Closed Loop Control For 3D Printers

One of the bigger problems with any CNC machine or 3D printer is the issue of missed steps when moving the toolhead. If a stepper motor misses a step, the entire layer of the print – and every layer thereafter – will be off by just a tiny bit. Miss a few more steps, and that print will eventually make its way into the garbage. [Misan] has the solution to this: closed loop control of DC motors for a 3D printer.

Most printer firmwares use an open loop control system for moving their motors around. Step a few times in one direction, and you know where the nozzle of a 3D printer will be. Missed steps confound the problem, and there’s no way for the firmware to know if the nozzle is where it should be at any one time.

[Misan]’s solution to this was a DC motor coupled to an optical encoder. Both the motor and the encoder are connected to an Arduino Pro Mini which receives step and direction commands from the printer controller. The controller takes care of telling the motor where to go, the Arduino takes care of making sure it gets there.

The entire build is heavily derived from ServoStrap, but [Misan] has a very cool demo of his hardware: during a print, he can force the X and Y axes to either side, and the Arduino in each motor will move the print head back to where it needs to be. You can check that out below.

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Choctopus Chocolate Printer x8

Valentine’s Day is about a month away, long enough for everyone to butcher upgrade their 3D printers to squirt out chocolate. Food printing was a hot item at this year’s CES, but it is hardly new. Before many of you were born [Hans] left his job at the Council for Scientific and Industrial Research to produce chocolate out of his garage in South Africa. This one prints 8 at a time!

HAD - Choctopus1Many years before he was extruding lawnmowers from raw pellets, [Hans] built the 8-tentacled Choctopus. He gets away with using only one chocolate pump – from some experience, by far the most challenging component – by simply splitting the ooze pipe with three tiers of T intersections. The whole design is actually patented and revolutionary for 19 years ago but to our readers probably unremarkable.

HAD - Choctopus4There is a business lesson here too. Once upon a time the Choctopus was a  3D printer but economic constraints have led to him downgrading to 2D. Any 3D requirements are served from an alternate RepRap. The purpose of an 8-armed printer is to mass produce, but for the price, most clients were only interested in a one-off. The products that pay the bills are the much more affordable 2d extrusions in bulk.

Any of our readers looking to impress their date make lots of money next month, consider this the kick in your pants to get started.

Check out these videos of the Choctopus churning out delicious delicatessens.

Continue reading “Choctopus Chocolate Printer x8″

First Ever Parts Emailed to Space

The shocking thing is not that this happened. The shocking thing is how normal it seems. An astronaut inside a space station needed a ratcheting socket wrench. Someone else on Earth drew it up on a computer then e-mailed the astronaut. The astronaut clicked a button and then the tool was squirted out of a nozzle. Then he picked up and used the tool for the job he needed done. No big deal.

The story itself is almost uneventful – of course we can do these things now. Sure, it happens to be the first time in mankind’s history we have done this. Yes, it is revolutionary to be able to create tools on demand rather than wait months for one to be built planet-side and put onto the next resupply rocket. But, amateurs living in places without even widespread electricity or running water have already built these machines from actual garbage.

Every once in a while a story slaps us with how much the future is now.

These particular 3d prints were duplicated on the ground, and both sets preserved for future comparative analysis to see if microgravity has any effect on 3d prints. They have an eye on sending them to Mars, a journey where resupply is more than just a couple-month inconvenience.

See the first link above for more detail and photos of NASA’s 3d printer and the Microgravity Science Glovebox in the Columbus laboratory module.

Prints In Space (Said In “Pigs In Space” Voice)

3D Printing on Earth is soooo last year. Recently, NASA has sent a 3D Printer to the International Space Station in order to test printing capability in space. The agency’s ultimate goal is to have a means to make parts and tools for astronauts that are far away from earth.

So, why should NASA have all of the extra-terrestrial printing fun? Three 15 year-olds thought that same thing and decided to build their own space printer. It’s goal, however, is a bit different from the one on the ISS. This printer is made to print on other celestial bodies such as the moon or Mars, not in a space station. The students call their project the DELTA 3 and as its name implies, is a delta-style printer and that’s where all similarities with conventional printers end. This printer has tank tracks so that it can maneuver itself around the planet. There is no print bed. The printer prints directly to the surface of which it is resting on. The frame is open at the front of the printer so that it can back up leaving a free-standing print in its wake. It certainly beats the hot-glue versions seen before and we think this is the Automated Build Platform of the future, today!

The DELTA 3’s electronic controls are also quite different from the norm. There is a Lego EV3 controller that is responsible for navigating the printer around obstacles to find a suitable print area. Once a location has been picked out, the EV3 triggers the standard Arduino Mega/RAMPS combo to coordinate the printing.

The young creators brought their DELTA 3 to the World Robot Olympiad just last month. They came in 4th in their division.

[via 3Dprint.com]

 

 

E-Waste Printer Looks Nice, Prints Really, Really Small

Prices of 3D Printers have certainly been falling quite a bit over the last few years. Even so, it is still, at a minimum, a few hundred dollars to get going in the hobby. [mikelllc] thought it would be a fun challenge to see if he can build a functional 3D printer for under $100.

To stay under his budget, [mikelllc] took a reasonable route and decided to use as many recycled parts as he could. In every DVD and floppy drive, there is a stepper motor, lead screw and carriage that is used to move the read/write head of the drive. These assemblies will be used to drive the 3 axes of the printer. Two DVD drives and one floppy drive were dissembled to access the needed components.

e-waste small 3d printerLuckily [mikelllc] has access to a laser cutter. He made the frame from 5mm acrylic sheet stock. All of the pieces have slots and tabs to ease assembly and keep everything straight and square. The motors and frames from the DVD and floppy drives are mounted to the acrylic frame pieces in strategically pre-planned holes. The Y axis is responsible for moving the print bed back and forth. It is mounted on screws so that it can be adjusted to ensure a level bed.

A little DVD drive stepper motor just isn’t powerful enough to be used as an extruder motor so a standard NEMA17 motor was purchased for this task. The motor is part of a MK7/MK8 style direct drive extruder that is made from mostly 3D printed parts. The extruder is mounted on the frame and a bowden tube guides the filament to the hot end mounted to the printer’s moving carriage. Remotely mounting the extruder motor keeps it’s mass off of the axes, which in this case may be too heavy for the small, scavenged drive stepper motors.

The electronics are standard RepRap type and the same with for the hotend. The recycled motors work well with the RepRap electronics. After all that hard work, the printable area is a mere 37mm x 37mm x 18mm, but that’s not the point of this project! [mikelllc] met his goal of building a super cheap printer from recycled parts. He has also made the extruder and laser cut frame files available for download so anyone can follow in his footsteps. If you’re digging this e-waste 3D Printer but want a larger print volume, check out this printer.

 

Ester, The Open Source SLS Printer

Filament printers are here to stay, and in the past year there have been a number of SLA and DLP resin printers that can create objects at mind-boggling high resolutions. Both of these technologies have their place, but printing really complex objects without also printing supports is out of the question.

[Brandon] has been working to create an open source printer using a different technology, selective laser sintering. That’s a laser melting tiny particles of stuff to create an object. This printer can work with any material that can be turned into a powder and melted by a laser, and also has the neat bonus of printing without any supports.

[Brandon]’s printer, Ester, uses small meltable polyester dust as both a print material and support structure. The object to be printed is created by shining a laser over a bed filled with polyester, drawing one layer, and putting another small layer of material over the previous layer.

The machine is using a diode laser, with a few experiments with a 1 Watt diode providing some very nice parts. The mechanics of the machine were built at [Brandon]’s local TechShop, and already he has an IndieGoGo for future development and a $3000 development kit. That’s a bit expensive as far as project printers go, but SLS is an expensive technology to get right; ‘pro’ SLS printers are in the hundreds of thousands of dollars.

Solar Powered Circuit Waters Your Plants

 

If you want your plants to stay healthy, you need to make sure they stay watered. [Dimbit] decided to build his own solar powered circuit to help automatically keep his plants healthy. Like many things, there is more than one way to skin this cat. [Dimbit] had seen other similar projects before, but he wanted to make his smarter than the average watering project. He also wanted it to use very little energy.

[Dimbit] first tackled the power supply. He suspected he wouldn’t need much more than 5V for his project. He was able to build his own solar power supply by using four off-the-shelf solar garden lamps. These lamps each have their own low quality solar panel and AAA NiMH cell. [Dimbit] designed and 3D printed his own plastic stand to hold all of the solar cells in place. All of the cells and batteries are connected in series to increase the voltage.

Next [Dimbit] needed an electronically controllable water valve. He looked around but was unable to find anything readily available that would work with very little energy. He tried all different combinations of custom parts and off-the-shelf parts but just couldn’t make something with a perfect seal. The solution came from an unlikely source.

One day, when [Dimbit] ran out of laundry detergent, he noticed that the detergent bottle cap had a perfect hole that should be sealable with a steel ball bearing. He then designed his own electromagnet using a bolt, some magnet wire, and a custom 3D printed housing. This all fit together with the detergent cap to make a functional low power water valve.

The actual circuit runs on a Microchip PIC microcontroller. The system is designed to sleep for approximately nine minutes at a time. After the sleep cycle, it wakes up and tests a probe that sits in the soil. If the resistance is low enough, the PIC knows that the plants need water. It then opens the custom valve to release about two teaspoons of water from a gravity-fed system. After a few cycles, even very dry soil can reach the correct moisture level. Be sure to watch the video of the functioning system below. Continue reading “Solar Powered Circuit Waters Your Plants”