I found a device that allows you to spot weld (real welding, not soldering) the shoes to the rails, thus obtaining permanent electrical continuity. It is an inexpensive (less than 30 euro) battery-powered device that generates currents up to 650 A and is commonly used to weld rechargeable batteries together. Once switched on, just apply the two electrodes on the points where you want to have the welding point and the metal is instantly melted in a point of about 1/2 mm in diameter. THE PROBLEM The permanence of the conductivity of the shoes is a problem recognized by layout makers . A little humidity is enough to create problems. But especially in realistic layouts, where the use of track painting and the application ballast exposes metals to the danger of oxidation or galvanic corrosion, conductivity is a problem. The common method of correcting the loss of conductivity is by soldering the shoes to the rail. Another way of containing voltage losses is to bring many current points (feeders) to the track. These also require soldering the wire to the rail. Soldering has the drawback that it heats the track a lot with the risk of melting the bed of sleepers which are made of plastic material. THE PROPOSED SOLUTION Spot welding creates a weld point between two sheets, by passing a very high current between them which melts the point on which the two sheets are pressed together. The metal heats up a lot only at the point of contact, but it remains at room temperature even very close to it. The device in question is small and charges with a USB-C phone charger. Two short pointed electrodes come out of the device. Typically, once switched on, the device emits current discharges every two seconds (but it can also be controlled differently). In the particular case of welding shoes, simply place the cylindrical side of an electrode on the rail (** on the side of the joint on which you want to weld) and point the second electrode on the shoe. The weld spot is created instantly. For good , I applied 3 spot. The rail remained cold and at the end of the welding the two pieces of rail were integral as if they were a single piece. I imagine that this method can be applied in other cases, such as for the welding of photo etched sheets, the welding of metal rods / wire to make railings or catenaries, and who knows what more. I will experience these things in the future. If interested just Google "mini-spot welding machine" Ciao G. ** if you put the electrode on the other side of the rail joint, the current will flow through the shoe and it will vaporize it... I had such experience.
I understand that some live and/or in widely varying environments (humidity and/or temperatures). But I have never heard or seen rail detach, unless the rails were soldered together. This is a no-no, as thermal expansion is amazing. Since track cannot be perfectly laid, there always will be a highly tensioned joint (and possibly several in a row) making the possibility a reality. If I am not mistaken, a Shoe is for 3rd rail pickup, which Z doesn’t use.
Jeff, my post is for those who already solder rail joiners to guarantee electrical conductivity. If you do not need to do so, lucky you. Whether you solder the rails or not, the track layout needs to be designed to account for thermal variation (expansion but also contraction). With respect to thermal variation (which induces both tensile and compressive stresses) the real problem is not the type of rail joining but the the way the track is fixed. If the track is rigidly glued over long length and it is not allowed to move, rails will eventually buckle, break the fasteners and detach. In modular layouts the problem is less seen as the track can eventually release longitudinal stresses at the module ends. For large unbroken layouts, one has to foresee curved sections that float over the layout deck so that the track changes slightly bend radius over the thermal change. In general about soldering rails, all real-size modern railways use continually welded rail (CWR); bolted fishplates (joint bars in US) are left for secondary lines. Management of rail buckling is indeed a problem, however in the real-size railways the, approach is to prevent rail buckling is often to actually make tracks and trackbed very stiff. A good read over buckling prevention techniques in real life is here. About the term shoe, I used a term commonly used in Europe for what you would call rail joiners, apologies for the cross-cultural misunderstanding. Ciao G.
As I started to read your first post about ‘shoes’, my elder years poured through ‘where have I heard that before’ . . .eh, had to look it up and all related to the 3rd rail contact (likely US searches 1st). So I began guessing, thinking (keeps me alive). All good. If I understand correctly, you are essentially welding the rail to the shoe (joiner)? And only 1 of the 2 rails? If so, would this not make the issue worse by no longer allowing the thermal expansion? There are a lot of variables here, as mentioned. Larger layouts with curves for sure at the top. If someone has issues with track running power and thought or read to solder the rails instead of just a few extra feeders, it’s sorta a life lesson. Not sure world wide this has happened but I have experienced when wife’s N scale module slow fell iut of the shade into a few hours of sun and a fellow Z trying to lay his own track (cheaper ) and with all those cm-spaced soldered ties, it didn’t take long. But even with a larger layout, section track or high flex (longer sections) that is all glued and/or soldered, I wonder how many have run into track warping?
Could see a mini spot welder being use to weld tabs to the bottom of rails for feeder points instead of having to solder wire directly to the rail. Would be good on track like Rokuhan where it's all too easy to melt plastic.
In the model fairs I attend, I see that most layouts end up having soldered rail joiners (on both rails), this particularly on switches. You can add feeders to track but with switches it is less common as it is more cumbersome. What I am using, replaces soldering with spot welding. Indeed I spot weld the joiner on its 2 facing rails. This does not make the issue of thermal expansion worse with good track. Good track is cut so that there is no rail gap when joining track sections. With a rail gap, two contiguous rails will thermally expand into the gap, and this will be allowed by the rail joiner that can slide over track. Indeed if the joiner is soldered/welded to both rails, the rails won't be able to expand into the gap and hence will need to expand elsewhere However, good track is cut so that there is no rail gap when joining track sections (at room temperature) . If there is no gap, it makes no difference whether you solder/weld the rail joiner or not. The problem you mention is a bit different. When you have self made track, with soldered ties, the problem of expansion is made more acute as the rail cannot move with respect to the ties. This is due to the solder joint. Furthermore, as the ties are embedded in rigid ballast, they cannot move also with respect to the layout deck. With heat the rail will expand and elongate. As it has no possibility either to slide over the ties (due to the rigid solder joint) or to move the ties with it (as the ties are blocked by the ballast) it will load the ties with huge shear stress. The latter eventually will crack the weakest part of the rack (normally the solder joint). With self laid track, one has to use non-rigid ballast Ciao G.
Yes this is what I do: Here is a picture of two Märklin track sections with their joiners spot welded and 2 nickel tabs also spot welded as feeders. It is before brushing off the spark dirt. I think it is very neat. At least much better than I could ever do with soldering.
I like the feeder tabs. I just noticed nickel strips on a Z supplier website. This looks like a perfect place to use them. Jim
