Cooking with Science!

Posted in Electronics, Things with tags , , , on April 5, 2013 by Spark

When I heard about sous-vide cooking, I knew I had to make a one.  It’s a way of producing perfectly cooked meat, and it involves messing around with electronics.  Right up my alley!   I decided to put one together for my girlfriend as a Christmas present.  She loves cooking, and making the project as a gift gave me a deadline and ensured I’d actually finish it.

Sous-vide cooking involves vacuum sealing food (usually meat) and cooking it in a temperature controlled water bath.  The idea is to set the water temperature to exactly what you want the internal temperature of your food to cook to, then leave it for a few hours.  It won’t overcook or dry out.  Then you can take it out, sear the outside to make it crispy and brown, and have a thick, juicy steak that’s cooked perfectly evenly medium rare straight through.

I decided to make a temperature controller that would switch power to an off-the-shelf crockpot.  I bought a thermocouple and a PID temperature controller with an autotune function and rigged up a proof of concept with a rice cooker from a thrift store.  I configured the PID controller to use the built-in relay and spliced it into the power cord of the rice cooker, and dangled the thermocouple into the water in the rice cooker.  It took a long time to get it running.  The thermocouple had three leads, two blue and one red.  I couldn’t find any description of which lead was which.  Most thermocouples only have two leads.  I eventually figured out that the two leads that were the same color should go to the + and – pins, and the odd lead should go to the R pin, but the setup still wouldn’t work.  I eventually replaced the thermocouple and it worked fine – the first one must have been either damaged in shipping or possibly fried when I hooked a multimeter up to try to determine which lead was which.  I never did figure out what the thermocouple labels on the PID controller meant, or why there was a third lead.  If anyone has an idea, let me know!

It took a while to figure out how to properly wire the thermocouple

Once I figured out the thermocouple setup, I bought some pre-sealed steak from Meat House in Arlington and tried out my bare-bones sous vide cooker.  I sat my rice cooker on a counter with the temperature controller spliced into its power cord and the thermocouple hanging into it.  I ran the auto tune function on the PID controller, set it 130 degrees F, and let it come up to temperature.  I threw in the sealed steak and left it for a couple hours, then pulled it out and seared it on the grill.  My setup may have looked like a couple components and a bunch of wires strewn across the counter, but it produced a damn good steak!

I found the clicking of the built-in relay on the PID controller to be pretty distracting, so I ordered a solid state relay to use on the final version.

I found a single power outlet with a built in switch at Home Depot that could provide both the outlet that the crockpot/rice cooker would plug into, and the power switch for the sous vide cooker.

Power switch and output outlet

Here is the wired up sous vide cooker with all the parts attached to the enclosure.  You can see the back of the output outlet/power switch, the solid state relay sitting on top of a large heat sink, and the PID controller.

All wired up!

This is what the finished sous vide cooker looked like from the front.  Pretty slick!

Aww yissss

Parts list:

PID Temperature Controller          $32.50
Solid State Relay                                  $8.50
Heat sink for relay                               $4.25
PT100 thermocouple                         $22.50
Switch and Power outlet combo    $7.99
Strain Reliefs
Enclosure

Additional Resources:

Guide to cooking with sous-vide
Cooking time and temperature reference

Advertisements

Pumpkin Marble Track

Posted in Sculpture with tags , , on February 22, 2013 by Spark

Wow, I’ve been terrible at updating this blog lately!  That’s partly because I haven’t finished very many projects in a while, and partly because I keep forgetting to post the projects I have completed.  I’m gonna catch up with a few old projects and then give some updates on what I’m working on now.

Back in October, I got to carve giant pumpkins with power tools along with a handful of other artists from Artisan’s Asylum.  I decided to turn mine into a marble track.  Check it out!

Here’s a video of it in action:

Check out the rest of the pumpkins here.  They’re all fantastic!

Personal magnetism

Posted in Uncategorized on May 16, 2012 by Spark

I’m magnetic!

Lifting a paperclip with my finger

Last week Nessie and I flew down to Pittsburgh for a day to have renowned body modification artist Steve Haworth surgically implant tiny neodymium magnets in our fingertips.  They give us a new sense – we can feel magnetic fields.

The magnets let us know how ferrous a metal is (useful when welding with scrap metal).  We can feel the field given off by a transformer or a motor and gauge the amount of power it’s using.  Microwave transformers are particularly strong – I can feel them a good six inches away.  If there’s a strong enough current moving through a wire, we can feel that too.  We can also lift small metal objects.  Nessie’s magnet is closer to the skin, so she can lift things like bottle caps.  The heaviest thing I can lift is a small paperclip.

Nessie lifting a bottle cap with magic

As someone who loves playing with electricity, this new way of experiencing the world around me is profound.  It takes an invisible force that is all around us and makes it tangible.  It’s one thing to know that a spot welder uses a couple hundred amps to melt two pieces of metal together.  It’s another thing entirely to actually feel the visceral thump of power when you press the switch.

The texture of magnetism

Magnets, ferrous metals, and DC magnetic fields like the one given off by the current in a spot welder feel like pressure in my fingertip.  I haven’t been able to distinguish pushing from pulling yet, but as the sensitivity increases and I practice more I should be able to.  The tug of a weakly ferrous metal like stainless steel is difficult to detect.  I have to move my finger back and forth across the edge of the metal, hovering just over the surface, feeling for a faint tug when I move across the metal.  My cast iron vice is ferrous enough that I can feel it just by moving my finger near the surface.

AC magnetic fields like those given off by transformers and motors create a buzzing sensation.  I’ve heard reports of people with these magnets being able to feel the current in an extension cord, but neither of us can yet.

The sensitivity increases for around a year after getting the implant.  Initially the incision needs to heal.  Even after it’s fully healed, the sensitivity continues to increase as the brain remaps the signals coming from the fingertip.

My Magnetic History

I’ve actually attempted to have this implant done twice before.  The first time was in March of 2011, when Steve Haworth was in NYC for a convention. I had the magnet put in my right pinky finger since it’s the only finger I don’t use to play guitar.  After about three weeks it started to reject, slowly pushing its way out of my fingertip like a splinter.  It took about 4 days to work its way out.  These types of rejections are very rare but are a risk with any subcutaneous implant.

Steve didn’t come back to the east coast until July 2011.  He offered to try again for free since it hadn’t worked the first time.  I headed down to NYC again.  This time I put the magnet in my right ring finger.  Steve recommends the ring finger since it is the least exposed.  We thought that the fact that my pinky was so skinny may have been a factor in its rejecting the first magnet.  I babied my finger for two weeks, not even going near anything magnetic until the cut was fully healed.  When I finally went to try it, there was nothing.  The magnet had disappeared.  I even went to have my hand x-rayed to be sure – it was definitely gone.  I know he put it in because he hung the suture needle from my fingertip when he was done.  I was mystified.  I still have no idea what happened.  My best guess is that I banged my finger on something when the cut was still open and the magnet flew out without me noticing.

I’m really hoping it works out this time.  I’ve missed my magnet every single day since it rejected the first time.  It feels like a sense I should have had my whole life.

Further Reading

Curious about magnetic implants?  Check out these links:

Steve HaworthA Sixth Sense for a Wired WorldMagnetic Implant – BMEzine EncyclopediaJaa’s Blog – Entries tagged as smiihttp://news.bmezine.com/2004/02/06/the-gift-of-magnetic-vision-the-publishers-ring/

http://news.bmezine.com/2006/01/15/magnetic-implants-a-six-month-retrospective-the-publishers-ring/

http://news.bmezine.com/2007/06/06/so-whats-it-like-having-magnetic-vision-bme-publishers-ring/

http://news.bmezine.com/2006/04/01/another-two-months-of-magnetic-implants-the-publishers-ring/

Hexapod on Wired.com

Posted in Robotics, Things with tags , , , on May 3, 2012 by Spark

The hexapod robot is making the news!  We’ve shown up on Wired.com, hackaday, slashdot, BoingBoing and a few others.

 

Gui rendered a concept model that gives a good idea of what the robot is going to look like:

 

Stompy, the hexapod robot

 

Right now, I’m working on the PID controller for the joint actuators.  I’ve got a bare-bones PID algorithm working and I’m going to add a few more features to make it a little more robust.

Trebuchet Competition

Posted in Things with tags , , , on May 2, 2012 by Spark

Last week I entered the Trebuchet Competition at Artisan’s Asylum!  Nick Anastasia, Alex Phillips and I made up team Percussive Maintenance.  We spent a week from Sunday April 22 to Sunday April 29 designing and building our trebuchet, the Small Adjustment Tool.  Artisan’s Asylum provided a pile of lumber and assorted hardware, and we had a week to come up with a trebuchet that would throw water balloons with a maximum counterweight of 100lbs at targets set up on Cambridge Commons.

 

 

There were a couple other floating arm trebuchets, but ours was the only arm-slides-over-cam style.  We were looking great in testing with a range of at least 150′ and good consistency between shots.

At the competition, we had a couple shots to calibrate our trebuchet, then ten shots to hit the first target twice.  The targets were plywood castles, set up at 50′ for the first round.  Our first calibration shot went a little long, so we pulled some weight off and tried again.  The next two shots were dead on target.  Figuring we were all set, we went ahead with our ten shots for the qualifying round – and not one hit the target!  They were going all over the place, landing anywhere from 10 feet to 100 feet in front of us.  The only thing we can think of is that the wind and unevenly filled water balloons combined to add a lot of variability.

Even though we lost in the first round, we had a great time and built a really cool trebuchet.  Overall, I’d call it a win!

Check out Kieth Simmons’ photos of the competition here

Robotic Hexapod!

Posted in Robotics, Things with tags , , , on April 26, 2012 by Spark

For the next four months most of my time will be going into the rideable hexapod robot class at Artisan’s Asylum.  We’ll be working to build a 1-2 ton hydraulic rideable 6-legged robot with a 12 foot legspan.

There are so many awesome things to do and to learn on this project that I had a tough time figuring out which part I wanted to work on.  I started off on the mechanical team welding together a cart for the test leg, but switched this week to the controls team.  I’ll be writing the PID controller for the joints.  I’m sure I’ll have more chances later on to get my metalworking fix in, and I’m really hoping to have a chance to work with hydraulics at some point.

You can follow our progress over at the Project Hexapod blog!

 

The definition of badass

I've always wanted to build this thing

 

When I first saw this photo I was disappointed that it was just a sculpture, because I really wanted to think that something like that was walking around the earth somewhere.  Now I’m building something even more badass, and I’ll get to ride it!

Hammock Part 2

Posted in Things with tags , on April 26, 2012 by Spark

The hammock is finished!  I ended up weaving it myself.  I made a shuttle out of scrap masonite to hold the bulk of the rope while I wove it through the loops.  I’m glad I decided to make the net myself rather than buying one.  The process was relaxing and meditative, and the result is much more satisfying.  It took about ten hours to weave the whole net.

I attached the net by spiraling rope through the loops at each edge and around the 4×4 at the top of the hammock structure.

Finished hammock

 

The final product is comfy and has more than enough room for five people.  I’d like to put some pipe insulation or cut up pool noodles on the inside corner of the 4×4 at the top to make it a nice place to rest your head, but other than that it’s complete!

Take a look at the full album here.