On3 Module Standards

On3 Module Standards as practiced by the Mid-Atlantic Narrow Gauge Guild

BASICS: Module length must be in even number of feet: 2, 4, 6, etc. A module may consist of sections of any length, but when assembled, the result must be a module of an even number of feet. The exception to this is a corner module, which is five (5) feet long on each ouside edge. Corners have been built with four (4) foot outside lengths, most we have encountered are using the five foot standard. Note that inorder to construct a loop, all four corners MUST be the same length. Module depth may vary so long as the minimum track setback is used. A depth of 30 inches is common, but we have units ranging from 18 inches to 47 inches.

INTERFACE: The mechanical connection to other modules must have a 3/8" plywood cleat attached to each end of the module. The bottom edge of the cleat must be 2 1/4" below the top of the rail. The thickness of both cleats must be included in the total length of the module. Adding two cleats to a 4' module would make it 48 3/4" long, which is 3/4" too long. The cleats of two adjacent modules rest on a supporting leg unit when the layout is assembled.

TRACK: We recommend Code 100 nickel silver rail, but many modelers who operate modules based on western narrow gauge railroads prefer to use Code 83 for the main track. Lighter rail may be used for sidings. Turnouts must be #6 or larger on the main track. Main line cuves should be a minimum of 42" radius, but tighter radii may be used on other tracks. Parallel tracks should be spaced a minimum of 3" between centers; 3 1/2 is common.
The main line track must enter and leave each module on a tangent (straight section). The centerline of the main track must be set back a minimum of 8" from the front edge of the module ends. Stop the rails 2" before the end of the module, but lay ties to the end. At operating sessions, use 4" sections of rail to join to the track on the next module.

ELECTRICAL: The main buss (through) wire should be #14 gauge copper. The buss wires should be long enough to extend at least one foot beyond each end of the module. To connect the buss wires to the next module, use Radio Shack 4 pin connectors #274-204 and #274-205. These connectors must be ordered as they are no longer carried as standard stock. Assign pins 1 and 3 to the white wire (front rail) and pins 2 and 4 to the black wire (rear rail). The male connector should be on the LEFT end as you face the front of the module. The female connector then goes on the right end. Track feeder wires should be #18. It is recommended, but not essential, that all rail joints be soldered or feeder wires attached to each rail length.

LEGS: One supporting leg unit is needed for each module. Corner modules or modules made up of sections may need additional supports. Two C-clamps of a 3" minimum opening are used to join two modules together with a cleat from each resting on one leg unit. Since the two interface cleats (3/8" each) rest on the leg unit, the thickness of the upper portion (3") of the leg must be 3/4" thick. If the leg unit is a solid sheet of 3/4" plywood or if the upper portion exceeds 3", two 4" x 6" openings must be provided for the clamps and electrical connections. The leg unit must not exceed 41 1/4" in height, including any height adjusters which are optional but recommended. See figure below.

Should you have any questions or need clarification of any of the information presented above,
contact Bob Beebe.

	BASICS: Module length must be in even number of feet: 2, 4, 6, etc. A module may consist of sections of any length, but when assembled, the result must be a module of an even number of feet. The exception to this is a corner module, which is five (5) feet long on each ouside edge. Corners have been built with four (4) foot outside lengths, most we have encountered are using the five foot standard. Note that inorder to construct a loop, all four corners MUST be the same length. Module depth may vary so long as the minimum track setback is used. A depth of 30 inches is common, but we have units ranging from 18 inches to 47 inches.
	INTERFACE: The mechanical connection to other modules must have a 3/8" plywood cleat attached to each end of the module. The bottom edge of the cleat must be 2 1/4" below the top of the rail. The thickness of both cleats must be included in the total length of the module. Adding two cleats to a 4' module would make it 48 3/4" long, which is 3/4" too long. The cleats of two adjacent modules rest on a supporting leg unit when the layout is assembled.
	TRACK: We recommend Code 100 nickel silver rail, but many modelers who operate modules based on western narrow gauge railroads prefer to use Code 83 for the main track. Lighter rail may be used for sidings. Turnouts must be #6 or larger on the main track. Main line cuves should be a minimum of 42" radius, but tighter radii may be used on other tracks. Parallel tracks should be spaced a minimum of 3" between centers; 3 1/2 is common. The main line track must enter and leave each module on a tangent (straight section). The centerline of the main track must be set back a minimum of 8" from the front edge of the module ends. Stop the rails 2" before the end of the module, but lay ties to the end. At operating sessions, use 4" sections of rail to join to the track on the next module.
	ELECTRICAL: The main buss (through) wire should be #14 gauge copper. The buss wires should be long enough to extend at least one foot beyond each end of the module. To connect the buss wires to the next module, use Radio Shack 4 pin connectors #274-204 and #274-205. These connectors must be ordered as they are no longer carried as standard stock. Assign pins 1 and 3 to the white wire (front rail) and pins 2 and 4 to the black wire (rear rail). The male connector should be on the LEFT end as you face the front of the module. The female connector then goes on the right end. Track feeder wires should be #18. It is recommended, but not essential, that all rail joints be soldered or feeder wires attached to each rail length.
	LEGS: One supporting leg unit is needed for each module. Corner modules or modules made up of sections may need additional supports. Two C-clamps of a 3" minimum opening are used to join two modules together with a cleat from each resting on one leg unit. Since the two interface cleats (3/8" each) rest on the leg unit, the thickness of the upper portion (3") of the leg must be 3/4" thick. If the leg unit is a solid sheet of 3/4" plywood or if the upper portion exceeds 3", two 4" x 6" openings must be provided for the clamps and electrical connections. The leg unit must not exceed 41 1/4" in height, including any height adjusters which are optional but recommended. See figure below.