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White metal Soldering


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32 minutes ago, Finlay Veicth said:

Hello all, I have gotten my hands on a white metal kit but I dont have a low temp iron, any recommendations?

Assuming you don't want to buy a new soldering iron then it depends what sort of kit your are talking about. A good quality, thickish, superglue should be OK for wagons etc.

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Antex 25 Watt with the correct solder and flux. Don't linger. Quickly in and out.

 

If you are a bit weary of using a 25 watt, then try a 15 or 18 watt. Couldn't get the hang of using temperature control irons, too much hassle IMO.

 

I would only use superglue on small parts, but after all other soldering is completed as it can give off really nasty fumes.

 

 

 

Jason

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I was recommended an Antex iron here;

 

 

The 120 is probably a bit overpowered for white metal as I usually have it near the lowest setting but I haven't looked back since getting it. Noting that they are a decent chunk of money, if you don't know if you will even get on with gas/white metal soldering, I previously used several gas irons from Screwfix. They did the job but just weren't particularly long lasting.

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I have used a 25 watt Antex iron for ages, in and out as quickly as possible with plenty of flux in the joint along with a small piece of low melt 70 degree solder. long enough to melt the solder but not the parts. You can always go in for a second or third go.

 

Larger parts act as a heat sink, so more heat is required to join larger parts together. its a simple skill to learn. I now have a 75 watt temperature controlled iron, I just turn the heat down

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The other good thing about using 70 degree solder is that you can put the work over steam from a kettle and the joint comes apart without damaging the parts, super glue is fine for the smaller detail parts, but you cannot beat a good solder joint and if enough flux is used it will fill up any gaps between the parts being soldered.

Edited by hayfield
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I think Low Temp for white metal is a bit misleading.  I have used 300C with my temp controlled soldering iron.  The trick is to have clean parts, lots of flux (I have found that pretty much any flux will work) and be quick.

 

John

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If you feel competent/confident, it’s dead easy to make a temperature control unit using a lighting dimmer switch of suitable rating. 
 

Mine consists of a 13A plug (3A fuse) on lead, the dimmer, and a 13A socket, plus a batten fitting wired across the dimmer output, into which is fitted an old 40W filament bulb, all fitted to a short length of plank.

 

It works a treat.

 

 

Edited by Nearholmer
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Something I didn’t really appreciate  for several years; when soldering  white metal (Which is my preferred approach) is the importance of cleaning the surfaces to be soldered immediately before soldering. The surface tarnishes quickly and then the flux is less effective.

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I have always used a 12volt iron run off the back of a old duette transformer cheep and cheerful  and you can dill up the tempature by twiddling the knob, I don't recommend a normal mains iron until your experienced as you will learn the hard way melting things that cost to much

happy new year

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Many use mains irons without any issue, its just a technique you learn. I bought a 12 volt iron and found it almost useless and it went into the bin. The simple trick is not too linger too long with the tip on the joint, much better to take the iron off too quickly and have to go back again, and use a smaller tip. As you have suggested learn on an inexpensive wagon first, then buy kits from companies who will sell you replacement parts (just don't expect free replacements)

 

The amount of heat you will require depends on what size castings you are joining, the vast majority use mains irons, just watch Tony Wrights video. There are plenty of myths about soldering, its a simple skill which has to be learnt.

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Quite possibly - what's the minimum and maximum load ratings in watts?  If the minimum load is higher than the iron wattage then all you need to do is connect an extension block into the dimmer so you can plug both a soldering iron and a small lamp into it at the same time (the lamp should be fitted with a good old fashioned bulb, not a low energy or led bulb etc.)

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2 hours ago, polybear said:

Quite possibly - what's the minimum and maximum load ratings in watts? 

 

I can't find any details of it online and they aren't mentioned in any of the deals papers I can find on their site. Frustratingly I didn't have time to check in store as I was with family.

 

What's the purpose of the bulb in the circuit when regulating an iron? I've never been sure?

Edited by SR71
Pressed go too soon.
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I have a 50 W Antex iron with three temperature settings (non-digital) which I've been using very happily for whitemetal wagons in 4 mm/ft scale. I have a feeling it was a special from Carrs or similar a few years ago and may not now be available, which isn't very helpful...

 

I've had one or two minor meltdowns with my regular 25 W Antex - generally when I've been adding detail to a brass component and forgotten which iron I should be using. It seems to me that there are two routes to getting enough heat into the work to get a good joint: a high temperature difference between iron and work (which runs the risk of raising the work above its melting point) and a high-power iron, set below the work's melting point. My 50 W iron set to 160 deg is at the limit for the latter case for some of the chunkier castings.

 

As @Darwinian says, cleanliness of the surfaces to be joined is absolutely essential.

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The factors which from what I have gathered from various sources is that the amount of heat delivered depends on the wattage of the iron, the tip size of the iron and the mass of the items being soldered, a further difficulty is introduced when soldering differing materials to each other. I believe the knack is to heat the joint not the whole item(s). Therefore it is possible to solder whitemetal castings with mains soldering irons, many of us use Antex 25 watt Irons, but I ensure I use a smaller 3mm tip.  

 

If soldering whitemetal to brass, the perceived wisdom is to tin the brass first, you will then be fusing solder to whitemetal to solder, not solder to brass and whitemetal

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13 hours ago, SR71 said:

 

What's the purpose of the bulb in the circuit when regulating an iron? I've never been sure?

 

If the Dimmer Switch is rated at 40w Minimum (a common value for the type of basic wall dimmer switch often used to replace a simply 240v on/off wall switch used for room ceiling lights) then if you are using (for example) a 25w Antex iron then by adding a lamp with a 40w incadescent bulb (a common rating) you'll be ok as it will increase the load to 65w, i.e. above the minimum dimmer rating.  Just don't go over the max rating (you'll blow the dimmer), don't use low energy bulbs (even if above 40w) and don't use with any form of solder station.  Just a basic mains soldering iron.

HTH

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I use my normal 50W electronics iron, without any adjustments for the normal soldering temperature.

 

Note that you must use low melting point solder though, as normal solder melts in the same temperature range as the white metal itself!

eg. https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=white+metal+solder&_sacat=0

 

My technique is to cut small fragments from the end of my bar of solder using electrical sidecutters.

 

I drench the parts being soldered in 6% phosphoric acid flux and place small chunks or particles of solder against the joint. Then touch the soldering iron tip to the solder and allow that to transfer heat to the parts. The flux starts boiling off just above the melting point of the solder, which is an indication the heat is penetrating the joint. As the sizzling slows, the joint is generally done - the flow of solder is normally very obvious.

 

I've done small parts to thin castings like that and never destroyed anything (yet...)

 

For white metal to brass, you can heat the less visible side of the brass to minimise excess tinning & flow. I've never bothered tinning first for white metal work.

 

 

There was one item recently that needed a different technique - a tiny, very thin casting that needed attaching to a large casting.

With that I wet the surface on the parts with flux and sprinkled some dust-like solder particles on the main piece then set the small disc on top.

 

I heated it by briefly touching a part of the large casting that would not be visible, something like half a second contact then the iron away for a couple of seconds, repeating until the flux boiled. 

 

 

For info, dry cotton buds work very well for pressing parts in to place or rotating / sliding them slightly while the solder is molten.

I also use a cotton bud for fluxing the parts or joints. 

 

You do not need to buy flux at stupid prices - get some phosphoric acid rust remover from ebay and dilute a small amount to get 6% concentration.

I got a litre of 70%; with that, one part acid to 11 parts water.

 

Example - not as strong but you could make 2.5 litres of flux for the cost of  100ml (or less) at ready-made prices. Dilute with 4 parts water to 1 acid.

https://www.ebay.co.uk/itm/500ml-Phosphoric-Acid-Descaler-Rust-Remover-30-Safe-On-Metal-Surfaces/254374843653?hash=item3b39ec1505:g:BQIAAOSwlFFdkexO

 

The excess it OK for etching parts prior to painting!

I use disposable polythene pipettes for measuring the water (deionised) and acid. They are also very useful for transferring paints & thinners to an airbrush.. eg. 100 for £2.71 from China: https://www.ebay.co.uk/itm/100PCS-0-2-3-5ML-Graduated-Pipettes-Disposable-Pasteur-Plastic-Eye-DropperRDUJ/253405241660?hash=item3b0021213c:m:mIe58KaeefBBUdGtT-qMGlA

 

 

Photos of my technique in an article I did on it a while ago, here:

 

Edited by RobjUK
typos.
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