Max, thanks for the video and explanation. Now I fully understand how it works. However, since you still have to futz around with the slide switch (to control the frog polarity), that IMO makes the spring point feature redundant. So this is simply done the way you did it to show a well-working scratchbuilt spring switch in N scale.
Another thing I like to mention is that when the loco's (traveling from he siding) wheels push the sprung points open, the wheel at the outer point has its flange on the inside of the outer point, not in between the point and outer stock rail like you seem to indicate. The flange of the outer wheel actually aids in pushing open both point towards the outer rail.
Yes, that's true, the outer wheel helps push open the point. I was more thinking about wonky problems like the inner wheel nudging the points open and the outer point rail pulling out from underneath the outer wheel. Picture fine-tread wheels with treads only .040" wide, flanges that push the points over by .020", and then a little error in the spread of the point rails and the spread of a wheelset.
As far as the slide switch, since you can't just run out of the siding onto the main and keep running without throwing the switch,
yes, it's more of a "for show" and "see if I can make this work" feature. If one used DCC, that would eliminate all the need
to control the polarity or kill power to the siding. You would only need a switch stand to lock the points open for running back into the siding, which is prototypical. Making all that work fully automatically with DC would require pretty elaborate train detection, which I really didn't want to get into with this.
