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December 8, 2011

I've been meaning to write something about espresso and the various technology options for making one, but I never get around to it. Now I have. I'm not an espresso-making expert, but I'm a guy who cares about espresso, has a moderate but not extreme budget, and can pull a fairly solid shot. As such, this might or might not be useful to you. There are many articles like this, but this one is mine.

The discussion below is restricted to what's called "semi-automatic" machines: those where you grind the coffee yourself but the machine has controls designed to regulate temperature and pressure. "Super-automatic" where you put in beans and water and they put out coffee are out of scope here.

The basic principle of espresso is simple: you grind up the coffee, pack it down and then force heated water through under pressure. The difference between swill and pure liquid perfection is in the details. Moreover, if you're going to get the details right, the first thing you need to do is get them consistent; the exact procedures and settings you need differ with each coffee and each machine, but if you can be consistent then you can dial them in over time. [Aside: when I took machining in college, the first thing the instructor told me was that machining wasn't about cutting metal, it was about measurement. If you could measure accurately, you could cut accurately.] The major variables you need to control are:

  1. The coffee itself.
  2. The grind.
  3. The amount of coffee.
  4. The dispersal into the portafilter basket and the tamp.
  5. Water temperature.
  6. Water pressure.

The coffee is something you buy, so you have some control over it but not complete control. With the right grinder, you can completely control the grind and the amount of coffee. Dispersal and tamp is a matter of personal technique and practice. With the right espresso machine, you can control water temperature quite precisely and with any pump machine, pressure control should be quite good. So, as you can tell, this is primarily a matter of getting good equipment.

The grinder thing is pretty simple: get a burr grinder with enough adjustments. Don't get a doser. Get one with a timer. A little elaboration: blade grinders (the cheap canister ones that you can buy for $20-$40) don't do a good job of getting you a consistent grind. The individual grounds aren't the same size and you can't control the overall size except by grinding longer. Don't buy one. You want a burr grinder and you want one that allows you to adjust the grind finely and over a large range. Different beans require different grinder settings, so easy adjustment matters if you change beans much.

The reason you want a timer is to let you control the amount of coffee you grind. This is a parameter people usually specify by mass, but using a scale is a pain in the ass. Grind time is a good proxy here. What I typically do is make some test shots and then set the grind time on my grinder (it has 3 presets). Then when I want to pull a shot I just put the portafilter under the grinder and hit the right preset button. None of this requires much thought once you get it wired.

There are lots of good grinders. What I have is a Baratza Vario. There are two features I like about this. First, it has easy adjustments with two slides up front, one for macro (espresso versus drip) and one for micro (grind fineness once you've selected espresso). Second, it has timer presets, which, as I said earlier, is super-convenient. There's a rest for you to put the portafilter on while you grind, but you need to hold it there or it falls off. I notice that Baratza now makes a weight-based Vario W. This seems like a good idea, but I don't know how well it will work with espresso, since you don't want to grind into a hopper but right into your portafilter, and it's not clear how the scale integrates with that. One caution I would have with the Vario is that the really gross burr adjustments are done with a hex wrench (included). They're easy but kinda scary (keep turning until the motor starts to labor), so if that freaks you out, you might consider another choice.

Espresso Machine
There are a lot of choices in what kind of espresso machine you buy, but let's get something out of the way now: espresso machines have pumps. Yes, you can buy a cheap machine that works off steam pressure, but that's not what you want.

The central problem that dictates the design of an espresso machine is this: The water you use to make espresso needs to be at one temperature (~200 F). The water you use to steam your milk needs to be at steam temperatures (~250 F). If you're going to make milk drinks (I don't, but Mrs. G. does) then you need to somehow address this. There are four basic approaches that I've seen:

  • Have a single boiler and a switch that selects which temperature to maintain at (a single boiler machine).
  • Have two boilers, one at each temperature (a double boiler machine).
  • Have a boiler set to steam temperature and use a heat exchanger to heat your water to espresso temperature.
  • Have a boiler set to water temperature and an electric thermal block heating system to make steam.

Single boiler machines are basically a terrible solution for more than about one or two people if you want to make any kind of steamed milk drink. Here's what the procedure looks like if you want to make a latte: set the thermostat switch to "water"; pull a shot; set the thermostat switch to steam; wait for it to heat up; steam your milk. This is all reasonably fast because the boiler heats up fast. However, say you want to make another latte. Now you have to set the thermostat back to water and wait for it to cool down, which can take minutes. You can accelerate this some by just running water through the group head which pulls cool water out of the reservoir into the system, but basically it's a pain. I've used this kind of machine in an office setting and it sucks.

The obvious (and best) solution to this problem is to have two totally separate boilers, with one set to water and one set to steam. This is of course more expensive, especially since manufacturers seem to have decided to engage in a little market segmentation. To give you an example, Chris Coffee's cheapest double boiler is the Mini Vivaldi II at $1995. They'll sell you a Rancilio Silvia (a very nice single boiler) for $699. This isn't an uncommon pattern: many double boiler machines sell for more than twice what a good single boiler would cost. I don't know anyone who has bought two singles instead, but it's sure occurred to me.

The other two solutions are compromises. In a heat exchanger machine, the boiler is set to steam temperature and then the water for the espresso runs through a tube set inside the boiler, thus heating up on the way (good description here. The idea is that as the water is being pulled out of the reservoir and onto the coffee it heats up. The obvious problem, however, is that when you're not pulling espresso, the water in the heat exchanger tube is heating up eventually to the temperature of the steam, at which point you're back where you started, as is the heavy metal group head which provides a lot of thermal intertia. Standard procedure here is a cooling flush which means that you run some water through the (empty) portafilter/brew group to get it down below the right temperature. Then you quickly pack the portafilter and pull your shot. This all requires some coordination.

About a year ago, QuickMill came out with a new machine (the Silvano), which has a single boiler for the water and a thermoblock for the steam. This has the advantage that you can tightly temperature control the water and the group head and still get decent steam fast. The steam isn't as good as it would be if you had an actual boiler, but it's pretty good, so it's a reasonable compromise. And since the water side is temperature controlled, you get to pull a predictable shot without much messing around, which is what I, at least, am after. It shouldn't be surprising at this point that I have a Silvano, which I'm pretty happy with. Here's what it looks like pulling a shot of Four Barrel Ethiopia Welena Suke Quto (and no, those two little spurts onto the backsplash are not intended. That's evidence of tamping error.)

Oh, one more thing: the water supply for espresso machines can either be plumbed (there is a water tube coming from your pipes) or unplumbed (there is a water reservoir you have to refill). Plumbed typically only comes on higher end machines. I don't know if it's worth stepping up to one of those machines to get plumbed, but I do know that my Silvano is unplumbed and I wish it were plumbed. It's pretty annoying to have the shot already to go and realize you're out of water. Doubly annoying if it's your last shot worth of coffee.


November 8, 2011

The MacBook (Air, Pro, etc.) are great computers, but the sealed battery is a real limitation if you want to travel with it. My Air gets about 5-6 hours of life if I'm careful, which is fine for a transcontinental flight, but not a transatlantic one. The fix, of course, is to buy a HyperMac external battery, which plugs into the laptop at the only real point of access, the magsafe connector. Unfortunately, in 2010 Apple sued HyperMac for patent infringement and HyperMac stopped selling the relevant cable (which, as I understand it, was actually a modified version of an official Apple cable). Without the cable, of course, the battery is pretty useless.

I'm lucky enough to have one of the pre-lawsuit battery/cable combinations but recently a friend wanted one, so I looked again. It seems that HyperMac is back in business, but they've resorted to a do-it-yourself kind of ethos. Basically, you have two choices:

  1. HyperMac will sell you a connector that impersonates a 12V air/auto power connector. You then buy the Apple air/auto to MagSafe adaptor and plug it into your Mac.
  2. They sell you a pair of jacks that you splice into the cable for a legitimate Apple power supply. The way that this works is you take a standard Apple power supply and cut the magsafe half of the cable in two. You strip the wires and attach them to the jack; repeat for the other side.

Without taking a position on the merits of Apple's legal claims, this seems like a pretty lame state of affairs. First, the original HyperMac design was better because you could charge your battery at the same time as you powered your Mac with it. This works with the air/auto version but not with the DIY jack version. Second, while it's not exactly microsurgery to splice the cables, it's still something you could mess up.

Moreover, it's not like Apple has some super-expensive power expansion solution that HyperMac is competing with and the patent is protecting them from. Rather, they're just making life harder for people who want to use Apple's products in situations which are just more extreme versions of the situations which motivated the device having a battery in the first place. I just don't see how this makes anyone's life better.


September 15, 2011

Heat exchanger stoves like the Jetboil are self-contained and convenient, but as this excellent Backpacking Light article [paywall warning] documents, they're not very weight efficient. The Jetboil PCS was 15 oz, whereas you can get down below 9 oz with a lightweight canister stove and cooking pot of comparable volume . Heat exchanger stoves are more fuel efficient, but you'd need to be traveling a really long time without resupply in order to reach the break-even point.

In the 7+ years since the Jetboil was introduced, however, they've managed to cut quite a bit of weight. The recently introduced Jetboil Sol Ti is nominally 9.5 oz, though some of this improvement is from a smaller pot and much of the rest is obtained by excluding stuff you don't really need, like the measuring cup/cover. (Redwood Outdoor has a really nice video review of this unit.) You can still do better with the lightweight stove/pot, but its advantage is shrinking, especially in light of the Jetboil's speed.


June 25, 2011

I recently started biking again and in the interest of being able to more accurately measure my workouts, I moved my SigmaSport BC1100 bike computer from my race bike onto my training bike. Like basically all bicycle computers from the pre-GPS era, the BC1100 is of the wheel magnet/sensor loop variety: you mount a magnet to one of the spokes and and a sensor to the fork. Every time the magnet passes by it induces a current which is transmitted to the computer.1 Of course, this mechanism just measures rotational velocity (rotations per second). In order to measure road speed you need to know the circumference of the wheel and as, the battery had run out so whatever calibration I used to have was long gone.

If you read the manual for a typical bike computer you'll discover not just one but many calibration techniques arranged in a hierarchy of both accuracy in inconvenience that goes something like this:

  • Look up your wheel size in a table.
  • Measure the diameter and multiply by 3.14.
  • Roll the bike one wheel rotation and measure the distance traveled.
  • Roll the bike one wheel while sitting on it (to compress the front tire the way it would be if you were riding it) and measure the distance.
  • Roll the bike N rotations (plus sitting in it, etc.), measure the distance and divide by N.

Regardless of the technique, the basic principle is that perform the above procedure, get the circumference, and enter it into the computer. In the specific case of the SigmaSport, you want the circumference in millimeters, so for a typical 700C-sized road wheel, you want something around 2100mm. Anyway, I dutifully performed the procedure as specified (see instructions here) and entered the desired number (2037) into the computer. So far so good, except that once I actually got on the bike, it reported that I was going about 25 miles an hour on average and 30 mph on the flat. Seeing as typical time trial pace for amateur athletes is around 25 mph and I wasn't even breathing hard, either I was ready to sign up for the Tour de France or something was screwed up with the calibration. The second of these seemed more likely.

A little searching around the InterWebs quickly revealed the problem: this model doesn't have an internal adjustment for English versus Metric, so you need to divide by 1.6ish to convert to miles/hour. I guess it was cheaper to just have the units setting change the labels than to actually include a circuit that divided by 1.6. Turns out that this actually is on the SigmaSport web site, though not in the owner's manual. Unfortunately, it's labelled "Attention BASELINE 400, BASELINE 700, BASELINE 1200 & BASELINE 1200+ owners!". which doesn't really help, since I have a BC1100. Outstanding!

1. The really cool Jobst Brandt-designed Avocet cyclometers instead used a ring of alternating polarity magnets mounted around the hub, allegedly for better precision. They don't seem to be available any more.


April 4, 2011

Most people who have backpacked in the Sierras have gotten to experience the fun of the bear canister. Traditional bear canisters are a big cylinder (I have the BV 500, which looks like a gigantic Nalgene bottle). Canisters are serviceable in the sense that the bears don't get your food, but they're heavy (the BV 500 is 1.16 kg) and awkward to carry. Also, in a lightweight pack with a thin framesheet/pad or no pad at all the canister tends to deform the shape of the pack, leaving a ridge down the center of the pack and you with a sore back, so backpackers have been on the lookout for something new for a while. Until now, the best alternative was the Ursack a kevlar bag with an optional metal insert, but it's not approved for use in Yosemite or Sequoia Kings Canyon, so it's not entirely optimal.

About a year ago I ran into some guys at the climbing gym who were producing a new bear canister and it looks like they have now got it almost ready for market. The Camp 4 Outdoors Bearier 700 is a roughly spherical plastic container in two halves which clip together. The Bearier is lighter weight than the lightest plastic container (< 2 lbs for 700 ci) and seems to be comparable to the lightest canister, the carbon fiber Bearikade. Because it separates at the middle the system is modular so that you can add a ring (called the Grubhub) in between the halves to expand capacity by another 300 ci. In addition, because the halves separate and have a drawstring closure to keep your stuff in, they can be packed separately. In particular, if you want to keep them in your pack you can pack each hemisphere with the face towards your back, presenting a flat surface and thus hopefully reducing discomfort. The major drawback seems to be that it's not going to be as comfortable to sit on as a canister, though supposedly the ends are flat so you can if you want to. (See various comments here.)

I haven't seen one of these in person, only in pictures, so I don't know how it will fit in my pack. Also, they have yet to be approved by any of the relevant bear approving agencies, so it's premature to get too excited. Still, it looks like it might be a cool innovation.


January 17, 2011

I recently concluded that I didn't have enough high-tech gizmos, and since a new car is really expensive, I decided to buy a new espresso machine instead. For the past 5 years or so I'd been uh, limping along with a Gaggia Espresso and a Gaggia MDF grinder, but it seemed like time for something new. (Those of you who are about to say "why can't you just use a Mr. Coffee like everyone else" can stop reading now.) After a bunch of research and a call to Chris Coffee I settled on a Quick Mill Silvano and a Baratza Vario grinder (total cost with accessories, around $1350). Now there's no doubt that this seems like a lot of money for a coffee maker, which it is, but let's actually do the math:

Consider two separate scenarios, both of which I actually have some familiarity with:

  • Home, both Mrs. G and I drink espresso at a rate of something like 2 shots/day each for a total of 4 shots/day.
  • Office, where we have something like 30 people sharing a single espresso machine. They probably drink around like 2 shots/day each for around 60 shots/day.

At home I buy either Four Barrel or Blue Bottle, both of which are just slightly more than $16/lb (454 g). A double espresso requires around 20g of beans, so in the best case with no lossage/sink shots you get 22 shots out of a bag of beans at a cost of around $0.70/shot. So in our home scenario we're spending $2.80/day ($1022/yr). If we figure the machine lasts 10 years, which isn't unreasonable for a good espresso machine, we're looking at another $140/year. In the office scenario we're spending $42/day, but only weekdays so around $8000/yr. You might be able to get a 20-30% discount buying bulk like this, but still we're talking around $5k/year in beans. You'd want a more expensive espresso machine for this use obviously, but even if you went nuts and spent $10K on the machine and grinder, you're still looking at only around $1000/year in capital expense (CAPEX) cost over the life of the machine. In either case you're looking at about 10-20% of your costs being CAPEX and 80-90% being operational expenses (OPEX).

What do these nubers tell us? First, it's a lot cheaper (and more convenient) to make your own espresso than it is to buy it. An espresso shot at Blue Bottle in the city goes for $2.50, so even if you live right next door and so there's no transportation costs, we're looking at a per-espresso price of between 1/4 and 1/2 that of retail. On the other hand we're looking at a relatively expensive caffeine delivery vehicle, comparable to buying every single soda you drink retail. That said, this applies to more or less every form of caffeinated beverage: bulk caffeine goes for more like $0.04/dose, as long as you're willing to deal with people looking at you like you're a meth addict when you tell them you take caffeine pills instead of drinking a 1/2-case of Diet Coke a day.

Second, as the vast majority of the costs are OPEX (and in particular supplies), so you probably shouldn't worry too much about your equipment costs (unless you're buying a Slayer or something). If you want to save some money you would do better to try to buy a cheaper brand of beans, negotiate a bulk discount, etc.


January 6, 2011

I'm probably like the 5000th person to point out the stupidity of this Macy Halford piece in the New Yorker about e-books:

The news made me feel like I'm not up to the challenges technology poses. Am I supposed to understand the desire of the Kindle to be held and read? Or the humans who prefer them to books? When I read a book all the way through to the end, I want the evidence stuffed and mounted on my bookshelf. My suspicion is that people who prefer e-readers use them primarily to read Harlan Coben, and are happy to be able to delete the physical evidence.

I had to look up Harlen Coben in Wikipedia, so I'm not sure what this says about Halford's taste versus mine. Regardless, I've read through plenty of books "all the way through to the end" (is this supposed to be some kind of achievement) and I indeed have them sitting on my shelf. However, that's primarily a function of not having anything more important to do with them, not of needing to display my reading prowess.

Really, it's not at all difficult to explain the appeal of e-books: it lets you carry a lot more reading material in a much lighter and more compact package. You would think that anyone who thought of reading as a pleasure rather than a chore would get that.

Obligatory Disclaimer: This isn't, of course, to say that existing e-books are perfect, just that the appeal of the concept should be obvious to anyone who likes to read.


December 11, 2010

As I mentioned earlier, the Kindle has a feature which allows you to group files into "collections". The effect is that instead of just appearing on the main menu screen, you just see the collection name and then when you click on that, you see the list of documents in the collection. Unfortunately, the only method they provide for you to manage files is via the Kindle UI, which, as I've said, is awful. What you really want is a way to manage this from your computer.

It's understandable that Amazon doesn't want to provide a collection mangement application and unfortunately, the collection structure isn't reflected in the Kindle's directory structure, so even though you can mount the Kindle as a file system on your computer, you can't use this to manage collections.

There's been a fair amount of research on how the Kindle collection system works. Basically, there is a single JSON file called collections.json which contains a dictionary of collections with each entry being a list of SHA-1 hashes of the file names in each collection. E.g.,

    {"items": ["*8f0abafc5f8e6686a882c78cac4bcb9f", "*614dd0e977becb4c6f7fa99e64549b12"], "lastAccess": 1291824173119},
    {"items": ["*7b3b4c3be6d20a51b1b75833a5a8a248"], "lastAccess": 1291824173119}

It's known how to compute the hash, it's a SHA-1 of the string /mnt/us/<filename> (there appear to be some funny issues about how spaces and dashes are handled). So writing a valid version of the file is mostly a matter of simple JSON programming.

There's one more problem: the Kindle seems to keep an in-memory cache of the collections.json file, so just changing the file doesn't help. What you need is to force a cache refresh. You would think a reboot would do it, but actually it seems to force the cache to be written back to permanent storage, overwriting your modified version. After all, who would go around writing the permanent version? The fix here is to do a hard reboot. The procedure I've found works on the DX is to unplug the Kindle from the computer, hold the power switch down for about 20 seconds (I hear it's 15 but maybe I'm counting too fast). This does a hard shutoff, and then when you press the power switch again it does a complete restart, reloads the collections.json, and you're good to go.

Someone has written a Kindle Collections Manager for Kindle, but I don't run Windows and I wanted to play around a little bit. You can find a primitive Python script that does this job here. Basically, you plug in your Kindle, then you can do kcollect add <collection> <file>.. and it will copy the files onto your Kindle (if necessary) and add them to the relevant collection. Just running with no arguments shows the contents of the collections on the Kindle.


October 25, 2010

While I love my Kindle, it does have some annoying features. The most annoying feature, as I've mentioned before, is the lack of a touch screen. However, nearly as annoying is that while you can read books on any Kindle you own, they're completely tied to your account. Seeing as the price of Kindle books is often nearly as high as the price of the corresponding paper book, this seems like a pretty significant drawback. Now, Amazon is apparently relaxing this restriction, but only fractionally:
Second, later this year, we will be introducing lending for Kindle, a new feature that lets you loan your Kindle books to other Kindle device or Kindle app users. Each book can be lent once for a loan period of 14-days and the lender cannot read the book during the loan period. Additionally, not all e-books will be lendable - this is solely up to the publisher or rights holder, who determines which titles are enabled for lending.

Now, I'm not saying I wasn't fully aware that Kindle books weren't transferable when I bought my Kindle and willing buyer/willing seller and all that. However, with that said I will observe that this is a pretty small concession (apparently it matches the behavior of the Nook). Kindle books would be a lot more like real books if I could lend them out permanently or at least semi-permanently.1 The analogous restriction would be that only one person could have the book attached to their Kindle account at once. That's still a pretty big pile of DRM, but at least in my case it would make me a lot more willing to shell out for Kindle books.

1. Digression: The early programming language implementation, "Turbo Pascal" was distributed on a "just like a book" basis, in which you were allowed to use it on multiple computers as long as there was no chance of it being used in two places at once."


September 2, 2010

As everyone knows, cats hate productivity and when I work from home my cat likes to curl up somewhere next to my keyboard half obscuring the mousepad. This of course means that you can't really use your mouse. After repeatedly kicking her off my desk, I finally realized who was in charge and decided to go for a technical fix: the Apple Magic Trackpad. I generally like trackpads and it's tall enough that the cat doesn't want to sit on top of it. She just curls up right in front of it.

Everything was going fine until one day it started totally flipping out. The magic trackpads are multitouch with no separate button; to get a double click I use two fingers to control the mouse and click the trackpad with my thumb. Suddenly, though, I started getting double clicks all the time. I was all ready to reboot or call support and then I realize the problem: one finger and one paw counts as two fingers. A small adjustment later and everything was back to normal.