Can someone tell me why my welding is so rubbish?

[Muddy42]

I am repairing rusted out holes on a mower deck that is about 2 or 3mm thick. I cut out the damage, ground everything clean and shaped pieces of metal for the repair using masking tape.  I did little tack joints to hold the patch in place whilst I did some bending, then welded the rest. The weld seems to be sitting on the surface, with insufficient penetration.

 

I am using a 200amp MIG with flux core, set to about 1/3 power (I tried a bit more amps but blew through).  Since I have reversed the polarity on the welder for flux core I was getting some OK results on thicker metal, but this is really poor.

 

Any tips welcomed. Thanks

[Retired Climber]

I'd say more amps and slow down both wire feed and travel speed. 

[GarethM]

And probably a bit more flappy disc prep as that rust won't be helping.

[woody paul]

What did you cut patch out of new or old steel. 

[Mike Hill]

Looks like your holding the gun a bit too far away from the metal as well.

[Muddy42]

53 minutes ago, Retired Climber said:

I'd say more amps and slow down both wire feed and travel speed. 

OK, will try that again

45 minutes ago, GarethM said:

And probably a bit more flappy disc prep as that rust won't be helping.

Thanks.  Maybe the photos don't show it, but I did do loads of prep and was only welding onto shinny metal. 

36 minutes ago, woody paul said:

What did you cut patch out of new or old steel. 

The patch was made of painted old metal.  I ground it right bad to shinny metal and I'm pretty sure it wasn't galvanised.

30 minutes ago, Mike Hill said:

Looks like your holding the gun a bit too far away from the metal as well.

OK

[GarethM]

Might also be a good idea to brake clean/acetone the oil away.

 

It's a mower deck so probably saturated from it's years of hard work 🙂

[Muddy42]

5 minutes ago, GarethM said:

Might also be a good idea to brake clean/acetone the oil away.

 

It's a mower deck so probably saturated from it's years of hard work 🙂

thanks

[woody paul]

1 hour ago, Muddy42 said:

The patch was made of painted old metal.  I ground it right bad to shinny metal and I'm pretty sure it wasn't galvanised.

Why I asked is I have had fun welding steel cut from old heating oil tanks as it gets in to it. 

[doobin]

It’s simple. It’s because you’re using flux core. 
 

flux core is nothing more than an auto feed arc welder. You will have all the same problems repeatedly striking and arc, of putting enough power into it to penetrate rusty metal without blowing through. So you set it lower to not blow through and you’re surprised when your welds are crap. 
 

Get yourself down your local motor factors and get a bottle of sgs or hobbyweld rent free 5% mig gas. 
 

basically until you strike the arc and start burning, the flux isn’t burning off the give your weld protection.  There’s always a delay when staining the arc and the protection is nothing like the surround of gas from a mig shroud either. Because you have to keep stopping and starting your welds are crap. Using a proper mig, the gas is always protecting your welds, so you can start, stop just before blow through, wait a split second for the red hot glow to dissapate and then go again, all whilst protecting the weld with gas. 

Edited 5 hours ago by doobin