The desire for a larger telescope. The urge to build a larger telescope became irresistible, so I decided to construct a 10" f/5 Newtonian on a fork mount. It had to be a heavy‑duty mount, capable of carrying a substantial telescope and suitable for astrophotography.

Construction of the RA axis The RA axis is made of stainless steel and was turned from material 100 mm in diameter and 500 mm long. Here the axis is shown on the lathe. After machining, it is important to let the lathe run so the axis can cool while rotating; this prevents warping. The bearing housing was welded onto an HE‑A beam. The reinforcing strips between the flanges prevent torsion. A precision reference surface was added on a boring mill.

The control system was a challenge of its own. Since I used only discarded components, the motors all had different operating voltages. Using a PLC was therefore not feasible without a large number of relays. For that reason, I built the entire control system using relays only, without a PLC. To achieve the correct rotational speed for the RA axis and to enable auto‑guiding, I used a frequency converter. Designing the schematics was quite a task; I am a mechanical engineer, not an electronics specialist. Between the flanges of the HE‑A beam, terminal strips were installed on both sides to handle the wiring.

This is the final result: a home‑built 10" f/5 Newtonian on a fork mount. The construction is so robust that even the Takahashi can ride along effortlessly as a piggy‑back instrument.

The telescope can be operated both from inside the observatory and from the control room. Switching between the two is completely smooth and shock‑free.