TheSamba.com :: View topic - Can I use flux core wire to weld body panels?

Thu Sep 28, 2017 9:29 pm

I'm not trying to convince anyone that what I'm doing is correct, I'm really just trying to understand the proper way of doing it (it's been very confusing trying to teach myself).

At the same time, this is all I currently have so I'm trying to see if I can get away with it. I really appreciate everyone's input. I understand that I need a proper gas MIG with thinner wire.

Thu Sep 28, 2017 11:24 pm

Yes it is a complex subject, with no real in depth places to learn how to do it well. There is a reason though.. sheet metal welding is not just a technical job; it truly takes an artistic understanding, or a designer’s eye.
You learn something new every single job. It’s like teaching crayon drawing or finger painting.. we all start at the basic level but few of us get really good, and even fewer master it.

The best way to learn how to do what you’re asking is actually really simple. Get a MIG welding setup, get a body hammer and dolly set, and spend some time welding sheet metal on junk. It’s not magic or mysterious at all, it’s like romancing your girlfriend... it takes time, patience, finesse, an eye for details.

Once you get your panel welded in, knock down the heavier spots with a 40-60 grit flap wheel on a 4” angle grinder.. don’t get into the base metal though. Once you knocked down the mountains, start working on the hills with a die grinder and 3M roloc dics, smoothing things out. Bump your grit levels up as you go, feeling out what the area needs. Shine a bright light behind your panel and look for pinholes or missed areas, then sharpie mark them and go back over with the welder.

Yes, your panel needs to be absolutely perfect when you finish with the rolocs... ideally if you started with a small uniform gap all the way around before you started welding, and you took your time tacking it in, there won’t be any major issues. Use a hammer and dolly every few tacks if possible; you’re just trying to persuade the metal back out a little to keep its shape and prevent the weld contraction from distorting the area.

Don’t use glass or body filler to compensate for an ugly finish job or poor welding. Ugly welds are usually bad welds. My preference is to spray my panels with a 2k epoxy primer, weld through it where I can, then shoot epoxy over the finished panel followed by a 2k high build primer. The high build is where you start to hide the minor welding imperfections... use Rage Gold body filler if you need it.

I see all the time in the Bay forum, guys will go to town cutting, then realize oh SH** bit off more than I realized! Then it’s followed with popcorn looking spattered welds, distorted metal, and finally a thick layer of body filler. We all started somewhere but it just really sucks to ruin an otherwise salvageable project with costly mistakes.

All that to say just work towards your goal. Once you have the right tools and some practice, you’ll know when you’re ready to jump on something as complex as a body panel.

Sat Sep 30, 2017 5:19 pm

From the image posted here https://i.imgur.com/qHz5TWU.jpg ,it looks like you have the process down. For most people the learning curve is too steep but you have managed it. You have to watch the heated weld zone and not the pool.

After you figure it out. MIG is mostly just faster than 'Flux Core Repeated Spot welds'. The same method is used with both on butted thin sheet metal. You have to grind down the welds on both so mostly the end result is the same.

The only big difference between the two is if you weld upside down , flux spatters a lot (it' does not use (Short Circuit Transfer) so you HAVE to use the proper safety gear like long welders gloves and DO NOT lay directly under the pool but to the side.

If your in doubt you can try to horizontal Flux Core weld on a test piece. I don't notice a difference.

Sun Apr 01, 2018 1:46 pm

Good evening,

First attempt of welding using flux cored wire following many hours practice I believe I have a good Weld

Front

Back

However I seem to have inconsistent penertration in the metal when I'm not blowing holes as you can see

Grinding down has highlighted missing weld

I will try gas welding tomorrow if I get the chance.

Sun Apr 01, 2018 3:30 pm

It looks like the metal is overlapped? I thought butt welding is preferred. Your last picture looks pretty good though!

Sun Apr 01, 2018 5:44 pm

What we really should be looking at ,is images of a series of spot welds ,started from the last spot weld ,done in a row to mimic a bead. The issue with Flux Core welding thin metal is that it welds hotter ,has more arc force ,and the wire is mostly flux and not metal. So its a challenge to start from scratch once. There is no point in repeating it. Do 3 or more spot welds to hold the piece where you want it. Then start your next spot weld on one of the last spot welds and overlap it by 1/3 to 1/4 of the diameter. Do maybe three of these in a row before moving to another area to keep heat down.

The same method is used for MIG but looks better and is a lot faster.

Mon Apr 02, 2018 1:16 pm

They are butt welded close together. I have read that the closer the joint the less chance of blowing through. I will give it another shot when I get chance

Mon Apr 02, 2018 3:51 pm

After coming to grips that overlapping body panels had many disadvantages I was lucky to come across this webpage.

https://www.cartechbooks.com/techtips/mig-butt-welding/

This explains it all.

Fri Apr 06, 2018 2:34 pm

Flux is fine, in fact better in certain circumstances, like if you have to work outside and there is wind.
If you clean off your welds well then you don't have to worry about paint reaction. Ive used flux for years, never had an issue.
In the end both do the same thing, they bond metal together. One is arguably more efficient but it's not like only one works. Both are also primitive technology, we all would be better off bonding panels with modern adhesives, far stronger and don't distort panels.

Sat Jun 20, 2020 3:47 pm

Evil_Fiz wrote: 67ctbug wrote: Mig all the way! So much more control over the job. Try to find a mig 135 from Eastwood, great welder at an affordable price.
If you can wait until Black Friday, you might get lucky and find a promo code on-line for a deep discount on the Eastwood MIG 135. I was able to score one last year (2016) for $199 + free shipping. It is a very nice welder for the hobbyist with infinite adjustability and an included gas regulator.

Adding an update for future readers.

The Eastwood MIG 135 has been performing well but I discovered the hard way that it has a strong limitation in relation to sheet metal welding. The welder does not have the ability to turn off shielding gas post-flow. The gas solenoid remains open for about one second after the trigger is released. When you are doing short half-second tacks you end up using three times as much gas as you would with post-flow turned off. I ended up going through a 40 Lbs. bottle of gas and only used 1/3 of a 2 Lbs. spool of wire.

For the reasons mentioned above I switched to using flux core wire to do my panel repairs. It took me a while to find the right settings. I am welding-in patches made from metal taken from another Ghia (OE metal, same gauge as the metal on my car.) The welds require some clean-up but the money I save is worth it to me. I am not building a show queen so I am not beyond using filler to cover up mistakes and imperfections.

Eastwood MIG 135 Flux core settings for sheet metal:
Wire Speed = 2
Voltage = B - B 1/2 (Mostly on B however)

-----
Emil

Sun Jun 21, 2020 1:09 am

yep that thing is a gas hog, not really a problem tho
Use straight co2 gas instead of fancy argon mix, it's cheap.

Sun Jun 21, 2020 1:30 am

You can also dial back your gas bottle pressure regulator, it won't stop the post weld flow but can reduce the volume used if welding in a still air environment like a closed in workshop

Sun Jun 21, 2020 5:03 am

modok wrote: yep that thing is a gas hog, not really a problem tho
Use straight co2 gas instead of fancy argon mix, it's cheap. Thanks for the tip. Based on what I have read on-line I wasn't sure if straight CO2 was a viable option.

66brm wrote: You can also dial back your gas bottle pressure regulator, it won't stop the post weld flow but can reduce the volume used if welding in a still air environment like a closed in workshop I dialed it back to almost nothing and it is still a "gas hog" as stated above. I am going to open up the welder and see if I can hack it so the solenoid cuts out with the trigger release.

-----
Emil

Mon Jun 22, 2020 5:09 am

Emil,

Wbat about trying another solenoid. My Lincoln 110 MIG was a flux core only but when I looked at the circuit board I saw the connectors there for gas. I ordered a solenoid from someone on Ebay and it was basically plug and play. It worked well. Well enough to get done what I needed. A better welder would have made my life so much easier. Mine was a basic machine.

Mark

Mon Jun 22, 2020 2:55 pm

Canghia wrote: Emil,

Wbat about trying another solenoid. My Lincoln 110 MIG was a flux core only but when I looked at the circuit board I saw the connectors there for gas. I ordered a solenoid from someone on Ebay and it was basically plug and play. It worked well. Well enough to get done what I needed. A better welder would have made my life so much easier. Mine was a basic machine.

Mark I will look into your suggestion. I need to figure out if the delay is built into the solenoid or if it's controlled by the circuitry.

-----
Emil

Tue Jun 23, 2020 10:10 pm

Evil_Fiz wrote: Based on what I have read on-line I wasn't sure if straight CO2 was a viable option.

wow #-o
I generally get my info from the Lincoln welding company.

Sun Jan 10, 2021 9:04 pm

I know this is an older thread but wanted to share this video. Found this video today and was curious what you all thought about what he is saying about flux core.

https://youtu.be/ic7Gwf8y4Yc

Mon Jan 11, 2021 11:46 am

See how he does that, tap and let cool, tap and let cool.

That's the way its done.

You can lay a nice bead like that. 8)

Mon Jan 11, 2021 5:21 pm

finray wrote: I know this is an older thread but wanted to share this video. Found this video today and was curious what you all thought about what he is saying about flux core.

https://youtu.be/ic7Gwf8y4Yc That video makes me both depressed and angry. As I mentioned above I switched to flux due to excessive gas consumption. I am able to do butt weld patches but, because of my failing eyesight, I keep blowing holes in the panels (so wire welding is no longer in my future). I can confirm however that it is possible and doable even by the most inexperienced welder.
I may consider torch welding/brazing as an option in the future.

modok wrote: Evil_Fiz wrote: Based on what I have read on-line I wasn't sure if straight CO2 was a viable option. wow #-o
I generally get my info from the Lincoln welding company. That did sound kinda boneheaded. What I should have said is that there is an opinion in the welding forums that straight CO2 is too hot for sheet metal welding. On your advice, I tried to get CO2 from Airgas but I would need to buy a different bottle and the cost of CO2 vs Ar/CO2 mix is only six dollars.

Canghia wrote: Emil,

What about trying another solenoid. My Lincoln 110 MIG was a flux core only but when I looked at the circuit board I saw the connectors there for gas. I ordered a solenoid from someone on eBay and it was basically plug and play. It worked well. Well enough to get done what I needed. A better welder would have made my life so much easier. Mine was a basic machine.

Mark I finally got into the welder. The post flow is controlled by the circuitry and not the solenoid. I took voltage readings from every possible tap on the board but none fit the bill.

-----
Emil

Mon Jan 11, 2021 6:57 pm

MIGs without the solenoid have a mechanical switch in the gun that works fine. Why not bypass the board and have the switch in the gun close the circuit with the solenoid?