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UPDATE: Upon further reflection, I don’t recommend you actually try this hack, but rather follow the Cooking Issues blog if you’re curious how it turns out.
This looks like a great project for getting the most out of your electric pressure cooker. Please pay attention to the warnings, use common sense and safety precautions. This is a potentially dangerous modification which could cause fire, explosions and possibly injury or death.

According to Dave Arnold, head of the French Culinary Institute’s Culinary Technology department, 15 psi is where it’s at for pressure cooking. 15 psi is what most stove-top cookers provide. At 15 psi you can make great stocks, remove the harshness from garlic, and make incredible slow-cooked Hamine eggs.

Unfortunately, the popular Cuisinart electric pressure cooker doesn’t get beyond 9 psi. At 9 psi none of the magic happens. So, Dave decided to overclock the Cuisinart to 15 psi, by adding a pot switch to fake out the temperature sensor.

The Cuisinart has both low and high pressure settings, but unfortunately the manual doesn’t tell you what those settings mean. I needed to figure out the pressures and temperatures myself. I couldn’t find a good way to measure pressure directly without drilling holes in the cooker, so I decided to measure temperature, instead, by inserting a thermocouple into the unit through the vent hole and then sealing it up. I measured a low pressure temperature of 230 F (110 C), corresponding to 6 psi. At high pressure the unit reached 237 F (114 C), corresponding to 9 psi — below the magic 15.

Here is the part where I void my warranty. I flipped the unit over, took out the two screws and popped off the protective plate. The temperature sensor was located on a spring-mounted button in the center of the unit and had two black wires coming out of it. I popped the connector off the circuit board and measured the resistance of the sensor as I changed the temperature with hot water. Boom. It was a simple temperature-dependent resistor (RTD), and the resistance went down as the sensor got hotter.

The temperature was higher than before -244 F (118 C) but not high enough. I cranked the potentiometer to 1500 ohms and got a temperature of 254 F (123 C). I dialed it back to 1270 ohms and got a friendly 249 F (120 C). Close enough for me.

With the modifications I made, the Cuisinart might be my go-to pressure cooker… I am unsure how durable the unit will be. Two points of concern: overheating because of my modifications, and the possibility that the insert will get damaged by typical use… the reason electric pressure cookers are set to a low pressure is that they can overheat. Time will tell.

Voiding Your Warranty: Hacking Electric Pressure Cookers at Cooking Issues


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Comments

  1. Woody says:

    Okay, most of the hacks here on the MAKE: blog are awsome. Not this one. When you “overclock” your PC’s processor, the failure mode is a dead processor and a lighter wallet. The failure mode for a pressure cooker could be an explosion of 250-degree liquid–bad enough if you’re not in the room, but if you are, I hope you’re prepared for having skin grafted off your butt onto your face, if you live. (Google “pressure cooker explosion” for the gory details.)

    If you want a pressure cooker that “goes to 15″, buy one. There’s a reason this Cuisinart cooker is cheap: it ain’t made to the specs of one that handles higher pressures.

    This is a stupid, dangerous hack, unfit for this blog.

    By the way, my family has always used pressure cookers and pressure canners. Growing up in the rural south, they are a wonderful way of putting up that excess of summer veggies, and cooking boiled peanuts faster, among other things. But we were taught from a very early age that pressure cookers are not to be messed around with.

    1. Woody, this project made me nervous too, and I had posted a “be careful” warning at the top. Now, I’ve added an update saying you seriously shouldn’t try it, just read about it if you’re interested.
      Now, as to weather a blog post is unfit for MAKE due to apparent possible danger, I’d love to see people debate that here in the comments. We’ve written about our fair share of dangerous things over the years. Things I personally wouldn’t try to replicate. I’m still happy to have had the chance to read about them and decide for myself. Thoughts?

      1. As long as you make the dangers of this failing  to hold pressure as woody said, i’m alright with knowing how it works and what someone did with it.

      2. I don’t think a simple disclaimer is enough.  I think that you should run a series of articles demonstrating the effects of these ‘Makes’ failing in service.  A lot of the people reading these articles see the cool or the wow factor and have absolutely no idea just how marginal some of these projects are in terms of safety.  Call it a ‘Make: PSA series’ or something.  I love tinkering as much as the next man, but I have 20 years of electro/mechanical engineering experience behind me, and even then there’s some things on this site I wouldn’t try

      3. Woody says:

        Thanks for updating the post, John. Maybe I was a little too harsh with the “unfit for this blog” thing, but mainly that was because of the lack of a strong warning about safety. I seriously love seeing all the fire-breathing, 20,000-volt-arc-spewing things here on MAKE:. But those things are visibly dangerous. This one, on the surface, just looks like a little tinkering with some circuits, and the danger is not nearly as obvious.

        I think Baldrick has a most excellent idea! “When Hacks Fail – A MAKE: PSA series” could be very entertaining, because you know, we geeks and makers really like to see stuff blow up. Adam Savage would be the perfect host. If it could help us anticipate why and especially how our hacks could fail, especially catastrophically, that would help us become better makers!

      4. Anonymous says:

        I would try this, but I’d make sure to add a “pop off” valve in there somewhere, maybe even add another pressure sensor that shuts down everything if it gets above a certain level.

  2. Rahere says:

    Knowledge is one thing, this is on Jackass territory. I trust he lives alone in a single-story block miles from anywhere – because if it knocks a hole in a tower block, drops glass from the floor above, oir hits anyone else, he could have homicide to worry about to boot. And yes, I too have and use one. Those vents are there for a reason and I find them venting about 20% of the time.

    1. Anonymous says:

      yeah, Jackass or MythBusters territory.  At initial glance at this project had me immediately reminded of the episode where the MythBusters over-pressured a water-heater. (lots of videos to had of that result: http://goo.gl/Zz1A2 )  So if anything at all, it should be suggested to the poster of this project that he place his effort in a brick bunker a half mile away and see what the fail (explosion) pressure of a Cuisinart pressure cooker really is …just for the sake of science and seeing the end of it ;) )

    2. Here is Dave’s comment on the venting: “I was initially concerned that the lid might not be designed to take the 15 psi safely, but in my tests, the safety vent on top didn’t release any steam (the pressure release on the Cuisinart doubles as a safety vent). My reasoning is: it would be a major problem if your safety didn’t engage before you exceeded the test pressure of the device.”

  3. MrMunki says:

    For everybody who can’t be bothered to click through to the original article, Dave Arnold starts the article with the header:

    “Warning! I do this for a living. Following my path will void your warranty and expose you to possible injury or death.”

    If you have even a passing interest in food and like “MAKE” you have to check out “Cooking Issues” / Dave Arnold. He has a kind of manic “need to get to the root of a problem, research it into the ground, solve it in the cheapest (not always), most elegant way”, that leads to wonderful things. He is a goddamn genius.

    Watch him break down fracking Nixtamalization: http://www.cookingissues.com/2011/03/09/mesoamerican-miracle-megapost-tortillas-and-nixtamalization/

    Even Nathan Myrhvold’s new opus “Modernist Cuisine” (2400+ pages, 50+ lbs. of paper & ink, $600+) fails to cover the rather broad subject of “Nixtamalization: Why the Native Americans Didn’t Fucking Die From Eating Corn 24/7.”  Also nixtamalization makes corn meal delicious.

    -Seth Munki

  4. Jojaf says:

    This is a great article.The entire range of pressure cookers are appreciated for Multi function of mechanical control.I am very impressed to this post.Thanks to share this blog with us.Keep it up.You are doing a great job.

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  6. mlenenski says:

    I thought this was pretty good. Too bad you couldn’t try and put another pot in that lets you turn this into a Ghetto Sous Vide. Guess that would be my project….

    So did you get the results with the food that you desired? Any recipes?

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