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Bitcoin Solves the Wrong Problem

Bitcoin has been in the news lately for its amazing run-up over the past year and recent crash. For those who have been living under a rock (or anyone reading this years in the future when Bitcoin has disappeared), Bitcoin is a "virtual currency" created through some clever cryptoanalytic techniques to ensure a limited supply of currency and unique ownership of the bitcoins.

I'm not an expert in these things, but by all accounts Bitcoin does what it claims to do. The total supply of bitcoins is limited and predictable, and ownership of bitcoins is provable and transferrable. Some people are promoting Bitcoin as a replacement for money, and claiming that it can be treated like virtual gold.

But it isn't, and I predict Bitcoin will never achieve anything close to mainstream success as actual money. The fundamental weakness with Bitcoin is that the underlying Bitcoin technology solves the wrong problem. The system uses the model of a physical commodity (like gold) as money, and therefore is engineered to guarantee a very specific and predictable supply of bitcoins.

In the real world, though, one of the most important characteristics of money is that it has a stable and predictable value. It's vitally important that a dollar today is worth very close to what a dollar was worth yesterday, and that we are confident it will be worth pretty much the same tomorrow. But the demand for money can vary widely, depending on whether people want to hold on to their money (like in 2007-2008 when the banks were collapsing) or spend and invest like crazy (like in the dot-com bubble). So the supply of money has to change to match the demand and keep the value stable.

Our financial system has a system for creating and destroying money: through fractional reserve banking, banks create money by making loans, and can destroy money by calling loans in (or simply not making new loans as the old ones are paid off). The system isn't perfect, which is why we have the Federal Reserve and why different currencies change value relative to each other. But on the whole, it's pretty good most of the time.

Bitcoin, though, has no such mechanism built in. With a predetermined bitcoin supply, the value of a bitcoin is guaranteed to fluctuate like crazy as demand changes (and this is, in fact, what has been happening), and that's useless for money. In order to give some flexibility to the bitcoin supply, you have re-introduce fractional reserve banking. That requires an oversight body like the Fed to make sure the banks do the right thing in both boom and bust. In the end, you've basically just re-created the banking system of 1928, which failed in part because the gold standard was not flexible enough to deal with the challenges of the Great Depression.

I do like the idea of having a peer-to-peer currency, where the system creates the right incentives to have a frictionless money with no requirement for central oversight. But the core problem to solve isn't fixing the supply of money, it's democratizing the process of matching money supply to money demand so that the value is stable. I don't have any idea how to do that, but I do know that Bitcoin is entirely the wrong approach.

This Annoys Me Every Time on Star Trek

There are two verbs which sound very similar but have very different meanings.

To damp means to diminish the activity of something, or to reduce the oscillations of something.

To dampen means to make something slightly wet.

So when Geordi LaForge uses a dampening field to counteract the alien probe's tractor beam (or whatever), he's actually getting it slightly wet. What LeForge really should use is a damping field.

(And yes, I know that the dictionary cross-lists both definitions for both words. To my great consternation, this misuse is now so common it has become acceptable usage.)

State of Home 3D Printing (Fall 2012)


It's hard to believe, but I've had my 3D printer for nine months. In that time I've printed hundreds of things, a couple dozen of which are my own designs. I've consumed something like 15-20 kilograms of plastic filament (yet still have an inventory of 20 kg in 15 different colors). I've replaced the platform heater on my printer about ten times, the extruder nozzle once, printed a half-dozen other replacement printer parts, and tweaked my printer in four or five ways.

So this seems like a good time to take a few steps back and make some observations about the state of home 3D printing as it stands near the end of 2012.

Home 3D Printing is Still a Hobbyist's Market

The first thing that's very clear is that home 3D printing is very much a hobbyist's market. The actual usefulness of a 3D printer in the home is still very limited, though they definitely have a role in education, architecture, engineering, and other professional settings. Arguably the most immediate economic impact of inexpensive 3D printing is to bring the technology within the reach of professionals who have a real need, but couldn't afford to spend five or six figures for a commercial-grade machine.

The vast majority of home 3D printers on the market today are very much hobbyist-grade. These are not plug-and-play: even the easiest printers require adjustment and maintenance from time to time, and most of them are very temperamental. With some of the kit printers, I've heard it can take longer to get the printer tuned and adjusted than to assemble it in the first place.

Makerbot made a lot of noise at the beginning of the year claiming that its Replicator was designed for the average consumer. Makerbot has a great history of making kits, but I don't think the company really understood what "consumer grade" means. Many reports I've seen are that the Replicator still needs fussing to get consistently good prints, and has some design and engineering defects. Makerbot recently announced the Replicator 2 which addresses some of the most obvious flaws of the Replicator (for example, the wood frame is now steel, which is important in a machine which has to be adjusted to within a tenth of a millimeter), but the Replicator 2 isn't shipping yet. I'm skeptical when Makerbot claims a product is "easy for anyone to use," so we will have to see.

My printer, the Up!, is now being OEMed in the United States by Afinia. I had a chance to meet the Afinia team and tour their facilities a few weeks ago, and I was impressed that they are putting some real design and engineering work into improving the product. The Up! is a good printer and produces very nice looking prints with only modest adjustment, but it also has its flaws. Some of the cables are underdesigned for the amount of heat, stress, and motion they have to handle (hence the ten heater cables I've gone through), and some of the adjustments have to be repeated too often. For the most part, these are solvable problems--they just haven't all been solved yet. Fortunately, the Up/Afinia is a very "hackable" printer, making it easy for other hobbyists to tinker with it and improve the design.

The printer which comes closest to being a true consumer-grade product is the Cube, a low-end product by 3D Systems. From what I've heard, the Cube requires a minimum of fuss (though it does require a little bit of adjustment, and the use of a proprietary "magic glue" platform adhesion material) and produces acceptable output. However, 3D Systems chose to lock the Cube into a proprietary filament cartridge, forcing users to buy consumables at wildly inflated prices. That may be okay for occasional use, but heavy users like me will wind up spending crazy amounts of money on plastic.

(How expensive is the Cube filament? Right now I buy filament in bulk and spend around $20/kg including shipping. Retail pricing ranges from $35/kg to $60/kg depending on the source. 3D Systems charges $50 for a filament cartridge and won't say how much it holds, but it seems to have between 200 and 500 grams. That's $100 to $250/kg, or between 5x and 10x what I pay now. Since I go through about 2kg/month, the Cube would cost me between $160 and $460 extra per month in filament.)

3D Systems is going after a mass-market audience with the Cube, but I think they are at least five years too soon to market. We are still at the point where the only people interested in buying a home 3D printer are hobbyists and hobbyist/professionals--and those people want a machine they can take apart and tinker with. Worse, if the Cube is discontinued and 3D Systems stops supporting it, there is no other place to get filament. This scenario would quickly turn a Cube into a brick.

My Personal Toy Factory

I usually get one of two reactions when I tell people I have a home 3D printer: either "Cool! Where can I get one?" or "What's that good for?"

The hobbyist printer manufacturers have sometimes bent themselves into knots trying to answer the second question: You can make replacement knobs for drawers! Personalized bottle openers!

Get real. Nobody is going to spend upwards of a thousand dollars on a machine just in case they need to replace a ten cent plastic knob someday. And until the manufacturers start posting 3D files for replacement parts you'll have to design your own, which is way more work.

In fact, the most popular "useful" things on Thingiverse are....replacement parts for 3D printers.

But there is one thing a home 3D printer is really good at: making toys. The ABS plastic is cheap, nontoxic and durable, there are thousands of toy designs on Thingiverse for all ages and interests, and you can design your own if you want. I've made toys for my kids, toys for my friends, toys for my kids' friends, birthday presents, you name it. For my nephew's birthday I designed and printed an entire gear toy system just for him (then uploaded it to Thingiverse for the rest of the world to enjoy).

For some reason, "making toys" seems like a trivial application for a high-tech piece of fabrication equipment. But I say: let's embrace it. The toy industry is a $21 billion dollar industry in the United States. There's nothing small or trivial about that.

The great thing about having a Personal Toy Factory is that it lets me get away from the mass-produced cheap plastic junk. It's still made out of cheap plastic, but the toys are now made specifically for the child. There are thousands of ready-made designs to choose from, and I can customize or design my own. If my nephew decides he wants to be a "Space Sheriff," then I can make him a badge with a starship on it and a six-shooter ray gun. Good luck finding that at Toys R Us.

Given that the average American household spends something like $200/year on toys, it's actually not so farfetched that an upper-income family with kids would spend a couple thousand dollars on a machine to custom-build toys for their kids. It's easy to rationalize as useful for school projects--my kids have all used 3D printed stuff for their classes--and the gee-whiz factor would close the sale.

Home 3D Printing is More Art than Science

One of the first discoveries for a new 3D printer owner is that the technology doesn't quite live up to the hype. Many people come in to 3D printing thinking that they can print Anything--that was certainly my thought at first.

And you can print Anything, as long as Anything:

  • Isn't too big: most home printers have a fairly limited print volume, and big prints can take a very long time (over a day in some cases).
  • Isn't too small: small parts and fine details might not print at all.
  • Doesn't have to be too strong: 3D printed parts can be quite strong if they are carefully designed and printed, but they can also be very delicate since the bond between layers is relatively weak.
  • Doesn't have intricate overhangs or interior voids: support material can be a difficult or impossible to remove without damaging the print.

Hobbyists also struggle with making sure prints stay attached to the print bed while printing (yet come off easily when done), and keeping prints from warping or splitting due to internal stresses. Commercial printers have solved these problems using techniques like carefully temperature-controlled chambers and disposable print platforms, but (for now) those techniques are proprietary and too expensive for the home market.

So there is definitely an art to getting good 3D prints from a home printer. You can't just throw any old 3D object at it and expect good results, and many hobbyists are still experimenting with new techniques.

There's also a lot of artistry in designing multi-piece things that fit well and have a "finished" look without too much cleanup work. Since 3D printed models tend to warp a bit, you can't just glue two parts together on a flat side without a visible seam. Joints need to be incorporated into the design, with allowances for gaps and other imperfections in the printing process.

More Fun Than....

I've gotten a crazy amount of enjoyment and satisfaction out of my printer. For me personally, it requires just about the right combination of tinkering and design to give me a perfect cocktail of artistry, technique, and instant gratification.

When someone asks me if he (it's usually a he) should get a 3D printer, my response is usually a little more guarded. This isn't for everyone yet, and it isn't even for most people. But if you are the kind of person who both enjoys working with mechanical stuff and also creative design, you will probably get a lot out of a 3D printer.

Our Shopping List


Our shopping list this week:

  • orange marmelade
  • cream cheese
  • parmesian cheese
  • toothpaste
  • coffee
  • stapler
  • frozen peas
  • pepperoni
  • liquid nitrogen

My brother had his 40th birthday party last week. My gift to him was to supply liquid nitrogen ice cream for all the guests. I've been wanting to try LN2 ice cream for years, but didn't know how or where to get my hands on the stuff. In grad school we just had a tank of the stuff in the lab. It was supposed to be for experiments, but a significant percentage was diverted for various graduate-level entertainments.

About a month ago one of the other geek dads at the twins' school served LN2 ice cream at his son's birthday party. The primary reason for enrolling one's children in a Gifted and Talented program is, of course, getting to socialize with geek dads.

I interrogated him and found out that, as long as one has the right equipment (a liquid nitrogen storage dewar), LN2 is easily obtained from your friendly local welding supply store. The nitrogen itself isn't too expensive, though the dewar is a few hundred dollars. On the other hand, the dewar will last for decades if properly cared for, so a one-time investment can mean years of uniquely nerdy party entertainment at a very reasonable price. My brother's milestone birthday gave me just the excuse I was looking for.

Unfortunately, we emptied the dewar before the kids got tired of ice cream. One of the twins (age 10) decided that more LN2 was an essential household supply.

And that is why we are the only family on the block with "liquid nitrogen" on our grocery list.

Now if you will excuse me, I need to go load the dishwasher and check on the cryo-tanks.

Seeking Plastic


My 3D printer consumes three things: my time, electricity, and miles (*) of plastic filament.

To date, I've been going through plastic at about two kilograms per month. At about $60/kg (including shipping) for the manufacturer's plastic, that's about equivalent to a bad Starbuck's habit--an affordable luxury, especially since I don't otherwise have a Starbuck's habit.

There are two problems with buying plastic from the manufacturer, though: first, it costs $60/kg and I'm cheap. Second, it only comes in white.

So I have been on a hunt for alternative sources of 1.75mm ABS filament to feed my 3D habit. Hobbyist 3D printers seem to have settled on 1.75mm ABS and PLA as the "standard," so there are may sources including other 3D printer manufacturers, third party vendors, and guys who bought a palletload of plastic filament and sell it on eBay.

So far I've tried five different sources of filament and I'm still evaluating two others. I've paid prices ranging from $25/kg (for bulk orders) to $60/kg. And I've discovered that all plastic is not created equal.

Size: To get the best and most consistest results in my printer, the actual diameter of the 1.75mm plastic filament needs to be between 1.70mm and 1.80mm. Plastic as small as 1.60mm and as large as 1.80mm can be made to work with some effort, but diameters outside that range will not feed properly.

So far this has been the largest challenge in finding reliable suppliers. I've bought reels of filament which vary between 1.55mm and 1.95mm over a distance of less than two meters. That's simply not going to work. The result is jammed filament, failed prints, wasted plastic, and frustration.

Of the five suppliers, three have delivered plastic which is consistently in-spec: Up (the manufacturer of my printer), Makerbot (which makes a competing hobby printer), and ProtoParadigm. The guys at ProtoParadigm get extra credit for offering bulk 30-lb spools at a substantial discount, but you have to special-order it and wait a couple months for delivery.

Plastic: It turns out that there are lots of different kinds of ABS plastic. The stuff Up sells is an extra-strong grade which gets extruded at 260C. Most other suppliers offer a lower grade of plastic which they recommend extruding at between 200C and 225C.

So far, every ABS plastic I've tried has extruded just fine in my printer, though with the lower grades of plastic it is often harder to remove support material and there tends to be more warping and lifting from the print surface. If I was trying to get perfect models every time this would bother me, but I consider this a worthwhile tradeoff for having a choice of colors and lower cost.

Colors: If Up offered a choice of colors I probably never would have started looking for other sources of plastic. Right now I have reels of about ten different colors, including glow-in-the-dark and metallic silver (which is more like graphite, but still looks sharp). Printing in color gives much more appealing results than boring old white.

Quantity: Most retail sources sell ABS filament in 1 lb or 1 kg reels, at prices around $45 - $55/kg including shipping. Special colors, like fluorescent, glow, and metallic, often cost a few bucks more. A few carry 5lb reels at a discount. ProtoParadigm lets you special order 30lb reels for a significant discount.

I'm just starting to explore ordering directly from wholesalers. Minimum orders range from 10lb to 25kg, making this a little risky since I don't want to buy a year's supply of plastic and discover it consistently jams my printer. On the other hand, wholesale prices seem to be generally around $20 - $25/kg including shipping, so there's the opportunity to save a lot of money if I can find a reliable source. Wholesale orders also seem to have one to three month lead times.

Stock: Right after Christmas, most sellers of 3D printer filament seemed to go out of stock on most colors. I'm not sure if this is a post-Christmas spike in demand or what, but at the moment it is a challenge to find many colors. I'm hoping that availability will improve over the next month or two as the wholesalers catch up.

My Buyer's Guide for Plastic to Feed an Up

Up: You can't go wrong with the manufacturer's own plastic. Pros: best performance and strength. Cons: comes in white only; more expensive than other retail sources; ships from China so options are limited for quick delivery.

ProtoParadigm: These guys are obsessive about quality, and their plastic works really well. Pros: Competitive prices, bulk pricing for 30-lb reels (by special order), very responsive and easy to deal with. Cons: Limited colors, but they say more are coming soon. Right now they have Natural, Black, Glow, and Fluorescent Green, all in stock.

Makerbot: A little more expensive, but consistently good quality. Pros: Lots of color choices, quick shipping, and easy to deal with. Cons: Right now most colors are sold out; prices are at the high end.

3dPrinterStuff: I can't recommend because the plastic they sold me was consistently inconsistent in the filament diameter. When I complained about the poor quality control they were not responsive. They used to have a good selection of colors and some 5-lb reels, but all they list now is black and white.

3dInk: Also can't recommend because of out-of-spec filament diameters, but the owner was helpful and offered a refund when I complained (I refused the refund and am using the plastic). There's hope here. Very competitive prices and respectable selection of colors, though all but one are sold out right now.


(*) My rough estimate is that so far I have used about one mile of filament in my printer. Give or take about a half-mile.

The State of Consumer 3D Printing


There were several new 3D printers introduced at the Consumer Electronics Show a couple weeks ago. The Replicator, from Makerbot, is probably the most impressive from a price/performance perspective: a large print area, two extruders, and fully assembled for under $2,000. Unfortunately, from everything I've seen, the software is pretty much the same as Makerbot has always used, and that's a significant weakness. I want to just print and not have to fiddle with the settings to get good results. Better software and less fussing is why I chose the Up even though it is more expensive.

Another new model, the Cubify, is aimed squarely at the consumer market with a $1,300 entry point and an aggressively friendly look. They take the inkjet printer approach by sellng the printer cheaply but using a proprietary cartridge design to force you to buy the consumables at outrageous prices. It's hard to tell exactly how much Cubify's plastic costs, but my back-of-the-envelope calculation is that it's between $0.10 and $0.20 per gram--which would make it as much as five times the price of the same stuff from a third party.

Despite these new products I'm skeptical that 3D printing is really ready for the mass consumer market. I (and many other hobbyists) really enjoy designing and printing stuff, and I'm willing to devote a lot of time to tweaking my models, seeing what works, and accepting a fair amount of failure along the way. Not every model will print well, and there's a certain amount of art and experimentation which goes into designing a model which gives good results. An ordinary consumer isn't going to expect that.

There are also safety issues. Not loss-of-life-and-limb safety, but lots of opportunities for minor cuts and burns. Parts of the printer get hot enough to burn, and cutting support material off a model entails all the normal hazards of working with sharp knives. I speak from experience, since I was careless when trimming the support raft off one of my models a couple weeks ago. The knife slipped, and I needed seven stitches in my finger. I am now much more careful, but these kinds of injuries will be common until multi-headed printers and dissolving support become the norm.

I still think there's a good chance that someday 3D printing will be a mainstream household technology. Just not today. For all the breathless press coverage over the past few weeks, this is not yet ready for the average Joe and Jane.

First 3D prints


I got my 3D printer late last week and have been having fun making a variety of models to see how it performs. I bought the Up Plus instead of one of the many kits like the Makerbot or the Reprap. The Up is more expensive, but everything I read suggested that the kit-based models require a lot more fussing to get working properly (even if you buy them preassembed) and the software is fairly painful to work with.

The Up, on the other hand, comes fully assembed and tested and has relatively user-friendly software which works out of the box. The software is a big deal, because it will automatically add support structure (for printing overhangs) and take care of other routine chores without too much tinkering from the end user.

Most hobbyist/home 3D printers work through extruding a thin filament of melted plastic--imagine a hot glue gun mated to an old-fashioned pen plotter. There are probably a dozen different basic technologies for 3D printing, but this one seems best suited for the hobby market: it is relatively inexpensive, the materials are also cheap and readily available, and safety issues are minimal.

On the downside, this method is slow, and limited in the materials you can use. The core of the unit (and most expensive component) is the print head, so hobby printers generally have a single head. That means that each model must be made from a single material, so only one color of material can be used and the support material has to be the same stuff as the model itself.

Professional units often have two or four print heads--that lets you use some other type of material for the support (making it easier to remove all the support scaffolding), and have several colors of plastic included in the same model.

I've posted some pictures of models I've build on Thingiverse. So far I've found that the printer can produce really amazing output, though sometimes the software needs some tweaking to get the best results. Support material is a pain to remove, so it's best to use the least amount of support which will still give good results.

I've also found that kids (of all ages) find the 3D printer endlessly fascinating--it's a great way to inspire interest in designing and building stuff, and my kids have already started making models in Sketchup to print.

Christmas Day Ride


The weather this "winter" has been shockingly dry and mild for Minnesota. As of today we have gotten a grand total of only a couple inches of snow, and no below-zero temperatures.

Yesterday, Christmas Day, it was in the 40's. I went for an 18+ mile ride to my parent's and back (the kids rode in the car with She Who Puts Up With Me). In anything close to a normal winter, that ride would be out of the question for me because of icy/wet roads and cold. I managed a similar ride on Thanksgiving Day.

The extended forecast is showing only slight chances of snow and nothing in the way of January-like cold for the next week. At the rate we're going this could be the year without a winter. January and February are normally the coldest months of the year, but we are now gaining sunlight every day and the lack of snow means that the ground absorbs a lot more solar energy.

Would you have bought a personal computer in 1975?


A personal computer in 1975 cost about $2,500 in today's dollars if you bought it assembled. It didn't do much, as there was no third-party software and it only had 256 bytes of memory. (However, for an extra $1,350 in today's dollars you could upgrade it with another 1,024 bytes of memory). A few thousand units sold that year, which was a shocking success.

As a laughably downsized version of what were then giant industrial machines, it was hard to see then what a personal computer would eventually be useful for. It would be another four years before Visicalc--arguably the first really useful thing you could do on a personal computer.

So would you have bought a personal computer in 1975?

In retrospect, many people would probably say Yes, but that's only because we now know how the technology evolved. It's much harder to be in 1975 and see how this expensive toy (which is all an Altair 8800 would ever be) would change the world.

It's this line of thinking which made me decide to buy a home 3D printer. I want to learn about this new technology not because it's useful today, but because it has such interesting potential over then next 10-20 years.

Commerical grade 3D printers are powerful pieces of industrial equipment, and have no place or purpose in the home. Their smaller cousins have only been on the market a couple years and are pretty much expensive toys with limited practical value.

On the other hand, a small 3D printer isn't much more mechanically complicated than an inkjet printer (in some ways it is actually simpler). There's no reason that, with enough manufacturing volume, someone couldn't sell a 3D printer for only a few hundred dollars and put one in every home.

The only reason nobody's selling millions of cheap 3D printers is because nobody knows what your average household would do with one.

I don't know if we will discover the Visicalc of 3D printers, the killer app which transforms this from expensive toy into useful tool. I don't think a lot of people in 1975 knew what the future held, either.

There was another interesting piece of industrial technology scaled down for home use which came around only a few years after the Altair 8800. Unlike the personal computer, however, not too many people today have a personal robot.

Optimistic about Carbon and Renewables


Three and a half years ago (in early 2008) I observed that the price of solar power modules had been dropping at a remarkably consistent 6% per year for 25 years, and that sometime before 2025 they would be cheaper than grid power in most places.

The exact year of grid parity depends a lot on where you live: sunny places with expensive electricity (think Hawaii or southern California) get there a lot sooner than cloudy places with cheap power (Seattle). For Minnesota, I estimated that sometime around 2015 a solar power system would pay for itself within the system's lifetime.

That estimate is looking pretty good, at least on the price of the solar modules (this Scientific American blog has an updated version of the graph I made in 2008). If anything, the decline in photovoltaic prices may be accelerating a little--though that could just be a short-term blip.

I'm optimistic that over the next decade solar power will become economically viable in more and more places. On a purely cost basis alone you will start seeing a substantial increase in solar power installations. That, in turn, makes me optimistic that we will manage to transition away from greenhouse-gas-emitting sources of energy in a reasonably graceful fashion.

I may be using "optimistic" in an unusual sense. There's no doubt that the earth's climate is changing, and much of the evidence now points to a faster climate change than most scientists had predicted. There's already a lot of climate change "baked in" to the atmosphere, as cabon dioxide levels have increased over 20% just in the past 50 years. What's more, moving a large fraction of energy production to solar and other renewable sources will take decades, as it's very capital intensive to build an entirely new energy infrastructure.

But I am optimistic that the long-term trends are in place to create a more sustainable energy system and eventually reduce or eliminate net emission of greenhouse gasses. It will take decades. Future historians may see the 21st century's energy revolution as just as important as the industrial revolution in the 19th century or the information revolution in the 20th.

In the meanwhile, global climate change will continue. Sea levels are likely to rise (maybe a lot), storms will get more intense, and a lot of people will have to adjust. Some cities may have to be abandoned or be put behind massive dikes like in the Netherlands (I'm looking at you, New Orleans and Miami).

But it will not be the end of civilization. We will--eventually--muddle through.