Archive for the Things Category

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

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!

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.

Hammock Part 1

Posted in Things with tags , on March 7, 2012 by Spark

Mom and Dad came up last Saturday to help me put together the hammock structure for my space.  I’ve had the plans for this thing since October, so it was great to finally buckle down and get it done.  Thanks to Leah and Andrew Kessel for stopping by to lend a hand!

 

 

The hammock will be a rectangular grid that fits across the top.  I’m waiting on some samples from cargo net suppliers, but there’s a good chance I’ll end up making it by hand with knotted rope.  Cargo nets are expensive!

Check out photos of the hammock structure construction here.