Newbie Mig Welder with questions

[msg]

I have a Hobart Handler and I am beginning to learn how to weld.
The local scrapyard let me have a door panel to learn on, so I cut the bottom portion off and tried to weld it back.



The metal thickness is 18 ga and the wire I'm using is Hobart .024 spool.
The argon/co2 gas is on and the gauges read...


The problem I am having is burn through when I try to weld a seam in that u pattern loop motion.



Tack welding seems to go well



here is the back of the panel



The chart on the door says that I should be at a setting of 2 on voltage and the wire speed at 50. I even lowerd the voltage setting to 1 and it still burns through


I have been told that 18 ga is best just to make a series of tacks vs welding a seam because of burn through and warpage.

Anyone have any advice on how to make continuous welds between tacks? I really want to get this down better.

[tinydb84]

You tack sheet metal. If you try to run a bead then you will burn through it and warp it.

[cg285]

make tacks only or longer tacks or short series of tacks and learn to cycle the trigger. go back and forth to other areas while your weld cools. you are most likely working on 19 ga or thinner material

[JointTech]

shouldnt you be using a butt spacer thingy? If you cut the door off and your cutoff wheel is Xmm thick and then you butt the peices together and tack them wont your door be Xmm short? Im a newb as well. just wondering

[cg285]

Originally Posted by JointTech

shouldnt you be using a butt spacer thingy? If you cut the door off and your cutoff wheel is Xmm thick and then you butt the peices together and tack them wont your door be Xmm short? Im a newb as well. just wondering

i believe he is practicing

[RidgeRaceCars]

Originally Posted by cg285

make tacks only or longer tacks or short series of tacks and learn to cycle the trigger. go back and forth to other areas while your weld cools. you are most likely working on 19 ga or thinner material

This!!!!^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[Rochlow]

You could possibly turn up your wire speed to "fill" it a bit more and lessen the chance of burning through.

[Bishops Trucks]

When welding body panels, a series of tack welds is the best way to go. It takes a long time to finish but the results in the end save you a ton of headaches. Making a continuous weld is best left to thicker stock that will not warp from the heat.

[dougf]

Like others said, the heat will build up if you try to lay a bead. Multiple tacks, and fill in with short tacks, working your way on different places so the heat doesnt build up.

[msg]

Thanks Fellas! I will definitely use the multiple tack method vs bead.
The butt weld spacers I did have on originally but the gaps seemed huge so I took them off so I could just practice without having to fill so much. Next time I'll use them and practice with the wider gap.

[BigDan3131]

This is why late model everything is R&R, sheetmetal is too thin to weld unless its all you have because the part is beyond expensive like a Audi hood for a non-USA Audi. Its also why Lord Fusor and those products came along.

So in other words get a scrap fender of the sheetmetal your going to work on more often because welding it is different then welding what you have.

[mongoose]

turn your gas down to like 10... no need to have 30 feet going through it if you're working inside.. plus your 60 dollars worth of gas will last 3 times longer.

[BurgerMan]

I'm in the same boat. Just bought a handler 140, but haven't gotten the gas setup yet. I have practiced a bunch on 1/8" and can do it well. So my only question is, for anything thinner is it a must to get a tank? Can it be done?

[BadaSs_Cal]

Originally Posted by BurgerMan

I'm in the same boat. Just bought a handler 140, but haven't gotten the gas setup yet. I have practiced a bunch on 1/8" and can do it well. So my only question is, for anything thinner is it a must to get a tank? Can it be done?

Flux is fine it just burns a little hotter. I won't say its as pretty, but if guys do it with Stick.. I think you'll be just fine Good luck

[66Project]

I had that same problem when I was trying to weld sheet metal with .035 wire. Seem to work 100% better when I went to .024. I was able to turn the heat up and not burn thru. I have the same welder Hobart 140 and Im welding sheet metal at 4 and 50. The gas is a 75/25 mix at around 20psi. Dont know if that is right but it works for me. Sometimes Ill turn it down to 3 if it starts to go thru but mainly keep it hot.
Small Tacks. If your on or close to a body line or a 90 degree brake you can get away with getting it hotter. Tack once...wait just until the red is gone and tack your next one right next to it. Building off your last tack. Depending on what it is you could go 1/4 inch before moving to a different spot.

Make sure your metal is clean on both sides. If you dont the contaminants will burn off and the gases will come thru your weld. Welder guys a work call them dickheads. When you grind on them your spot weld will be hollow from the gas pocket.

Keep your gaps close together and if you have to fill some in use copper on the back side to keep it from burning thru.

.02 cents

[Grumpy old man]

turn the gas down and wire speed down and tack every 2 inches along the panel then go back and repeat the whole line eventually tacking the entire seam , gas should be about 7 and turning up the wire is not helping think TACK NOT WELD ! And be patient it's not a race ! think quality not speed !

[racecougar]

Originally Posted by BurgerMan

I'm in the same boat. Just bought a handler 140, but haven't gotten the gas setup yet. I have practiced a bunch on 1/8" and can do it well. So my only question is, for anything thinner is it a must to get a tank? Can it be done?

Yes, you can use flux-core on sheetmetal. There's a bit of a learning curve, but it is completely doable. Check out my build thread (link in sig). Thus far, I've replaced the cab floors, front and rear door pillars, front and rear cab supports, kickpanels, lower firewall sections, rockers, cab corners, and more on our '65 using nothing but a 0.035" flux-core setup.

[MP&C]

Responses in Blue

Originally Posted by msg

I have a Hobart Handler and I am beginning to learn how to weld.




The second weld dot up from the bottom looks good, nice wetting (flow) to the parent metal


here is the back of the panel




.....and looking at it from the back side you have full penetration weld. Not much weld proud on the back, but the seam is not visible. Setting the welder's heat setting should first and foremost produce a full penetration weld. If you can see the seam (joint) between the panels after welding, it is a cold joint and subject to failure from vibration exposure.


The chart on the door says that I should be at a setting of 2 on voltage and the wire speed at 50. I even lowerd the voltage setting to 1 and it still burns through

Increase the wire feed. If there is not enough filler going into the "molten pool" it is always going to burn away the parent metal.

I have been told that 18 ga is best just to make a series of tacks vs welding a seam because of burn through and warpage.

You were told correctly.

Anyone have any advice on how to make continuous welds between tacks? I really want to get this down better.

If using a mig on sheet metal, you have reached the end of your options. If welding thicker metal, you want the weld pass, sheet metal- dots only

Getting all of your tacks looking similar to the one I mentioned above is going to help with consistency, and will help reduce the warping, but with any mig welding, the weld dot shrinks circumferentially as it cools. You need to use a hammer and dolly to planish each dot afterwards, grind them down just above surface of the parent metal (gets the dots out of the way for planishing the next sets), then weld the next set. I would also say that once the dots are spaced at about 1-1/2" apart, now you should start overlapping the next set as opposed to welding a dot between the last ones. Overlap will help to eliminate pin holes and missed welds.

Originally Posted by JointTech

shouldnt you be using a butt spacer thingy? If you cut the door off and your cutoff wheel is Xmm thick and then you butt the peices together and tack them wont your door be Xmm short? Im a newb as well. just wondering

No, the joints should be as tight as possible, and as consistently tight as possible. Varying widths of weld gap will take more weld, thus more heat, thus more shrinking and movement for the wide gaps. This inconsistency more than anything is going to cause more pronounced warping. Leaving a gap also leads to more blowout. If you're blowing holes when the panels are tight as shown, how well is it going to work when you're trying to weld thin air? But more than anything, leaving a gap is risking panel movement. You have enough issues to deal with considering any shrinking that occurs from the welding process. Leaving a gap only allows more panel movement. Place that weld in the middle of a low crown panel (roof, hood, etc) and any extra movement is only going to assist in losing crown and resulting in a loose oil can. Now place that weld joint next to a door jamb and you are risking altering the door gap's consistency. Here is a repair that came in the shop, the owner's first attempt shows how too much heat from filling in gaps has pulled the door/rocker to fender gap, for much inconsistency.





For a repair like this, my choice is to make the rear fender edge as part of the patch, to limit the number of vertical welds (and thus shrinking) and also to keep the weld joint from behind a fender brace, where ever possible, to allow access for planishing. By butting the panels together tightly, you eliminate panel movement from the equation, and then shrinking effects are the only issue to deal with.

Originally Posted by Rochlow

You could possibly turn up your wire speed to "fill" it a bit more and lessen the chance of burning through.

Bingo! Start your adjustments by setting the machine to perform a full penetration weld, wire feed to accommodate that heat without burn through, and then adjust your weld dot size by length of the "zap". Keep consistency in your methods throughout to help keep warping in check.. You need to become OCD consistent, for best results.

[Grumpy old man]

When someone is brand new to welding the idea is to teach them control and avoid burn thru , increasing feed will only lead the new welder to inconsistent tacks and arcing way above the surface ! low voltage /low wire speed let them learn how before they just start with bad habits in my opinion ! it;s not a race ! take your time and learn how before you try to finish fast !

[cg285]

i say a newbie should learn oxy/acet first before mig but everyone wants to short cut. o/a will teach puddle control. a mig can make you think you are actually a welder

[Grumpy old man]

I'll agree that running a mig does not make anyone a welder , many people today couldn't tune a torch to save their lives . it's all a learning process and with welding correctly I think the best way is to teach technique before speed I was taught to run a torch in the early 1970's welding rust out panels in 1940's single wall jeep bodies . we didn't have rust repair panels we made them from scratch ! if you wanted to restore a truck or car you had the kitchen phone a few junk yards and the yellow pages as parts sources ,Thats it !

[MP&C]

Originally Posted by Grumpy old man

When someone is brand new to welding the idea is to teach them control and avoid burn thru , increasing feed will only lead the new welder to inconsistent tacks and arcing way above the surface ! low voltage /low wire speed let them learn how before they just start with bad habits in my opinion ! it;s not a race ! take your time and learn how before you try to finish fast !

Unfortunately I have seen far to many examples of cold welds from people who have not learned correctly to set their machine up for full penetration welds. So the first bad habit they learn is to set the heat too cold, and it tends to lead people to believe that they can just add on more weld, and sooner or later you end up with something like this:



Minimal/insufficient weld penetration, missed welds, can you say MUD DAUBER? Bad habits start by learning incorrectly from the get go, just as shown above. I never mentioned anything about going fast, welding one dot at a time is never fast. But I can also show some pictures to document the process I described in my previous post, which stresses the importance of a full penetration weld above all else.


Tight fitting panels, no gaps..




First set of tacks...








Weld penetration, the back side....








Weld, planish, grind, overlap, repeat...








Planishing as you go helps to keep the panel's shape in check...











When welding patches and panels together you need full penetration welds to duplicate the factory metal by filling the seam. With a bit of metal bumping, the results above are about as filler free as you can get.

A cold weld will leave the seam showing on the back side and be prone to structural failure given exposure to road bumps/vibrations/conditions. Then there is the Bondo needed to cover up a mess like this below: So which bad habits look more like a cobbled up mess to you? I'll take my bad habits any day of the week.

[msg]

Thanks for all the feedback fellas,
I'll do the following based on what Ive read here.

• Switch the setting on the voltage to 2 as the chart states on the the Hobart for the 18 ga.
• Now that I understand the continuous bead isn't going to work, I'll try the alternating tacking method- but on the wire speed, should I keep it at 50 as the chart reads or switch it up a notch to increase?
• Tack with 1" to 1.5" spacing
• Adjust the gas down to 10 to conserve the tank
• Practice
• Practice more

[MP&C]

The tacks you showed above are darn close to where you need to be. If a heat setting two gets you full penetration weld, stick with it. If not, add to the heat until it does. Adjust wire feed as needed to insure you don't burn away at the parent metal.. Once you find a happy medium you can tweak the settings from there if needed.

Tack from one end working to the other, aligning the panel as you go. This will help to insure you don't get a mis-alignment with more metal on one side of the weld than the other. Weld tacks, planish (hammer and dolly), grind, repeat. Let us know how it works out in case other "adjustments" are needed in you methods, but you are right there....

[BurgerMan]

Wow guys this is extremely helpful. Thanks for all the great pictures too