7 replies to this topic

[antcole]

When plug welding seams together, is it adviseable to apply weld-through zinc primer on the mating faces?

I know its 'weld-through' but will it have any adverse effect if used between lap joints prior to welding.

Thanks again.

[Artful Dodger]

yes, do it

and no, if its used as weld through paint, then it shouldnt be effected by welding. obviously, some will be burnt off when welding, but it wont affect the quality of the weld, as some normal paints will

[Tupers]

No punch the holes on the panel you'll be welding through then line it up and only remove the black coating where the holes line up on the next panel.

[antcole]

No punch the holes on the panel you'll be welding through then line it up and only remove the black coating where the holes line up on the next panel.

Ok, so you wouldnt recommend the weld-thru primer on the mating surfaces?
Im just paranoid of the dreaded tin worm and wondered what was the best way to protect the minute gap between the lap joints.

[Artful Dodger]

No punch the holes on the panel you'll be welding through then line it up and only remove the black coating where the holes line up on the next panel.

Ok, so you wouldnt recommend the weld-thru primer on the mating surfaces?
Im just paranoid of the dreaded tin worm and wondered what was the best way to protect the minute gap between the lap joints.

i would certainly do it, the black e-coating burns off really easily, and if the welds are close together then the coating comes striaght off, showing bare metal. the weld through stuff ( i use the copper rich weld through paint ) doesnt burn off as easily, and will give some resistance to rust.

[antcole]

No punch the holes on the panel you'll be welding through then line it up and only remove the black coating where the holes line up on the next panel.

Ok, so you wouldnt recommend the weld-thru primer on the mating surfaces?
Im just paranoid of the dreaded tin worm and wondered what was the best way to protect the minute gap between the lap joints.

i would certainly do it, the black e-coating burns off really easily, and if the welds are close together then the coating comes striaght off, showing bare metal. the weld through stuff ( i use the copper rich weld through paint ) doesnt burn off as easily, and will give some resistance to rust.

Sounds good to me, i think ill have a practice on some test pieces.
Cheers for the replies folks

[Tupers]

Weld through primer is deigned to be used with electronic spot welders not plug welding with a MIG. An electronic spot welder creates much less heat than the mig method meaning the primer is safe from burning off. When plug welding with a MIG you create much more heat and this will burn off weld thru primer as well as causing havoc with the welds them selfs.

You are much better off keeping as much of the chemically adhered e-coating on the panel only removing it from the area that will be welded directly. Real E-coating such as that on heritage panels will hold up the the heat a lot better than any weld thru primer.

If you wish to add extra protection it may be advisable to run a bead of seam sealer along the back of the seam before painting to help stop anything from getting in there.

[antcole]

Thanks Tupers.

That makes sense, im going to do some practice welds and see how it turns out anyway.

I wasnt sure if i should prep the panels in 'weld-thru' at the the mating faces before sticking them together.

Good info mate, thanks.