With the correct solder and flux it is far easier to solder than to try and weld the rail together. While you can create a weld of sorts by shorting the two ends of the track to-gether a the correct amperage and voltage combination, you do not have the controls to control the process so you would not have a good weld and micro welding needs special equipment and tools to work properly and the cost far exceeds several engines. If it were practical and cheap it would already be a viable option in the hobby mags.
--- In firstname.lastname@example.org, Alan Cox <alan@...> wrote:
> > As an indication of the what can happen with excess potential power, consider this, at 9vdc and 20 amps you can weld code 55 rail together. Once welded if the power is maintained it will turn the joint red in colour and that is red as in very hot like an element on the stove top or a soldering gun.
> I have to ask - has anyone tried this seriously. I've got a 12v 18A power
> supply beast and Z scale track is a pig to solder ...