way, likely just the most important stuff. I will say that I often witnessed this car leaving at 6000RPM on the transbrake and shifting at 7500 with zero drama.
The Nova was sold years ago to USA and the guy was quite happy with it. He used the Nova cash to get a dragster that was already built when he got it - he only added the Nova's drivetrain. His daughter is licenced to race it as of 2013 and will take over the driving duties this up coming season!

-- Edited by Fordy Acres Car Farm on Wednesday 15th of January 2014 10:50:21 AM

For the purposes of testing out your machine, it will be just fine.

my question to you is whats wrong with good old fashioned gas welding with good steel wire
everything you read is tig this, tig tha,t - whatever did we do before tig torches
I cant tig weld worth a dam, but I sure can gas weld

 

I have a good miller stick machine that hasn't been turned on in years, a 180 SD mig, and gas torches - sold my 250 miller tig machine cuz you cant weld with it standin on your head, under a truck

-- Edited by Seeker1056 on Friday 17th of January 2014 08:29:30 PM

really - you can run a foot pedal while standing on your head?

That's part of the problem,  you are only watching.

Seeker1056 wrote:

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really - you can run a foot pedal while standing on your head?

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 Uh, no ! Thumb throttle.... 

Lightspeed Mike wrote:

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If you want to feel really bad about your welds or be inspired to try better click here.

 

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 Damn you Mike !! Just when I thought I had a nice bead, ya gotta post this link !! Geeezz...

el toro wrote:

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Some Purdy tigger stuff rite thar. Talkin' about gas welding we built a mess of bike trailers out of exhaust tubing back in the 70s and everyone at the King St. garage became an expert by the time they were done. Coat hangers for welding rod.

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 We all did, 40 friggin years ago!! Heck, that's all we had !! Today however TIG welders have become cheap enough that the average Joe can afford it, and will give you 10X the quality of coat hangers. 

Its becoming a lost art. There's still instances where it cant be beat. Braze welding for example. I know guys who give up if it cant be tigged, migged or stick welded...come one guys, its not beneath you.

Aircraft restoration guys still gas weld tubing. Don't have an AC TIG to weld aluminum? Do it the old school way with gas, filler rod and paste flux.

toomuchjunk wrote:

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Gearhead wrote:

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Its becoming a lost art. There's still instances where it cant be beat. Braze welding for example. I know guys who give up if it cant be tigged, migged or stick welded...come one guys, its not beneath you.

Aircraft restoration guys still gas weld tubing. Don't have an AC TIG to weld aluminum? Do it the old school way with gas, filler rod and paste flux.

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 Anyone remember the process to gas weld aluminum? 

I remember doing it at trade school and after a few hours of practice you could make it look like a pro had welded it.

I do remember using an eraser that had grit in it similar to a eraser for ink. Covering the weld area with carbon first comes to mind also, but maybe that was something else.

 

 

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 The carbon trick if for annealing harder alloys (6061) for bending.

Here's a link to what you need. I've always been a fan of Fournier's books. 

http://www.youtube.com/watch?v=nmXXE2Os8N0

 

Gearhead wrote:

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toomuchjunk wrote:

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Gearhead
thanks for the help and the link.
You could be right on the carbon thing but I don't think I would have been involved in annealing harder alloys.
Wow it's annoying when the memory isn't what it used to be.
Thanks again
TMJ

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 my bad, it can make ordinarily soft (3003 series, or utility grade) aluminium even softer for working also. I've only ever done this to keep higher alloys from cracking during a forming process.

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 The carbon trick is just a way to visualize the temperature of the metal. It can be used to know when aluminum is ready to be quenched for annealing, or preheated hot enough to weld. This is also used on steel when preheating before welding. If I recall, the metal will be 550F when the carbon disappears.

-- Edited by hemi43 on Tuesday 21st of January 2014 05:19:59 PM

I still have an exhaust system i did on my old two stoke using coat hanger and body tin.

Heating 6061 then cooling it with water does soften it. I've been bending aluminum this way for years and it does soften it. right or wrong, it works.

It actually isn't Flux core MIG, even though that's a common name used by most including me - It's actually called FCAW (careful where you say this acronym). The noxious fumes and slag are likely two of the biggest concerns of the average hobbyist, but for me the excessive smoke generated can actually impair your ability to see the weld pool. Let's face it, it's much dirtier than MIG - just look around your work area after a heavy day of welding. Real MIG is cleaner, but the gas costs money - keep in mind when comparing costs, the flux core wire costs more than solid core.

Here is a positional welding table using a bowling ball as a pivot. I thought it was very creative.

Lightspeed Mike wrote:

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Here is a positional welding table using a bowling ball as a pivot. I thought it was very creative.

 

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 I have also seen bowling balls set on a pipe and rim as a form for metal shaping and dent removal .

Dave Scott: Hey, why does everyone crap on flux core mig welding? To simply say "it's not worth the box it came in" does not explain it's downside. As you can guess, that's what I'm using at the moment.

Slim: For welding in a shop solid wire its cleaner ,produces a nicer looking weld and needs next to no treatment when done. less likely to burn through on thinner material . flux core will work well in the wind and on dirtier material ,More easily portable and is said to give better side wall adhesion. both have their pros and cons but most of us are working indoors in smaller spaces so solid wins Just for the fact that its cleaner and requires less work.


My answer is basically identical to Slims answer as all of my welding is done inside my garage. I don't weld in wind and I meticulously clean ALL material before I weld (this includes "cleaning" brand new steel) to prevent any weld contamination so I don't gain anything by using flux core over using my Mig (although flux core would eliminate the cost of tank rental/gas). Not hating on flux core as it has it's benefits, it's just that none of its benefits, benefit me in my particular situation. I started out with an arc welder. I tried a Mig many years ago and LOVED that I didn't have to chip off any flux or wire brush each weld (like with arc) so I rushed out and bought a Mig, got rid of my arc and have never looked back. To be completely honest, I have zero experience with flux core, I am just assuming there would be a need to chip/wire brush the same as an arc weld.

As for my comment of cleaning "brand new steel" before any welding. The owner of a chassis shop/racecar building business taught me that and I've done it ever since.

Lightspeed Mike wrote:

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Here is a positional welding table using a bowling ball as a pivot. I thought it was very creative.

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 That is brilliant

I was bored so I decided to experiment with the flux core (specifically on body metal) discussion that Dave brought up and share here. I'm working on a '67 Cutlass and the inner trunk lid had some cancer, I also had a "donor" shell that was crap too but had a patch piece I could use which was handy!

 

 

Results and review coming up!!

 

 

Nice work and thanks for the post Reg . Your results are pretty much textbook on the subject . For the most part solid wire is just that much easier for the material and conditions we use them in