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Free-Mo-SLO Standards-&-Recommended-Practices FAQs

Free-mo SLO
Standards & Recommended Practices

   Free-mo Standards & Recommended Practices
Free-mo Module Variations
 Free-mo Standards & Recommended Practices Revision History

Frequently Asked Questions Index:


1.0 Introduction

Free-mo FAQ 1.1 How can a module have one or three ends?
If you build a loop module it will have only one end, a wye module will have three ends.

Free-mo FAQ 1.2 - Shall, Should and May

  • Requirements/standards use "shall" and are mandatory.

  • Recommended Practices use "should" and are optional.

  • Acceptable/Permitted Practices use "may" and provide exceptions or qualifications to the standards.


Free-mo FAQ 1.3 Is Free-mo a Concept or Standard?
Free-mo is a Concept and a Standard for building model Railroad modules.

Free-mo the Concept - Double sided modules that can be swapped end for end with no problems, Designed to be operated. The Free-mo concept was developed to get away from the standard two track oval display with orbiting trains.

A Free-mo module is a free form module that conforms to the Free-mo standards as outlined below. A Free-mo module can be any length and the endplates can be at any angle to each other. A Free-mo module can be one section or a set of two or more sections that forms a module. The Free-mo standards govern the ends of the module and basic track requirements. Most Free-mo modules have two ends, but modules can have one, two, three or more ends.


Free-mo FAQ 1.4 What Scale is Free-mo?
The Free-mo concept can apply to any scale. The standards are tailored for HO scale, it being the most popular scale.


Free-mo FAQ 1.5 I like the standards all but...
When you decide to join an organization that already has adopted a set of rules or standards, you, by the fact of freely deciding to join, accept those rules. If you didn't like those rules (standards), then continue your search for a group, any kind of group - model railroad, civic, religious, whatever - whose rules you agree with.

As Free-mo has grown lots have people have asked this question. We are open to change, but a standard that changes too easily or fast cannot be followed. Many groups are following this standard and it works. When there has been a real need to change, it has changed.



2.0 Frame and Legs

Free-mo FAQ 2.1 - Why not use Pine 1X6 lumber?
Pine dimensional lumber has a tendency to bend, warp and twist. Plywood tends to stay straighter over time. The use of Plywood over dimensional lumber will help keep your module flat straight and true.


Free-mo FAQ 2.2 - Nominal and minimum rail height is 50 inches above the floor?
The nominal (noraml) value as measured from the top of the railhead to the floor is 50". This is also the minimum, since Free-mo allows grades the max rail height is 62". There is no spec for 49", you may have inferred that from the 1 inch adjustable feet. But the adjustable feet are to deal with uneven floors. So a layout can be set at 50" and kept level over a floor that may be dipping and bumping up to 1" of uneven-ness.

The 1" leg adjustment is a minimum. We've encountered many floors where a 1" adjustment wasn't enough.


Free-mo FAQ 2.3 Can I put a backdrop on my module?
NO! Your module HAS to be viewable from both sides and look "realistic" from both sides. Back drops are not allowed on Free-mo modules.

This precludes the use of sky-boards on a Free-mo module. Since sky-boards are usually placed on a non-viewing side, by being visible from both sides, a Free-mo module shouldn't have a sky-board.


Free-mo FAQ 2.4 - Can I build a double track mini-mo that is 8" wide?
No, a single track mini-mo can be 8 inches wide but, a double track mini-mo can not be less than 10 inches wide. "The centerline of the track will always be 4 inches or more from the edge of the module". So, 4 inches from the edge to the first track, plus 2 inches between tracks, plus 4 inches to the other side equals 10 inches.


Free-mo FAQ 2.5 - I do not understand why a mini-mo needs legs "if it does not need to stand on its own"?
When using a mini-mo in a setup, if it has one leg on each end, one person an install the mini-mo. It can be balanced on the legs while it is clamped in place. If it has no legs, both modules on either side need to be in place for it to be installed. It is all about gravity.


Free-mo FAQ 2.6 - What is Nominal Mean?
Maybe the confusion is with the word "nominal." Mechanical engineers use it to mean the intended dimension. This dimension is then given tolerances. Two parts are never exactly the same. Tolerances allow slightly imperfect parts to actually fit together. So when I read the standard I get the following:

  • The target minimum (or nominal) height of the rail is 50" from the floor,

  • level track is more important than distance to the floor,

  • floors are not level,

  • So legs need to adjust to allow an actual rail height of 49" (or 51") over the floor in the interest of keeping the track level.

In addition to this the standard does require that we be prepared to put 3/4" shims under our modules to raise them as high as 62" (again plus or minus 1").

This is also the reason for the requirement that grade modules change elevation in some even increment of 3/4"s. Technically, a 61" height is not compliant--but 61 1/4" is.



3.0 Track

Free-mo FAQ 3.1 Why does the centerline of the all tracks have to be 4 inches or more from the edge of the module?
This is for two reasons. 1) To protect models, if something was to happen and a train derails, we do not want the cars or engine to fall to the ground. It will be bad enough to have them on their sides. 2) For scenic looks. It looks better if there is scenery between the track and the edge of the module.


Free-mo FAQ 3.2 - Why the 1 inch set back on the rail, why not take the track all the way to the edge of the modules?
Laying the rail to the edge of the module does have the advantage of allowing a nicer scenery transition to the end of the module, but there are some problems with the design.

  • The first and most import to is that the rail at the edge of the module is frequently damaged in transport and set up, requiring immediate repair at set up time. This is not that easy to do and seldom results in the track looking or performing as well as it did before the repair.

  • The second major problem is getting the tracks to properly align. Using a 2 inch piece of rail allows for slight mismatches to be smoothed out. Having the rail end at the module some times results in a kink (horizontal mis-match) or what we call a "ski jump" - a vertical mismatch of rails.

Both conditions are moderated by the addition of filler pieces.


Free-mo FAQ 3.3 - Code 70 to 83 transitions on the module ends?
Free-mo ends are specified to have code 83 rail. If a module is built as a branchline module the rail on the through route can be less then code 83 but not less than code 70. If a smaller code rail is used, the owner is responsible for supplying a solution to transition from the smaller code rail to code 83 to comply with the Free-mo standard end.

If two branchline modules are both made with code 70 on the through route, code 70 joiner rails can be used and it is not necessary to transition to code 83 at the joint between the two modules.

If two branchline modules are joined and one has code 83 on the through route and the other has code 70 on the through route; It is the responsibility of the owner of the module with code 70 rail to supply a solution to transition up to the code 83 rail, (i.e. code 70 to code 83 fitter rails or code 70 fitter rails and code 70 to code 83 rail joiners).


Free-mo FAQ 3.4 - What does a Single Track Endplate look like?

Free-mo FAQ 3.5 - What does a Double-track endplates look like?


Free-mo FAQ 3.6 - I do not understand how grades work.
A grade module will have 5 areas:

  1. a Free-mo End
  2. an Easement into the grade
  3. the Grade itself
  4. an Easement out of the grade
  5. a Free-mo End

1 and 5: the Free-mo Ends
These would meet all existing Free-mo end standards: 6" long, straight, level, square at the end, rails stopping 1" from the end, ties and ballast continuing up to the end. ANY other Free-mo module (flat, grade up, grade down) can be mated to these ends, at whatever height these ends start and finish at. You would still have the combined 12" of straight and level track.

2 and 4: the Easements
Just as you don't (shouldn't) suddenly lurch into a curve without an easement between the straight track and the curve, you can't (I say again, can't) jump right into a grade from the level section. Imagine viewing your track from the side (a profile) - without the easement, your track would be 2 straight lines meeting at a hard angle. Going into an upwards grade, the wheels would risk jumping the track as they hit the angled track, the cars would uncouple as the one car is angling its coupler down below the level of the next still on the level track, and just imagine the shaking of every car as it went into that angle - would be worse than any gap in the tracks. Coming back out of the curve, without an easement, the cars could bottom out, wheels leave the tracks, cars uncouple, etc. If a downwards grade, would be the same but in reverse. So you must have an easement in and out of a grade.

3: the Grade
As per Free-mo specs, you can have any grade, up to a max of 2% on a Mainline module or 4% on a Branchline module. , or as was mentioned about 1/4" height change per foot. Nothing too fancy about it, as long as it follows any other normal track laying standards. Could even curve, again following Free-mo standards for max curve, and with an easement into the curve. (The grade easement areas could even curve too, meaning they'd be easing into the grade and easing into the curve.)

Only concern is meeting the 3/4" incremental height requirements at the module's ends. You can either take your grade (plus easements and 6" Free-mo ends), and work out how long the module would need to be so that it would end up at one of the approved heights (50.75", 51.5", etc). Or, you decide how long a module you want to build, subtract the 6" Free-mo ends and easement lengths, which then determines how steep a grade can fit within that space. You can stretch the grade through the entire length, or run your level sections longer than the min. 6" required, or have an even longer/smoother easement. As long as the math works out so that at the end of it all, you meet the incremental 3/4" specs.

Note: Using some general numbers for the lengths of the different sections and assuming a 2% grade. The lengths of the different section 1 to 5 would be:

  1. 6 inches
  2. 18 to 24 inches
  3. 36 inches for every 0.75 in lift
  4. 18 to 24 inches
  5. 6 inches

Using the low end of the scale for 2 and 4 of 18 inches. A module will take 24 inches on each end to get into the grade. This gives us the following:

Module length to lift:
7' = 0.75"
10' = 1.5"
13' = 2.25"
16' = 3"

This puts the whole grade issue into perspective.


4.0 Wiring

Free-mo FAQ 4.1 Where can I get Cinch Jones Connectors, Radio Shack is not caring them any more?
The two part numbers are S-302-CCT and P-302-CCT (Socket/female and Plug/male). Use this link to check the Cinch web site for availability. You do not want the S-302-CCT-K and P-302-CCT-K parts, these have "lock socket".


Free-mo FAQ 4.2 - Which pin in the connector is pin 1, the wide one or the narrow one?
You need to look very close at the connector, the pins are labels. To avoid confusion we talk about pin 1 and 2 not wide and narrow. The wide connector on one goes to the left track and the wide connector on the other goes to the right track. We have found if we use connector 1 and connector 2, instead of wide and narrow, there are fewer errors.


Free-mo FAQ 4.3 - Don't you mean AC & DC for the accessory buss?
Accessory bus can carry either an AC signal or a DCC signal. A spare booster can be used to power the accessory buss.

Free-Mo FAQ 4.4 - It seems like the track buss wires are crossing from end to end, what is up with that?
When thinking about the end of the module you need to look at each end by it self. The ends are wired the exact same. This allow a module to be flipped end for end and still work. This simple drawing might help some. Module Wiring Image


5.0 Control


6.0 Scenery


7.0 Glossary

Free-mo FAQ 7.1 -  What is a Printed Circuit Board Tie Plate? 
See the Free-mo Monthly October 1999 article.


8.0 Revision History



Page Last Updated 06/13/2009