3D Printering: Hobbs Meters And 3D Printer Reliability

February 10, 2015 by 40 Comments
A direct link to Makerbot's 3-pack of Smart Extruders is very hard to find
A direct link to Makerbot’s 3-pack of Smart Extruders is very hard to find

It’s been a little over a year since Makerbot introduced their new line of printers, and since then there have been grumblings about the quality of the Smart Extruder that each one of these printers comes with. While there is no 3D printer extruder that will not eventually clog, wear down, or otherwise break, there are reports of the Makerbot Smart Extruder failing in only hundreds or even tens of hours of use. Considering that a single large print can take a dozen or so hours to complete, you can easily see the why the Smart Extruder is so despised and why even the availability of a three-pack of Smart Extruders is a joke in the 3D printing community.

Of course a cheap shot at Makerbot that plays right into your preconceived ideas and prejudices is far too easy. We’re here to solve problems, not just state them, so here’s what we’re working with: to quantify the long-term reliability of 3D printers we need a way to measure the mean time before failure of extruders. This is already a solved problem; it’s just not implemented.

On aircraft and some very expensive engines that power things like buildings and ships, there’s one gauge, tucked away in the control panel, that keeps track of how long the engine has been running. It’s called a hobbs meter, and the idea behind it is extremely simple – when there is power going to the Hobbs meter, it counts out hours on a small clockwork display. The resolution of the display is only tenths of an hour, usually, but that’s good enough for scheduling maintenance and to be mentioned in NTSB accident reports.

Spend enough time with a 3D printer, and you’ll quickly realize the ‘estimated print time’ is merely a ballpark, and with failed prints the ‘total print time for this object’ isn’t exactly a perfect measure of how many hours you’ve been using your extruder. Only by directly measuring how many hours are logged on a hot end or how many kilometers of filament have been sent through an extruder will you ever get an accurate idea of how long an extruder has been running, and how reliable a printer is.

Hobbs meters are available from Mouser, but you’ll be overpaying there. The better option is from a vendor in a different niche; $30 for a meter that can connect directly to the extruder heater. If enough people add this and keep proper logs, there’s a slight chance of improving the state of 3D printers with real data and not the prejudices of people trying to justify their own designs and purchases.

But perhaps that’s too hard; adding a $30 item to a printer’s BOM just for the sake of data is a bit much. Luckily, there’s an even simpler solution that won’t cost a dime. Just measure the time a heater has been on in the firmware, or save the total length of extruded filament in a microcontroller’s EEPROM. Every printer firmware out there, from Marlin to Repetier to Sprinter has in it a way to calculate both the length of time a heater has been on or how much filament has been pushed through a nozzle.

However, this is 3D printing we’re dealing with. An organized community is not a luxury we currently enjoy, and for this to work several things are needed. The first is somewhere to upload failure statistics. This would be a web site, naturally, with the ability to input the printer make, extruder and hot end model, and the time since last clogged nozzle. The website itself is just a database, some JavaScript, a bit of CSS, and some hosting costs; not hard until you consider tens of thousands of operators would have to know about this website and contribute.

Secondly, if we’re not going with mechanical Hobbs meters there would need to be a ‘total time heater on’ or ‘total length of extruded filament’ variable in the various firmwares. There would hopefully be standardized Gcodes or Mcodes to read and reset this variable.

Will this happen? Of course not. Organization isn’t a strong suit of the RepRap project, and any company that implements Hobbs meter functionality will probably lock that up in proprietary obfuscation. However, Makerbot isn’t dumb, and given they’re selling three-packs of extruders, I would bet they have some data on the MTBF of their extruders. A community-based measurement of the most common cause of broken printers is certainly possible, but like all problems it’s one of organization, not technology.

3D Printering is a semi-weekly column that digs deep into all things related to 3D Printing. If you have questions or ideas for future installments please sending us your thoughts.

Android Tablet in Car Dash

Android Tablet Finds New Home In Car Dash

February 10, 2015 by 51 Comments

[Matt]’s 2008 Subaru’s stereo wasn’t really cutting the mustard for him anymore. He wanted to do something, something a little more custom than just an aftermarket stereo. After giving it some thought he decided he would try to mount an Android tablet in his car’s dash to act as a media player.

The HTC Evo View tablet appeared to be a great size to fit in the space left over from the stock radio, and it did fit nicely but there was a problem, the AC vent was in the way of the headphone and USB jacks! This was only a minor inconvenience for [Matt]. Instead of butchering the AC vents he decided to disassemble the tablet and see what the other options were. Luckily for him, both the USB and headphone jacks were on their own PCB boards. A quick slot cut in the rear tablet case allowed both connectors to now face towards the front of the car into the gaping crevasse the stock stereo once filled. Since the manipulated tablet case was facing inside the dash it wouldn’t create any unsightliness for the passengers.

With those connections out of the way it was time to focus on mounting the tablet in the dash. The stock trim panel that housed the old radio and two AC vents was modified with a hand-made fiberglass bezel to fit the tablet screen and make it look like the car came that way. The bezel was sanded smooth and painted to match the rest of the interior.

Originally,  [Matt] had to turn the tablet both on and off when starting and stopping the car. He then stumbled upon a product called the IOIO. The IOIO allows an Android device to interact with the inputs and outputs; both digital and analog, I2C, SPI and UART. It even has a voltage regulator that can take the car’s 12v supply and knock it down to 5 for the tablet. [Matt] also connected the IOIO to the car’s ‘ignition on’ circuit to turn the unit on and off with the car.

[Matt] plans on doing more with the IOIO’s capabilities in the future, but until then, he still has a pretty nice looking and unique car stereo.

Converting Morse Code To Text With Arduino

February 10, 2015 by 34 Comments

Morse code used to be widely used around the globe. Before voice transmissions were possible over radio, Morse code was all the rage. Nowadays, it’s been replaced with more sophisticated technologies that allow us to transmit voice, or data much faster and more efficiently. You don’t even need to know Morse code to get an amateur radio license any more. That doesn’t mean that Morse code is dead, though. There are still plenty of hobbyists out there practicing for the fun of it.

[Dan] decided to take a shortcut and use some modern technology to make it easier to translate Morse code back into readable text. His project log is a good example of the natural progression we all make when we are learning something new. He started out with an Arduino and a simple microphone. He wrote a basic sketch to read the input from the microphone and output the perceived volume over a Serial monitor as a series of asterisks. The more asterisks, the louder the signal. He calibrated the system so that a quiet room would read zero.

He found that while this worked, the Arduino was so fast that it detected very short pulses that the human ear could not detect. This would throw off his readings and needed to be smoothed out. If you are familiar with button debouncing then you get the idea. He ended up just averaging a few samples at a time, which worked out nicely.

The next iteration of the software added the ability to detect each legitimate beep from the Morse code signal. He cleared away anything too short. The result was a series of long and short chains of asterisks, representing long or short beeps. The third iteration translated these chains into dots and dashes. This version could also detect longer pauses between words to make things more readable.

Finally, [Dan] added a sort of lookup table to translate the dots and dashes back into ASCII characters. Now he can rest easy while the Arduino does all of the hard work. If you’re wondering why anyone would want to learn Morse code these days, it’s still a very simple way for humans to communicate long distances without the aid of a computer.

Retrotechtacular: Multi-Purpose Military Magazines Make Maintenance Memorable

February 10, 2015 by 18 Comments

Whether you’ve been following Retrotechtacular for a while or have firsthand experience with the U.S. Army, you know that when they want to teach something to a someone, they’ll get the job done in spades with a side of style. The era between WWII and the Vietnam War was a golden age of clear, simple instruction that saw the Army use memorable material to teach a wide array of topics. And speaking of golden ages, the Army found success with comic book-style instructional magazines drawn chiefly by [Will Eisner] of Spirit fame.

ps-coverThe first of these rags was called Army Motors, which premiered in 1940. It introduced several memorable characters such as a Beetle Bailey-esque bumbling soldier named Private Joe Dope, and no-nonsense gal mechanic Connie Rodd, a sharp cookie who’s as brainy as she is buxom. Educational and entertaining in equal parts, the magazine was pretty well received.

Its successor, known simply as P.S. started its run around the beginning of the Korean War in June 1951. These magazines were intended as a postscript to the various equipment maintenance manuals that soldiers used. They offered all kinds of preventive maintenance procedures as well as protips for Army life. The eye-catching depictions of Connie Rodd demanded soldiers’ attention while the anthropomorphic equipment illustrations encouraged them to listen to what their equipment told them.

Additional artists including [Joe Kubert] and [Dan Spiegle] were brought in to produce P.S. on a monthly basis. As the years marched on, the magazine’s character base expanded to include representatives of other military branches solving specialized problems. The bumbling idiot types were 86’d pretty early on, but cheesecake was served well into the 1970s.

Did we mention that they’re still making P.S.? Here’s the February 2015 issue and a friendly PDF warning.

Thanks for the tip, [Itay]!

Retrotechtacular is a weekly column featuring hacks, technology, and kitsch from ages of yore. Help keep it fresh by sending in your ideas for future installments.

VendingTweets

A Tweeting Vending Machine

February 10, 2015 by 12 Comments

[Sigurd] manage to obtain an old vending machine from his dorm. The only problem was that the micocontroller on the main board was broken. He and his friend decided they could most likely get the machine back into working order, but they also knew they could probably give it a few upgrades.

This system uses two Arduino Pro Minis and an Electric Imp to cram in all of the new features. One Arduino is connected to the machine’s original main board. The Arduino interfaces with some of the shift registers, relays, and voltage regulators. This microcontroller also lights up the buttons on the machine as long as that particular beverage is not empty. It controls the seven segment LED display, as well as reading the coin validator.

The team had to reverse engineer the original coin validator in order to figure out how the machine detected and counted the coins. Once they figured out how to read the state of the coins, they also built a custom driver board to drive the solenoids.

A second Arduino is used to read NFC and RFID cards using a Mifare RC522 reader. The system uses its own credit system, so a user can be issued a card with a certain amount of pre-paid credit. It will then deduct credit appropriately once a beverage is vended. The two Arduinos communicate via Serial.

The team also wanted this machine to have the ability to communicate with the outside world. In this case, that meant sending cheeky tweets. They originally used a Raspberry Pi for this, but found that the SD card kept getting corrupted. They eventually switched to an Electric Imp, which worked well. The Arduino sends a status update to the Imp every minute. If the status changes, for example if a beverage was dispensed, then the Imp will send a tweet to let the world know. It will also send a tweet to the maintenance person if there is a jam or if a particular slot becomes empty. Continue reading “A Tweeting Vending Machine” →

A Pocket-Sized Warp Core

February 9, 2015 by 14 Comments

Designed in the 2350s at the Utopia Planita shipyards, the warp core found in Galaxy class starships Yamoto, Odyssey, Challenger, and yes, Enterprise was a incomparable work of engineering, leading to more than one Daystrom Prize for its development. We’re still at least fifteen years away from the great [Zefram Cochrane]’s birth – and another 200 years until [Richard Daystrom] is born – but now, thanks to our advanced technology, a miniature warp core is within reach.

About a year ago, [Alex] found a warp core table lamp based on the one found on the Enterprise. it called out to him, but it’s a an extremely large build and only having a Solidoodle 2 as a 3D printer, [Alex] decided to scale it down to 25%.

Inside the warp core are a few Neopixel strips driven by a 5V Trinket. It’s not the ideal solution – if all the LEDs are turned on at the same time, the Trinket will brown out. It’s enough for an accurate pulsating effect, though, and was a nice enough gift to appease even the most discerning Trek fans he gave these mini models to.

Video below.

Continue reading “A Pocket-Sized Warp Core” →

Castellated Breakout Is Pitchin’ Brilliant!

February 9, 2015 by 31 Comments

Radio, WiFi and similar modules are getting smaller by the day. Trouble is, they end up having non-DIY-friendly, odd pitch, mounting pads. Sometimes, though, simple hacks come around to help save the day.

[Hemal] over at Black Electronics came up with a hack to convert odd-pitch modules to standard 2.54mm / 0.1″. The process looks simple once you see the detailed pictures on his blog. He’s using the technique to add 2mm pitch modules like the ESP8266 and XBee by soldering them to standard perf board. Once they are hooked to the board, just add a row of male header pins, trim the perf board and you’re done. Couldn’t get simpler.

Another technique that we’ve seen is to solder straight across the legs and cut the wire afterward. That technique is also for protoyping board, but custom-sized breakout boards are one good reason to still keep those etchants hanging around. If you have other techniques or hacks for doing this, let us know in the comments.