[Patrick Herd] was in Sweden recently and decided to help out a team of high school students in the International Young Physicist Tournament — The challenge? Chocolate Hysteresis.
Chocolate what? When chocolate melts, it doesn’t actually re-solidify at it’s melting point — in fact, it’s quite below that. The challenge here is figuring out a scientific way of measuring the time (and temperature) it takes to return to a solid state. This in itself is kind of tricky considering you have to accurately measure the temperature and be able to empirically tell if its solid or liquid.
The first scientific apparatus they came up with was the Chocolate Rig V1 – a very simple peltier heated and cooled calorimeter. They used an Arduino to control the temperature and a motor shield to power the peltier plate. It kind of worked but they discovered it was difficult to assess the physical state of the chocolate. This is when [Patrick] started doing some research and discovered rotary viscometry.
Continue reading “Melting Chocolate – FOR SCIENCE!”
Hot glue falls into the same category of duct tape and zip ties as a versatile material for fixing anything that needs to be stuck together. [Ed]’s Bosch glue gun served him well, but after a couple of years the temperature regulation stopped working. Rather than buying a new one, he decided to rip it apart.
With the old temperature regulation circuit cooked, [Ed] looked around for something better on eBay. He came across a cheap PID temperature controller, and the Frankengluegun was born.
A thermocouple, affixed with some kapton tape and thermal paste, was used to measure the temperature of the barrel. Power for the glue gun was routed through the PID controller, which uses PWM to accurately controller the temperature. All the wiring could even be routed through the original cord grips for a clean build.
Quality glue guns with accurate temperature control are quite pricey. This solution can be added on to a glue gun for less than $30, and the final product looks just as good.
Heated beds for 3D printers help reduce the amount of curling and warping of parts. The warping happens when the part cools and contracts. The heated bed keeps the part warm for the entire print and reduces the warping.
As an upgrade to her Printrbot, [Erin] added a heated bed. The first plan was to DIY one using Nichrome wire, but heated beds are available at low cost. They’re basically just a PCB with a long trace that acts as a resistor. She added a thermistor to monitor temperature and allow for accurate control.
The Printrbot heated bed worked, but didn’t heat up quite quick enough. [Erin] was quick to scratch off the solder mask and solder new leads onto the board. This converted the board into two parallel resistors, halving the resistance and doubling the power.
This version heated up very quickly, but didn’t have a steady heat. The simple control that was being used was insufficient, and a PID controller was needed. This type of control loop helps deal with problems such as oscillations.
The Printrbot’s firmware is based on Marlin, which has PID support disabled by default. After rebuilding the code and flashing, the PID gains could be adjusted using g-codes. With the values tuned, [Erin]’s printer was holding steady heat, and can now print ABS and PLA with minimal warping.
For some reason or another, the Hackaday tip line sometimes sees a short burst of submissions for the same project. The latest one of these was for toaster oven reflow stations. They’re both great builds and different approaches to making a useful tool out of home appliances.
First up is [Richard]’s build. he ended up with a fairly high-end build using a Rocket Scream Reflow Oven Controller Arduino shield. This shield accepts a normal K-type thermocouple and controls an external solid state relay with the Arduino’s PID library. [Richard]’s build has a few neat additions – a properly dremeled enclosure, computer fan, and a welding blanket for insulation. Now that we think about it, it’s odd we’ve rarely seen any sort of insulation in these reflow oven builds.
Next up is [Ray]’s version of a Black & Decker reflow oven. While not as fancy as [Richard]’s build, this one does have a few features that make it very interesting. Instead of messing around with thermocouples, [Ray] simply took a digital kitchen thermometer – a neat tool that already a thermistor in a compact metal probe – and read the analog value with an Arduino. To control the power, [Ray] is using a cheap 433 MHz radio transmitter to control a few remotely operated power sockets. It’s a very clever and inexpensive replacement for a SSR, especially since [Ray] had these power sockets just lying around.
So there you go. The same tool, built two different ways. A great demonstration of how you can not only build anything, but you can build anything any way you want.
[Matt] wanted to have more control over his meat smoker so he built this advanced PID smoker controller. It uses the solid state relay seen in the bottom-right of this image to switch the smoker’s heating element. But all of the other goodies that are included add several features not usually found in these builds.
This is a replacement for the commercial PID unit he used on the original build. That monitored the temperature in the smoker, using predictive algorithms to maintain just the right heat level. But this time around [Matt] is looking for extra feedback with a second sensor to monitor meat temperature. Using an Arduino with an SD shield he is able to data log the smoking sessions, and his custom code allows him to specify temperature profiles for resting the meat after it has hit the target temperature. It kind of reminds us of a reflow oven controller… but for food.
[Willy Wampa] is showing off his self-balancing robot. What strikes us about the build is how well tuned his feedback loop seems to be. In the video after the break you will see that there is absolutely no visible oscillation used to keep its balance.
The parts used are quite easy to obtain. The acrylic mounting plates are his wife’s design and were custom cut through the Pololu service. They were also the source of the gear motors. He’s using a SparkFun IMU with an Arduino and a motor shield. He first posted about the build about a month ago, but the new revision switches to a Pololu motor driver shield which he says works much better, and adds control via a wireless Wii Nunchuck.
The PID loop which gives it that remarkably solid upright stance is from a library written by [Brett Beauregard]. Once again the concept of open source lets us build great things by standing on the shoulders of others.
Continue reading “Wii Nunchuck controlled robot exhibits rock solid balancing”
Bringing that smoky goodness to your cooking is neither hard, nor is it expensive. [Alton Brown], who we consider to be the MacGyver of cooking, always seems to be able to build cooking contraptions from common items. The smoker he built from a flower pot was the inspiration for [Tom’s] own project. But [Tom] added in PID hardware to smoke at just the right temperature.
The enclosure hides a single electric burner at the bottom. A metal tray full of wood chips sits on top of it, smoldering as the burner gets hot. You could just set it and forget it, but it will take a lot of trial and error to figure out which setting achieves the best results. [Tom’s] additional hardware, housed in the grey electrical box, switches the burner with a solid state relay. The PID controller takes measurements from a temperature sensor inserted in the lid of the smoker, ensuring perfectly prepared food every time.
If you’re interested in making your own you could try building a heating element from toaster oven parts.