Yum!

When I became sous vide enabled (controlled water bath, anyway, a proper vacuum chamber is on the to-buy list), it immediately dawned on me that a tightly temperature controlled water bath would be perfect for purposefully growing microorganisms as much as for preventing the growth while achieving perfectly done foods.

Roger has long been a fan of yogurt and yogurt is nothing more than milk fermented by a lactose consuming bacteria of, most commonly, the Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus varieties.

And, yes, it has proven incredibly easy, cost effective, and exceptionally delicious to cultivate these bacteria in the milk of your choice using a sous vide rig. Note that you really don’t need a water bath; a cooler, some hot bottles and towels can work well enough.

However, you do need the precision of a water bath to achieve consistent results of the highest quality!

The Recipe

Milk Divided

1. Divide a gallon of milk amongst 5 1-quart Bell canning jars (which aren’t actually 1 quart in many cases — go figure — just divide the milk evenly between them). Lids on loosely!

We often use generic organic whole milk, but low-fat works, too. It cannot be ultra-pasteurized (as ultra-pasteurization breaks down the proteins to the point that the bacteria can’t survive. The implications on the healthiness of said milk are quite bad). Raw milk works beautifully, but is expensive. I’ve been meaning to try a mix of sheep and/or goat with the cow’s milk.

Lately, I’ve taken to using a gallon of 2% mixed with a quart of raw whole milk. The result is a bit richer in flavor and texture while not being the whole fat experience.

Making Yogurt; Scalding the Milk

2. Place in an 75C water bath for ~2 hours (long enough to heat the milk thoroughly to 75C for at least an hour).
3. Cool milk to 47.5C. I find it easiest to scoop out the hot water and replace with cold water to bring the temperature down rapidly.

I usually set the target temp of the water bath to 46C initially. By doing this, the residual heat from the milk will leach out into the water bath and you can tell when it is stable when it holds steady. You can inoculate and bring the temperature back to 47.5C simultaneously (Yogurt cultures will incubate fine up to just above 50C and, in fact, I used to do this at 50C. I’ve since found that 47.5C produces an even better result.). The key is to make sure the milk is solidly below 55C before inoculation, otherwise you’ll run the risk of killing off the live cultures!


Innoculate at 50C

4. Stir in one tablespoon of the plain flavor of your favorite brand of yogurt into each jar. Place lids back onto jar loosely.

You can use previous batches to inoculate new batches, but it is generally recommended that you refresh with new yogurt every few batches. Honestly, I’m not sure how much this matters. It’d seem that as long as you store your live culture yogurt properly, you shouldn’t have any more of an issue than one might with, say, a sour dough starter. Mostly, I end up “starting over” with store bought plain yogurt simply because we eat the previous batch so quickly and we forget to preserve enough to start the next batch!
5. Leave in the water bath for at least 12 hours and up to 24 hours (maybe even longer). The longer they are in the bath, the more greek-like sourness to the yogurt. I usually target 18 hours, maybe 22, and everyone in the family eats the stuff like crazy.

Done!

6. Tighten the lid and submerge in ice water to stop the bacteria from continuing reproduction as the temperature falls (more below). You should hear a “pop” as each jar seals itself.

7. Refrigerate. We’ve had jars sit in the fridge for 4+ weeks with no off flavors or nasty bits forming. Others have reported keeping the sealed jars in the fridge for 6+ weeks without issue.

You’ll get a bit of whey on some jars, some more than others, I typically collect the whey and use it in bread making.

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For the Teensy Blaster, I used a Teensy v2.0 board from PJRC. It is a tiny board containing a not-so-limited AVR chip (32K of flash, >2K RAM, 1K of EEPROM, and a slew of I/O pins) and a mini-USB port with the ability to be USB bus powered. Tiny. Versatile. And cheap at $16/board! $24 nearly gets you nearly 4x the memory and nearly doubles the I/O ports.

Today, I ran across Teensy v3.0 on Kickstarter. In pretty much the same sized package, the Teensy v3.0 features a 32bit ARM Cortex-M4 board with 128K of Flash(!!), 16K of RAM(!!), 2K of EEPROM, and a slew of I/O options. If that weren’t enough, it includes support for IR, a high quality audio interface, an optional real time clock, 4 DMA channels, and support for touch sensor inputs. And more. Much more. Holy cow! Truly, a nutty amount of computing power in a 1.4″ x 0.7″ package!

And it can be used from both Arduino and C.

So, yeah, funded. No brainer.

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Then, at the thank you for funding this project page, there is a thing you might be interested link that leads to the Digispark.

Wait. What? A board barely bigger than a USB connector that features an Arduino compatible CPU with multiple I/O pins, 8K of flash, PWM on 3 pins, ADC on 4 pins and many many different shields?!

For $8-$10 / board?!

Sign me up! (And I did!)


In my “spare” time (hah!), I hack on Arduino a bit. Mostly because there are tons and tons of 3rd party libraries that make hacking up a hardware solution mostly a bit of soldering followed by gluing together some pre-made software bits. The Arduino IDE is Java based and… well… not terribly awesome (to be fair — it isn’t awful, just quite lacking beyond the basics).

With the release of Mountain Lion, most Arduino installations were broken. Fortunately, this can be fixed by grabbing the latest bits from here and there.

  • Grab the latest Arduino.app for Mac OS X
  • Run it and it’ll insist on installing the latest Java VM. Do so.
  • If you use Teensyduino, grab the latest installer and install it. If Mac OS X (rightly) complains that the software is from an unidentified source and can’t be opened, you can ctrl-click on the installer, select “open” and it will present the option to bypass the security check. Do so, but not without a bit of misgivings.
  • Install the latest FTDI driver.
  • If all went well, you should see the device show up in /dev/ as something like /dev/tty.usbmodem12341.

    Playing with an iPad

    We spent a week at the end of June on the Amazon River in Peru with International Expeditions. Fantastic trip, more on that in a later post.

    One afternoon, we visited a village — Nueva York — along the Amazon. We spent some time with the children of the village, learning a bit of spanish and teaching them a bit of english (Head! Shoulders! Knees and Toes! Knees And Toes!).

    Fun with Photobooth

    One of our guides asked me to show the kids my iPad as they had never seen anything like it before. It took a moment, but they were enthralled. The big hits were Photo Booth and a simple finger painting app.

    It was quite gratifying to see the kids take to the iPad and start using the apps so naturally. They quite quickly learned how to change and control the effects in Photo Booth. Including taking their own pictures, as seen at the right.

    Of this wonderful experience — the kids were fantastically good natured and the adults were warm / welcoming — there were two standout events that I shall relay, one purely cultural and the other just flat out cute.

    When I first launched Photo Booth and showed it to one child, I was a bit surprised by the reaction. It was sort of, “Well, that’s neat.. but.. meh, weird pictures of a person isn’t that interesting”. When I turned the iPad so his friend could see, the second kid’s reaction was the same, but the first child completely lit up with laughter as soon as the second kid’s face was on screen! Then the same happened when I rotated back to the first child.

    As it turns out, there are pretty much no mirrors anywhere outside of, maybe, a hand mirror or two. Children really don’t see themselves on a regular basis save for on the back of a digital camera in the hands of a tourist (we were encouraged to always show them any pictures we took). Thus, seeing “self” just wasn’t very interesting at all.

    Once I suspected this was the case, I saw this same behavior with pretty much every child who saw Photo Booth for the first time!

    The really cute event happened when I was showing a little girl — maybe 6 or 7 years old — the finger painting application. It took her a second, but she got into it and had quite a bit of fun making a smily face. I showed her that the color could change and then left the color picker (a little grid of color swaths) on the screen for her to pick.

    She thought about it for a moment.

    Then carefully tapped light blue.

    Then looked at the tip of her finger to make sure the color was picked up.

    Disappointed that her finger wasn’t blue, she tried again with yellow. Same thing.

    Then I showed her that the color really did change and she was happily drawing away again. Still, every new color required a finger tip inspection…

    Neat folks. I hope to visit again.






    After nearly 5 months, the first run of herbs in the Aerogarden were finally tired to the point of no longer useful (I started with AeroGarden Gourmet Herb Seed Kit (6-7-Pod) and it worked really well — way more than $18 worth of fresh, tasty, results).

    Pods Installed (Basil Sprouted!)

    One of my goals with the Aerogarden is to gradually replace all the pieces until I’ve effectively created a homebrew Aero-Hydro solution that will eventually integrate with our atrium’s pond (fish poo fertilizer FTW!), use LED lighting, and, hopefully, be an interesting conversation piece.

    The next obvious step was to replace the seed pods and baskets. The seed pods/baskets are the one piece that needs to be replaced with each planting. The baskets — white plastic things that fit in the holes on top of the Aerogarden — can be mostly reused, but the original design is obviously optimized for cost, not effectiveness (they don’t actually fit correctly in some of the holes!). The seed pods, themselves, are little bundles of seeds in growing medium; Aero’s are good quality, but relatively expensive and the seeds are of unknown variety (i.e. generic curly parsley and not some particular strain).

    At left is the current phase; seed pods and growing medium replaced with Basil sprouts showing some signs that it is working!

    After a while with the Ultimaker, a series of notes on the various things one can do to tune the 3D printing experience.

    Some of this is specific to the Ultimaker, but most of it is not. Much of this is personal preference and, frankly, there is probably some stuff in here that is wildly sub-optimal. But, hey, it has worked for me and it worked better than it did when I started.

    I.e. feedback and corrections are quite welcome!

    First, a note on consumables. I have stuck with PLA (polylactic acid) exclusively. It is a plant derived material that requires a lower temperature and is quite thoroughly non-toxic (there are lots of articles about fume-venting ABS… not so with PLA). As well, when I screw up — which is often — the resulting garbage is biodegradable (however, I’m donating my “pile of PLA” to someone who needs input into a PLA scrap-to-usable-filament project).

    PLA also doesn’t require — though it can benefit from — a heated print bed. ABS, the other common material, seemingly really does (though one can live without).

    Thus, these tips are optimized to PLA.

    These tips are also somewhat ordered in the steps that they should be done to maximize benefit. In some cases, that is because the earlier steps have a bigger ROI than later ones. In others, it is simply that the later steps really require the earlier steps first.

    Evolution of a Design

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    When I started this, as can be seen in the image at left, the case was two parts that fit together in a semi-complex manner (Actually, the very first version just had a little plastic square that covered the AVR, but nothing else). It was hard to print with any quality and, frankly, the front looked awful. So I simplified it such that the IR LED could stick out a small hole, as seen in the middle. But then it dawned on my that the translucent plastics might just be transparent enough to IR that no hole was needed at all.

    And sure enough, it just worked!

    Thus, the design is now even simpler (assuming you have translucent filament).



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    Both professionally and as a couch surfer, I’ve found myself interacting with a great deal of devices that can be controlled via infrared remotes. Often, remotes lost in the depths of a couch or misplaced in the fridge (it happens). Clearly, I needed an IR blaster that could be controlled from a computer to both eliminate the “losing the remote” problem and to integrate control of multiple devices into a single UI. Conveniently, Arduino micro-controllers with integrated USB ports are commonly available and quite cheap. Adding an IR LED to an Arduino is trivial, as the ever popular TV-B-Gone project demonstrates.

    Thus, the Teensy IR Blaster was born. I started with the Teensy v2.0 AVR-based micro controller that includes USB support. It unofficially supports Arduino using the Teensyduino extension. To this, I added Ken Shirriff’s IRremote library modified fro the Teensyduino environment and

    Out of the box, the Ultimaker shipped with a stable, but relatively ancient, version of the firmware. This, combined with the stable, but relatively ancient, version of ReplicatorG available from the Ultimaker site was sure to produce useful prints with a relatively minimal of fuss, but nothing that remotely approaches either the blazing speed or amazing quality possible from this printer.

    To achieve that requires some significant upgrades to the software stack. And, in some cases, it requires outright replacing some of the pieces entirely.

    While this writeup is specific to the Ultimaker, there is a lot of general knowledge in here, and the various bits of software are largely universal to a number of printers. When my Printrbot shows up, I’ll write a revised version specific to that printer while generalizing this a bit.

    Note that this is all moving very quickly. When I first wrote this, it required about 3x more steps and was considerably more fragile. It is improving rapidly! However, there is still a long way to go before any of this is easy.

    Note: At the time of writing, you need to perform both of these upgrades simultaneously. ReplicatorG really does’ want to talk to the new firmware (of course, by the time I write this, it’ll likely be fixed).

    This is a short video of the printing of an Octopus I’ve been using as a test model. The Ultimaker is printing at 250% of normal speed. I started at 100% for the first layers until a solid base was created and then cranked the speed to 250%. It could go faster, I think.

    At that speed, the quality of the print suffers a bit. I believe, is mostly due to slop in my belts. I need to print some belt tensioners which will take up the slack nicely.

    The print quality is both better than the out of the box experience and tons faster.

    This is the result of a combination of upgrades:

    • Upgraded the Ultimaker’s firmware to the latest beta version. It has all kinds of features that enable both higher quality and higher speed prints.
    • Upgraded to using Pronterface to send the G-Code to the printer. It allows for communication at 250kbaud and doesn’t periodically pause like Replicator-G does if you forget and leave the temperature monitor panel open.
    • Moved to using SkeinForge-48 as the slicer.

    All three of these tasks were a downright pain to do. All three have been written up in another post.

    For now, enjoy some 3D printer music….


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    Some build notes from my Ultimaker build experience…..

    Overall, it took me roughly 4 days to build the Ultimaker. The first two days were a couple of long stretches and the last two were much shorter. Tuning the device to yield usable prints has taken a bit more time, too, and I still have a long ways to go.

    At left is a print made using the default firmware with relatively default settings in ReplicatorG. Stringy as heck, but otherwise quite good! Software and hardware tuning are reserved for another article.

    This is some random build notes from the build and roughly correspond in order to the assembly instructions themselves.

    By and large, assembly was relatively straightforward. The only real disaster I had was with the cooling fan used on the extruder. When I tried to mount it, it shattered — literally disintegrated into dozens of pieces — in my hand.

    The Ultimaker arrives in a surprisingly small, heavy, box. No surprise; wood is heavy and the Ultimaker is largely a wooden box with some very crafty electronics built into it. Frankly, the laser-cut wood based construction is, in and of itself, a bit of a hobbyist kit revolution. Wood is cheap and very strong, yielding kits that can be quite precise, extremely durable, and still remain accessibly affordable.

    Random notes below the fold…