As I begin to work on more white metal kits like the PECO Nn3 tram kit, I’ve been thinking of changing my white metal construction tools from epoxies and CAs to low temperature solders on the larger parts of my kits. The trick to soldering white metal is in the metal itself, generally a tin and lead alloy but can include several other metals as well. Each kit manufacturer can have their own white metal recipe but they all share one important characteristic, a low melting point. Conventional soldering tools can turn your white metal kit in to a white metal puddle if you’re not very proficient with a conventional soldering iron.
For most of my soldering needs I use a resistance soldering setup and I love working with it, it’s both effective and fun to use. For white metal kits though, the resistance soldering unit can cut through a low melt point white metal kit like a hot knife through butter, with little warning.
I thought about going with a low temp or adjustable temp soldering iron until I saw a video on YouTube showing a very cool technique for low temp soldering using a small torch. Let’s have a look at this torch technique below.
I have to admit I’ve only practiced this torch technique on a couple of scrap pieces of white metal so far but after just a couple of tests, I’m no longer melting the white metal scrap pieces, instead I’m getting really nice solder joints.
Rather than talk about specific low temp soldering materials or techniques in this article, I’d like to focus on the torch I recently bought, the Bernzomatic ST200 Micro Butane Torch. Since I didn’t know how well I’d take to the torch technique, I didn’t want to spend too much money, at least not initially. I looked at several online stores including eBay and Amazon and went with this Bernzomatic torch from Home Depot. It was priced right at just under $10.00 plus another $5.00 for the butane and as important, it’s a very comfortable size to work with. The body of the torch measures 5 ½ inches in length, similar in size to a Sharpie marker, and it’s very comfortable to work with and to get the heat on and off as soon as the solder has melted.
At the base of the unit is the fueling point, a full refill from the butane supply can takes about 10 seconds, you can tell the torch is full when the butane begins to overflow. On the back of the unit is a slide switch to regulate your flame with output levels marked 1, 2, 3 and 4. Moving up to the business end of the torch there’s a blue on/off slide switch. Below the on/off switch is a small flip-out stand to hold your torch while the flame is on or when you shut the torch off but the tip is still hot. Very handy.
This unit also comes with a screw-on tip that lets you use your soldering torch as a more conventional soldering iron. As this was purchased for its open and direct flame however, I won’t be using this accessory.
Even on a $10.00 purchase, I did check out some online reviews of this Bernzomatic ST200 prior to buying. There were some complaints but these more had to do with the user becoming familiar with the unit rather than any serious product flaw.
Here are the major complaints I found online from some users of the Bernzomatic ST200, along with my take on them:
The unit doesn’t have a built-in igniter
This is correct; you have to use a lighter to light this torch. Given the price, this wasn’t an issue for me.
It’s difficult to light
What works well for me is to keep the flame output slider at the 1 or 2 setting, then simply put the torch end to an open flame. If I have the torch set to the 3 or 4 setting, it either blows out the external flame of a lighter or it keeps blowing itself out from the pressure of the fuel coming out.
When I first tried to light this torch though, even keeping the torch output slider at a low setting didn’t work. I did read a tip online suggesting you actually heat up the tip of the torch, the cylindrical bit at the end, with a lighter and you could then light the torch as normal. Maybe there was some machine oil or some other coating from the factory in the tip, I tried this “pre-heating” the tip of the torch and it did make lighting much easier. After using the torch now a couple of times, I find I no longer need to heat the tip of the torch prior to lighting.
At the highest flame setting the torch blows itself out
This one is true; I find the highest setting I can use on the output slider is 3 without the torch flaming out. This isn’t an issue for me as I find a setting of 2 on the slider more than enough for working with the solder I’m using, Carr’s 70 Low Temp Solder.
I’ve probably practiced 10 joints or so at this point without needing to refill the torch, so it seems as if it makes good use of its fuel. Overall, I think this Bernzomatic ST200 Micro Butane Torch is a terrific and inexpensive tool for soldering white metal kits.
Category: Useful Tools