Loco Kit Assembly

Almost completed an old white metal K's coal tank. Had soldered the odd bit on a couple of others, but this one is my first nearly all soldered. Incredible the ease and speed it goes together, plus hardly any clean up required. Much easier to get things lined up correctly - esp side tanks at start as well as can fix if need to change later without masses of cleanup. Also bent top of tank too much and it was about to break under its own weight - quick solder, fixed solid in seconds.
Realise most kits say soldering preferred, but didnt realise the benefit till now.
Cheers, Simon

simon wrote:
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The first kit I put together with 'Superglue' fell apart inside 18 months. The ones I soldered are still complete. One advantage of superglue is you can have all the fun of assembly at regular intervals without buying a new kit! ;-)
Greg.P.

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I had that problem when first tried to use araldite only it was 18 hours. Then realised mix thoroughly and casually introduce were not quite the same.
Cheers, Simon

simon wrote:
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Been there, done that too :-( One sign you've got it mixed properly is the constant colour throughout. Trouble with the 5 minute stuff is it takes 6 minutes to mix it properly.
Greg.

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Incidently did soldering with cheap 30w iron without problems but some concern about the temp, however asked trader about minmum wattage for Antex iron and was told use temp controlled one as 18W may not deliver enough heat to the joins. However, I dont want to pay that price, would prefer basic 15 or 18W - anyone know if they would be powerful enough ?
Cheers, Simon

simon wrote:
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Temperature and power are not the same things at all.
Wattage is the amount of power an iron can sink into a piece of work. A bigger 100W iron can sink 100W of power into a big-ish lump of metal. Whereas a 15W iron can only sink 15W, and then its temperature plummets as the big piece of metal can absorb all that heat and more.
Temperature is degrees C at the tip. A temperature controlled iron lets you decide what value that should be. Different types of solder melt at different temperatures, typically "low melt" for whitemetal kits can be below 100 degree C, whereas the old lead-based plumbing and electrical solder is 188 degrees C.
With a lump of metal on a whitemetal kit, you may find that the 18W (or 15W) iron will drop to about the right temperature. Or you may find it drops too low (and nothing melts), or you may find you touch a small detail and it delivers 15W at 300 degrees C into a detail and destroys the detail.
You can get a crude, though effective, form of temperature control with an old light dimmer powering a small iron. One or two makers used to sell similar devices in a little plug brick. Or, sometimes, discounters such as Maplin have cheap temperature controlled irons on sale.
- Nigel

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Thanks for the full answer, suppose it comes down to trying it out. Has anyone tried to solder the major parts of a whitemetal loco kit using an antex 18W iron ?
Cheers, Simon

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Yes, and I now had a Weller temperature controlled 40W soldering station. http://www.brewstersbatteries.co.uk/catalog/weller-whs40lt - solder-station-special-edition-p-49.html
Although I got mine from Expo tools - always get exceptional service from them but thier site's a bit "sh 1 T" http://www.expotools.com (Looks like their currently the victim of "passing off" as the ".co.uk" diverts to someone else.
I'd echo everything Nigel says, it makes such a difference to have constant power at the right temperature - regardless of what you're doing, brass, NS, white metal.

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I've had an Antex temperature controller for about 20 years like: http://peats.com/cgi-bin/catalog_v2.cgi?id 83&type=product but it was only about 10pounds. There is a newer model at a more reasonable price at: http://www.rapidonline.com/1/1/2816-energy-regulator.html
Alan

On 17/01/2011 4:59 AM, simon wrote: [...]
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No. Problem with a low-power soldering iron is that heat is not transferred fast enough, which in turn means that the heat has plenty of time to migrate away from the joint, which means it takes even longer to heat it up, and so on. On large parts, you'll never get the joint hot enough. Low-power irons are made for fine electronic work, where the mass of the parts to be joined is very small. That's not the case with white-metal locos.
Even 30W can be problematic on larger parts. I use a 50W/100W gun, and heat sinks on either side of the joint. If there's no room to clamp them in place, a wet rag as close as possible to the joint will work.
All this implies that you can hold joints securely in position for soldering. A tip I learned years ago was to keep a lump of plasticine handy. You can make all kinds of ad-hoc supports with it.
HTH Wolf K.

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Good point about holding parts, was doing that - great warning mechanism. Will stick to current iron then - it works for me.
Cheers, Simon

On 17/01/2011 15:20, Wolf K wrote:
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I was about to say the same, but Wolf beat me to it. I have a 50W adjustable temperature iron, and that works really well.
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Nah - singed fingers are part of the fun :-)
Incidentally, Simon, which solder are you using? Hopefully 70degree stuff. That's quite a "lumpy" solder so it's particularly good to use as a filler. I do also use 188degree, but you need to be quick and have chunky castings!

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Yep its Carrs's 70degree along with thier red flux. Have used as filler on part built kit where boiler jooin was a bit prominent - saved splitting and refixing, had to make sure fresh surface available though. One time accidently used 140 degree and lingered there was slight damage to white metal - best way to learn :-)
Thanks, Simon

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Blue tack for me :-)

simon wrote:
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Hi Simon,
short answer: NO.
Look at the quantity of metal attached to the bit of the iron. Look at the quantity of metal attached to the join you want to solder.
Broadly speaking, if both are equal then the temperature is going to average between the two chunks of metal.
Little iron needs to be very hot to balance out at solder melting temperature. Big iron can be much cooler to balance out at solder melting temperature.
Really hot bits tend to melt the whitemetal before they solder it. (Not good)
The wattage needs to be sufficient to maintain the required heat over the bit and soldering object. It's quite depressing to end up with a 20w iron soldered to a large loco casting!
Adjusting the temperature of an iron can be achieved by putting a lamp dimmer in series with the iron, or even just a standard batten lamp holder in series. Adjust the iron temperature by varying the wattage of the light bulb you put into the bulb socket. A wattage equal to the iron's wattage is a good place to start. Get some whitemetal spruhe from the kit and adjust the temperature down until it is just below melting a small piece of spruhe.
Unfortunately every soldering task is different so there isn't one standard answer.
Greg.P.