Makerbot Replicator 5 gen lab notes.

For the past couple of weeks we have been playing with our Makerbot Replicator 5 generation PLA 3D printer in the office.  We use it for a project in the Exploratory Engineering department at Telenor Digital.   Exploratory Engineering is a program for allowing employees in Telenor Digital spend 3 months on a project of their own choosing.  The idea is that they get to do something that would otherwise be hard to realize, and at the end of the three months they pitch the product/project to management for funding.  Exciting stuff.

Mostly we use it to prototype enclosures for devices we are working on, but we also use it for printing various odds and ends that we need.

PLA plastic.

Previous to getting this printer I had mostly printed things using the older Makerbot products that use ABS plastics.   I had heard a lot of bad things about PLA plastics, but I have to say that it isn't that bad.  The parts are a bit more brittle and not as heat resistant.  On the other hand, the parts are much harder and more rigid.   It also seems that there is a lot less warping on big prints.  With ABS and early Makerbots I had to design and orient parts specifically to avoid warping, and it was always a nightmare with people walking in and out of the (heated) room and not closing the door after themselves.  Depending on your use this may or may not be to your liking.  For prototyping I don't find this to be a problem.

Extruder problems.

The extruder is the weak link in this printer.  Since you are using PLA, the extruder will clog sooner or later.  And chances are it will clog so badly you can't get it to work again no matter how many times you cycle it through unload/load filament cycles.

If you pick it apart I guess you will void the warranty -- but I would actually recommend you do pick it apart.  It is actually worth having to buy a new extruder rather than having to wait for 2-3 weeks for a new extruder to turn up.  If voiding the warranty is not your thing then I would advise against buying the Makerbot Replicator.

Thankfully, taking the extruder apart is relatively easy.  You have to be careful when opening the casing so you don't break the clips, but the insides are very easy to understand and to take apart. Beware that there is a spring inside which pushes against the nozzle at one end and the contact sensor on the other end.  The contact sensor is the little plastic thing with a magnet inside it.  It seems like the contact sensor actually uses a magnet and a hall-effect sensor -- which is a pretty clever design since mechanical switches aren't all that precise.

There is a video on youtube of how you do it.  The video is low quality, but it is helpful in showing you the order of operations when you pick apart the extruder.

Z-axis alignment before printing.

Before printing the Makerbot will go through a calibration procedure to determine the exact position of the Z-axis. If you have problems with the extruder rubbing against your build plate when it starts printing, it probably has misjudged the print plate position.  This will lead to the nozzle getting backed up and could end up clogging your nozzle.  You will hear a ticking sound come from the extruder, which means that the filament is slipping -- the stepper is pushing the filament but the filament has nowhere to go.

Sadly, the Makerbot doesn't have any configuration where you can adjust the Z-axis calibration and offset the print head, so instead you have to trick the calibration procedure.  What I've done is that I have 4 sheets of paper that I have cut into a long strip;  when the printer starts its pre-print Z-axis calibration I slip the sheets under the nozzle as it measures the build plate position.  Then, before it starts printing, I retract the paper again.  This way it will start printing at a slight offset over the Z-axis and it won't grind the nozzle into your build plate.

It seems that if you print things on a raft, the extruder will start a bit higher and pump out a thicker extrusion on the first pass and that this lessens the chance of getting a Z-axis problem -- but this is just guesswork on my part.

Wishlist for Makerbot gen 6

  • Make the extruder user-servicable.  It will clog and it will be more expensive to engineer an extruder that guarantees you won't have clogging than to make it user serviceable.  I wouldn't even bother trying.  Get rid of the fragile clips, at least for the main housing, and use proper torx head bolts.  Provide instruction videos for how to pick it apart.
  • The calibration/measurement sequences are slow.  Dead slow.  This smells of bad programming rather than a conservative approach.  Levelling the build plate shouldn't need to take more than 30 seconds.  The pre-print Z-calibration should be a 5-8 second affair.  I have no idea why it steps down so slowly when lowering the extruder to the plate to trigger the touch-sensing.
  • Make the firmware more configurable -- both up front and during printing.  Things like travel speed, temperature, Z-axis offset etc might as well be configurable.  If people screw up then they screw up.  (Being able to adjust travel speed while the printer is working enables you to find good settings faster since you don't have to start an entirely new print).
  • Document the network API of the Makerbot so users can easily write software for interfacing with it.  Give it a proper REST API and put libraries for different languages on GitHub. Encourage third party developers to make libraries.
  • Redesign the build plate guide and attachment.  It has a tendency to not slip correctly into place.
  • Fix the top of the extruder where the filament guide tube attaches to the print head.  It has a tendency to slip out and taping it in place doesn't work well either.  I've been thinking about designing and printing a kludge for this.
  • Make all the values editable in the print profiles.  Sure, most people who care are fully capable of editing the JSON file with the config values, but having a proper UI for doing this would be nice.
  • Make it more hackable again.  The product isn't a traditional consumer item anyway, so you might as well go back to your roots and design the thing to be user-modifiable.  If it voids warranties:  fine, I can live with that.  I'd rather risk breaking the bot and have an easier time repairing it than being guaranteed humdrum performance.



A few days ago I had the pleasure of driving +Ståle Dahl's 1972 Bertone-designed Alfa Romeo 2000 GT Veloce from Trondheim to Lom.  Or rather, Ståle and I shared driving duties along this scenic route on our way to a company offsite.  (We usually just refer to the car as "The Bertone" or fondly: "Bertis")

Most motorists today have so few opportunities to drive an older car -- and in particular an older car that is in excellent condition and which can offer an exciting driving experience.  Apart from being a beautiful car, it is a pleasure to drive.  The 2 litre, 4 cylinder Nord engine from Alfa Romeo provides a characteristically wide power band.  It growls, fizzes, crackles and barks thanks to a refreshingly simple exhaust system and not least a pair of decent sized Weber carburettors with trumpets, rather than the large filter-boxes used to neuter most modern cars.

Norwegian author Kjell Aukrust has written extensively about the joys of motoring, and it is not hard to understand why the Alfa Romeos always had a special place in his heart.  There is something very special about the combination of stunning Norwegian scenery, with mountains plunging into the water, curvy roads hugging the mountain sides, and the sound of a Nord engine.   Slower cars are dispatched quickly.  Approach carefully from behind, so as not to startle the victim prematurely, then downshift in two takes, blipping the throttle between gears, allowing the trumpets to bark, before burying the pedal.  When your vision becomes blurry, that means it is time to shift up.

One does not need to go particularly fast to have an engaging experience in the GTV.

The difference between driving an older car and a modern car struck me a I was trying out a new car for my daily driver.

It has been clear for some time now that my daily driver, an Alfa Romeo 156 Selespeed, is becoming somewhat long in the tooth.  We are now at that magic crossover point where the cost of repairs relative to the monetary value of the car means you keep asking yourself if it is worth investing more in the car.  By all means, the car is still a brilliant drive in many respects.  In particular I love the precise and perfectly balanced steering feel.  And thanks to a diligent mechanic, it will still out-brake most other cars by a good margin.  But I need a younger workhorse.

The choice landed on the relatively new Alfa Romeo Giulietta.  More specifically the Quadrofoglio Verde, which has Alfa Romeo's brilliant 1750 TBi strapped under the bonnet.  The same engine that you will find in the gorgeous Alfa Romeo 4C.  The key figures are pretty exciting for a 5 door hatchback: 1350 or so kg, 235hp, 340Nm of torque and a clever front differential that will deal with the embarrassing tendency of front wheel drive cars to uselessly direct power to the inside wheel and light it up during hard cornering under power.

The thing about modern cars is that they are fussy.  There is so much stuff in them.  Stereo,  multiple climate zones, seats that contain more electronics than your TV.  The interior is a museum of all the various polymers humankind has come up with over the last 100 years.  And this is without even beginning to describe the infuriatingly useless computers that are strewn throughout the car running shit software written by underpaid engineers on strict budgets under unrealistic deadlines.

True, modern cars are more comfortable.  If I were to drive this car for 12 hours straight I'd arrive well rested and able to feel most of my extremities.  12 hours in the Bertone, which encourages you to drive "con spirito", means you probably need to rest up for a day.  Preferably in a hotel overlooking some body of water.  While imbibing bubbly and nibbling on cured meats.

Also, modern cars are fast.

It may seem odd that a confessed petrol head would complain that a car is fast, but hear me out.  The problem is that you want the feeling of speed, of danger of drama -- but not necessarily very high speeds.  The Giulietta QV is so easy to drive, so quiet and so effortlessly light-footed that you think you are going 80km/h, but when you look at the speedo, it says 130km/h.  I suppose that to recreate the oh-my-god-we-are-going-to-die-feeling you get in older cars, I would have to drive at speeds that lead to carpentry (building pallets is the stereotypical prison job in Norway -- whether this reflects reality or not -- hence "building pallets" is a euphemism for "going to prison").

I like braking hard, cornering fast, place the car precisely and hit the fun pedal before most people have discovered that they are even in the corner -- but thundering down a straight piece of road at warp speed....even the land-boats of the colonies can do that.

Of course, then there are cars from the 80s.  When there was electronic injection systems and car designers were struggling to get to grips with this newfangled thing called a "turbo".  Now, the turbo wasn't a new invention, but strapping them into road cars and, in some cases, tripling or quadrupling the top end power output, did not come without challenges.  Apparently this was so hard to sort out that for a decade, nobody had time to design cars with curvy bodies.  The ruler was the main design tool and I suppose Giugiaro and Cressoni enjoyed the 80s since it meant they could go home early every day -- after spending most of the day drawing essentially straight lines.

While the 60s and 70s was about bone-rattling, yet rather linear engine performance, the 80s was the nuclear age.   Nothing at low revs, still nothing, nope and then, suddenly, hundreds of crazy horses come gallopping out of the gate at the same time, turning your tyres into plumes of expensive smoke and depositing your car in the nearest tree.

I happen to have one of the most frightening cars from this era:  the 1987 Alfa Romeo 75 Turbo Evoluzione (Interestingly, almost everything on the Wikipedia page is wrong about this car, so I should get around to fixing that some day.  Not only did they make 509 rather than 500 cars, but they were also more powerful than claimed by the factory -- because Alfa made a V6....and a 4 cylinder engine isn't allowed to be more powerful than a V6 in their universe...so obviously they had to lie).

It was made as a homologation vehicle -- meaning, to race in certain series, you needed to make at least 500 cars to be able to claim that it was "serial production".  Alfa made 509 of these cars.  Sadly the timing was a bit off so they only raced briefly.  Again meaning that development of the car never really got going.  Which again means:  this is a frightening car.

While the 1972 GTV is the sort of car you can drive in a tweed jacket, and the Giulietta QV allows you to thunder along in comfort while checking your mobile phone, the Evoluzione should probably come with a straightjacket and anti-psychotic drugs.  Give it the beans and within short you will start suffering from ischemia of the knuckles.  It is recommended that you bring a change of underwear and arrange for some sort of plastic covering for the seat.  At least until you get used to what happens when the little turbine up ahead wakes up and starts cramming obscene amounts of oxygen into the cylinders.

Owning a 75 Evo is like owning a bear:  pretty cool, but there's always the risk that this is the day it is going to eat you.

But you do feel alive when driving it :-).


Consumer grade health monitoring equipment.

Right now a somewhat new category of health/medical equipment is beginning to emerge.  These devices are not your traditional medical devices, with their bureaucratic, long-winded approval processes that guarantee that whatever comes out the other side is ten times expensive and several years behind the technological status quo.  These devices are for everyday use of consumers to have some idea of how their health is doing.

When I talk about measurement devices to track your health, you probably think of glucose meters and blood pressure measurement cuffs.  Expensive stuff that needs to be carefully calibrated, tested, rated and approved.  Well, those are critical and very nice to have.  But there are lots of other parameters that you can look at and analyze to gain useful information.

For instance body weight.  For people with certain medical conditions, keeping a close eye on developments in their body weight is critical.  And this is much harder than you would think using old-fashioned bathroom scales.  Since your weight will vary throughout the day and even between days, trends can be hard to spot if you do this by eye and by memory.  But if you store the measurements and you have software that can smooth out the rather noisy data, you will be able to spot trends much easier.  For instance I can easily spot a 200 gram gain or loss over a week using my internet-connected bathroom scales with data visualization software -- I seriously doubt that even if you record your weight carefully with pen and paper you'll spot that change unless you do a bit of work.

And that's an important point.  If you want people to measure something related to their health, you have to automate it and preferably, not have it interfere with their lives.

Taking a weight measurement with a WiFi-connected bathroom scale takes zero effort.  You just step on the thing for a few seconds while you are brushing your teeth and you are done.  If you brush your teeth 2-3 times per day, that's 3 datapoints right there.  (Compare to one datapoint at your doctor's office during the yearly checkup.  An almost worthless measurement).

Taking a BP reading, on the other hand, is a pain in the neck.  The traditional way to measure BP is with a cuff -- a device called a sphygmamanometer.   The measurement procedure calls for sitting down, putting the cuff on, and performing a series of measurements.  To the greatest degree possible you have to try to eliminate sources of error and to make the measurement the same way every time in order to produce data points that can be compared reasonably well.  This takes real effort.   So you won't get people to gather lots of BP data points every day.  This is a parameter in dire need of a proper measurement technology.

What will be an important focus is how we can instrument ourselves and our surroundings in order to measure health-related parameters without effort.  And there are a lot of opportunities. Just take your bed.  You can monitor movement to determine how well you sleep.  It should be possible to pick out your pulse either by sound, or by making sheets out of fabrics that can utilize contact with your skin and make use of conductive materials embedded in the sheets.  If you have enough leads, proper signal processing and some software to figure out how the sensor grid is aligning with your body, there is no reason you wouldn't be able to produce many hours of EKG-data every night. Meaning that not only will you know more about your heart than was previously possible -- it is going to be possible to detect heart problems much, much, earlier than before.
Ditto for breathing.  Combine audio analysis with the minute movements of your bed as you breathe and it should be possible to detect a number of anomalies.

Recently I built a prototype for monitoring body temperature while in bed.  My theory was that it should be possible to automatically detect if someone is running a fever.  Without having to get up and use a traditional thermometer every now and then.  The sensors are just embedded in your bed (no pun intended) and you log the measurement values over the network.  It took me just a few afternoons to build and even after the first full night of testing it was obvious that non-intrusive fever detection is feasible.  I'm still working on it, but I've already reached the cost goal:  you can do it for under $100 in materials cost.  And that is for a WiFi-enabled device with a big, bright LED display.

So to sum up:  here are some of my beliefs around consumer health monitoring:

  1. We have to develop cheap, automated technologies for health monitoring to free up the time of medical personnel so they can spend less time on menial measurement tasks which they are not very good at anyway since they are humans -- and humans are terrible at observing and recording physical phenomena.
  2. It has to be non-intrusive.  If it takes effort, users won't stick to it.  The goal has to be to hide these measurement devices in everyday objects and to opportunistically gather data whenever data is available.
  3. New high quality sensors available for very little money combined with cheap connectivity and high capacity computing means that observations that would have been pretty hard to come by a few years ago are now easily attainable.
  4. Privacy and security will be a huge problem.  On one hand you want to keep this data private. On the other hand, you want it to be easily available to you and your healthcare professionals.
  5. Regulatory bodies and traditional makers of medical technologies are slow and incremental -- meaning that there will be an unresolved tension here for years.  Ultimately this means that public healthcare organizations will forego incredible cost savings opportunities because they lack the kind of people needed to figure out how to expedite this.

(When I say that humans are terrible at measuring things, I mostly base this on papers I've read that quantify the error rates of defined measurement tasks where the accuracy of the measurement devices are known.  For instance for a given urine collection device used in many hospitals the theoretical accuracy would lead you to believe that errors would typically be in the 2-5% range.  The observed error is as high as 25%+.   Measuring well is hard.  Leave it to the machines if you can.

Of course, I am beating myself up over being really bad at referencing these papers when I discuss things or when I write.  This leads to misremembering the precise figures as well as not being able to provide helpful references for people who wish to understand these things.  I'll try to get better at this. Sorry.  Of course, it also doesn't help that some of these papers are behind paywalls -- which is just the disgracefully obsolete way scientific publishing works)


Teachable moment: Watch Polar die.

If you want an opportunity to watch an established market leader falter and eventually die, you should have a look at Polar Electro.  I think it is very likely that they are going to be the next Nokia.  Grab some popcorn and watch as they are going to get their lunch taken away by newcomers.

Years ago Polar would be your go-to brand if you wanted a heart monitor.  By virtue of the competition being either non-existent or offering significantly worse products.  I remember buying one of their high end models which would log my pulse at 5-second intervals or so.  It was incredibly fiddly to use and it didn't offer much in terms of usable software or meaningful interoperability (which in my book means: easy access to the raw data).

Today I think Polar is poised to go the same way Nokia, Blackberry and a lot of other companies run by people who are mere businesspeople -- people who are out of touch with the rest of the industry and who are not properly attuned to how the world is changing.  Here are some reasons why:

Products are not improving.

Polar's products have not improved significantly over the past 15 or so years.  In fact, the last time I bought one of their pulse monitors it turned out to be a huge step back from my old monitor from the early 2000s.   But I digress:  their biggest accomplishment over the past 15 years is that last year they managed to put a GPS into a heart monitor.

I am not making this up.  This was their accomplishment in 2013.

Their heart monitors haven't grown any significant new features and they still rely on really clunky technology:  belts around your chest.   We do have the technology to avoid this crude method of measuring pulse,  so you would think that Polar would be really interested in developing it before anyone else does and aggressively push it into the marketplace.  They aren't.   They think their unpleasant and clumsy old solution is just dandy.

They also have not developed new categories of sensors.  As we speak there are lots of small startups making wearable technology to analyze any number of things from pulse, O2-saturation, muscle activity to what your brain is doing.  And everything inbetween.  And we are not talking about high end stuff that only professional athletes can afford;  we are talking about consumer priced stuff.

Their product strategy is obsolete.

If you have not visited the Polar website yet, please do.


What did you see?  See anything familiar?  If you are perceptive you will no doubt have noticed that Polar is clinging to the old ideas of aggressive segmentation.  Without going through the tediuos exercise of detailing what segments Polar thinks exists, the main upshot of this is that it is not IMMEDIATELY clear to you what product you want.  This lack of clarity translates into hesitation.

Years ago, this is exactly what faithful Nokia customers experienced.  They'd need a new phone and it wasn't immediately clear to them which phone they wanted.  They'd have to browse and compare. Sometimes for days and weeks.  This is not a good way to approach the market.  In fact, it is exactly how you do NOT approach the market.

When product lines are properly put together, prospective customers do NOT need to visit a website or look through a catalog which product they want.  They know.  As an experiment: ask anyone which model iPhone or which Tesla they want.

If you think this comparison is unfair, you are absolutely right:  it is unfair because both Tesla and Apple know exactly how much product line complexity consumers can take.

The Polar product range is old fashioned in that they do not have the confidence to offer a single product line where only a single product line should exist.   They have multiple product lines and none of the marketing material gives you a very good reason why they would need lots of different devices to do more or less the same thing.

The competition will make far better products.

Right now everyone is waiting for Apple's watch.  When Apple enter a new product category they usually redefine what that category is all about.  They did so with computers, music players, phones and tablets.   Despite Steve Jobs no longer being with us,  there is a chance that they will do the same with watches.

Their newly unveiled APIs reveal that Apple are taking aim at two areas:  home automation and health & fitness.  Combine this information with whom they have been hiring lately and it is quite obvious that we can expect Apple to do some new stuff.  Like heart monitoring directly on your arm without the need for any extraneous sensing nonsense.  No more awkward belts around your chest.  No more pausing whatever activity you are doing to press your finger against a sensor.  None of that nonsense.

Expect a bloodbath.  Polar isn't going to be the only manufacturer which will find itself with obsolete products.   Products like the Pulse 02, Fitbit and a raft of other products will all be obsolete in a few months.  Most likely because they can't measure pulse properly -- which is to say: continously on the wrist.

I think that Apple are aiming for the ultimate body monitoring device that will start off by doing fitness stuff and which will then extend into health and possibly even healthcare.  This will accomplish two things:  it will move the goalposts and it will result in more specialty sensing hardware falling in price to consumer-tolerable price points.

(It is also going to lead to an interesting conversation on automating healthcare and how the world's most technophobic professionals will have to adapt to a new reality, but that's the topic of a future blog post).

Before long you will have cheap-ass heart-monitors that beat the shit out of anything Polar has ever made at a fraction of the cost.  Made by Chinese companies you have never heard of.  Designed by people in their 20s.

But first, someone has to move the goalposts.  And it isn't going to be Polar.

Watch and learn.

I think there is a significant chance Polar may be the next company to do a Nokia or a Blackberry.  This makes it worth keeping an eye on Polar over the next years to learn how companies shrivel up and die.

You might wonder why all of a sudden I am picking on Polar.  There's a good reason for this:  we are on the verge of an explosion in wearable computing.  In a few years wearable computers will be everywhere.

Polar has occupied a niche of wearable computing for decades -- a niche that is no longer a niche but is rapidly turning into a huge mainstream market.  You would think that years of expertise and experience would give Polar an unique opportunity to capitalize on their potential market growing by orders of magnitude.  My guess is that the opposite will happen:  the wearable market will develop in ways that will eventually make Polar irrelevant.

Hey, if everything else fails, Finland will be the place to learn about how to doom your company by allowing yourself to be disrupted to death.


Ignorance and uncertainty.

Years ago I was involved in building a web scale search engine.  At the time this was the sort of undertaking that wasn't really well understood by a lot of people.  Information retrieval had existed for many years and was well enough understood, but almost nobody had any practical experience applying it at a massive scale.

And back in those days: 100 million documents was massive.  Computers were dog slow, we didn't have a lot of them and there wasn't a lot of open source software to help you do things at scale.  Not like today, where searching 100 million documents on a device that fits in your pocket is easily within practical reach.

What was hard back then is easy now.  Well, easier, at least.

But when I think back at those times it isn't really the technology that interests me.  By today's standards what we did was pretty crude,  but it did represent some of the best work that was done up until that point. Ever.  Anywhere in the world.  This is increasingly rare today:  the opportunity to work on something very few people have figured out how to do really well.

What interests me are two things.

The first is: what it takes to do something much better than anyone else.  I think the biggest advantage we had was that we had no idea what we were doing.  Which meant that we were not anchored by whatever other people did.  We truly had to explore and invent ourselves.

If you spend too much time trying to solve a given problem using whatever approach other people are following, you will be held back by the same limitations that they are going up against.  Worse yet, you will be tempted to not spend a sufficient amount of time trying to understand the problem you are solving.  Understanding the problem or problems you need to solve is always where you should start. This is why you should always try to spend a few weeks thinking about a given problem yourself.

This is why I avoid paying too much attention to what people who came before me did to approach a problem.  I might inform myself of their general approach, but I try to develop my own before devoting time to understanding theirs.  This doesn't always yield results, but if inspiration or deep understanding does strike, I will have an advantage.  Once I feel that I am starting to understand the problem and I know how I want to attack it I start to peek at what other people have done.

This is applicable to a surprising breadth of fields.

The other thing that interests me is the continuum from ignorance and uncertainty to cocksure certainty. While we were building a web scale search engine there was the engineering effort on one side and the sales people on the other side.

On the engineering side the basic question "can we do it?" wasn't a given.  Whether it was solving some problem of a deeply theoretical nature, turning ideas into working implementation or just delivering a product within an acceptable set of parameters (time, cost, quality etc.).   The sales side, as seen from the engineering side, seemed to take for granted that we had an infinite supply of magic hats from which we could pull rabbits at the last moment.  Theirs was a world that was about promises and at least the pretense of certainty.  Ours was one of sleep deprivation and raw panic.

I used to say that the salespeople sold our customers technology that we hadn't yet imagined we didn't know how to realize.

I liked to compare much of what we were doing to when Grumman built the Apollo Lunar Module. Nobody had built a lunar lander before.  Which meant that there was no known right way to do it.  Nor was there any meaningful way to estimate how long it would take or how much it would cost -- or indeed if it was at all possible.

In particular I got a facefull of this when we indexed one of our very first indices and performed searches against it.  The results were atrocious.  The results were so full of duplicates that for some searches you would get just pages and pages of identical results.  This was a wednesday.  I was asked to look into the problem.  The initial guess was that we should have a workable solution within a week. On sunday I had to call my boss and say "listen, the duplication problem is much harder than we had feared -- it'll take a bit longer".  Turns out there are several classes of duplication on the web.  And sorting them out is properly hard.

Note that it wasn't just about being able to do it -- it was about being able to do it in a practical manner. And most published efforts up to that point assumed small document sets and lots of time within which to do the deduplication.   Which meant that a "solution" that has quadratic (or worse) complexity just doesn't work.

We eventually came up with a battery of solutions.  All of them much faster than the feared quadratic solutions.  Many of them completely novel.

However, in retrospect, the interesting bit is the dynamic where people who like to deal with certainty and hard promises need to deal with uncertainty and ignorance.  For most complex technology projects, delays, disappointments and setbacks are inevitable because there are huge unknowns.  And more so for the projects that are really worth doing.

On one hand, hiding uncertainty behind a wall is dangerous because it makes our approach to hard problems fragile.  On the other hand, the pressure it creates can be valuable in spurring on discovery and progress -- by assuming "you will be able to figure this out".