Backdrop painting on the upper deck commenced with clouds.  Initially I planned a few light cumulus clouds but found scattered clouds looked less convincing than overlapping long banks of rolling cloud.

I used white mixed with varying amounts of sky blue to create subtle shading effects on the clouds. Distant clouds were formed with a dry brush technique whereas foreground clouds were created by stippling paint in random patterns.  Acrylic paints were used athough their rapid drying time can make blending colours challenging.

I tried defining the undersides of clouds with grey, but was not happy with the result.  Sticking to blue and white mixed in varying degrees seems to create the best looking clouds. 

The final cloudscape suggests a warm and windy spring afternoon.  The banks of cumulus clouds are growing rapidly in size and showers or a thunderstorm could definitely be in the forecast for Fort St. John.

Next step is to fill in the distant hills, fields and trees on the backdrop and then fill in foreground trees that line the north edge of the Fort St. John rail yard.

Over the last few weeks i have been able to complete and install the remaining upper deck benchwork modules.  This completes my goal of having all the tedious and messy heavy construction out of the way by the end of 2011.  The only remaining benchwork items are a narrow shelf for Fort Nelson staging tracks, but that can wait for a while.

The upper deck will be entirely dedicated to representing Fort St. John yard and industries.  Some editing will be required to fit everything in.  The track layout will represent viewing the yard from the south.  The old grain elevators will sit along the front fascia with the station buildings and CANFOR facility along the backdrop.

I decided to use a ‘hillboard’ view block in order to partially screen the Fort Nelson subdivision mainline.   As in the prototype I wanted this line to curve away from the main yard tracks and head north.   Without screening its exit, the line would appear to head south behind the yard spurs.  I just knew that this would have irritated me so i used this method instead

Hillboard viewblock to help screen exit of Fort Nelson subdivision track

Small structures, trees and other painted backdrop hills will eventually help hide this hillboard better, but I am quite happy with this compromise that allows the track to appear to head north towards Fort Nelson even though it heads the opposite direction to a future staging shelf under the window.

Future site of Fort St. John yard on upper deck.  Peace River bridge below

The masonite backdrops have been given several coats of the light blue I used on the lower deck sky.   The fascia and light valance have a matching coat of green used on lower deck fascia.  I am quite pleased with the presentation of the layout at this point, even though there is still lots of work to be done.

Future site of Fort St. John yard throat and CANFOR plant on upper deck. Taylor on lower deck.  Helix on right.

Upper deck lighting will be the same under cabinet strip fixtures I used for the lower deck.  The integral backgrop and lighting support structure has been deliberately over-engineered to hold the relatively heavy under cabinet fixtures.

I plan on taking a break from the heavy construction over the next few weeks and putting some serious time into painting the upper deck backdrop and also completing some unfinished areas of the lower deck backdrop.

Currently I have completed 3 modules with one more needed.  The upper deck will be entirely dedicated to to the sprawling Fort St John classification yard and industries. Construction is a standard open grid topped with 1/4 inch plywood to keep weight down.  The backdrops are cut from sheets of 1/8th inch masonite.

As constructed the benchwork modules can be lifted  off  ‘somewhat’ easily.  Although light in weight, the corner and end units especially, are large and cumbersome.  The plan was to lift each module off and perform track laying and wiring at the work bench.  Now they will likely be left in place as much as possible and only removed to accomplish any difficult to reach wiring that cannot be performed from underneath the L girder support structure.  On the upside, the 18″ tall backdrops which make these units so cumbersome will be a great canvas on which to paint a sweeping northern backdrop.

Work is continuing on the remaining module and on a narrow upper deck staging shelf that will form Fort Nelson staging.  When complete that will mark the end of all remaining benchwork on the layout.  The goal is to get that done before the end of 2011.  Building model railroad benchwork in a condo is a challenge and I will be very glad to see the back of it!

Glueing plan for the other 4 towers.

I have used the strategy of ‘front loading’ all helix assemblies into 4 support posts until completion then attaching the opposing 4 towers at the end.   The opposing towers in question are: 1A, 2B, 3A and 4A.

I carefully fit each of these towers into place.  This required a bit of gymnastics and a step ladder to reach 4A.  Fitting in place requires gently manipulating each helix curve to fit into the tower slot.  Because you must align 4 or 5 loops into the slots simultaneously this is a bit of a tricky operation.  An extra set of hands is definitely advisable. 

It took me about 10 minutes of gentle persuasion to get each tower to fit firmly.  For this reason I applied glue to the join areas after fitting.  While not ideal it removes the stress of trying to fit the towers onto the helix loops before the glue starts to set.  

Apply glue after firmly dry fitting the towers.  Bond may not be as strong as pre-glueing the slots, but there is no stress associated with trying to fit the towers before the glue sets.

I proceeded in the order of 4A, 1A, 2B and 3A, applying glue to accessible areas of the tower-helix join as best as I could after installation.

After the towers had fully dried, I performed the wire management.  Vertical trunk wires were secured into the clasps on tower 3A.  I pushed the clasps into the tower with gentle pressure. Looping branch wires were secured into the clasps on the inward-facing towers also.  Clasps were pushed in but still given enough play to allow the wire to slide through.

Keeping the wires neat. Wires hang from clasps attached to the inward-facing towers.  Small binder clips secure wires between the towers.

Final wire management was performed using small binder clips (Staples sells a pack of 40 for under $5).  These were clamped to the inside of the helix at key locations to keep the wires neatly contained.  Binder clips are perfect for this task as they let the bus wires slide back and forth while keeping them neatly attached to the inside of the helix.

Wire management close-up.  Binder clips secure firmly to helix but provide enough room for wires to move through.  Nail clasps on tower are pressed into pre-drilled holes which provide a firm fit but also allow them to be pulled out and pushed in using pliers.

Final testing under DC power allows locomotives to ascend at a constant speed, indicating that the branch and loop bus wire system provides a constant voltage for the entire ascent.

This concludes the helix build thread.  Overall it went a lot quicker than I expected.  I believe that the use of fixed radius curved track was worth the expense. I would recommend these Ashlin kits.  Providing that the grade issue documented in Part 2 is addressed, they build up in to reliable assemblies.

End Note…..

I am still exploring options for ‘guard rails’ around the inner and outer edges of each loop to prevent any derail disasters.  That may be documented in a future update.  For now attention is being focused on upper deck benchwork.  This will start with Alaska Hwy crossing at Baldonell and lead to the main Fort St. John yard.

The final loop was completed using Atlas code 80 flex track. This was because I ran out of the Peco fixed radius 14″ set track at this point. 

Preparing the final loop using soldered lengths of Atlas code 80 flex track

To avoid kinks at rail joins I soldered 3 flex track lengths together before forming them into a curve.  The long flex track unit was then draped around the helix in advance of installing the curved plywood sections and road bed.  I found it relatively easy to maintain a constant 14″ radius by just proceeding one quarter turn at a time with final track installation.

Feeder installation on final flex track loop.

Feeders were installed every quarter turn.  These had to be soldered as track was laid, making access a bit tricky at the rear of the helix.  The fixed radius curves had allowed soldering to be performed at the work bench which was much easier.

Installing a custom cut ‘exit ramp.’ Note spacer to ensure clearance from lower track

Finally, a custom shaped ‘exit ramp’ was cut from 1/8th inch plywood.  This leads the track out of the helix and towards the exit point on to the visible portion of the upper deck.  A 50 cm tall spacer was added under the exit point to ensure adequate clearance with the helix track below.  The same 50 cm tall spacers were added on the outside of all helix curves to add stability between the towers.

View of helix exit.  Track will emerge on upper deck, cross the Alaska Highway and then enter Fort St. John.

I am using the following steps to add loops to the helix:

1.  Cut red and black branch 14 AWG bus wires to between 6 and 7 feet in length.   Wrap and solder to the 14 AWG vertical trunk bus wires.  Seal joins with electrical tape or heat shrink tubing.   Drape the branch bus wires loosely around the inside of the helix in advance of the helix loop to be installed.

Bus wire preparation for loop starting at Tower 3. (Tower 3A is not glued in place at this point)

2. Glue a helix plywood curve to tower 3B and 4B.  Towers 3A and 4A should not be glued to either the helix base or plywood curves at this point.  When glue has dried, attach foam road bed using Woodland Scenics Foam Tack glue.

Installation of helix curve and foam road bed. (Towers 3A and 4A are just dry fit in place at this point.  Do not glue)

3.  Solder together 2 sections of Peco 14 inch radius curved set track to form a 90 degree curve unit.  Solder 22 AWG solid feeders to this track unit.  Cut away tie webbing to form a slot for the red wire to pass under the track towards the centre of the helix.

Exact position of feeders is not important but I try to have them connect to branch bus wires half way between the towers.  This provides even power distribution and also anchors the branch bus neatly into position on the inside of each loop.

Completed track unit with feeders

4.  Place curved track unit on new roadbed but do not glue until the next plywood helix curve and road bed is installed and can fully support end of track (see 5. below).  Wrap feeder wires around branch bus wires.   Twist the bus wires together before performing the join with the feeders.  Twisting helps keep the wires neat and also prevents DCC signal noise.  Solder, clean and tape the feeder-bus connections.

Feeders wrapped around bus wires (note bus wires twisted before connection).  Making wire connections before securing track to roadbed makes this step easier.

5.  Add the next helix quarter turn section.  Glue this section to the outer towers (4B and 1B) only.  Do not glue to 4A or 1A.  When dry, install foam road bed.

Extending helix and foam roadbed from Tower 4B to Tower 1B

6.  Now secure wired track to the helix using Foam Tack glue.  Apply weights to track until glue sets (canned goods work best)

While glue is setting, prepare the next curved track unit by repeating step 3.

7.  Add the next helix curve and secure to Tower 1B and Tower 2A (outer Tower 1 and inner Tower 2).  Add foam road bed, connect track feeders to bus and secure track to roadbed using the same methods already described.

8. Add the final helix curve between Tower 2 and 3.  Glue to 2A and 3B only.  This completes the circuit.  Install foam roadbed and prepare a track unit (step 3).  Twist branch bus wires before securing to track feeders.  The branch bus wires are trimmed to end just before Tower 3A.   A new branch bus wire is started for the next loop.

Completion of helix loop.  Note twisted bus wires terminating before Tower 3A (which is not glued to any helix curves or the base) and the new branch bus wire which starts at Tower 3A to feed the next loop above this one.

9.  Before proceeding to the next loop add extra supports on the outside of the helix between the towers. Ashlin kits do not provide these parts, but 50cm tall blocks of 1.5 x 0.25 inch strip wood works well for this.  Use a level on the track to check for lateral alignment.  Sand or shim these supports as required to ensure level track.  Check that the inner edges of these supports provide enough clearance for rolling stock in the helix.  You can add similar supports around the inner edges of the helix if you wish.  I find that the outer supports are sufficient however.

Intermediate supports added between primary support towers.

With the transition from flex track to curved set track completed in the last stage, progress on the remainder of the first loop of the helix proceeded as follows:

Completion of the first loop of helix

1. Glue foam roadbed to helix curves using Foam Tack glue.  Perform this step prior to installing helix curves into towers.

2. Prepare curved set track units in advance by a) soldering two curved sections together and b) soldering 22 AWG feeders to the completed track unit.

3. Glue in Towers 3B.  and 4B and, before they set, glue in the third and fourth quarter turns of the first loop

4. Before glue sets make sure that the end of the first loop aligns exactly over the entry ramp of the helix below it.  Use clamps and squares to ensure that Towers 3B and 4B are true in the vertical plane as the glue sets.  Towers 3A and 4A can be placed in position for support while glue dries but should not be glued in themselves.

5. Prepare the red and black “branch” wires for the second loop.  Cut wire to approximately 70 inches long.  Strip and solder to vertical “trunk” bus wires approximately 2 inches above the point where the first branch bus wires diverge from the trunks.  Soldering two sets of stranded 14 AWG wire is a bit challenging as it is difficult to get sufficient heat into the dense mass of wire to fully melt solder deep into the join.  A high powered soldering gun is essential for this and even then it requires patience and lots of flux and solder to form a firm join.  Clean all joins and wrap in electrical tape.

6. Use Foam Tack glue to mount the previously-prepared Peco curved set track units on to the roadbed.  Connect the 22 AWG feeders to the second loop of branch bus wires.  This completes the first loop of powered helix track.  Test under DC power.  The looping branch bus wires should supply a constant voltage to the helix track via the track feeders. Locomotives should ascend the loop at a constant speed as a result.

7.  Add additional lateral support between towers.  While the design of the Ashlin kits is generally solid, the lack of support between each of the four tower pairs may result in the outer perimeter of the helix drooping downward and outward.  This could cause uneven track and may lead to derailments.

Use scrap lumber to add supports under the helix at the 45 degree points (i.e half way point between towers).   A small level placed across the track is makes it easy to detect and fix lateral deviations.  With extra support installed the track should be consistently level in the lateral plane around the entire first turn of the helix.  Note that the process of propping up the helix at these points may slightly stress the glued-in towers and push or pull them out of the vertical plane.  This can be corrected during installation of the second loop

Extra supports added underneath the helix between towers

Gluing in Tower 1B.  Note clamped square used to ensure tower sets in a vertical position

Next step was to install wire clasps to the backs of all the “A” Towers.  These clasps will support the spiraling “branch” bus wires.  An additional set was installed in “3A”.  These are to support the vertical “trunk”  bus wires.   I used standard nail-in clasps available from hardware stores.  I drilled small pilot holes and pushed the clasps in with pliers.  Leave about a 1/8th inch gap between the clasp and the tower wall so that wires can be hooked in.

Wire clasps secured to all the “A” towers.  Note the extra set on 3A to secure the vertical trunk bus wires.

Tower 1A was temporarily moved into place but NOT glued.  Feedback from other builders has been that towers should be added on one side of the helix only.  The opposite towers should only be permanently attached when the helix has reached its full height.

With 1A in place the second curve of the first helix loop was added.  Glue was only applied to the 1B tower slot.  Foam Tack glue was spread on the second curve and foam roadbed was installed.  At this point the black branch bus had been connected to the trunk bus and was being wrapped around the red branch bus in a spiral pattern inside the helix.

Installing the second curve.  DO NOT glue in Tower 1A.  It is just placed in position for support at this stage.  Second curve is only glued to 1B.   Note Foam Tack glue spread in preparation for road bed installation.

After mounting the road bed, second helix curve was secured to tower 2A which was then glued to the platform.  Clamps and a square were used again to ensure it dried in a vertical position. Tower 2B was placed in position for support but NOT glued.

Glueing in Tower 2A.  2B placed in position for support only.  Do NOT glue 2B.

Beyond the second curve of the first helix loop I am transitioning from Atlas code 55 flex track to Peco fixed radius 14″ code 80 set track (Peco calls it “#4 Radius”).  This is a personal preference in that it makes it easier to maintain a constant radius throughout the helix.  I will be soldering together 2 sections of curved track to form a standard unit.  Each unit will have feeders which will be connected to the branch bus wires.

Using Peco set track is significantly more expensive than using flex track.  I was able to pick up a box of it while in the UK and even then the price was very high compared to flex track.

I joined the Atlas code 55 to the Peco code 80 by soldering the code 55 on top of the code 80 rail joiners.  Flattening the rail joiner ends helps establish the correct rail height transition.  I also had to shim the code 55 under the ties to help lift it up to the higher rail height of the code 80.  A sliver of thin balsa wood strip did the trick here. Plenty of solder was applied to form a strong bond between the two different rail types.  A bit of filing and the transition was smooth.

Transitioning from Atlas code 55 flex to Peco code 80 fixed 14″ radius.

With the transition to Peco set track complete, the third helix curve of the first loop was placed roughly in position and its road bed secured down with Foam Tack glue.  The branch bus wires were continued to their end points between Towers 2 and 3.  Another set of branch bus wires will start from Tower 3A and follow the second loop of the helix around to end at the same point above.

Preparing the third turn of the first loop.  Road bed installed and Peco curved set track being placed in position.  Red branch bus wire trimmed to its end point.

With the helix footprint marked on the base platform it is easy to continually check alignment of the first loop.  Completion of the first loop will stabilize all support towers and keep subsequent loops in correct alignment.

The first helix curve was glued and screwed to the base platform at its entry point only.  Woodland Scenics foam roadbed was secured to the curve using Foam Tack glue.  I prefer the contact adhesive method. (Spread the Foam Tack on both the helix surface and the foam.  Let both dry for 15 minutes then secure foam to helix inch-by-inch to form the curve).

Next step was to vertically align the Taylor benchwork extension with the beginning of the helix.  The extension, like most of the main benchwork surface is 3/4″ chipboard.  It is anchored to the Taylor benchwork but the helix end floats free.

Track was temporarily placed across the junction between the extension and the helix entry.  Roadbed heights on both sections were accounted for.  The extension was shimmed with 1/8th inch masonite strip to bring it up to the helix entry track level.

Adjusting Taylor extension benchwork to vertically align with helix entry curve (glued and screwed to base platform)

Track was then laid across the extension and into the first curve of the helix.  Atlas code 55 flextrack is being used for the initial entry.  Prior to installation, 22 AWG solid feeders were soldered to the flex track. The rear red wires are looped and tucked under a notched cut out in the foam roadbed so that they point in towards the centre of the helix.   Having all bus and feeder connections inside the helix will make everything more accessible.

22 AWG solid feeders pre-soldered before securing track to helix.  Note how red feeder is bent and fed through a gap in the foam roadbed so that it can be connected to the bus wire on the inside of the helix.

Standard soldering technique applies.  Tin a spot on the rail and the feeder wire first then apply flux to joint and briefly heat with soldering iron to form the join.  Scrub soldered joins with an alcohol soaked toothbrush to remove traces of flux.  Wrap all joins in electrical tape (or heat shrink tubing).

Track was secured using Foam Tack glue.  Canned goods make the perfect weights to hold track in place.

Securing track around the helix. Proceed 6 to 12 inches at a time.  Apply Foam Tack glue, form flex track to correct curve and weigh down until glue sets. (I allow about an hour).

Key wiring was roughly laid in at this point.  This includes the 14 AWG stranded bus wire “trunk” that will run vertically up helix post “3A”.   The first 14 AWG “branch” was connected and draped around the inside of the helix.  The branches will form a circular pattern around the inside of each helix loop.  They will connect directly to the track feeders.

Initial wiring preparation.  Black “branch” bus has yet to be installed in this photo.  Note helix curves and section joins traced on the platform in blue pen.  These will help guide the precise alignment of each quarter turn in the first revolution and prevent radii deviations from propogating to the subsequent levels.

There had been some feedback suggesting that some Ashlin kits may suffer from milling errors that can result in an inconsistent grade.  There is an easy way to check your kits (or your own risers) for this.

1. First establish the the helix deck separation.  On my kit it is 2.25 inches per revolution.

2. Next divide this by the number of helix towers..  In my case this is 4.

3. This gives you the vertical rise per quarter turn..  in my kit this is 0.56 inches.

Lay out the  “B” series towers in the order 4,1,2,3.  Make sure the the bases of all towers are aligned to each other.   Measure the vertical distance between the bottom (or top) of all the angled notches between successive towers.  If they are all equally increase in height by 0.56″ you will have a constant grade.

On my kit these spacings were not consistent.  I noted the following rise values

Tower 4 to Tower 1 = 0.39 inches (approx 1.75% grade)

Tower 1 to Tower 2 = 0.56 inches (correct 2.2% grade

Tower 2 to Tower 3 = 0.34 inches (approx 1.49% grade)

Tower 3 to Tower 4 = 0.65 inches (approx 2.8% grade)

As machined this would have created a very problematic helix.

The fix is to modify the base heights of key towers to both increase certain grades while easing others.
My solution is as follows:

1. Remove 1/8th inch from the bases of towers 4A and 4B.  This increases the Tower 4 to Tower 1 grade to 2.2 %

2. Add shims beneath towers 3A and 3B.  They can be 1/8th of an inch to 3/16ths of an inch thick.  This will increase the Tower 2 to Tower 3 grade to between 2 and 2.2% while simultaneously reducing the Tower 3 to Tower 4 grade to 2.2%.

Inspecting support towers for grade inconsistencies.  Tower 4B has already had 1/8th inch removed from its base in this picture.  Note how 3B needs to be raised 1/8th of an inch in order to maintain a vertical rise of 0.56″ relative to 2B.