Signs for our village camp at Borderland


Our camp at Borderland festival is named “The Elements”, and a nice sign will make it stand out.


I laser cut out the letters out of plywood, and the mounting holes in the back plate as well. I screwed in the letters with a few centimeter spacers between.


I made a nice control interface for setting light levels and modes of the sign. I encapsulated it in a great looking aluminium case with rubber seals for weather protection.
The control interface was also engraved by a fiber laser.


WS2812 LED strip was attached to the underside of the letters, aimed to reflect the light towards a light background that would diffuse the light around the letters.
And lastly the letters painted with corresponding colors to make the sign visible in daytime as well at night.

The ultimate Microbit Set


I made the ultimate Microbit set for my purposes. I combined several kits in to one kit, and also included a ES121 electric screw driver and tweezers.


These are the original kits that I combined to get multiple bits.


I found a good sturdy case for fishing flies.


I found out that a common laser cut friendly foam is polyethylene foam (PE foam or PEF). It’s commonly used for tool cases.
I calculated all the bits I wanted, and made slots for them together with some of my tools. Then I laser cut them out and hot glued them into place the case.


The end result is an awesome Microbit set that is very portable.

Folkrace 187


In Swedish Robot Championship there’s a tournament that is called Folkrace where autonomous cars is racing around a track. A sub class of this is a miniature race in scale 1:87.


So I started out on a Fuller Car system truck in scale 1:87. It have some really nice suspension and drivetrain but is made for following a iron track.


A NodeMCU development kit (ESP8266) almost fitted the truck bed, if i filed of 0.5mm of it i fitted perfectly.


I solved the steering by cutting a hole, big enough for a small servo, in the trucks chassis.
Then i glued on a small magnet that aligned with the already existing magnet in the steering system.


I then mounted 3 VL53L0X ToF (Time of FLight) distance sensors inside the cab of the truck. The sensors is pointing out from the same holes the windows are located.
The sensors will be used to locate walls and other trucks, it’s gives a pretty low resolution, but should be enough.


The space inside the truck bed is cramped, and I mean it. After fitting a small H-bridge, a couple of batteries and some cables together with a start module nothing more can fit.

As if the cramped space inside the truck bed was not a challenge big enough I choose to run Micro Python on the MCU.
It’s pretty nice and all, I could remotly upload new Python code to the flash and run my test scripts inside a Python interactive terminal.
You can find the code here: https://github.com/TimGremalm/Folkrace187

I found the challenges of the small form factor thrilling, it was a really fun adventure puzzling everything together and make it look pretty stock.
But there is room for many improvements! The Fuller Car system have a very nice steering system, and it’s very useful for a future design.
But Fullers drive train is a worm gear, it makes it strong but gives the drive train some momentum that makes the car slow in response when braking och switching between going forward and backwards. For future builds I would have to build my own drive train.

The cramped space inside the truck bed is due to a lot of premade modules and a lot of cables. A more effective way of doing it would be to make a PCB with a ESP8266, H-bridge and sensor bus built in.

Also I think I would abandon Micro Python for C and Free RTOS. The VL53L0X driver is very slow in Micro Python and it takes too long to read 3 sensors. The whole driver thing is pretty hard to fault find and gives great me a great hazzle.

Prop for Downton Abbey larp


For the larp 1912 we wanted to have servant bells like in Downton Abbey.


Carl Nordblom made a nice looking construction for the bells using leaf springs.


An ESP8266 is listening on some bell topics for messages. If a message is received it will swing the corresponding servo with a bell hooked up.


To trigger the bells we built a box with a auto returning string to pull. The strings is hooked up to a micro switch witch triggers the reset pin on a ESP8266.
When the ESP8266 starts it sends a message on the corresponding MQTT topic to ring, then enter heavy sleep mode.

Cooking food with a robot – a good learning experience


So we have this awesome Universal Robots arm at work. One night my colleagues had been experimenting with emptying the coffee grain, and after that it was just standing there mounted and everything.
I couldn’t miss this opportunity, so I decided to cook with it as my first robot programming experience!

So I thought about what food would be the most easy to cook, and then it hit me; premade tomato soup. I rushed to the store and got some soup.
The programming experience was easy to pick up I didn’t read anything out of the manual.

I wanted a pretty simple program:
* Pick up stiring device
* Move to pot
* Stir until cooked
* Remove and drop stiring device

I made some absolute key frames and let the robot handle the interpolation and movement.
I also hooked up a switch and made the robot stir the pot until the switch was activated.

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. https://smidyo.com/


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.
https://github.com/TimGremalm/SkrivbordDeskStepper
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.

Alco Bong revisited


I previously made Alco Bong 9000, but it had some flaws. The alcohol chamber was too small and it need some volume to hold more alcoholic mist. It also run on a 6S LiPo battery that was stepped down to 24V.


So with the improvements in mind I started out on a new alco bong. I found a big beaker in a second hand shop and started out from that.


Another problem with the alco bong was that people who used it didn’t understand that they could release the vape-button. So by introducing a progress bar it would be more clear. I installed a analog volt meter and controlling it by PWM.


Because a non-LiPo-knowledgeable person would be using it I installed a battery pack holder using ordinary AA battery.

Prop Interactive Water effecet lamp


For the larp Do Androids Pray? we wanted to recreate the companys corridor scene from Blade Runner 2049 where some beautiful water light seemed to follow the persons who walked up the stairs.

I thought that it would be doable using multiple water effect light and dim them up when movement was detected.


I purchased some cheap water effect lamps of eBay and took them apart to inspect. The LED was hooked up to some mosfets, så I just removed the resistor leading to the original MCU and hotwired some leads to my own MCU.


I drilled out a small cut out for a 3 pin header an glued it into place and put a PIR module in.


The whole assembly kind of look like it’s original except an exposed PIR module.

Prop Sign “Rund” for the larp Do Androids Dream?

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For the larp Do Androids Dream we needed a lot of small props to give a Blade Runner feeling of the scene.
Small lit up signs would give that Hong Kong look that is so common in Blade Runner. Carl Nordblom, the set designer, had some ideas about how the sign should look, and had found some sample pictures.

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From the sample pictures I got an idea of how to produce a design. And from that idea I started to make a CAD-design.
The finished design ended up being almost exactly like the CAD-design.
Here is the Drawing of the Round Sign (Do Androids Dream).pdf

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Small wooden block for holding a aluminium plate in a slot.

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The wooden blocks attached on to a sheet of flexible PET plastic.
The sheet is bent around the round aluminum plate with the help of the slots.

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The PET ring is transparent with a blue tint which would not be fitting in a light fixture. So we painted the PET ring in black to make it opaque.

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Warm white 5050 LED strip was glued on to the aluminium plate.
9×6 strips with 54 LED’s on each side makes 108 LED’s in total
108 * 20mA = 2.16A
2.16A * 12V = 26W

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The LED strips is driven by 12V that comes in from JST-connector.
But the sign is supposed to look like an old florescent light, so to give that look the light should look like it flicker occasionally.
I hooked up an N-channel MOSFET IRLML6344 and connected it to a Arduino Nano for timing the random flickering.

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A big steel angle attached to the heavy aluminium plate of the sign, this is used for screwing the signs to a wall. Also the JST power connector, hidden in black heat shrink tubing.

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In the outer sides of the sign round white acrylic plates will be inserted. They will rest against the wooden blocks and hold back by small sprints.
Each side of the sign is mirrored, so one sign have two faces.
The light is powerful enough to project through the white acrylic plastic. And with opaque paint on top will make a huge contrast perfect for a sign.