Advice from self taught welders?

Hey All,

  I am trying to learn using flux core and a harbor freight welder.  All I want to do is stitch weld sheet metal on cars.  I am having a miserable time.  One minute I think it's good and the next I am burning through.  I am practicing on metal I picked out of an autobody dumpster.  

  I've been told  by a  couple of self taught people that flux core is harder to learn?  Is the harbor freight wire junk as well?  I'm looking at videos of course.  Chris fix just did a video that made it look easy to stich weld, but he was using a cheap gas set up.

What say you?

Doc

"They Say" that the HF wire is not as good as the name brand wires from welding supply stores.  Just keep practicing. If you can, put one of the copper HF spoon thingies behind it and it won't tend to burn through.

You can also use the NOHOME method of a series of tack welds.

I work with 4 auto body guys. They are replacing sheet metal 5 days a week 8 hours a day. I am not sure I have ever seen any of them run a bead. All they do is overlap tacks.  

Trev's Blog is a great resource

Welding thin sheet metal with fluxcore (especially HorribleFright flux wire in a HorribleFright welder) is a complete PITA if not impossible.  If you absolutely cannot find a gas mig welder to use, then see if you can make some copper or aluminum backing strips to put up against the back of whatever sheet metal you are welding.  They work as both a heat sink to pull heat out of the weld bead, and as a backer to hold the liquid metal in place to prevent it from falling out.  

fluxcore sucks for thin stuff.  It's a bit hotter, and the difference between a penetrated spot weld and gaping hole is nearly impossible to control.

I am terrible with sheet metal.  I can smack the heat to 1/4" plate and build a great hitch, or patch a hole in a frame, but sheet metal is not one of my strong points.

It is harder to weld sheet metal with fluxcore wire, but far from impossible. 

Unless you are using a live wire fluxcore machine. Those are the ones where the welding wire is always "hot" even if you aren't pulling the trigger. Those are the cheapest of the cheap fluxcore welders and they are absolutely useless for thin stuff.

If you have inconsistent results, make sure you don't have inconsistent conditions. Make sure the wire stick out, the gap between the panels and the cleanliness of the panels are all consistent.

And yeah, use NOHOME's method. It works great. No one runs a bead on sheet metal unless you LOVE working with Bondo.

Sorry, NOHOME's method?  I will google.  It sounds like I should look for a gas set up.  I am at the point where I am going to rivet sheet metal to this car.  If I do it in a decorative way, it will at least be better than rust.

Thanks guys, I will keep going, change the wire and look for a gas welder.

 NOHOME, I googled it, he is on here.  I thought that sounded familiar!  Thanks for having my back!

OK, disclaimer time.

I have never welded with a flux core welder. Since I had heard the same story about flux core not being good for thin sheet, I actually worked up a theory about why it would not work.

Then Mr Crackers came along and blew a big huge hole in my theory by essentially doing a body swap with a flux core. I had to stuff a crow in to a hat and make a crow sandwich.  So, it is possible.  He makes it look easy.

https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/uncle-ben-rambler-american-wagon-lexus-sc300-body-swap/122125/page1/

That said, here is a link to how I do it using a Lincoln 185 Gas shielded MIG welder. Before you even start reading, I will point out the need for clean, bare, grease free metal on both sides of the weld. At least 1" back from the seam.  Makes a huge difference.Average time to teach this method to anyone in attendace in the shop is under half an hour if I set up the welder for them a full hour if we include welder set-up..

https://grassrootsmotorsports.com/forum/grm/mig-welding-where-to-begin/130571/page1/#post2322241

Do check that the polarity on your welder is correct as it is the opposite of gas shielding.

https://makemoneywelding.com/how-to-set-your-mig-welding-polarity-settings/

I went down the same path as you- taught myself on a HF 170a welder with HF flux core wire.  It was hard to get an acceptable result on anything, but sheet metal in particular was almost impossible.  The inability to control current/heat, the bad grounding clamp and the cheap wire just made a splattery mess out of everything.  I thought maybe I was just too stupid or too clumsy to weld.

The HF welders are convertible to MIG.  I went to PraxAir, got a small tank of MIG gas and a couple spools of good 0.030 wire.  Ordered a gas regulator off of Amazon for like $20.  Ordered a Lincoln Electric grounding clamp.  First time I tried with this new setup, I was laying neat, clean beads.  I still wish I had variable current control, but I can lay down an acceptable weld on just about anything steel now.

But the single biggest improvement I made was getting a better welding helmet.  The HF auto-darkening helmets are trash, you can't see the weld pool at all and your eyes still get flashed.  The same Praxair sold me a Lincoln branded helmet that's made by Viking for around $100.  Again, night and day difference.

I just welded in floors today with the $89 harbor freight welder. Hell, i restored a rusty 64 el camino with it!

My method: Lincoln .030 flux wire and tip. Clean all connectors in the machine before using it the first time. Make sure the ground wire is tight in the clamp (mine wasn't). 

My machine setting today was min power, 3-4 wire speed. On this cheap machine,  the rocker is huge adjustment in heat, the speed knob is the fine heat/feed control. Higher the speed, more heat.

I then do nohome overlapping tacks. Every inch or two hit it with the wire brush to clean the E36 M3 off. Repeat until finished. 

I did all the sheet metal on my FB with a flux machine. It's doable, it just takes patience. As said above, you aren't going to be running a bead. It's just a endless series of tacks. I usually start about an inch apart tacking the fill piece in and then go back and fill in between the dots with more dots. 

I have a gas machine now. I still run a endless series of tacks because it reduces panel warp and reduces the chance of blow through. 

Don't wear sandals.

earlybroncoguy1 said:

Don't wear sandals.

Flip flops work much better. You can at least kick them off when the slag starts burning the bottom of your foot. 

BTDT

I "learned to weld" using an HF flux core welder (which i still own and still works 11 years later). Honestly, what's probably the most helpful to understanding welding is understanding some basic electrical concepts and basic physics. Easy to say, incredibly tedious to explain. Just remember that you are completing an electrical circuit with the weld arc and the amount of amps (heat) that flows through that circuit is dictated by the resistance (at least, that's the only factor you can control). So for example if you place your ground lead far away and then weld closer and closer to it the weld will get hotter and hotter as you get closer. Fancy welders have fancy controls but an HF welder has a hi/lo switch. If you need resolution within that range you can get it by moving the ground around. I've even added a set of jumper cables between the ground lead and the work piece to add resistance and drop current for some little bracket i welded. A lot of the rest of it has to do with your hands. The angle and distance (stickout)  from the welding tip to the puddle have a big influence on what the puddle does. 

And yes, in my experience switching to 'name brand' flux core wire had a HUGE effect on the ease of doing decent welds!! I'd drop the HF wire asap unless it's improved in the past decade (haven't bought any since that first realization).

I dont know if the cheap HF flux core wire is still like this, but on my ~2009 model the mig wire was always hot and the trigger just controlled the wire feed motor. My welder has been rewired with a contacter (basically a relay) to make the wire only hot when you pull the trigger as god intended. Again, basic electrical knowledge comes in handy there although i think there are lots of threads about it on the internet.

Trying to learn how to weld with a FCAW on discarded automotive sheet metal sounds like a miserable time. 

Honestly, deliberately burn holes with a low wire speed until you learn how long it takes to burn through. Then stop short of burning through. Then adjust feed speed until you get a good bead profile. 

Butt welding a gap will take a little more wire speed, or lower amps with longer trigger time to help get the base metal up to temp a little slower. Just be aware the longer you pull the trigger, the more heat you put in the part, and the more distortion you'll get. But sometimes that's really your only option with FCAW. Poor prep, or contamination will require the puddle to stay wet longer and add filler wire to get the junk to boil out. 

Speaking of which, make sure your panels aren't galvanized. Lots of (or most) newer cars are galvanized. In addition to being deadly, the galvanizing will boil and off gas blowing all of your molten metal out of the puddle. With sheet metal it will act like burning holes even if your welder is set up properly. 

In reply to Vigo (Forum Supporter) :

I've experimented with the new HF Vulcan flux core. Check where it's made on the label, the stuff from Italy is the better of the two. I can't tell much difference between it and the Lincoln wire I usually use. I've also only used about 10lbs of wire total, so still learning.

I've got the 240v hf welder, central machinery black box. Still haven't hooked the gas up to it, but it's made everything I've tried to stick together stick together. 

I'd be reluctant to learn it on sheet metal. 1/8"bar stock was what I used to learn with, and that was a bumpy road in the beginning. Turns out just because a weld is "pretty" doesn't mean it's properly penetrated or very strong. 

I have never used a HF welder, so I can't speak to that, but I have used flux and mig on different things. I think you are probably trying to learn the most difficult way possible. I used flux when building a cage for my trail jeep. The tube was around 1/8" wall, maybe a little less, I can't really remember. It worked great, had good penetration and good beads, but it is splattery. I used mig when I did the sheetmetal work on my mustang. I think for trying to learn to weld you should get thicker material to practice on. It is a lot easier to get good at and then when you can consistently make a good weld then try sheetmetal. The problem with flux welding sheetmetal is that flux wire makes slag. It's incredibly difficult to run a continuous bead on thin sheet, that's why everyone does the stitch (a line of tack) welds. When you are doing this each tack has to stick to three pieces, your two pieces of metal, plus the last tack in the line. With flux wire your last tack has slag on it, and your next weld wont stick to slag, just lay on top of it. So for it to work, you need to clean the slag off of every tack. That isn't a big deal if your going to do a small rust repair once in a while, but it will suck big time if you are installing two full floorplans in a car that need around twelve linear feet of weld each. 

I like flux welding for some things. I like to weld outside when possible because the lighting is better and it gets me away from any fire hazards in the garage. Since flux welding uses no shielding gas its unaffected by wind and can be done outside on windy days.

For learning there is a youtube channel called weld.com, it is very educational and each video feels like sitting through a class in a welding course. They teach the hows and whys and help to understand what is actually going on when a weld is being made. I very much recommend them if you want to learn.

Toyman01 (Forum Supporter) said:

earlybroncoguy1 said:

Don't wear sandals.

Flip flops work much better. You can at least kick them off when the slag starts burning the bottom of your foot. 

BTDT

I was welding a couple of weeks ago and a drop of slag fell in my shoe. It wasn't bad until it started my sox on fire and that's what really burned me.

It's all better now but it happened while using my TIG and not MIG which is the more common occurance.

What about removing the flux after you weld  so that you can get a good paint job , 

I am not sure about steel , but when gas welding aluminum with flux , you really need to clean out the left over flux or it bleeds thru the paint.......

californiamilleghia said:

What about removing the flux after you weld  so that you can get a good paint job , 

I am not sure about steel , but when gas welding aluminum with flux , you really need to clean out the left over flux or it bleeds thru the paint.......

Really not a problem as the flux comes off easily mechanically (wire brush/sandpaper etc) unless you have pits/porosity with flux in them. Aluminum gas welding flux on the other hand is actually corrosive and leaves a fluid residue that needs fluid removal. 

Crackers said:

Speaking of which, make sure your panels aren't galvanized. Lots of (or most) newer cars are galvanized. In addition to being deadly, the galvanizing will boil and off gas blowing all of your molten metal out of the puddle. With sheet metal it will act like burning holes even if your welder is set up properly. 

So how to handle newer galvanized body panels?  Wire wheel it off (whilst wearing a respirator obv)? 

In reply to Toyman01 (Forum Supporter) :

The last time I did that my flip flop looked like a Frisbee going across the garage. 

gearheadmb said:

. The problem with flux welding sheetmetal is that flux wire makes slag. It's incredibly difficult to run a continuous bead on thin sheet, that's why everyone does the stitch (a line of tack) welds. When you are doing this each tack has to stick to three pieces, your two pieces of metal, plus the last tack in the line. With flux wire your last tack has slag on it, and your next weld wont stick to slag, just lay on top of it. So for it to work, you need to clean the slag off of every tack. That isn't a big deal if your going to do a small rust repair once in a while, but it will suck big time if you are installing two full floorplans in a car that need around twelve linear feet of weld each. 

 

F

That was the line of reasoning that I had compiled in my head for why flux core was not ideal for tin. Then Crackers proved me wrong so I guess something in the above argument is not correct.

I suppose if doing a long weld seam you could do a tack, skip to the next and then clean off the slag from the sum of tacks and repeat, at least you would be doing more than one tack per cleaning session.

The other approach I considered was to reverse the workflow a bit. Rather than laying the next tack on the side of the last one, start a bit off to the side at a slag-free location, and do a slight move towards the last tack. The approaching heat might boil off the slag and allow the newly deposited metal to wet into the previous tack. Just a thought.