Kategori Projekter

27 okt

Kommentarer lukket til Access Control System

Access Control System

Af

Our space has been equipped with an RFID-based door system since the beginning. It has worked well, but when we got the laser cutter, it was necessary to restrict access to the cutter to members who had received training. At first, the laser cutter had its own simple ‘database’, but it soon became inefficient to maintain two separate fdsfsystems. Also, the door system was not integrated with the member database, so we actually had three different databases that had to be maintained.

So we started talking about making a new system, and after extended discussion we actually started to code. The center of the system ia a backend, written in Rails. The backend provides a web interface for administration, and a REST interface for use by the various peripherals – called ‘machines’.

Configuring a user’s permissions with the web interface.

Viewing the log.

The primary ‘machine’ is the card reader located at the door. It uses the REST API to determine if the card is associated with a user who has access to the space.

Card reader at the entrance

In the same way, a number of other machines (lathe, mill, CNC router, 3-D printers) are equipped with a box containing an RFID reader, a relay, and an ESP8266. The ESP8266 connects to the backend over WiFi. For most of the machines, the power is only on as long as the card is inserted into the reader, but for the 3-D printers, the card can be removed once the print is started (the box measures current consumption of the printer, and shuts off once the print is done and the printer has cooled down).

Card reader at Bungard CNC

Access control box mounted on the Lulzbot Taz printer

Inside of access control box showing PSU, relay, and ESP8266. The version for the 3-D printers has an additional current sensor so that they can determine when the printer is idle.

The front of the access control box seen from the inside, showing card reader loop antenna/switch, OLED display, card reader PCB, and indicator LED.

The backend runs on a Cubieboard (an SBC based on an Allwinner ARM core, with on board SATA) with an SDD for storage. The connection between backend and the door ‘machine’ is USB, so you can open the door as long as there’s power, even if internet access should be down.

The backend is placed near the door and has a display and two buttons; the green one unlocks the door for fifteen minutes, and the red one locks the door.

The door is locked.

The door is open for 15 minutes.

Counting down.

Gemt under: Projekter

20 okt

Kommentarer lukket til Aarhus Mini Maker Faire 2018

Aarhus Mini Maker Faire 2018

Af

For femte gang var vi afsted til Mini Maker Faire i Aarhus.

Vi er lidt for dovne til at lave en rigtig blog-post, så I må nøjes med lidt billeder og video.

Først en video fra vores stand, hvor man kan se næsten alle de ting vi havde med. Dog kan man ikke se de to fine flipdot-displays, hvor det ene efter lidt hacking på stedet kom til at køre Game of Life.

Vi havde i år lavet en flok simple bristlebots, som var en stor succes.

Ligesom sidste år vandt vi også præmien for bedste badge, se video på Facebook.

Gemt under: Events, Projekter, Udvalgte posts

07 nov

5 Comments

Motorising my old Long John

Af

A few months ago I decided I wanted to start biking to work. Being lazy and living in a hilly town, I started looking at E-bikes. I already had an old Long John (from 1941), and really like how it handles, so I looked a bit at the modern equivalent: Harry Vs. Larry’s Bullit, but the price, about the same as a used car, for the electric version, was just too high. So next step was looking for a conversion kit for my old bike. It was in real bad need of a new bottom bracket and new pedals, so naturally I started by looking for a crank motor. After being confused about the whole 8fun/Bafang stuff, I figured out that they don’t support coaster brakes, which is the only form of brake on my olde bicycle. So that solution was out of the question. Next I looked at hub motors, but because both the front and back wheel are odd ball size, I quickly hit the wall again.

Luckily @mchro pointed me towards Boxbike, who luckily had a crank motor, which supports coaster brakes. The price wasn’t too bad, so I ordered a kit consisting of a motor, pedal arms, battery, chain, controller and all the various wires. Boxbike really provided nice support. I had ordered a brake lever, which was not supported by the controller I had ordered, so they called me up, to make sure I knew what I was doing, which I obviously didn’t, and offered me a larger battery instead. They also told me to call them any time, incase I had any trouble figuring out how to mount the kit.

My bicycle loaded with goodies.

My bicycle loaded with goodies.

To have an easier time with the job, I made a small side project, and mounted a bicycle hoist in our space.

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Next step was removing the old bottom bracket, the previous owner had mounted pedals of the wrong kind for the bottom bracket, so about twenty minutes with an angle grinder later, I had the following view:

img_20161023_152551

I thought that i needed some sort of hook or c spanner, to unscrew the bottom bracket, but behind a cover plate, it turned out that I needed some sort of weird 3mm pin spanner. Which of course I didn’t have. So after a break I ended up welding an old spanner directly to the bottom bracket bearing face.

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Wohoo, on the the next problem 🙂

So the state after removing the bottom bracket looked like this.

img_20161026_183728

Sadly the motor needs just about 180 degrees to fit, which the frame obviously didn’t have.

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So long story short, took a hack saw to the frame, and made room. And a very simple installation, and a lot of cable ties later, and my bike was upgraded with a 250W motor 🙂

img_20161026_222700 20161026_222806

Gemt under: Projekter, Udvalgte posts

01 okt

0 Comments

Laserskåret parametrisk syæske

Af

Nu hvor vi har fået en lasercutter i spacet, er vi mange der har leget med at lave blandt andet æsker og kasser. Jeg faldt over denne fine fold-ud-kasse, men den var designet i 3 mm plade. Jeg havde ingen 3 mm plade, men derimod læssevis af billig 4 mm krydsfinér. Og da larsch fra spacet havde lavet en fremragende kassegenerator i OpenSCAD, var det nærliggende at bruge det som udgangspunkt. Mit hack kan beskues på GitHub, og den første udgave kom til at se sådan ud:
foldet
udfoldet

Gemt under: Projekter

23 maj

0 Comments

OpenSCAD: Funnel and Cylindrical Coupling

Af

As part of another project, I found myself in need of a funnel shape as well as a cylindrical coupling in OpenSCAD. Now, the straight forward approach would be to make a first-order approximation using a cylinder with two different radii to create a cone. While this solution would surely work for most cases, it is not as aesthetically pleasing as the real things, at least in my mind. As I couldn’t find any existing reference designs online, I decided to make and share a solution. The modules can be found on my GitHub: https://github.com/alexbirklykke/openscad

Both solutions use the rotate_extrude function in OpenSCAD, which takes a 2D polygon and rotates it around the z-axis. For the funnel I used a 2D version of the funnel surface function and for the coupling I used a selection of sigmoid functions. In both cases, the modules behave like the native cylinder module, but with additional shape and slice parameters that control the contour and number of polygon points of the drawn objects. For the cylindrical coupling it is also possible to choose between different sigmoid kernels (the standard sigmoid function, tanh, linear, and two other algebraic sigmoids) to tweak the contour even further.

Funnel

Funnel

Cylindrical coupling

Cylindrical coupling

Gemt under: open source, Projekter