Please advise on my welding...

[GeorgeK]

To make it short and sweet: I can't weld thin sheetmetal for *****.

I keep blowing holes. I tried more wire feed, less, backing with a copper plate, a steel plate, nothing works.

When I get to 2mm thick steel, no big issues (not nice, but holds).

I fully intend to invite a welder friend for teaching, but in the meantime, some of the good people here could offer advice (or trash talk, I have thick skin).

See damage below (yes it's a Beetle, I was not about to start on a 911...)

[quattrorunner]

Crickets.
Well I’m no expert either but I find that moving the gun (is that what it’s called?) it seems to be a smoother process. Of course after all the cleaning and brushing etc.

[tocobill]

Its hard to tell but that doesnt seem to have alot of settings on that welder. I would set it to the lowest setting ... A /Min and Light Blue on the knob? Does the knob control wire speed? If your blowing through most likey your to hot. Get the weld to sizzle with out adding to much wire. Youll have to play with it. IF the gun is pushing and your popping then the voltage is to high and/or the wire feed to to fast. If your at min setting on the voltage then all you can do is adjust the wire feed. I would get some 19-20 gauge and practice. Newbie welders do better with spot welds then trying to weld 1 inch beads. This helps with heat input. That gas is 80/20 mix. That gas should work fine for what your doing.

[Rodney Nelson]

Hi,

Maybe I can help with some hints...

When Mig welding thin metal you only trigger the power button. You never hold it down. Basically as fast as you can pull the trigger then let it cool for a second. In the quick second you are pulling the trigger make a quick circle pattern.

Then aim for the weld you just made overlapping it 50% - 25%. This way you make a cleaner weld, you are targeting the weld material which will be less likely to blow through.

First tack around the patch panel you are doing or along the line that you are welding to hold everything in place before you start welding.

Jump around to minimize warpage. Maybe do around 8 welds then jump ahead or back to keep the metal cool.

It is about fine tuning. Meaning that you need to adjust the power and speed perfectly to get just the right welds.

For example. If you are welding on a vertical surface you are going to want to ramp up your speed. ON my machine I will run at a speed of 3.75 when I'm welding on a horizontal surface because gravity is on your side. but when I'm welding vertically I ramp up the speed to 5.2, because if I don't the weld wire will ball up and pull away from the surface I'm trying to weld. Now you will also have to increase the power just a bit. But you still have to be careful because you can burn through.

if your welds are proud you need to turn up the power to get them to be more flat.

When you are trying to fill a hole or bridge a large gap then you want more wire speed. If your gap is tight you can slow down on your speed.

I hope some of this helps.

Rodney

[Rodney Nelson]

[GeorgeK]

Many thanks. I have info to try again, on scrap sheet.

[962porsche]

in most cases what causes blow throughs is to much heat. there are others but this tends to be the main reason.
if butt welding two panels together about the thickness of a sheet of paper between the two butted panels is a gap you would want to have to far apart or having the panels butted right up to each other will warp the panels. this would be for about a 22 gage metal.
the heat setting on the welder should be turned down pretty low.
make dam sure you have a good ground too.
gas set at about 12 to 15 LBS.
taking into account all welders are a little different and even the same make and model welder you may have to play around with the setting some.
when cleaning the areas to be welded do not grind the edges of the panels to be welded. this will end up grinding the very edge of the panels to a knife edge and also cause blow throughs.
use a strip and clean disc or a sander with 80 grit to remove the primer , paint or other coating.
you want to keep the panels edges that are getting welded as thick as possible.
when stripping off the coating sand off the edge not into the edge.

when you strike the welding ark just do one small weld at a time let that weld cool down to the touch before you try and place another weld.
you may want to add more wire speed but this is as needed to obtain a good weld.
if you do blow thru do not try and keep going trying to fix and fill in your blow thru.
again let it cool back down and hit it again.
if you keep trying to weld after you blow thru you will only keep blowing the hole bigger because the metal is still hot.
the best average gas mix is 75% argon 25% C02
I'm not seeing what gage wire your using but .025 to .030 wire is best in many cases.
some times upping the wire size a little will give you the more filler material to work with in order to melt into the panels with out having to speed up your wire speed.
I will often go from a .023 to a .025 or .030 if I'm dealing with blow outs.

[Dpmulvan]

Chill blocks and good mig wire help a lot, also all mig guns and welders not created equal some of the cheaper welders don’t have the best sensitivity in their guns.
I bought some mig wire from Italy that is great for low voltages/ sheet, I’ll try to post a name later.
I prefer tig for everything auto related tig welds are not as brittle and easier to smooth. Also with the pulse option you can use lay wire technique haul ass and not put too much heat into the panel.

[Dpmulvan]

Don’t do a lot of mig anymore but I found this wire a few years ago works very well for 20gauge sheet.

[GeorgeK]

Thanks all. I have been practicing, and I am getting better at it.
It is alot like skiing: Keep in mind the basics. Clean sheetmetal, good ground, clean gun and mask, good lighting, short bursts, grind often, let cool.
And mostly: practice, practice, practice.

I realised that the lower setting is not enough to do a complete penetration on the sheetmetal, the joining line was still visible on the other side of the weld. I upped from A min to A max, and with short bursts, I have good weld through.

But forget a single one of the basics, and you'r in for a world of hurt.
So between the good guys here and across the hall, I am down to practice. See you in 3 rolls of wire.

[Dpmulvan]

A huge mistake with body work is to have the mentality that you can grind and sand away because it’s steel. If you treat sheet metal like balsa wood, carefully avoid panel when smoothing welds, don’t go ape **** with the flap disks et your welding of butt joints et will have fewer blow outs.

[962porsche]

Originally Posted by Dpmulvan

A huge mistake with body work is to have the mentality that you can grind and sand away because it’s steel. If you treat sheet metal like balsa wood, carefully avoid panel when smoothing welds, don’t go ape **** with the flap disks et your welding of butt joints et will have fewer blow outs.

good point!
the trick to getting nice patches welded in is to take your time this goes thru out doing the hole patch from fitting to finish work on it.

[Joe Bob]

I've found a good grinder makes a lousy weld job look a lot better.

There's a guy called "greasy fingers" in the upper Midwest that does some remarkable restos and post his efforts on UTube.

[Dpmulvan]

Sometimes just a little dab of nozzle gel will make you a better welder.