over penetration

[BrokenBiker]

I found some 1mm steel, cut it from the centre silencer of the megane...

cleaned it all up with a wire brush and started playing with the setitngs on the mig...

now the only way i can get it to run a nice bead, or even tack properly, is to set the voltage to about 4 and WFS to 5...anything lower than this and the wire burns right back to the tip as soon as it hits the metal...this is higher than the setting in the book, but the book says to use .6 wire, im using .8 so i assume the higher CSA of the wire is cooling the puddle more than .6mm would...

the good news is i can run a bead as long as i want on the steel wiithout even trying to blow holes...bad news is the bead on the back is bigger than the bead on the front...

is this an issue? im more concerend with when i eventually move to car repairs i am going to have a load of weld metal on the inside of the panel that has had no gas coverage and will potentially rust?

am i just worrying too much or is it an issue?

 

[123hotchef]

is it doubled skinned cant u paint the rear after too

 

[BrokenBiker]

is it doubled skinned cant u paint the rear after too

it would depend on the panel, i dont know what im going to need to repair yet

 

[Burdekin]

You need to get .6mm wire.

When butt welding 1mm I actually like to have the amps up so when the two pieces are butted together with a slight vee prep I get 100% penetration. I only weld in short hits and with the amps up it is quick and minimises heat input (my theory anyway). The back of the weld is always quite flat. I never run a bead on 1mm, it's all just short tacks joined up. If running a longer section I do a tack, stop, keep the nozzle in the same place while waiting for the weld to stop glowing, then another tack and move a little forward, stop, repeat etc etc, it's quite a neat technique that looks good as well. That's my technique and works for me. I wouldn't know what the welder is set up at, I just set it up so it sounds and looks right.

 

[Burdekin]

Conversely, you don't need to get 0.6mm wire... 0.8 is fine

As a learner the 0.6mm will be easier and less heat I'd imagine.

Try and get your weld as flat as possible as that means less grinding after which is one downside to mig welding car stuff.

 

[BrokenBiker]

You need to get .6mm wire.

When butt welding 1mm I actually like to have the amps up so when the two pieces are butted together with a slight vee prep I get 100% penetration. I only weld in short hits and with the amps up it is quick and minimises heat input (my theory anyway). The back of the weld is always quite flat. I never run a bead on 1mm, it's all just short tacks joined up. If running a longer section I do a tack, stop, keep the nozzle in the same place while waiting for the weld to stop glowing, then another tack and move a little forward, stop, repeat etc etc, it's quite a neat technique that looks good as well. That's my technique and works for me. I wouldn't know what the welder is set up at, I just set it up so it sounds and looks right.

ive never used .6mm wire before for car panels...i used to only use 0.8 gasless for it until buying this mig...i used to use the stitch method then as it was impossible to get a run going on 1mm,


right, i have slowly been bringing the volts and WFS down, praticing until i can get my technique right and the welds have started getting smaller...that was until i got down to where i was starting to be happy with it and then noticed a very jerky wire feed...had a bit of an investigation and im not very happy with what i found...the euro torch connection is broken...i hadnt noticed it before but ive had the wire feed up on 6 until now so i assume its just had enough force to get the wire through...now that ive got it down to about 2.5 everything is jerky and ive noticed the plastic clip on the euro socket is broken and the connector is free to flop about a bit...if i hold the euro plug up a bit it feeds fine, if i let it go it drops a bit and everything is jerky again...

email to CWS to see what they say...i have just had a look in the box and cant see any broken bits in there, and there arent any bits of plastic where i have been welding or where i have been storing the welder either...

 

[Ton-up]

If its cut out of a silencer it will probably be zinc coated and have soot inside. Make sure its spotless and give it a good grind/sand.

 

[Bill Edwards]

Regardless of how far you penetrate and the gas coverage any weld or welded metal will rust very, very quickly unless it's rustproofed. Gas shielding doesn't stop that.

 

[BrokenBiker]

Regardless of how far you penetrate and the gas coverage any weld or welded metal will rust very, very quickly unless it's rustproofed. Gas shielding doesn't stop that.

im not saying gas coverage stops rust.....

however, from what i have seen today, no gas coverage leave horrible welds, some with porosity...this isnt going to help it not rust is it?

 

[Bill Edwards]

im not saying gas coverage stops rust.....

however, from what i have seen today, no gas coverage leave horrible welds, some with porosity...this isnt going to help it not rust is it?

Yes gas coverage is very important to achieving a sound weld. But rust isn't something to bother thinking about, if there's porosity that's far more important to think about.
I don't find I get porosity on the reverse side of a well penetrated weld with MIG, it doesn't seem to be an issue. Not like TIG where it's necessary to keep air away from it.

 

[BrokenBiker]

Yes gas coverage is very important to achieving a sound weld. But rust isn't something to bother thinking about, if there's porosity that's far more important to think about.
I don't find I get porosity on the reverse side of a well penetrated weld with MIG, it doesn't seem to be an issue. Not like TIG where it's necessary to keep air away from it.

i have only noticed it while playing with the settings and getting massive build up on the back of the weld...the welds with smaller build up arent too bad...

still waiting for a reply from CWS about the jerky wire feed and broken euro socket so havent done much more since

 

[trewjohn2001]

You need to get .6mm wire.

When butt welding 1mm I actually like to have the amps up so when the two pieces are butted together with a slight vee prep I get 100% penetration. I only weld in short hits and with the amps up it is quick and minimises heat input (my theory anyway). The back of the weld is always quite flat. I never run a bead on 1mm, it's all just short tacks joined up. If running a longer section I do a tack, stop, keep the nozzle in the same place while waiting for the weld to stop glowing, then another tack and move a little forward, stop, repeat etc etc, it's quite a neat technique that looks good as well. That's my technique and works for me. I wouldn't know what the welder is set up at, I just set it up so it sounds and looks right.

Same for me - and if your quick you can get away with a quick flick of the torch back to the last tack avoids any pin holes between the tacks.

 

[BrokenBiker]

just a quick update...the jerky wire feed has been sorted...it was a case of tightening one nut and now everything is solid and the wire feeds fine on all settings...

the knock on effect of this is that now i can set the volts low, the wire feed low and get welds with relatively little build up on the rear compared to the previous attempts...im going to try going down even lower now (currently on 42 amps and 3WFS) to see just how low it will go and just how little build up i can get but its looking promising

 

[Bill Edwards]

I've come to like welding thin stuff with a 1 second (ish) tack on high power, but because my welder doesn't use a gas solenoid I can half release the trigger and it'll still flow gas to cool and protect the weld. So the gas keeps flowing but I can start and stop exactly as I want.

 

[BrokenBiker]

I've come to like welding thin stuff with a 1 second (ish) tack on high power, but because my welder doesn't use a gas solenoid I can half release the trigger and it'll still flow gas to cool and protect the weld. So the gas keeps flowing but I can start and stop exactly as I want.

I have a few seconds post flow on my mig so no problem doing lots of tacks or short runs