The Helix Build Thread – Part 6
October 2, 2011
With the first loop complete, the helix is rising rapidly. I consider the start point of each loop after the entry loop to be at Tower 3 since this is where the vertical bus wires are located.
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.
