Best filler for soldering

[Tōtōchtin]

Hola,
I need to install some 2" ferrules in a 30l keg. No even spots on the bottom so I will need to fill 1/4" gaps. I am trying to stay away from going to borrow some welding equipment from the village. I only have a weak ass propane torch to work with. Any ideas what's the best material to use with a propane torch.
Tōtō

[Steve Broady]

Have you considered grinding the ferrule to fit the shape of the keg? Or flaring the hole in the keg so that it fits the ferrule? I realize you’re not in the US, but if you can get things through customs, there are tools available relatively inexpensively which are designed to flare a hole like that.

[Salt Must Flow]

So you mean on the side of the keg or literally on the actual bottom/underside? If you mean the side, just grind the ferrule for a tight fit.

When I installed a ferrule on the top of my keg, it wasn't flat either. I cut on the red line (cutting away the high spots) and that allowed the ferrule to sit flat on the low spots so it could be welded. I know you're soldering, but that would work for soldering too. Once the ferrule was completely welded, I ground the interior protrusions smooth.

[Tōtōchtin]

As you can see thru the weep hole where the bottom is. The sides are raised about 3/8 -7/16" ths, so no grinding on my ferrules. Being here I almost was going to use a cheap coat hanger, what we used back before the wheel was invented.
I will probably use a 60% stick(last one) I have as a filler and use the Harris 8 I have to glue the ferrules on. It's for a heating element so not much stress on the fitting.
Tōtō

[Salt Must Flow]

Ahhhh I see now. I would cut a hole and grind it out just the right size for the ferrule to slide THROUGH perfectly. Nice & tight so there's no gaps.

[Sporacle]

Yep, as SMF said drill and grind to get tight fit with the ferrule into the keg.
You could slightly taper the ferrule male with a grinder and then lightly tap the ferrule into place.
Make sure it's cleaned and prepped prior to fitting so you can go ahead and solder once it's tight.

[acfixer69]

You can hammer a flat spot at the location on the keg and you can make a good fit no filler needed.

[Tōtōchtin]

I thought of that when I saw the picture I posted. I made this a problem getting my 2 inch ferrules with narrow shoulder, 1/2".

[ecir54]

a 1/4" gap is not a feasible situation to any welder don' try it. couple ways to avoid have been discussed, befriend a experienced tig welder is recommended either way that's a tough joint to make with strength being a key factor

[Oldvine Zin]

You can hammer a flat spot at the location on the keg and you can make a good fit no filler needed.

Stay safe
OVZ