A Cozy Weekend in Odense: XMT7100 Based Sous Vide
During a quick visit Mads Lykke Jensen and I decided to make a sous vide for christmas in 2020. The Covid-19 year had ensured that we had nothing better to do on a friday night. The hardware list is as follows:
In total the hardware list equals roughly 50$ which is competetive with most commercially available sous vides. Spending 50$ on a weekend project is a good investment and thus here goes:
Designing the box enclosure in Adobe Inventor
We strived for a quick solution with plugs at hand in the scrap yard. This resulted in the following enclosure which is freely available at Thingiverse. A quick render of the enclosure is shown below. All hardware is flush with the front and back cover.
Printing Box Enclosures on the NEWTEC Printer Farm
The box enclosure shown above can readily be 3D-printed without support. The box is assembled with M3 screws. In this test we used 5 NEWTEC Prusa I3 Steel printers. The filament used was PETG with Carbon dust embedded. Printing time was almost 24 hours.
DAY 2 - Assembly and Testing
The main assembly of the sous vide relates to the wiring. A simple diagram is shown below. We use the physical relay present in the XMT7100 controller. Thus, the sous vide will make a 'clicking' sound when the relay is turned on and off. The lifetime is about 100.000-500.000 cycles, which is more than enough for a modern 2020 red meat diet.
XMT7100 Sous Vide Wiring
XMT7100 Settings and Testing
In order to make the XMT7100 compatible with our european SI unit system, we set the general parameter settings by entering the set code 0089. We change the CoeffY setting from 1 (degrees Fahrenheit) to 0 (degrees celsius). Additionally, we use the physical relay for our PID control and therefore we change the IntY parameter to 1. We use a type K thermocouple and therefore change the Hy setting to '4'. We figured out that the precision on the temperature reading was reduced to ± 1 degree C, and therefore we might change temperature later to a PT100 thermistor probe where the controller is capable of measuring with a ± 0.1 degree C precision.
During the first run-in test the controller is performing autotuning of the P,I and D parameters. We used a bucket of water and a set-point value of 70 degrees C. Hereafter the sous vide runs smoothly, and we are ready to eat some well prepared food. The final result is shown below. EzPz lemon sqz.
