Joining
The mechanical join between two T-TRAK modules is just two pieces of Kato Unitrack pushed end-to-end. The Unijoiner — the small metal slip that bridges between two pieces of Unitrack — does both the electrical and mechanical work. Get the alignment right and it's effortless; get it wrong and you'll bend Unijoiners, which means a layout that won't run cleanly until they're replaced.
The procedure:
- Stand the two modules side-by-side on the trestle, with their fronts aligned along the same line. Don't try to join in mid-air or while only one is on the table.
- Sight along the rail tops on the joining ends. If one module's rails are sitting higher than the other's, wind the levelling bolt of the lower module upward until the rail heights match. This is what the levelling bolts are for.
- Slide the modules together. The Kato Unijoiners on each module's protruding 1 mm of Unitrack click into each other. They want to mate — don't force the modules together; if there's resistance something is misaligned.
- Run a finger across the join. The rails should feel continuous — no step, no overhang. If you can feel a step, lift the joining face apart, look for a Unijoiner that has been pushed sideways or bent, straighten or replace it, and try again.
Separating
This is where modules get damaged. The whole layout has run beautifully all day, the show is over, and someone — sometimes the modeller themselves — grabs two modules and pulls them apart by hand. The force goes through the Unijoiners, which bend, and that module is now broken until they are swapped.
The procedure:
- Don't pull modules apart with bare hands. All the separation force ends up concentrated on the Unijoiners, which are thin metal and not designed to take a tensile pull. They bend out of shape and they don't always look bent.
- Pick up a 300 mm steel ruler — or any flat thin metal strip about that length. A pallet knife or a plastering tool works too.
- Slide the ruler down between the two module ends from above, working it into the gap at the joining face.
- Twist it sideways. The ruler acts as a wedge, and the modules spring cleanly apart with the Unijoiners staying with their own track.
- Inspect the Unijoiners on both module ends. A bent one will refuse to bridge to its partner next time and needs to be replaced — Kato sells them in packs and they're not expensive. Carry spares to every meet.
The 1 mm rule
The whole join only works because every module's Unitrack protrudes exactly 1 mm beyond its module end. When two modules butt together, that produces a 2 mm gap between their track ends — and that 2 mm gap is what the Unijoiner is sized to bridge. Build a 1 mm styrene shim once and use it to check every track end on every module before painting goes on. A track that sits flush with the module end won't reach across; one that protrudes too far will hit the neighbour's track and bind.
Spare Unijoiners
Always bring spare Unijoiners to a meet. Kato part #24-815 is the standard conducting type; #24-816 is the insulated equivalent for block boundaries. The same part fits HO and N — the Unijoiner is identical between scales. They cost almost nothing per pack, and a layout with a single bent Unijoiner is dead at that joint until the part is swapped, which is a poor reason to lose half a show.
Tunnel-fight a corner
Most off-the-shelf N tunnel portals on the market are too tight against the Australian clearance envelope — they'll catch on a tall wagon or a pantograph. If you're modelling a tunnel, plan to either modify the commercial portal (file out the inside), scratch-build to clearance, or warn the meet coordinator in advance that your tunnel needs a 3–6 mm module rise to clear before bringing it to a show. Don't discover the problem on set-up day with a queue of modellers behind you.
What can go wrong
Bent Unijoiners are the most common joint fault, but not the only one. A short list of the recurring problems — rail height mismatches, dirt under the joiner, levelling bolts wound past their travel, modules whose ends have been crushed in transit — and what to do about each is collected on the troubleshooting page. Most are quick to fix with the right tool in hand, which is why a meet's set-up bench should always have a steel ruler, a packet of spare Unijoiners, and a length of clean cotton rag.