Garden Railway Forum

The IP kit that I am currently trying to build has a fair chunk of whitemetal bits that build up into the bonnet and radiator assembly. I decided to solder these together as I fancied a challenge and have not soldered any white metal since I built a 00 LNER B1 about 20 years ago.

I know that many people don't really do soldering and whitemetal soldering is even more of a black art that can result in an expensive puddle on the work bench. So I decided post some information. Please note this is not a "How to do it" but more of a "How I do it" and there are people out there much more skilled than me.

The pictures are not great as it is hard to hold a camera and a soldering iron at the same time.

Equipment:- Low melt solder, I am using 70oC melting point, others are available. If you are building something that has lots of little bits and some big chunky bits, it is worth using a higher melting point solder (100oC) for the main build and then adding the detail with the 70oC stuff.

Flux - I use a brass flux that is phosphoric acid based, helps clean the joint and allows the solder to flow.



Soldering Iron - Some clever blighters will tell you to use a normal iron, you can, I have, I don't anymore. I use a cheap temperature controlled iron.



You will need the iron set higher than the melting point of the solder. For 70oC solder I have it around 150/170oC. At this temp there is little risk of melting the whitemetal.

Technique:- File and sand the parts until they fit well together. Ideally you want a very small gap between them to allow the solder to flow by capillary action. So you may not want to smooth the mating surfaces too much.

Position the parts correctly, off cuts of wood are your friend here, avoid using blocks of metal as they will act like a heat sink, avoid plastic for obvious reasons. As you get more confident you may find that you can hold larger parts as you solder them.

If I am soldering larger parts together I will put a few shavings of solder in the joint to make life easier. Nothing too large about the thickness of a finger nail will do.

Paint the joint with flux

Apply the iron to the solder - you will get a nice sizzle as the flux evaporates, the solder may get drawn into the joint as the metal gets warm, or you may need to run the iron along the joint to spread it out. Whitemetal castings will draw a lot of heat away from the iron. Add more solder as required, but be careful as any excess will need cleaning and this can be a pain. I use a desoldering bulb or even an old screw driver to remove excess before it cools. Like football, your first touch is often your best touch, knowing when to stop is the key.

Now leave to cool and admire your handiwork.

Clean up with old files, sandpaper or fibre pencils. You may wish to wash the job in clean water to remove any traces of flux.



The tank of the rad was separate from the core, not a bad job even though I do say so myself. You can hardly see the join.

I do urge anyone to have a try at doing this, don't be afraid. Practice with a scrap kit or buy someones aborted project from ebay to have a go with. It is not hard, it just takes a little patience and the results are well worth it.

I am not great at white metal soldering having only assembled one small locomotive kit with a white metal body using solder. I tend to go for kits using brass or nickel silver as It is harder for me to make a mess of the parts! I usually cop out and use two part epoxy for white metal. Any tips will be appreciated by me.

Ian

Jim,
I agree with all you've said. I haven't had cause to do any white metal soldering for 20+ years but back in the day I put together many 4mm locos and wagons. I used to use a crude version of a temperature controlled iron which was simply a 12v iron sold, I think, for car use and run off of an old 12v controller. Simply set the controller to about the right speed and the tweak it up or down by how well the solder melted and/or if a bigger piece needed a bit more heat.

For flux I used Carr's White Metal flux, as sold by Hubert Carr himself back then, which was Phosphoric Acid based, as you say.

Useful info, thanks. I think the trickiest part for me was finding some way of holding the parts securely together while doing the soldering. Asbestos fingers would have been ideal, if only I could have perfected them.

Rik

I think this is worth being a 'Sticky' post so I have made it one, well done.

Euuurrrggghhhh!
I'm all sticky.

For years, I resisted soldering whitemetal and soldiered ( or should that be soldered) on with epoxy. When I eventually bit the bullet and had a go I was surprised at how easy it was. Much easier than epoxy. For a start, the solder sets almost immediately, so there's no waiting impatiently for the epoxy to set. Also, joints can be easily redone if the parts are crooked.

Rik

It seems that many feel the same way Rik. There is a feeling that it is too hard and too much trouble attempt. It can be tricky, but like most things the hardest part is actually deciding to have a go.

I think for me is that I don't have a temperature controlled soldering iron, any suggestions that aren't hundreds of pounds?

This is what I use
http://uk.farnell.com/duratool/d02265/s ... 0001689534

I got mine from Maplin, but the same product

Rik
PS - Get a spare spade or chisel bit for it to transfer heat quickly to larger surfaces
PPS - If you buy a couple of other bits and pieces to get the cost over £20, then postage is free.

Mine is digital and it wasn't much more expensive.

I suspect the cheaper ones are not as good at maintaining a fixed temperature. Mine fluctuates a fair bit, but not enough to make a real difference to what I do with it.

Big Jim wrote: ↑Fri Jul 20, 2018 9:56 am I suspect the cheaper ones are not as good at maintaining a fixed temperature. Mine fluctuates a fair bit, but not enough to make a real difference to what I do with it.

Good stuff. Hopefully it will encourage more people to solder whitemetal instead of reaching for the glue.

The variation you mention is a function of the soldering station power rating. The higher the power rating (and thus the price), the faster it can replace the heat that is conducted away from the joint.

Using a wide tip as suggested by Rik also helps, as it can transfer heat into the work faster.

Spare tips are cheap enough and I keep separate ones for soldering low melt to prevent cross contamination.

Regards,
Graeme

Bit confused here, the iron in the link is only 48watt but I already have a 40watt and 100watt so what's the point?

You can control the temperature of the bit with this one. The wattage is more to do with how quickly it can get the heat into the metal.
A non adjustable 40w or 100w will reach a temperature that will melt the white metal.

tom_tom_go wrote: ↑Fri Jul 20, 2018 1:26 pm Bit confused here, the iron in the link is only 48watt but I already have a 40watt and 100watt so what's the point?

Wot Jim sed ....

Big Jim wrote: ↑Fri Jul 20, 2018 2:26 pm You can control the temperature of the bit with this one. The wattage is more to do with how quickly it can get the heat into the metal.
A non adjustable 40w or 100w will reach a temperature that will melt the white metal.

There's a knob on the box for varying the temperature of the bit.

Rik

I see, thanks Jimbo.

A few more images from today's activities on the metal melting front.

Just to prove that things don't need to get too hot while using lowmelt.


A close up without the iron in the way, my fingers are in the position I held the bits in while applying the iron.



By tacking the pieces on the inside you can make sure they are in the correct postition before you run a fillet down the joint and if you solder on the inside, no cleaning up required.

The last pic is my handy solder stick holding tool. Invaluable when you run out of hands.

More stupid questions, you mention tacking but what are you using in that pic to do that?

Not a stupid question at all.
Tacking is just using a small amount of solder on the tip of the iron to get the joint to hold. No real strength in it but enough to keep it all together.

(Iffy diagram coming up)

If you were joining parts A & B you might tack at the points marked X.



You can then check it is all in place, adjust if needed and then run a fillet of solder down the whole join.



If it is not correct and it does need taking apart again it is easier to split parts and clean it before you fill the whole lot up with solder.

Ah, I call that tinning rightly or wrongly.

I thought tacking was holding a piece in position somehow which I have always found difficult when it comes to soldering brass together.