Building a Motorized Dobsonian Telescope Mount in My Living Room

I’ve built and modified things for as long as I can remember.

Most of my earlier projects revolved around home improvement rather than hobby projects. I always repaired our household appliances myself, something I learned from my father, who was both highly technical and incredibly handy. In my younger years I also maintained my own motorcycle. Every winter it came apart completely and went back together piece by piece.

My educational background reflects that fascination with technology. I started with vocational school (LTS) and technical college (MTS), both focused on electrical engineering, with additional training in machining and mechanical design. Later I graduated in electronics engineering (HTS), and many years afterward I added an MBA. Technology and making things have always been part of who I am.

Long before the existence of my current 9 m² workshop – the 9m² Creatory – all of my projects were built in whatever space I had available. Which, in this case, was our living room.

And that is where this story begins.

The old Bynolyt

For many years I owned a Bynolyt Bynostar 4595 Newtonian telescope. A modest instrument by modern standards, but one that had accompanied me for nearly thirty years.

Specifications:

• Aperture: 114 mm
• Focal length: 900 mm
• Focal ratio: f/7.9
• 2× Barlow lens
• H-20 mm and H-6 mm eyepieces

At some point I became fascinated by astrophotography and wanted to automate the tracking of celestial objects. A traditional Dobsonian mount is manually operated, but I wondered whether I could build a fully motorized version myself.

Naturally, the answer was “why not?”

Starting with Wood

Like many Dobsonian builders, I started with wood.

The first design was created entirely in 2D using an ancient CorelDRAW X7 version. Fusion 360 and things like parametric design would only enter my life a few years later. The mount itself was built from waterproof MDF, which was later treated even further against moisture.

Front View

Side View

Ground Board Detail

Altitude Bearing Detail

The design was fairly conventional, using a rotating ground board for azimuth movement and a horizontal altitude axis supported by side bearings.

The First Working Mount

Eventually the design became reality.

Wooden Dobsonian Mount

Wooden Dobsonian Mount – Detail

The telescope itself was suspended between two side panels, and the altitude axis was driven through a worm gear arrangement. It worked surprisingly well and, looking back, the wooden construction had one major advantage:

It was light. An advantage I would only fully appreciate later.

Inspiration from the Internet

While searching for ideas, I came across an inspiring project by another enthusiast who had built a Raspberry Pi powered tracking mount.

Please see this Reddit post I made my own Raspberry Pi powered tracking telescope mount! from u/8PumpkinDonuts

That project convinced me that I could push my own design much further. And… Inspired by that work, I decided to redesign the entire mount from scratch.

This time in aluminium. After all, aluminium had to be better… right?

Enter Aluminium

The new mount became far more ambitious.

Instead of wood, the structure was built around aluminium profiles. Electronics would live inside laser-cut acrylic enclosures. Bearings, gears, chain drives and stepper motors would provide motion on both axes.

Front View

Top View

Pivot Detail

By then I was already becoming increasingly obsessed with mechanics and precision. Looking back at those drawings, I still smile. They were all made in 2D. Fusion 360 and fully parametric 3D design were still in the future.

When Your Living Room Becomes a Workshop

At that time, there was no 9m² Creatory.

There was only our living room.

Soldering irons, electronics, tools, wires, aluminium profiles, stepper motors and telescope parts were scattered everywhere. My wife deserves a medal for putting up with it.

But little by little, the system came together.

The Final Machine

Eventually the project evolved into something far beyond the original wooden mount.

Photo 11 – The finished aluminium mount

The frame consisted mainly of aluminium profiles, while most enclosures and mechanical parts were fabricated from colored acrylic.

The yellow transparent covers became something of a signature look. Through them you could see chains, gears, springs and adjustment mechanisms moving while the mount tracked the sky.

ALU Dodsonian Mount – Detail 1

ALU Dodsonian Mount – Detail 2

Inside the acrylic housing lived the electronics, display, motor drivers and control hardware. I always liked making the mechanics visible instead of hiding them away.

Some Valuable Lesson

Unfortunately, the aluminium version introduced a problem I had underestimated.

1. Weight.

The moving section became significantly heavier than the original wooden design. Every step made by the stepper motors induced a tiny amount of oscillation. After each movement, the structure would “waggle” ever so slightly.

For visual observing that wasn’t much of a problem.For astrophotography, however, those vibrations translated directly into softer less sharp images.I spent quit some time trying to eliminate that behaviour but never managed to get rid of it completely.

Ironically, the simpler wooden version had actually been the better engineering solution.

Sometimes lighter really is better.

2. The Chain

Looking back, I eventually traced most of the oscillation problem to the chain drive itself. Tightening the chain reduced the wobble, but at the same time increased friction and load on the stepper motors, which then struggled to deliver smooth motion. Leaving the chain looser reduced the load, but introduced just enough compliance to allow the whole assembly to oscillate after each step.

In hindsight, a properly engineered worm gear and worm wheel arrangement would probably have been the better solution, but by then I had already invested a considerable amount of time into the existing design and never got around to redesigning it. The inexpensive bearings I had used also exhibited a tiny amount of play, which proved to be a poor combination with a heavily tensioned chain drive. Eventually, I settled on what engineers everywhere sometimes have to accept: good enough. I knew I wasn’t extracting the maximum performance from the system, but it performed well enough to continue enjoying the project rather than endlessly chasing perfection.

The Telescope Had Aged Too

By that time, my old Bynolyt had nearly thirty years of service behind it.

It had accumulated a bit of “field damage”, and I strongly suspected that the primary mirror needed realignment. Unfortunately, I never got around to restoring it.

Two years later I sold the complete setup to another hobbyist who was particularly impressed by the aluminium mount. He planned to replace the Roller bearings and the chain mechanism (by a worm gear) and use it with a heavier telescope, which suited the construction better.

The new owner also had a clever workaround in mind. Rather than fighting the tiny oscillations mechanically, he wanted to use a precision accelerometer and delay the camera exposure until the mount had completely settled after each movement. I always liked the simplicity of that idea, but I never learned whether he succeeded in getting it to work.

A nice surprise though…

One unexpected highlight came much later. One fun detail worth mentioning is that the yellow acrylic used throughout the project wasn’t chosen purely for aesthetics. I had deliberately selected a fluorescent variety that reacts to ultraviolet light and appears to glow from within. It’s the same type of material often used in nightclubs to create those dramatic blacklight effects. Under UV illumination, the mount looked like something straight out of a science fiction movie—which, admittedly, I considered a nice bonus.

About a year later, I entered the design in a competition dedicated to projects made from acrylic. To my surprise, I won second prize. One of the comments from the jury was that they particularly appreciated the futuristic appearance of the design, with its visible mechanics and translucent glowing panels. Not bad for something that had started life on the dining table in our living room.

Looking Ahead

Several years later I entered a new chapter in my Astronomy hobby and purchased a completely electronically controlled telescope: a Seestar S50 Pro.

Being incapable of leaving things alone, I eventually built an equatorial mount for it as well. Tracking celestial objects around a single axis instead of two significantly improves stability and image quality.

But that story deserves a post of its own.

And yes…

That one was finally built in the 9m² Creatory.