"close enough"


Yet Another DIY Sous Vide

I don't like having lots of kitchen appliances believing that with sufficient skill and a couple of good cookwares, one can cook about anything with a stove and an oven. However, one lazy sunday morning, I found myself craving a poached egg and realized that I can't make that just creamy yolk reliably. So I decided to suck it up and make a sous vide controller (again). Last one was a PID controller which is unfortunatley stuck in storage on the other side of the country. This time I went with a simple cut-off temperature controller based on this instructable. While it didn't hold the temperature as accurately as my old PID controller, the results were fine. I hadn't worked with sheet metal before so I took the opportunity to make a case out of some scrap aluminium we had in the lab. All together it came out to $30 in parts.

So if you want to make one, follow along. Of course, we are talking about mains AC current, home made circuits, water and raw food. Death in the family can ruin in your whole day so don't follow along unless you know what you are doing.


For the guts:

For the case:

If you are in the lab, you should be able to salvage most things except for the controller and maybe the C14 inlet.


Wiring is pretty straight-forward. Here is a handy diagram:

Output is standard US socket which is NEMA 5-15. For output ground pointing down has neutral to the right (bigger socket) and live to the left. Inlet socket is the IEC320 C14 socket or computer power thingie. The part listed above has a fuse built-in and comes with a lit up switch. The switch is double throw, that is to say both wires are connected or disconnected with the switch. Here is a close up of the C14 wiring.

I used wire-nuts to do the 3 wire junctions instead of soldering those. This allowed me to easily take the components apart. At this point, you are good to go to try your sous vide machine. Plug in some water heating device. I used a manual crock pot. Cover up all exposed terminals with electric tape, use GFCI wall outlet, wear insulated shoes, stand back, and flip the switch. If you hear a loud beep, press a button to reset the controller. You did read the controller instructions, right?


To set the temperature target:

RTFM for the rest. Set temperature to 62.8 and throw in some eggs in their shell for some creamy deliciousness.

Takes about 45 mins at the right temperature.

The other classic is of course the medium rare steak. Here is a NY Strip steak about 1.25" thick cooked at 57.2 for an hour 20 mins.

The sides are seared 1min on one side and about 3 mins on the other.


Exposed mains electronics is no fun so you will want to make a case. If you want to remake the same case I made, just to skip to the cutting


I used Solidwork's sheet metal tools to design the case. I found this video to be a helpful introduction to sheet metal. The case is in two pieces: a tray that provides base and the front and back plates where the components will go; and a lid which provides the top and the left/right surfaces. The bottom tray has flanges coming out of the front and back plates which the lid screws into.

Roughly, here is the process if you want to design your own:

Cutting the case

Here are the DXF files if you just want to cut the case I made:

On the OMAX water jet:

btw, if you hit e-stop on the water jet, you will have to turn water pressure back on with the switch on the left.


The sheet metal bender uses small handles to clamp the metal under the brakes and the big handle to do the actual bending. Screws on the back move the brakes in and out to set radius of curvature. This part is unfortunately shoddy and requires extra care to not screw it up.

If you are bending my case:

Putting it together

If you had wired the components together already then this is pretty easy. Undo the wire-nuts, jam the components into the case and redo the wire-nuts.

This is also a good time to put a nut and a bolt into the case which you can then wire to the ground pin.