Heat break between heater block and heat sink in a 3D printer.

Design

Thin tube inside a wider tube: 3 mm ID, 1/4" OD - [1]. Wall is a bit thick.
4.5 mm ID - for nominal 5 mm filament - [2]
Or super thin wall for 2.92 mm ID with 5 thou wall - [3] - super high performance heat breaks? For 30000 psi stainless and 0.001 cross section area, first order calculation says 30 lb breaking force for the heat break. That could be doable for a heat break outside of direct ramming into immovable objects, in which case 1 x motor drive is 24 lb and thus almost able to break the heat break.

Sourcing