Rocky Mountain Pacific in Fn3

Rocky Mountain Pacific Logo-1

The Rocky Mountain Pacific is Bruce's Fn3 garden layout. Fn3 uses 45 mm (typical garden railroad) gauge track and a 1:20.3 scale ratio to model accurately 3 foot narrow gauge railroads.

The name is registered with the NMRA. It came from the idea of southwestern Colorado narrow-gauge railroads that were always short of cash and long on ideas. Everybody seemed to be planning on running to the coast or Mexico, when really they didn't have enough cash to get over the next hill!

The reporting marks for the Rocky Mountain Pacific are RMP. That can also stand for Real Money Pit.

This is being built in our back yard here in Goodyear AZ. It will use an NCE 10 amp radio DCC system.

Link & Pin coupler conversion

I have many AMS 1:20.2 narrow gauge cars. I like the detail on them.

I recently got a logging disconnect. It has link & pin couplers for the disconnect and for connection to the train. That’s fine if you have a full logging train that’s all link and pin. In fact, I have a mine train and I converted one loco to link & pin to pull it.

However, I want this logging car to meld into my mixed freight consists. So, I need to add a coupler that is compatible with the AMS couplers to this car.

Here’s how to do it in one minute or less. First you buy a set of Kadee 908 couplers. Put all the hardware in your junk box. You only need the two heads.

In the photo below, here is the logging disconnect car with its receptacle and pin and the Kadee 908 coupler.

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Next, I took a pair of wire cutters and cut off the “ears” - everything that sticks out on each side of the mounting boss.

Then, remove the pin and insert the Kadee coupler into the pocket. It will be a nice tight fit. Insert the pin and run your train.

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You can always go back to the link & pin setup by pulling the pin and removing the Kadee. Or, for a permanent conversion, a 2-56 (black) bolt and nut would work, but you’d have to drill the bottom of the pin pocket. Or, you could drill and tap the bottom of the pocket and forget the 2-56 nut.

Ready to Party

Today (October 10, 2015) we are hosting the West Valley Model Railroad Club and tomorrow a group of neighbors, including members of the PebbleCreek Model Railroad Club (

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While the track is all wired, the electronic connections (in the barn at the far left of the photo above) are not complete and the track has not been cleaned and tested. Turnouts may have rocks in them and there is a bit of ballasting to be done (in the area near the barn).

So, I decided on a static display. Many of the structures (depots, for example) are just pieces of the kit held together with tape or a bit of caulk, to provide an idea of the planned town and on-line industries.

One of the scenes was designed to show the difference between 1:24 (G-scale narrow gauge) and 1:20.3 (scale narrow gauge). The two boxcars parked on the spur headed to the passenger depot, see detail photo below, are the same series of box car from the same railroad. The one on the left (on the bridge) is 1:24 and the one to the right (sitting in front of the mock-up of the freight depot) is 1:20.3. The Goose in the foreground is 1:20.3.

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When these show-and-tell sessions are over, then it will be back to wiring.

Here’s the panoramic view. Click to enlarge.

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Over the weekend, we (Linda and I) got most of the track leveling and ballasting done. There are a few spurs that still need ballast and a turnout to repair.The large piles of stocks and dirt have been removed or leveled.

Our back yard is starting to look like a railroad, not a dirt pile.

I even started getting some of my Fn3 rolling stock out.

Track work continues

All of the bridges scratch built and exhibited at the NMRA AZ division meet in June have been installed. The track is now connected all around the layout.

On 9/25/15 I graded the yard - the last task in rough track work.

Now comes the ballasting.

Also on 9/25, I ballasted the yard and leveled the entire area. Once the ballast settles, it will be walkable, allowing for train make up and break down.

I’m using the same methods the prototypes did, except somewhat in reverse. 

The ground level was established by the landscapers I hired to build up the area and bring in topsoil.

The track was laid on that base and the track plan verified.

Next, I shim the track to the desired height and grades. Most shimming was done with 1 x 2 garden stakes. Occasionally more or less shimming was needed and smaller sticks and rocks were used. This was shown in a prior post - CLICK HERE to see it.

I used several levels to establish level and grade sections. The level used to establish grade is 48 inches long and has a ¾ inch copper pipe coupling zip tied to the end. This provides 1 inch in 48 worth of rise for a 2% grade.

Once an area was shimmed,  landscape decomposed granite was tamped under the rails. Here I used a tool of my own design - a truck with a bubble level attached. It helped me to maintain grade and to establish the desired right-to-left level.

Once the granite was under the track the area was ballasted. I used what landscapers call ¼ minus rock. This is what comes through a ¼ inch screen. When it gets wet, it sets up almost as if it had concrete mixed with it. However, it can be broken loose if desired.

A single track cement culvert

On June 10, 2015, I finished a scratch built culvert for the final bridge I need to complete the main layout. The mine-to-stamp-mill track needs a replacement. That’ll come later.

Here is a photo of the culvert. I’ll be taking it to the AZ division NMRA meet this weekend to show. Then, it will be installed on the layout.

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After showing it at the Arizona division NMRA meet on June 13, 2015, it is now installed and ballasted on the RMP upstream from the patio. In the photo (below), you can see the old rail - hopefully to be weathered by exposure to the elements in Arizona - holding back boulders and rocks to allow drainage into the wash without loosing fill or ballast.

Fn3 single-track cemet culvert

A double-track angled timber culvert

In the lower right area of the track plan, the two main tracks cross over a ravine. This ravine will carry rainfall runoff from the layout, as well as providing a visually interesting section.

I built this culvert to carry the rainwater under the tracks. The photo below is of the upstream side (away from most viewers). The downstream side does not have the angled wing walls, but short straight ones, as can be seen in the background.

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After showing it at the Arizona division NMRA meet yesterday, it is now installed and ballasted on the RMP near the patio. The photo above shows the upstream side with the 30˚ wing walls. The patio, below, is on the downstream side where the ballast is retained with old rails and boulders.

Fn3 dual-track box timber culvert - 1

A MOW shed for the RMP

My proto-lanced Rocky Mountain  Pacific railroad needs to store MOW supplies (spikes, plates, hardware and tools) along the pike. This shed was built to fulfill that need. The design was based on normal construction techniques with a few modifications to withstand life on a garden railroad.

9 Fn3 Narrow Gauge MOW Shed

A short trestle for the outer loop

I scratch built a short (one-bent) trestle for the main track crossing over the stream bed. The stream runs up and down on the drawing below to the right of the yard.

I will be showing it at the NMRA AZ Division meet on June 13, 2015.

Here is a photo of it taken in the studio, as it won’t be installed on the layout until after the meet.

Fn3 Single Bent Wood Trestle

The design was adapted from drawings in the Model Railroader book Model Railroad Bridges & Trestles (PP124, 125).

I did find one design flaw in the book drawing. The wing walls were positioned so that they would keep the dirt, etc. from holding up the footers at each end of the trestle. I redesigned them to fix that issue.

Starting on leveling and grading

The weather has gotten warmer, but there is still some cool time in the morning to spend an hour or two on the leveling and grading.

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Wiring is done

Got the wiring done on both loops now. Wrote a column about how I did it for the July 2015 issue of Model Railroad Hobbyist.

Here is how I used landscape staples to keep wire buried.

Bus in the garden

The first photo shows the wire as it laid on the ground.

In the second photo the trench is dug, the wire placed and the staple started into the ground - look for the shadow of the staple.

The third photo shows the staple seated.

Int the last photo you can see the end of the brush that was used to sweep the dirt back over the wire.

Copyright © Bruce F. Petrarca 2007 - 2015; All Rights Reserved