How do you plan to support (stabilize) the cassette and pivoting arm when using the cassette before you construct/install the yard shelf? As drawn, you'll need a way of securing it at exactly the same angle every time you set up the cassette, because even a very slight difference will produce a shortening or lengthening of one flex track rail compared to the other. Have your son put on his track inspector's hat and grab his experimenter's clipboard to do some investigating: Use rail joiners (either the metal ones or the plastic insulating kind) to connect a piece of straight or curved sectional track to a piece of flex track. Use track nails to secure the sectional track and the first 6 inches of a 30 inch long piece of flex track to a long board or piece of foam. Make sure there is no gap at the rail joiners. The flex track should be perfectly straight and the flex track rails at the opposite end from the sectional track, should both be even. Have the track inspector gently push the loose end of the flex track about 1 inch to the side so there is a slight bend or arc to the flex track. At the secured end of the flex track, check that there is still no gap between the rails connected by the rail joiners. Back at the loose end of the flex track, have the track inspector measure how much longer one rail is than the other. At one inch deflection, the difference will be hard to see. Repeat measurements when the flex track has been displaced 6 inches to the side, and measure again at 12 inches deflection. the difference between rail lengths should become more noticeable as the amount of deflection increases. Regardless of which way the flex track was pushed, the rail on the inside of the curve will be longer, and the rail on the outside of the curve will be shorter. If there is more than a 1/8th inch difference in the 2 rail lengths (and if your were actually going to install the track on the layout with a comparable curve), then track reliability would be compromised and you would probably want to cut the longer rail so both rails at the loose end of the flex track are evenly matched again.
The cassette will be secured in exactly the same way as the yard section. I'll be using furniture dowels in a pattern (holes and dowels on both sides) to ensure proper and precise alignment. Underneath will be a spring-loaded clamp type lock to keep the cassette (or yard section) stable until it needs to be removed (probably something like a heavy duty equipment case lock). Wires will be configured with an appropriate removable plug (din, banana plugs, or whatever else I can come up with). Also, I'm very familiar with how flex track works. I've been working with model railroads since before I could walk. Hand laid track, built open benchwork, scratch built and kitbashed locomotives, rolling stock and structures, and have even been knee deep in hydrocal and chicken wire. Basically the only stuff I'm not yet experienced in is DCC, and that's out of our budget anyway, so not an issue (not that it isn't freakin' amazing stuff, though!). Since the cassette will always connect in the same way (exact same angle), the length of the rail will be correct when the angled portion is fully pivoted open. Also, I did some build testing in XTrakCad and have decided that rather than a middle track, I'll probably use a simple crossing in the middle for switching to the opposite side. Otherwise the switches will route trains to their correct lane. Been there and done that. That was probably one of the first things I showed him about model railroad tracks. Nevertheless, I do appreciate your attention to detail. I definitely don't want to make costly mistakes (especially since we can hardly afford to do this in the first place) and your feedback has been super helpful in making sure that I don't leap before I look. And not to worry. Before I spend a lot of time/effort/money in building a cassette this way, I'll be testing it on a mockup, probably made of cardboard, to see if it will work the way I think it will. OK, off to sleep. Thanks again Dave. You rock! -Matt
And yet another revision. In this revision, I took the switch for the fuel oil facility and moved it to the main line feeder, then added a 15 degree crossing. This makes it easier to drop off and pick up tanks, as well as bought me another inch on the big grade up to the coal mine. I also smoothed out the main line on the right side to give a little more space. You know, if XTrakCad didn't have a "run trains" feature, I don't know if I 'd spend so much time working on the layout design...
