Skrivbord – An overengineered workstation

So I have wanted to build a desk for many years now, ideas have grown and so has the big feature list. But since my interest have moved away from software to electronics my requirements have changed. I need a lot bigger work space for tools and more shelves for instruments, and still a lot of screens.
So 3 years ago I started on my desk design. I decided that I wanted to go for aluminium profiles for my frame, both because it’s flexible and something I had not tried it before.
I also wanted as much of the construction to be as precise as possible, so everything is constructed in CAD. Mechanics strength tested, mechatronics is movement tested, material purchase planned and material is CNC cut as much as possible.
By the end of 2018 I started the weeks long process of assemble it all.

I made a drawing with assembly instructions based on my CAD design Skrivbord (Workstation, Gremalm).pdf. But I quickly decided to change the assembly order to make two stable outer pieces to build the rest on, it also meant that I didn’t have to turn the whole assembly too much.

The two outer pieces assembled.

Sliders for the raise-able desk and shelf are mounted on the sides. It’s MGN12H linear sliders often used in smaller CNC builds.

Desk assembled.

Center pieces to hold the two sides together.

To make the desk move up and down in the sliders I’ve constructed a linear actuator using a threaded rod, some pulleys and a stepper motor. It all goes together in this lower center assembly.

The desk was lifted in place and screwed into the MGN12H blocks. It should have been a lot of over constrains in the desk assembly, but it could move up and down pretty easy.

The desk shelf will hold all the monitors, and is attached to the big desk. That means when the desk is raised or lowered the computer monitors will follow. I used an old used actuator for this purpose that I had laying around.

Instead of using CNC cut polycarbonate I ordered laser cut ABS sheets for the desk because it was a lot cheaper. I found this neat laser cut order system where I could upload my DXF-files directly on the web and isntantly get a quote.

To raise and lower the desk I made a small control box. It have two stepper drivers inside that drives each side of the desk.
A VL53L0X ToF (Time-of-Flight) sensor is measuring the distance to the desk so the control box can regulate the height. This also gives me an absolute height of the desk when restarting the MCU.
An ESP32 connects to a MQTT server and serves a desired height topic, when a new goal is set the control box will start to raise/lower the desk until the goal is set.
There’s also manual override for the desk with ordinary switches.

So in the end, was it worth it? No; the whole construction ended up far too expensive both in cost and time. But it was a nice experience to design something this big and follow through building it.
A far more effective workstation would be to purchase a cheap Ikea shelf and then place a raisable desk in front of it.

Laser-cutteed acrylic angles for bending polycarbonate in to fixed angles

For my and Vilses speaker-backpack it’s really crucial that we bend our angles straight and in the right angle.
We developed our own heat bending machine to make straight bends, but we needed a fixed angle to bend it in the correct angle.

So we extracted all the angles from our CAD-drawing and placed them on a new drawing. We had this idea about a multi-angeled hexagon, containing all the angles needed.
But we couldn’t fit all angles on one sheet, so we had to make two sheets.

After that we cut the angles with the laser-cutter, we also wrote the angles on top.

Here is the result:

Speaker backpack

Here is the speaker backpack that me and my friend Vilse is building. The system will be a fully portable PA-system with integrated DJ-booth and lightning-effects.

It will be powered by LiPo-batteries. LiPo-batteries contains high energy relative to the weight.

We estimate that the system will be quite heavy, around 30kg. We will attach wheels on the bottom for easier transport.


It will contain this elements

  • 4 x P.Audio HP-10W (Link)

    Effect: 100 W RMS
    Sensitivity: 96 dB
    Frequency range: 50-4000 Hz
    Impedance: 8 Ohm
    Recommended frequency band: 90-3000 Hz
    Qts: 0.40
    Vas: 55 L
    Fs: 48 Hz
    Yttermått: 260mm (10″)
    Depth: 125 mm
    Weight: 2.8 kg
  • 2 x Motorola Superhorn A125 KSN1025B (Hifikit Link)

    Effect: 300 W
    Frequency range: 2000 – 20000 Hz
    Distortion at 105 dB: Less than 1%
    Känslighet (1m, 1W): 100dB
    Weight: 0.130 Kg
    Outer dimensions: 188x80mm
    Depth: 106mm


The speakers will be powered by a AMP9 Basic (41Hz Link):

  • Four channels of Tripath sound quality, based on Tripath TAA4100A
  • Output 4x50W at low distortion, 4x100W peak
  • Suitable for low impedance loads, 4 x 2 ohms 12V typical
  • Up to 27V supplies make them suitable for 12 or 24V systems

Audio crossover filter

We will be placing a audio crossover (frequency splitter) filter on the signal input before the amplifier.
If we would place the filter after the amplifier we would loose effect, and we want as long battery-life as possible.

In the future we will use a digital audio crossover, like the miniDSP (miniDSP Link)


We have choose a pretty unusual material for this speaker, polycarbonate. It’s a material that is easy to work with and it looks great.

What is even more unusual is that we are making a holdable design:

This will give us a almost completely air-tight box, but! it’s going to be really hard to fold it correctly. Therefore we have designed the fold-able lines pre-milled with 90°.

As we don’t have a big CNC-mill, we let the company Plastmästarn mill our project.


The speaker-box will contain 94 liters of air.