Ringbom displacer cap for an 8 mm rod, 2 in shell displacer — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/tri-clamp-ringbom-displacer-cap/  (CC BY 4.0)
Basis: Shell spigot and flange as the displacer cap on this site (2 in shell Ø46 × 1 mm wall); Ø8 rod and M4 grub sizes are design values
Catalog version: 2026-10-20

Sizes: see table below
- Closes a 2 in shell displacer like the standard cap and holds an Ø8 rod instead of an Ø3 one. The rod is the Ringbom drive: its cross-section (50.3 mm²) times the gas pressure minus air pressure is the force that moves the free displacer.
- The rod's D-flat end goes in the Ø8 socket, 12 deep, and the M4 grub seats on the flat.

part  spigot_mm  flange_mm  boss_mm  socket_mm
ringbom-cap-2in-r8  Ø44 × 3  Ø46 × 1.5  Ø16 × 14  Ø8 × 12

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/tri-clamp-ringbom-displacer-cap/index.json
API: https://xemstudio.com/api/geometry?object=tri-clamp-ringbom-displacer-cap