Single Mini-T module
A Mini-T module keeps the same N-scale Kato Unitrack and the same 33 mm track-centre spacing as the standard N module — but at half the depth and a much finer length step. Two parallel running lines fit comfortably across the 150 mm deep deck, and the length is built up in 62 mm increments rather than the 310 mm increment used by the main N standard.
| Width / depth | 150 mm | Two tracks at 33 mm centres fit |
|---|---|---|
| Height | 70 mm | Australian standard; Japanese Mini-T is shorter |
| Length granularity | multiples of 62 mm | Much finer than the standard 310 mm step |
| Track centres | 33 mm | Same as N standard |
| Baseboard material | 12 mm hardwood ply | Three pieces; pine and MDF NOT recommended |
| Outside corner | based on 290 mm sq. | Square-ish footprint |
| Inside corner | based on 290 mm sq. | Two design options published |
| Track system | Kato Unitrack | Same as N-scale standard |
Mini-T transitions
Front-to-back transitions on Mini-T — for routing one running line behind the other, or smoothing a Mini-T section into a deeper module — are made from a pair of 15° curves with a short straight between them. Three radii are described in the standard. The 282 mm design comes out about 1 mm short of the geometry it needs to fit cleanly, so it asks for a small amount of track stretch at the joint. The 315 mm and 481 mm designs both fit cleanly without that fudge — those are the ones to reach for first.
| Tightest transition | 282 mm radius, 15° | ~1 mm short — needs a slight track stretch |
|---|---|---|
| Standard transition | 315 mm radius, 15° | Fits cleanly |
| Easy transition | 481 mm radius, 15° | Fits cleanly, gentlest curvature |
Compatibility with the main N standard
Mini-T uses a 62 mm length granularity against the main N standard's 310 mm step, and a 150 mm deck depth against the standard's 300 mm. In practice that makes it a sub-system in its own right: the Australian guidelines do not specify a converter module for bringing Mini-T modules onto a standard T-TRAK loop. Plan a Mini-T loop as Mini-T end-to-end, not as a section grafted onto a full-depth layout.
Material warning
Pine and MDF are explicitly not recommended for Mini-T baseboards. At Mini-T's smaller footprint, both materials warp and swell with age — pine cups across the narrow deck, MDF expands at the edges as soon as it picks up workshop humidity. The standard's recommendation here is firm: use 12 mm hardwood ply for all three baseboard pieces (top, front face and back face) and accept the slightly higher material cost as the price of a deck that stays flat for the life of the module.
Reference designs
Reference designs for both an inside-corner and an outside-corner Mini-T module are published in the Australian guidelines, with John Rumming's drawings the most widely cited source. The same set of drawings appeared in N Scale Modeller Issue 20 as a magazine feature — that printed article remains a good companion to the guidelines, especially for the corner geometry, and is the citation to reach for if you need a paper reference rather than a link.