Model Railway Forum

Brian wrote: ↑Sun Apr 30, 2023 10:11 am Hi
2.5mm brass wire? is this 2.5mm2 or are you actually trying to use 2.5mm dia. wire?

Even 2.5mm2 wire stripped from mains cable is very large for droppers. 1.0mm2 is ok and more than ample.

The problem can have multiple causes....
Soldering Iron not producing enough heat - low wattage. 25 watt absolute minimum and higher wattage is better.
Soldering Iron hasn't been allowed to reach full operating temperature - allow 5 minutes for a standard iron
Soldering Iron tip is too small or in poor state. 1.5mm-2.0mm chisel bit is about the smallest needed.
Solder being used is of the Lead-Free type. Try to obtain Lead content solder 60/40 type.
Surface of rail and item to be soldered is not clean. Use a fibre brush etc to 'scrub' the surfaces clean.
Allow time for the iron to pass its heat into the two items being soldered.
Try presoldering both items before placing them together i.e. coat each in a little of the hot solder. Then fit together and wet the irons tip with fresh solder and allow heat to transfer and melt both pre solders. add a little more solder if necessary while the iron is still on the items heating them.

Simon_100 wrote: ↑Mon May 01, 2023 6:33 am Thanks for this Brian, point by point if I can:

Yes, that's 2.5 mm diameter wire, I saw this in a DIY superstore, it's about five wires together without any sheath, I guess it's for earthng buildings?
Would 1 mm bell wire do? 2.5mm dia is Huge! I guess its not Brass but is actually Copper? TBH one stand would be more than ample for a rail dropper. Bell wire rail to bus wire is fine keeping the length of bell wire as short as practicable and ideally not more than 400mm.
My soldering iron has 40-48W output so that should be enough. Thats good
That took some practice but I now leave plenty of time for warming - but a good point tho' Yes do allow time to heat fully while iron and its tip is heating - make a coffee or cup of tea!
The tip is brand new and looks to be in good shape. Excellent
Hmm, yes, my solder is lead free. I'll have to try and obtain some 60/40 as you say, not so easy out in the back of buying but I have a trip to a city booked in the next weeks or so. You may struggle to find Lead content 60/40 solder but it is still sold and despite what some retailers may say it is not illegal to use on home equipment its only illegal on items that are sold!
OK; All of the surfaces are new but I'll try cleaning as well. The heart of soldering is spotless clean surfaces.
How much time? I get tired as it is trying to hold it in position! Problem is the 2.5mm wire is sucking all the heat out of the irons tip before the iron heating element can replace it. Use one strand or bell wire as suggested earlier.
That looks like a good tip!

I guess I'll have to wait until I find some 60/40 solder but I've got plenty of other stuff to do and at least I'm soldering the switches for the control panel ...

Walkingthedog wrote: ↑Mon May 01, 2023 11:12 am Brian there is loads of 60/40 on eBay with 2 day delivery. Would you not recommend it?

Walkingthedog wrote: ↑Mon May 01, 2023 11:12 am Brian there is loads of 60/40 on eBay with 2 day delivery. Would you not recommend it?

Brian wrote: ↑Mon May 01, 2023 11:32 am Yes, I know and that's where I buy mine from, but Simon_100 lives in Catalonia Spain.

Brian wrote: ↑Tue May 02, 2023 8:42 am AFAIK Lead Free solder is an EU requirement and part of being environmentally friendly.
It works well, but only with solder flow temperatures higher than most domestic soldering iron tips can reach. The exception being soldering irons with adjustable thermostatic settings. Lead content flows at a lower temperature and is OK with all soldering irons.