The High Energy Accelerator Research Organization (KEK) has been developing the beam separation dipole magnet for the High Luminosity Large Hadron Collider (HL-LHC) upgrade. The magnet has a coil aperture of 150 mm, using Nb–Ti superconducting cable, and a dipole magnetic field of 5.6 T will be generated at 12 kA, at 1.9 K, to provide the field integral of 35 $\text{T}\cdot\text{m}$. To verify the mechanical behavior of the magnet and to optimize the fabrication processes, we develop a 200-mm short model, which is the cross-sectional cutout of the magnet. The development includes validation of a series of fabrication processes. Coil stress in pole was monitored by strain gauges during collaring, yoking, and cooldown test.