LilyGo T-CAN485 DIN-rail enclosure

A 3D-printable enclosure for the LilyGo T-CAN485 (ESP32 + RS485 + CAN). The box is just big enough for the PCB. The screw-terminal plugs stick out through slots in the end walls, and the box clips onto a TS35 DIN rail.

Files

• base_heatpump.stl: base with two DS18B20 cable entries

• base_fancoil.stl: same base without the DS18B20 entries

• lid.stl: lid, already flipped for printing

• din_clip.stl: DIN rail clip, already flipped for printing

Layout

• Board: sits 10 mm above the floor, leaving room under it for DS18B20 wiring on the back 2×6 header. The board has no mounting holes, so it's clamped at 5 points on component-free strips of the PCB edge, between floor pads and lid fingers. The end walls sit 0.25 mm from the PCB ends and stop it sliding lengthwise.

• Terminals: the RS485, CAN and power plugs pass through U-slots in the end walls. The slots are open at the top, so the board can go in with the plugs already wired. Tongues on the lid close each slot down to just above the plug. The plug screws and wire entries stay outside, so you can unplug a cable without opening the box.

• DS18B20 (heat-pump base only): two 4.5 mm entries low in the power-end wall, each with a floor bridge for a zip tie. Solder a right-angle header to the back with the pins pointing toward the middle of the board; the DuPont plugs then lie flat under the board.

• USB-C: a 13 × 7.5 mm opening in the long wall, so a normal cable fits with the lid closed.

• Lid: 2.4 mm poke holes with guide tubes for BOOT and RST (use a paperclip), a 3.2 mm light tube over the WS2812, and engraved labels. Two countersunk screws go into posts in the end walls, between the plugs.

• WiFi: everything is plastic. The DIN clip is offset toward the RS485 end, so the metal rail stays about 30 mm from the ESP32 antenna.

Outside dimensions: 86 × 42 × 26.5 mm (98 mm long including the lid's screw ears). The plugs stick out about 11 mm beyond the walls. The clip adds 10.3 mm at the back.

Printing

• Material: PETG. Utility rooms get warm, and PLA creeps near heat. 0.2 mm layers, 3–4 walls, 20 % infill.

• Base: print upright, no supports.

• Lid: prints top face down, no supports.

• Clip: prints with the flat box side down. The latch beam flexes in the layer plane, so it's strong. Don't scale it.

Hardware

• 6 × M3 helicoils (wire thread inserts): 2 for the base posts, 4 for the clip. Holes are printed at Ø 3.2 mm and need the helicoil (STI) tap. Base-post holes are 8 mm deep, fitting coils up to 2×D (6 mm) plus the tang. Clip holes go all the way through, so you can push the tang out on the rail side.

• 6 × M3 × 8 countersunk screws (DIN 7991 / ISO 10642): 2 for the lid, 4 from inside the box floor into the clip.

• Small zip ties, 2.5 mm wide.

Assembly

1. Tap the 2 base-post holes and the 4 clip holes with the helicoil tap. Wind in the helicoils and break off the tangs.

2. Screw the clip to the floor from inside. The square bolt pattern lets you mount it in 90° steps. By default the rail runs across the box, so the box hangs vertically. Turn the clip 180° to choose which end faces down.

3. Wire the DS18B20s to the back header (IO32/VDD/GND), with a 4.7 kΩ resistor between IO32 and VDD. Feed the cables in through the low holes and zip-tie them to the bridges.

4. Wire the terminal plugs. Drop the board in with the USB-C toward the wall with the opening; the plugs go down through the slots.

5. Close the lid. The fingers clamp the board and the tongues close the slots. Hook the fixed side of the clip onto the rail first, then snap it on. To release it, lever the pull tab on the sprung side with a screwdriver.