HO Scale

This page lays out the guidelines for modelling Free-Mo in standard HO scale and gauge. It is a compilation of Free-mo and Fremo in a South African Context.


this image is for reference

1. Introduction
S1.1. the S prefix denotes a Standard, these must be followed. Standards can however be superseded by Recommended Practices.
RP1.2. the RP prefix denotes a Recommended Practice. These are for better operation and prototype fidelity.
S1.3. South Africa uses the metric system therefore all units will be SI based.
S1.4. the purpose of the Standard is to:
S1.4.1. create a uniform code of construction, while remaining flexible.
S1.4.2. allow interoperability of different builders' modules with minimal effort.
S1.4.3. emphasis is on prototypical operation and realistic scenery, even if it freelance work.
S1.4.4. reliability of track work through sound wiring practices.
S1.4.5. move free-mo principals beyond the limit of what has usually been done or the accepted standard.
S1.5. this is based on the use of standard HO track (16.5mm). Deviations from the Standard are listed in the relevant scale tabs.
S1.6. standard scale used for Free-Mo ZA is HO Scale, 1:87.
S1.7. free-mo terminology references:
S1.7.1. a side is what is exposed when modules are joined together.
S1.7.2. an end is what inter-connects modules.

2. The module
S2.1.1. single track module end plates will be a minimum of 600mm wide at the end plates.
RP2.1.1.1. single track end plates are allowed to be 650mm wide to match double track end plates.
S2.1.2. double track module end plates will be 650mm wide at the end plates.
S2.2. end plates must be made out of 18-20mm plywood or equivalent engineered timber to provide sufficient clamping strength to adjacent modules.
S2.2.1. end plates must be 150mm high.
S2.3. avoid dimensional timber as it is prone to warping and distortions. Engineered timber is far more stable.
RP2.4. the track road bed should be cut out of timber or fibre board to create an adequate support base for track work.
S2.5. a cork roadbed must be placed on top of the wooden roadbed to create a prototypical ballast profile.
S2.6. 50mm foam is acceptable filler for the scenery work but must be sufficiently braced to avoid sagging with age.
S2.7. modules can be any length or angle.
S2.7.1. standard modules will exceed 300mm.
S2.7.2. mini Modules are shorter than 300mm.
S2.8. modules can be made up of any number of sets.
S2.9. top of track must be at 1200mm from the floor.
S2.10. the module legs must be adjustable up and down by 50 mm, they must be rubberised to avoid damage to floors.
S2.11. a minimum of four legs are required to give sufficient support to the module as it stands.
S2.12. modules can have any number of end plates.
S2.13. modules must be viewable and operational from both sides.
S2.14. facias must be painted an appropriate colour as not to detract or distract but compliment the scenery. A dark green/black is recommended.
S2.15. there is no requirement of how modules are to be constructed other than what has been prescribed above.

3. Track
S3.1.1. mainline must be Code83 Nickel Silver, preferably hand laid or appropriate prototypical looking flex.
S3.1.2. branch line must be no smaller than Code40.
S3.2. #6 equivalent or bigger turnout/point must be used.
RP3.2.1. #8 equivalent or bigger turnout/point is recommended.
S3.3. minimum mainline radius must be 1000mm.
RP3.3.1. a radius of 1200mm or larger is preferred.
S3.4. minimum track centres of 50mm or wider must be observed to prevent rolling stock collision.
RP3.4.1. track radii should be in accordance with NMRA Track centres.
S3.5. track must be straight and level on all three axes for the last 150mm before an end plate.
S3.6. track must be straight for at least 200mm between opposing curve angles (S curves).
S3.7. mainline gradient must never exceed 2.0% (20mm elevation per 1000mm distance).
RP3.7.1. mainline gradient recommendation is 1.5% (15mm elevation per 1000mm distance).
S3.8. track centre lines must be more than 100mm from the edge of the module. Exception is made for industrial modules
S3.9. track must be laid on top of 5mm (3/16") cork or firm closed cell foam.
S3.10. track sleepers must be appropriately ballasted for a prototypical ballast profile.
S3.11. track in the last 30mm of the module leading to the end plate must be soldered to a PCB sleeper plate and must be flush with the end plate.
S3.12. turnout control must be available from either side of the layout, mounted on or recessed in the fascia.

4. DCC
S4.1. a LocoNet compliant system must be used.
S4.2. a cab connection panel must be on either side of the module.
S4.3. a LocoNet bus must run the entire length of the module.
S4.4. flat 6 core telephone cable must be used for the LocoNet bus. Do not use Cat5/5e/6 cable.
S4.5. RJ12 wall box must be at each end plate or an appropriately wired RJ45 wall box for the LocoNet bus.

5. Wiring
S5.1. mounted screw terminals must be located at each end plate for each bus wire to be connected.
S5.2. leads from the screw terminal must terminate with an appropriate coloured Anderson connector and must not exceed 200mm in length.

S5.3. DCC bus:
S5.3.1. black (-) and red (+) 14 AWG wire must be used as a bus though the length of the layout.
RP5.3.2. 12AWG is better suited as bus wire. Solid is preferred where movement of wire is null.
S5.3.3. Anderson connectors must be stacked on top of each other.
S5.4. accessory bus:
S5.4.1. blue (-) and white (+) 14 AWG wire must be used as a bus though the length of the module.
RP5.4.2. 12AWG is better suited as bus wire. Solid is preferred where movement of wire is null.
S5.4.3. Anderson connectors must be stacked side by side.
S5.5. leaders off the bus wires can be anything bigger than 20AWG but no longer than 150mm.
S5.6. IDC Splice connector (Suitcase) must be used or soldered with shrink as insulation.
S5.7. all frogs are to be live by either electrical or mechanical means. Using points to electrify frogs is unacceptable.
RP5.7.1. frog juicers are the recommended practice of electrifying frogs.
S5.8. common ground:
S5.8.1. green/green-yellow 12 AWG wire must be used as a bus though the length of the module.

6. Scenery
S6.1. all bench work must be sceniced.
S6.2. all track work is to be appropriately prototypically ballasted.
S6.3. with the discontinuation of Floquil and Polly Scale paints colour matching is still to be determined. It must be a natural brown dirt colour.
S6.4. All track is to be appropriately weathered

7. Sundry
S7.1. do not daisy chain extension cords. One extension cord must run from a wall socket to the desired location of the transformer.
S7.2. South Africa uses 230V; please ensure all equipment is compliant. Please be aware of the new SANS 164-2 regulation.

8. Revisions
8.1. 28/01/2014 Free-Mo ZA Standard drafted.
8.2. 24/06/2015 Cosmetic/spelling corrections.
8.3. 24/01/2016 S2.2. Face plate thickness set to 18-20mm
RP5.3.1. and RP5.4.1. Wire Gauge correction 10AWG requires larger Anderson connections, 12AWG recommended.

9. End Plates Appendix