Tunnel portals at Palisade Ranch

The next expansion of the layout will include this scene.   This is one of the most photographed areas on the prototype.  On the layout the scene will be viewed from the left as indicated by the arrow and after entering the tunnel portals the tracks will cross the lift bridge which was the subject of this recent post.  I already have the two  bridges and those were featured in this post.  Now it's time to create the tunnel portals.

This will be the portal for the SP line which is on the left in the above reference photo.  The curved top of the tunnel liner was made by cutting a section of 1-1/2 ABS drain pipe in half then adding sidewalls of 1/4 inch plywood.  The face and angled retaining walls are 1/8 inch hard board and a scrap of .060 x .060 styrene strip finishes the top.

Once the basic structures were finished the tunnel portals were placed over a straight section of track on the layout and all of the larger rolling stock were driven through to verify that they would clear.

The portal for the WP line was made the same way but without the wing walls.  It is longer and more of the top is finished as it will be exposed.  Both were painted with Testors concrete acrylic paint.  They will get a light smoke weathering and another pair will be needed later on the other end of the tunnel.

More experiments with Azatrax

Lately I have been finding more ways to use the Azatrax Infrared (IR) train detection circuits and sensors. Recently I received a pair of single channel detector circuits that operate a bit differently than the 8 channel circuit that I featured in the posts Experimenting with Infrared detection circuits and Automation of the yard's reverse loops.

This is the MRD1-V.  The V in the model number is for variable delay.  When the timing adjustment is turned all the way counter clockwise,  the relay will turn on for 1 second then turn off even if the beam is still blocked.  This is called one-shot operation.

The one shot operation is like pressing a momentary button on the control panel.  By connecting the relay in parallel with a panel button this could allow for some automation of the staging yard.  I built a small brass structure to mount an IR transmitter on top looking down with the receiver in the track.  The actual IR beam is invisible but the green line indicates where it would be.

The 1-1/2 inch spacing of my yard tracks is enough for the the trains to clear the 1/8 inch poles of the structure.

So with the relay output connected in parallel with one of the push buttons on the control panel this concept was successfully tested by pushing various cars through the structure.

Here is the MRD1-V temporarily sitting under the staging yard with the beam blocked indicating occupancy.  There is an occupancy LED on the board plus connections to have a panel mounted occupancy LED if desired.

I also tried out the reflective mode with the IR transmitter and receiver mounted through an old section of Kato track.   This also worked quite well with several different cars and locomotives but passing a hand over the sensors also could trigger the circuit so I will be careful where I use this setup on the layout.

Building an entry lift bridge

Over the past week I have been designing and building a lift bridge to carry the layout past the entry door way.

It has always been planned that there would be a lift bridge of some sort here and when I built the room in 2013 I added short sections of half walls on either side of the door to give the bridge something solid to attach to.

There will be tunnel portals on the layout at each end of this bridge so this bridge will actually be a pair of tunnels on the layout.

Here is the left bridge in the up position.  Anything that will go through the doorway such as modules will also pass by the gate.

When the tracks are installed there will be a short feeder cable on the hinge side to power those tracks.

The deck of the bridge is 1/2 inch plywood with 3/4 inch bracing on the bottom at each end.  This gives the hinge screws thicker material to go into.  The sides have 3/4 inch thick rails on the top side of the deck.

Both ends of the gate rest on 3/4 inch thick rails that are attached to the wall structures.   The entire bridge and the supporting structures were sealed with a primer then the outside parts were given two coats of the gray enamel that I use for my fascias.

So when the next layout expansion comes, the gate will be ready.

Modern truck for the diesel distributor

The fuel truck presented in the recent post "N Scale roots - cast resin vehicles" is OK for my 70's-82 era but I needed something more modern for the later eras.

I discovered a new line of 3D printed vehicle model kits from Royale Models.  I ordered this fuel tanker with trailer kit from their web site www.royalemodels.com.  These kits come in a package like the one shown in this photo.

This is what the 3D printed parts in the kit look like.  They are printed from the bottom up with many support fingers rising from a base.  There are no instructions included.

These fingers need to be carefully cut from the models.  I used a flush cut spue cutter to separate all the little fingers from the models starting on the outside edges and working my way in.  There was very little sanding needed with a 600 grit sanding stick to clear away any remaining nubs.

The only problem I had with this kit was getting the tank to sit correctly on the truck frame.  I ended up adding .020 x .040 styrene strips along the truck frame to raise the tank above the rear wheel fenders.  I also made a hitch on the rear of the truck for the dolly to fit onto.

There was not a very solid pivot connection between the trailer and the dolly so I made my own using .047 styrene rod then drilled out the hole in the dolly to match.

The truck chassis, tank, dolly, trailer, and wheels were all painted prior to final assembly.  Details were added with Sharpie pens.  Then it got decals and a spray of Dullcote.

Since the label on the box identified this model as being part of the Interstate Series, it seemed right to display it on the short section of I-80 that is on my layout.

These are excellent models and in my limited experience with 3D printed models represent the best available in that medium.