I did a few practice runs on some old rail that my dad had left (brass, Code 100), since I don’t have any “spare” track yet. Everything else I have is new Code 83 flex track. The third attempt was messy but seemed to be solid, so I took a deep breath and tried a joint on two pieces of my new flex track. I’m not sure it looks like it should. Below you can see the outside of one rail and the inside of the other.
On both rails, I put the soldering tip on the top or the outside, not on the inside. I didn’t do anything on the inside of the rails except put (rosin core) flux paste there. I hoped the solder would flow to the insides. Hard to tell whether it worked. However, before I pushed the rail ends together I actually put a dab of flux right inside the rail joiner. I think the outside top/right one looks okay, but a dab of solder got onto the top of the rail there, and on the lower/left rail the top got quite a bit of solder on it. I’m just clumsy.
Questions:
In your view will these soldering jobs hold on a curve, or do I need to redo?
How should I get the solder off the top of the rails? should I file it? Sand it? What do you do (besides not get solder on the top of your rails)?
Where do you guys actually touch the soldering iron to the rail to heat it up? On top? On the outside?
My next questions are about the strategy for where joints go around my curves. In the picture below, I’ve marked with a red pin where one three-foot section of flex track will end. It’s not quite out of the curve. There’s a short straight section there that you can see better in the last photo (to avoid an S curve) but that track won’t reach the straight.
I wouldn’t worry about where one length of rail ends - figure out roughly how far you need to go before you come to a turnout (or the end of a siding), then solder together enough lengths of flex track to get there.
If you overshoot it a bit, cut off the excess, add the turnout, then carry on in the same manner.
This will allow you to do the soldering as a straight length of track, which can then be curved, as required, to follow the cork roadbed that you already have in place.
You can use a not-too-coarse file to clean the solder off the top of the track - leaving it in place is a derailment waiting to happen.
As you continue to add and solder subsequent lengths of track, your confidence will grow, as will your abilities. It’s good to be cautious, but don’t let it make you timid…you’ve already made some solder joints, simply carry on - you can do it!
Your solder joints look OK. The solder is shiny, the mark of a good joint. Joints that have a frosty look to them are called cold solder joints and should be reheated with the soldering iron and allowed to cool without moving them.
I get unwanted blobs of solder off with a small file.
I use a big iron or a soldering gun good for 100 watts or more. I keep the tip clean and shiny (tinned). That black crud that builds up is an insulator and will slow the flow of heat to the joint. I press the iron right on the rail jointer. We want solder to flow by capillary action all down the inside of the rail joiner. This works best if the rail joiner is good and hot. I use a couple of alligator clips as heat sinks on either side of the joint to cut down on the melting of ties. I use 60-40 tin lead solder. Avoid the 50-50 solder, that is only for plumbing. I use rosin flux.
Always hard to tell by a photo, but your joint does look fine. Give it a gentle tug. If you can’t pull the joint apart, it should hold just fine.
Yup.
On a side (inside or outside), but never on top.
Not necessary. Joints in curves is a reality of layout construction and done properly (you are well on your way to that) won’t be a problem.
As the last piece laid down. Trying to guess what length filler piece you need, and then putting it in the middle of the run opens you up to having to cut the length down again because you misjudged and made your filler too long, or worse, too short and have to work in more. Just work from one fixed point to the next (turnout to turnout for example) and cut you last piece to fit.
Your soldering job looks sufficient to me, but I always make sure that the solder covers the entire entire rail joiner. I can see the ends of the rail joiners in your photo.
There is no need for solder to enter the inside of the rail, and you want to avoid that as it could interfere with wheel movement.
As far as the blob of solder on top of the rail, place the hot tip of the soldering iron to melt it and rub off the melted solder with a rag. Gotta act quickly before the solder cools.
You are worrying unnecessarily about short sections of track. Once the entire length of flextrack is soldered between sections, it becomes one long section of flextrack that you can bend without kinks to the desired shape. I don’t see any problems in those 2nd and 3rd photos.
In general, when soldering (by whatever method of heating) the substrate – here, the two rails and the joiner – are heated enough to melt the solder and flux that are applied. The liquid solder will then run into the joint with capillary action. The indirect heating from the iron is continued until that has happened.
I advise applying the iron to the outside of the joint (and incorporate any feeder wires there). That is because the gauge corner and flange face of the rail are important to running, and you want to minimize buildup and blobbing there. You can build up about as much metal as you can stand on the outside faces of the rail and it won’t affect running…
Some solder is made to be ‘sludgy’ for a time while it is hardening. That’s an advantage in some applications, but not here: if you move the joint, or let it move or ‘spring’ even a little, you’ll get that frosted appearance that says the joint isn’t as strong. There are compositions of solder ( for example in the 63:37 range) that harden nearly at once. Those have the fancy name “eutectics”. I advise you use them for this kind of work.
As a general rule: don’t apply the iron, and don’t apply the flux, to any surface you don’t want solder to adhere to. You can reheat the joint area (from the outside) and use a piece of solder braid to ‘wick up’ any solder that’s gotten where it shouldn’t be.
You file the rails, not sand them, for a simple reason: you want the finished railhead and gauge corner to be clean and flat. Unless what you use is very flat and rigid, you’ll tend to get a bump at the solder blob.
The solder joint looks good to me. I’ve never been great at soldering so I clip heat sinks on before soldering. That way if it takes a little longer to heat and appy the solder, the ties won’t melt.
As others have said, everything looks fine. Ugly soldering joints are okay of they are on the outside and facing the backdrop. You wont see them.
For the track that faces the benchwork edge, I solder on the inside of the rail. I would not want to get a lot of solder in the joint where a wheel might hit it.
Always placing the tip on the inside or outside of the rail, never on top.
If you get too much solder in the joint where you don’t like the appearance, I shmear flux over the blob and the bare side of the rail. Applying heat to the solder with the flux tends to melt and thin the solder so it flows throughout the joint.
For really heavy or unsightly solder blobs, you can heat up the solder the same way and wipe off with a wet paper towel. The towel needs to be quick, almost touching the iron tip as you remove the iron and follow quickly with the wet towel.
Same here. I’d rather not risk any solder interfering with the flanges. You can solder on the out side of both rails and it will be fine. As long as there isn’t a ton of solder, after you paint the track, it shouldn’t be a detraction from the appearance.
I’ve done this, but only when/where I’ve had to due to not being able to see what I’m doing on the outside of the joint. One has to be VERY careful doing this though.
The number one mistake in soldering is using too much solder. That’s what causes the bumps and lumps you need to grind off with a fine needle flat file or a Peco track cleaning block.
The soldering iron isn’t used to apply the solder, it heats the joint so the solder melts when applied to the joint. If you avoid touching the soldering iron with the solder (apart from tinning the tip of the iron) you’ll have better success with the blogging problems.
You want the solder inside the joint. The heat from the iron draws the melting solder inside the joint you want without the iron touching the wire solder end. Rail joint soldering is more like plumbing pipe soldering (a dying skill btw) than electrical wiring soldering. Touch the solder to the joint not the iron.
Having said that, your soldering job is pretty good and you’ll rapidly get better as you do more joints and need less time for each. Less time with the iron on the joint automatically reduces the amount of solder you end up using. If the joint is just hot enough to draw in the molten solder you’ll get a hot joint.
As for moving the rail joints, yes, by all means plan your flex track pieces to put joints where you feel they will experience less bending forces. Atlas flex track is the stiffest and takes the most force to put a permanent bend in. Atlas flex track is very springy.
Atlas also still makes nice sectional track which is handy to use to move flex track joints to a different spot. The straights are especially handy. For instance, one piece of straight track connecting to your turnout would move both curved joints. The 24" radius curved sectional track can also be handy if you are tolerating that as a minimum radius.
Another tip is to connect the turnouts last because those usually cannot be moved, at least if your plan is good. Turnouts anchor your curves whereas you can alter the radius and easement of any curve if you choose to. Same for choosing where to begin an
You want to make it pretty, just get the iron up to temp and swipe it over all offending soulder. I tend to end a joint by running the iron over the head real quick to smooth out any stray soulder and thin it out if it exists, make any touchup filing effortless. Even major messups can be fixed, once had a joint on a curve that was done after it was laid as the whole curve setup was too long to do in one piece, it looked like it was kinked but it wasn’t as I filled in and filed the offending kink and filed away the kink on the other side, a lot of work but it ran perfectly but would find another way if I had that situation again but a good example of you can fix it.
That is: I agree that your solder joints are good. You want a nice smooth good-looking flow.
But let’s talk about ties:
You might heat damage a tie. This is NOT a problem. Cut it off with your rail nippers.
Whatever you do, you’ll likely have a tie-less section. One option is to insert single replacement ties underneath. You’ll probably have to clip off the “spikes”, but you might get lucky and snap them on.
For the rail joint section, you do NOT want to do this, as it will raise the rail at this point, since there’s the additional thickness of the rail joiner. You might file those replacement ties thinner, but I cut my ties into pieces, removing the section at the rail joint. Then I just drop them down from above. You can’t see under the rail joiner, so the missing section isn’t a problem.
The big thing is to not have a bump caused by you replacing the missing ties.
If you use the foam trackbed such as from Woodland Scenics you don’t need to worry about bumps from the joiners (or messy solder for that matter).
That foam track underlay actually mimics real ballasted track much better than any other type of underlayment. Real ballasted track floats within the ballast. That’s how ballasting works.
Laying real rails onto very rigid subgrade with no vertical movement compliance is a specialized process. Railroads aren’t built like vehicle roads, although very interesting designs have involved laying concrete roads over a layer of asphalt “cushions” and in deep frost areas like mine over thick styrofoam insulation layers. Our downtown LRT rails are embedded in concrete which in turn sits on about a foot of styrofoam and then the subgrade. Only outside the street areas is the LRT ballasted normally.
PS it is obvious you can’t solder rails while they’re actually sitting on this foam underlay. No?
Yes, I’ve always soldered on the side of both rails that face the backdrop. Done probably over 100 joints over the years.
If you use enough flux and not too much solder, the solder flows into the cracks and doesn’t leave any blobs. Make the rail nice and hot before applying the solder to the (GERN) fluxed joint.
BTW, if you use GERN Flux, it will be a solid joint!
Ditto. And slide the tip over the joiner back and forth to smooth out the work. If the solder sticks to the tip as you raise it, there is way too much solder on the joint.
And the proper way to do it, would be to heat the opposite side of the rail from where you apply the solder, to draw the solder through the joint.
But I’ve found that heats up the rail very hot and it tends to melt the ties that are even half an inch away.
Its not a plumbing joint where we need to avoid voids and leaks. We’re just securing some rail joiners.
Guys, thanks so much for all this. Good to know I haven’t completely flubbed the job, and there’s lots of good sound counsel here. I feel a lot less intimidated having done one joint.
Mike, I think you mean exactly the opposite, right? That the final joints will be easier if they are NOT within a curve, or? At the end of the day, though, there will be joints in curves. I’m taking the advice to solder together several flex-track lengths to reach from one fixed point to the next, and only cut down one piece.
Douglas, what is GERN flux and why do you like it? I have two tins of rosin flux already, one of Kester 135 Rosin Core that I ordered online and another of Weller rosin core that came with the soldering iron cleaning and tinning kit. I was originally hoping to get liquid no-clean, but I find that the paste is very nice in that it starts to sizzle and go opaque when it gets hot enough to solder. I like tools that talk to me. [:)]
