I have had trouble with soldering irons/guns before. I have a Weller (I think a 75 Watt) [W] gun that hasn’t worked right from about when I bought it several years ago. After fooling with it extensively to get it to work right, I’m trashing it and getting a new one. I also have a little 25 W iron that works OK, but it is only good for soldering small jobs, like splicing two wires together; it doesn’t work well for trying to solder wires to rail, as it has to heat too long before it melts plastic ties. Also, in my case lately, I’m building my own turnouts and the heat to adjacent welds will melt the solder causing the adjacent rail to come loose using this iron.
My question, then is: what is a good wattage soldering iron to go with for those critical jobs that require quick heating to get solder to flow into the soldered area without affecting the other work? And, (yes, I’ve used a heat sink. I’ve been told that a 75 or 100 W tool works best, but I’m not sure about that. Also, what brands have any of you had the best performance out of? Thanks
You are looking at two distinctly different kinds of soldering - which requires two different soldering tools.
One - soldering small wires to each other, to pins in a plug/socket or to traces on a PC board - low-wattage pencil iron, preferably temperature controlled.
Two - soldering more massive items, where the need is for a lot of heat in one spot NOW. For that kind of work (assembling brass models, soldering hand-laid specialwork, soldering drops and jumpers to rail without melting plastic ties) the tool of choice puts a lot of hot tip in contact with the work for a very short time. My weapon of choice is the biggest soldering gun Ace Hardware offers - and give that big chisel tip time to get hot BEFORE touching it to the work.
In order to keep heat from undoing earlier soldered joints, use heat sinks. Paper clamps, damp paper towels, even modeling clay will absorb/dissipate excess heat before it migrates to places where you don’t want it.
An all-important consideration is that any joint to be soldered has to be squeaky clean and mechanically stable BEFORE heat and solder are applied.
Chuck (Modeling Central Japan in September, 1964 - with LOTS of soldered joints)
I’ve got a Weller in my cabinet that hasn’t been turned on in 7 or 8 years.
I was at an electronics place, and I bought a small iron with a variable-heat dial on it. It’s got enough to solder to rail, but I can dial it back when doing circuits and chips. I think it cost me $15. Yes, it has to heat up, but patience is a virtue.
For soldering rail, an iron of 100 watts or better, or a soldering gun of 200 watts. Irons have larger tips that hold more heat, so they can raise the work to soldering temp faster than a gun. Actually, you want the biggest iron that will fit into the work. They don’t sell big irons anymore, I had to go on E-bay to turn up an old Craftsman 150 watt iron.
Instead of investing in bigger and bigger soldering irons and guns, I would invest in some soldering lessons from a trade school, community college or someone skilled in electronics assembly work. With the right skills, you’d be surprised at how well you can solder together large items with even a small iron.
The gun is great where you need a lot of heat quickly. For example, I am building a small industrial locomotive (critter if you will) using brass sheet and wire. It can be very tricky soldering a piece on without melting previous joints. I use wet paper towels as heat sinks, and with the big gun once you have the (very clean !) tip hot it takes only micro seconds to make the new joint and the rest of the work is not disturbed (at least most of the time anyhow, I am not perfect!).
For circuits, decoders, light bulbs, LEDs etc. I had a 25W fine tip iron. For track, esp building turnouts, I use a Weller 80W.
I still have both irons and several 40W I used to use, until I came across a Digital Iron. The temp is variable from about 300F to 845F. I haven’t tried it on building turnouts, but it makes super easy soldering everything else.
I tried guns before, and they’re more trouble than they’re worth. They may say 100W, 150W, 200W, but they are a lot heavier, and more clumsy than a light weight Iron.
I now only have two tools, a variable temp 45 watt soldering station, which works for fine circuit boards, decoder wires, on up to soldering track. And I have a 100+ watt gun for soldering the heavy bus wires under the layout.
A variable temp station is the best investment you cna make - and good ones are under $50. The Weller one where the iron plugs in to the side with a normal 3 prong AC plug is NOT the one to get.
Why? Because a normal iron keeps heating as long as it’s plugged in. The tip gets way hotter than needed to solder, and quickly oxidizes. The blocks heat transfer, making you press harder and hold the tip on the joint longer to get the sodler to flow. This is what melts things around the area yoiu are soldering. A temperatuire controlled unit only heats up to the set temperature. The tip stays cleaner longer, which makes the heat flow to the touched area immediately, so you can flow the solder and remove the heat source before it has time to migrate to nearby components or plastic pieces.
That’s fine if you are making one or two connections and then are done for the night. Usually I sit down and build a bunch of things all at one time - stack of Tam Valley Singlets, for example, or even a decoder installation, which can take significant amounts of time (espcially if you trim all the wires neatly, and insulate with shrink tube). If there will be a dealy between solding operations, I can turn my station down to minimum, it heat right back up in seconds when I need it. Also turned down low, I can shrink the heat shrink tube without melting it. It’s so much better than a simple iron, I can’t believe I waited so long to get one. And it replaced three stadard irons of various wattages.
Thanks, guys, for the information. I am for sure getting a variable setting soldering tool. That looks like the way to go. The long heating of the small iron also may be the reason I’ve melted some plastic ties in the past. It makes sense that the excess heat from the iron will cause it to heat up the area to be soldered, plus everything around it too.
[tup][tup] Unless you know how to use one, a larger iron will just melt more ties quicker… I learned how to solder form an electronics repairman locally who learned how to solder form his father who owned a TV repair shop who learned to solder in the Air Force! Here is what he taught me:
I’m using a 25w Weller iron. You don’t need a lot of heat. You need a quick transfer of heat as fast as possible right where you want the joint. Then get out of there. You will not have a cold solder joint with this method and the trick is to use a rosin flux separate from what is in the solder. The molten solder on the tip of the iron transfers the heat very fast as it has a much larger area of contact than just the iron. You will not melt the tie doing this. The little fake spike probably, but no damage to the ties. the video is from a clinic I did for my local division of the NMRA a few years ago.
Very good demonstration! I’m going to practice this method on some scrap track. My question is: can you use this same method for soldering rail to PC board ties on hand laid turnouts without affecting other work using this method?
Thanks Tom! Quick answer is yes. I use the method as much as possible. However, soldering next to the point rails, I use a piece of card stock to make sure the points don’t get soldered down in the process. Again the secret is the use of some rosin flux besides that which is in the solder itself.
