Date: Thu, 26 Mar 1998 From: Peter B. Smith Subject: Sn3 Module Standards Greeting to All: About 10 years ago I developed some standards and organized an Sn3 Module group in the St Louis area. In the succeeding years, many of the members built layouts and the modules were integrated into the system. Now that I too have a basement, I plan to follow suit. We always displayed at our local semi-annual narrow gauge meets and I claim a couple of converts to Sn3 as a result. I borrowed ideas from the San Diego Sn3 modular group (now extinct) run by Tom Dush and company and from a group in Minnesota (also extinct) who had discussed module standards in an early issue of the "Sn3 Modeler". As I recall, our standards were published in an issue of the "3/16 Scale Modeler" (do I have the name right?), but I don't recall what issue. We ran a point to point operation. One end had a turn table and passing track, the other had a wye and a passing track. Under this concept, we never had to manage corner modules (will those four guy always show up?) and the members could build any length of module that suited the scene they were modeling or would fit in their car trunk. The modules were wired for two cabs with teathered throttles. We operated out in front with the spectators. It was a single track mainline. The track could meander however, as long as the meandering stayed within the standards and everyone used the same color ballast. Also, we were concerned with ugly bridge tracks that connect most HO modules. To overcome this, we ended the rails 2 inches from the end of the module, but ran the ballasted ties right up to the edge. Two four inch rails, with rail joiners, were then placed in the resulting gap. The effect was good, but having to do it all over again I would spec it to run the rail right up to the edge (much easier set up). In this case, you leave the last inch or two of rail unspiked, and use joiners between modules to connect the rails. You will need some kind of simple device to protect the rail ends during transport. Here are the standards we operated under. Perhaps they can form a basis for future discussions on the subject: Pete Smith THE Sn3 SHORT LINE MODULE INTERFACE STANDARDS Minimum Mainline Radius (note 1) 28 inches Track Centers Parallel Tracks 2-1/4 inches Curve Track Centers (minimum) 2-9/16 inches Rail Size Code 70 Module Height at Railhead 48 inches Bridge Rail Allowance (note 2) 2 inches Interface Tangent Length (note 3) 3-5/8 inches Maximum Mainline Grade (note 4) 4 % Minimum Mainline Turnout Nr 6 Track Set Back (Track center line to table edge) 6 inches Module Width 24 inches Module Length Even feet-2-4-etc. Transom Height 4 inches Notes: 1. NMRA standard is 31". 2. The single track mainline must cross the module edge level, at right angles, and at the 48 inch elevation. Ties and ballast will continue to the module edge Each module owner will provide two pieces of rail, four inches long, plus two regular and two insulated rail joiners to bridge to the next module. 3. Tangent track length is the distance from the end of the bridge track at the interface to the first deviation in mainline, i.e., a switch, curve, crossover, etc. 4. That equates to a 5/8 inch rise every two feet. 5. Top-to-bottom dimension of the board which abuts the next module, normally a 1 X 4 piece of wood--part of module frame. Peter B. Smith