Thursday, September 4, 2014

cheapest U$5.97 DIY sous vide setup

Yours truly is no stranger to DIY sous vide setup, having dabble in various microncontroller based home made sous vide setup. The PID controlled arduino sous vide setup by yours truly can be found here This PID controlled arduino sous vide has been instrumental in setting up for the perfect dinner dates with the missus. I have cooked fabulous steaks, short ribs, lamb racks, and the epitome of my DIY sous vide home cooking: the effortless Beef Rendang. Details of the beef rendang can be found here

After rubbing shoulders with humans at several maker faire, or maker inspired activities across the continents spanning many miles apart
humans often remarked: "it looks so complicated/dangerous/scary!", "I want to have one but I can't write the program/wire the electrical/solder the electronics", " i want to buy a commercial one/the parts/components, but it is out of my reach", etc.

After seeing a fellow foodie and sous vide enthusiast trying to justify to own a sous vide setup; considerations include the cost, the complexity of setting up, the safety. Perhaps there might be something I can help to bridge this money/time/technological gap. Note: sous vide campaigns on kickstarter is tempting, but the waiting time for delivery is causing him anxiety.

After some searching online for cheap alternatives, I came across this temperature controller from aliexpress that cost U$5.97 with free shipping (to Singapore, that is). It sports an 8bit 32pin MCU the STM8S103K

On the aliexpress product page, nothing was written about the control theory used to ensure the settling time, the rise time w.r.t to the target temperature. This module also sports a relay that is capable of 10A to be used to control a heating apparatus. The other nice thing is, it fits in a regular name card holder. Nonetheless, the entry price is low enough to tempt me to click "BUY". There is a caveat, the manual that comes in the package is in chinese.

parts needed
1. U$5.97 temperature controller module from "middle kingdom"
2. a modified single face plate AC socket & plug (UK standard socket and plug)
3. a heating vessel

instruments needed
1. digital thermometer
2. Fluke wireless thermometer is optional

prep the U$5.97 temperature controller. The exposed AC end that is very close to the LHS push button has to be insulated. I have used some hot glue, and also a casing to isolate from human touching the PCB connectors accidentally. Thus module comes with screw terminals as connector for the DC supply and AC load. Solder a DC connector to the supply side. For the AC load side, I have used 2 wires, one end is cript with a fork cable lug, the other end is tinned, and to be connected to a screw down terminal block.

modified AC socket & plug (UK standard socket and plug). This step can be potentially hazardous if safety procedures are not observed. Do NOT work on an electrical AC socket while it is plug into a live source. Make sure the exposed leads are properly insulated. Wear proper foot wear that comes with rubber sole. Check the working environment has an ELCB tested to be functional. Do NOT use thin wires for AC load. Use the wire from a standard 3 core power cable.

Wire a standard single face plate AC socket & plug as if it is going to be used as an extension. Now, instead of the live wire (brown colour, UK standard) going directly to the socket pin where it is supposed to be; make an "open circuit" on the live wire and connect the exposed ends to the screw down terminal block. This terminal block will act as a "switch" to be controlled by the relay on the temperature controller module.

Please note this might not be the best way of doing it with the wires exposed. If you have a better way of connecting a relay to an AC live wire, give me a shoutout.

step 3
prep a heating vessel. I have used a cheapo 1.3L mini heater jug cum cooker as my heating vessel. It comes with an adjustable knob for the heat setting and is rated as 1100w (max) on the box.

connect all the components together. before turning it on, perform a final check for correct wiring, proper insulation, AC safety standard, etc.

perform intial heating/temperature test. make sure the temperature register by the sensor of the temperature controller module is approximately to the digital thermometer.

test cook an 64degC 45min egg.

Friday, August 29, 2014

ET1010 MAPP design contest entries

Wearable Assistive Tech Gripper

automatic braille

DICE creamaker

Friday, July 25, 2014

techno mohawk, maker faire, arduino, ATtiny85, WS2812 RGB LED

yours truly has devised this Q&D contraption for singapore mini maker faire #SMMF2014

Check this previous post on how to use Arduino, ATtiny85, WS2812/2811 RGB LED strip

The contraption below use almost similar components, except the fiber optic 5mm strands as mohawk.

Wiring of this contraption is as per the following diagram.

The following diagram describe the crafting of this contraption.

video here

code here

Friday, July 4, 2014

3D printing with wood filament

3D printing with wood filament
This week the wood filament by laywood is explored for 3D printing using makerbot replicator2. 3D printing in wood offers a new range of application.  Experimentation with this new medium to explore the possibilities of what can it used for. The beauty of this wood filament, it can be post treated as per the usual wood working, sanding included.
Loading of the wood filament into makerbot replicator2 for 3D printing is a breeze. Check out the previous post of modifying the loading mechanism
Standard PLA setting from makerware is used, but the temperature is set to 180degC instead of the usual 210degC to explore the texture and colour of the 3D printed parts. “Oozing” is observed from the 3D printed parts. Oozing in this context refers to the web of fine threads hanging from wall to wall of the model akin to a spider web. It has a term for it: “oozing while printing”.
Further refinement of the speed of filament extrusion/retraction, speed while extruding, and speed while travelling need to be tweaked to achieved a “cleaner” 3D printed parts.
A challenging model to print without support, due to the overhangs that are spiralling up.

This is the final output is plague with “oozing while printing”. Mentioned earlier, tweaking of the movement speeds of the 3 parameters are still waiting to be tweaked to perfection.

This website offers some suggestions such as lowering the temperature of the hot end, reducing the movement speed, and increasing the retraction length. All the above requires time to discover the best settings!

Engrave photo on wood with a laser cutter

Engrave photo on wood with a laser cutter
A photo or image can be realized on a piece of wood with the use of laser cutter. The process is simple. First, the photo has to be digitally manipulated. This photo is then sent to “print” via the laser cutter using popular vector drawing software such as coreldraw.
To digitally manipulate the subjects composed in a colour photo, popular vector drawing software such as coreldraw (proprietary), inkscape (open source) can be used for manipulating it into greyscale, and then subjects are outlined in black. The varying shades of grey, and black outlines determines how much power the laser cutter should output to engrave the piece of wood via the “rastering” mode. The darker the region, the more power will be output to “engrave” the wood by burning parts of it.
In FabLab@SP, 3 laser cutters are available; The Epilog, The Rayjet, and the HAS. The general steps to engrave photo are similar, but the parameters to set for laser cutting associated to different type of laser cutters are slightly different.
Parts needed
  1. A piece of wood; balsa, plywood will do. Preferably 3mm or 5mm.
  2. Access to a laser cutter. This guide assumes access to the epilog laser cutter
  3. Access to a vector drawing software, or photo manipulating software such as adobe photoshop, coreldraw, inkscape, etc. In this guide, an online photo editor is used.
  4. A photo of choice.
Step1: upload photo to be edited to
Step2: Click on “effects”, then scroll to “Extra Black&White”. Manipulate the 2 sliders “Brightness” & “Contrast” to achieve the desired outcome as per depicted in the following diagram. Desired outcome to be achieved can be defined by “high contras on specific features, such as facial features of the subject(s)”, “white-out background to give a strong highlight on the subject”
D:\Users\s41764\Desktop\laser cut stuff\ribbet1.PNG
Step3: Still in “effects” tab, scroll to “pencil sketch”. This effect will highlight outline the subjects as per the black & white photo, by giving a darker shade of grey at the edges. Manipulate the sliders “radius” and “strength” until the subjects are “standing out” from the background and gives a lasting impession.
D:\Users\s41764\Desktop\laser cut stuff\ribbet2.PNG
Step4: save the manipulated photo on the computer as *.JPG.
Step5: On the computer that is connected to the laser cutter, use coreldraw to create a new canvas of the type “fusion table”. Open the manipulated photo in coreldraw, position the photo such that it corresponds to the piece of wood where it will be laser cut. Select the box drawing tool on the LHS and enclosed it on the picture. Then select the line thickness of the box to be “hairline”. This setting corresponds to cutting a box shape surrounding the photo. The following diagram explains it all.
Step6. Load the piece of wood into the laser cutter
Step7. It is crucial to ensure the canvas chosen for laser cutting is of the type “Fusion Table”. File-> print OR Press on the “print” logo. A popup box will then appear. Ensure that the printer is “Epilog” and not your regular paper printer, and then click on preference to modify parameters that are essential to the quality of the laser cutting output. The following diagram illustrates it.
Step8. Select laser cutting parameters such as thickness of the material, job type, speed, power, and frequency and then press “OK”. Each of the manufacturers has meted out recommended settings to the parameters in a lookup table form for different type of material. In this guide, a 5mm thick plywood is used. Assuming the output of this laser cutting is very faint or hardly noticeable, it is recommended to crank up the power and lower down the speed. Otherwise if the output of this laser cutting appears to be burnt at the edges.
Step9: Close the protective cover of the laser cutter with the wood properly aligned in it and then press “GO” on the control panel. Observe the magic!
Brought to you by FabLab@SP