I have been trying to get the 2.5mm rivets but I am finding it difficult to get a minimum order quantity from the company who makes them. I am going to have one last try . I do know that members have used the 2mm rivets although I imagine that the the soldering could be tricky
I have to say, I’m not convinced that the difference of half a millimetre in diameter (so 0.25mm either side of the rail foot) makes any practical difference at all when soldering rail to them.
In all the trackbuilding I’ve done with ply and rivet over the years, I’ve only ever used 2mm rivets and never found a problem. My technique has changed over time. I started off using solder paint. I think that this may have been one of the suggestions made by Iain Rice in the 1990s in one of his early articles or books. Either way, I found that it spat too much when it was heating up, and there was a risk of charring the sleeper because it needed a lot of dwell time with the iron because the soder paint didn’t melt consistently.
I then used cored solder, of the type used for attaching electrical components to PCBs. This was much neater. However the problem I found from this was the brown waxy resin residue that found its way into the web of the rail, and took a lot of scrubbing to remove.
Now, if I’m using rivets for trackwork, I only do it is strategic places and use plastic chairs for the rest, and I use normal 179 solder and liquid acid flux, just like you would for a brass or N/S kit. It makes a clean joint, and cleans up well afterwards with no residues.
Bob is right in that you can use the plastic chairs. It does use more solvent as the ply soaks it up and it takes a little longer to grab. I have used this method successfully. I was told the ideal way is to coat the sleepers in the solvent you buy from diy stores for plastic waste pipes will make the whole bond stronger
I’ve heard elsewhere that drain pipe solvent used by plumbers is basically the same as Daywat sold to modellers, but a lot lot cheaper…
However, I’m intrigued by the idea of coating the sleepers with it. How does that work, and to what benefit? Because the majority of the sleeper is not and never will be in contact with the plastic chair. There is some osmosis of the melted plastic into the grain of the timber, as that is how a very strong joint is formed. But in my experience this is in an area little more than the base of the chair, not across the whole sleeper.