Hi Irish.

Yeah, when you solder large wires like that, you end up with more heat being conducted away from where you are trying to focus it. It will "flow" down the wire because of the basic quality of copper wire being so conductive to both electricity and heat.

The trick is to have a hot enough soldering iron to get the heat to the point of focus quickly so that the solder will flow properly and to where you want it to flow. When the heat draws away from your point of focus faster than you can heat it up, well, you get a ball of solder and no flow. So, the way to get it done is to have a very hot iron of sufficient size (pencil solder irons just don't have enough mass) to stay hot long enough to allow the solder to flow.

That 100/140 should do the trick.

The other problem is this new lead-free solder. It's crap. I have a couple of rolls of very fine rosin core lead lead solder that I use sparingly. It flows much better than that stuff they are selling now. If you can get your hands on real 60/40 lead/tin rosin core solder, then you will have half of the problem solved. The other half, well, looks like you have a handle on that.

CGr.