OK_WB - North British 225hp 0-4-0DH

You seem to be having a lot of trouble soldering the nuts to the footplate top, I don't knowwhat sort of soldering iron/flux you are using but the method I use gives no trouble at all. Some grease under the footplate helps but is not essential, I bolt the parts together, run a little flux (phosphoric acid) around the nut and touch the soldering iron to the side of the nut and footplate. The solder quickly flashes round the nut as long as enough heat is applied (40w iron for this) and the screw can then be removed. We supply steel screws and brass nuts to make this easier and they are the best quality available (and quite expensive)

Michael Edge

You seem to be having a lot of trouble soldering the nuts to the footplate top

 

I hope I did not give the impression it was the fault of the kit - It most certainly was not.

All down to my hamfistedness I am afraid, that and trying to do things at the wrong time of day (for me).

 

I use an RSU for most kitbuilding soldering tasks with solder creams. Though here used my usual Antex 25W - sometimes it is just easier to wield what is at hand and i had just used that to run round the inner edges of the footplate.

 

Having made a mess of one of the nuts and cross-threaded one of the "expensive" bolts into it - I resorted to what I had in the spares box - some poor quality brass Obviously a mistake - and now need to stock up again with some of better quality. I have had similar problems with this in the past so it is not new. Hopefully with the other's in the kit I'll be more careful.

That answers my question, rsu and solder paste is definitely not the way to do this, most solder pastes have very active (and corrosive) flux in them. Phosphoric acid is much safer, also your rsu heats everything up, what you want is local heat (quickly) just around the nut.

Michael Edge

In my experience, an RSU is precisely the thing for applying local heat. On most settings however, it probably applies too much rapid heat, and this can tend to 'cook' solder pastes, resulting in a joint that would have been stronger with ordinary solder wire and an iron. I think to categorise most solder pastes as having corrosive fluxes is incorrect, but I agree that phophoric is sufficient for most brass and nickel work.

That answers my question, rsu and solder paste is definitely not the way to do this, most solder pastes have very active (and corrosive) flux in them. Phosphoric acid is much safer, also your rsu heats everything up, what you want is local heat (quickly) just around the nut.<br />Michael Edge

 

But Michael, as I said above:

I use an RSU for most kitbuilding soldering tasks with solder creams. Though here used my usual Antex 25W - sometimes it is just easier to wield what is at hand and i had just used that to run round the inner edges of the footplate.

 

Yes, used a 25W Antex - and in most things 4mm have never had any problems with heat output.

The solder cream (Carrs range) is actually far less corrosive than most phosphoric acid fluxes - it has an organic base.

The issue here was purely carelessness with the supplied nut and bolt followed by my own poor quality and brass replacements.

 

The RSU is superior for small items on larger items as it not only acts as a third hand (you can hold a part in place with the tip, apply heat, remove heat and then remove the RSU electrode) but also because the heating is very localised. It is also great for overlays and laminations. Its biggest downfall is in the ability to seam and patch/fill with solder.