Welding Gal Mesh to RHS

[acton]

On the weekend I was knocking up a quick gate which was made out of 30x30x2 RHS with 50mm galvanised mesh as the infill. All went smoothly until tacking the mesh on. I found it very difficult to get the mesh to solidly attach to the face of the rhs without melting through the wire. I suspect the galvanising was part of the problem as a lot of the time it ended up being just connected with slag. The mesh is a pretty fine gauge (I'd guess 3mm or less). I was using the 2.5mm rods with the amps wound down to around 70 amps.

Any tips?

[Grahame Collins]

The problem in essence is welding a item of low mass/volume to an item of a higher mass/volume.

To put it another way,the difficulty is to match the arc power to not blow away the mesh but still sufficiently powerful to fuse to the box section.
The gal provides another layer of difficulty to the problem.

I would remove the gal on the weld bead surface with a file. grinding may be too severe and will remove half the wire volume.

if you have a Lp torch or oxy heat the wire in the appropraite area until red hot and gal flashes-usual warnings about gal fumes apply-wire brush residue

Try striking the arc adjacent to (but not on the mesh) and move to just kiss the edge with the edge of the arc.

It takes a bit of practice but is achieveable.
Grahame

[acton]

Thanks for the tips. I'll try heating it up next time. I had some success starting off to one side on the rhs then drifting in to the wire and back out again ... just didn't look very pretty.

[Grahame Collins]

The other side to the story is that with an inverter the soft start on the arc does not explode the mesh on contact.

The trick is to drift in as you say.
2 points

1. use the edge of the arc to just lap the mesh
2.Get rid of the galvo

Grahame

[scanfor]

Timely advice thankyou, I'm about to do the same with the mesh cage for my trailer.
I had almost decided to take the easy way out and use the mig, but I will now try it with the stick.

[Grahame Collins]

I am not claiming its easy for a novice welder and would advise a bit of a practice on some scrap materials first.
Look at using 2.5diam rods rather than 3.25mm.

Grahame

[buildspacetrain]

I bought a packet of 1.6 mm rods at bunnings and they seem to work well on about 50 amps at 75 volts on the arc welder. Might be worth giving them a go.

[jatt]

I had almost decided to take the easy way out and use the mig

Works for me, especially when its a case of thin wall section gal and gal mesh. eeesh