Stepper motors divide a full rotation into hundreds of discrete steps, which makes them ideal to precisely control movements, be it in cars, robots, 3D printers or CNC machines. Most stepper motors you’ll encounter in DIY projects, 3D printers, and small CNC machines are bi-polar, 2-phase hybrid stepper motors, either with 200 or — in the high-res variant — with 400 steps per revolution. This results in a step angle of 1.8 °, respectively 0.9 °.
In a way, steps are the pixels of motion, and oftentimes, the given, physical resolution isn’t enough. Hard-switching a stepper motor’s coils in full-step mode (wave-drive) causes the motor to jump from one step position to the next, resulting in overshoot, torque ripple, and vibrations. Also, we want to increase the resolution of a stepper motor for more accurate positioning. Modern stepper motor drivers feature microstepping, a driving technique that squeezes arbitrary numbers of microsteps into every single full-step of a stepper motor, which noticeably reduces vibrations and (supposedly) increases the stepper motor’s resolution and accuracy.
On the one hand, microsteps are really steps that a stepper motor can physically execute, even under load. On the other hand, they usually don’t add to the stepper motor’s positioning accuracy. Microstepping is bound to cause confusion. This article is dedicated to clearing that up a bit and — since it’s a very driver dependent matter — I’ll also compare the microstepping capabilities of the commonly used A4988, DRV8825 and TB6560AHQ motor drivers.
The bachelor in question, [drandolph], rightly points out that a $6,000 build that takes up a significant fraction of the floor space in one’s apartment is better attempted without the benefit of spousal oversight. Still, what spouse couldn’t love the finished product? With a custom aluminum extrusion frame (which barely made the trip from China intact) it’s a sturdy affair, and who could deny the appeal of the soft glow of an LED-illuminated work chamber? A custom exhaust system with sound-deadening, a water chiller for laser cooling, an Arduino-controlled status beacon – there’s even a 3-D printed beer holder on the control panel! And think of all the goodies that will come off the enormous bed of this thing. Note to self: make sure wife sees this post.
There are cheaper and smaller laser cutters, but what’s the point if you have the freedom to go big?
The Joint Quantum Institute published a recent paper detailing a quantum computer constructed with five qubits formed from trapped ions. The novel architecture allows the computer to accept programs for multiple algorithms.
Quantum computers make use of qubits and trapped ions–ions confined with an electromagnetic field–are one way to create them. In particular, a linear radio frequency trap and laser cooling traps five ytterbium ions with a separation of about 5 microns. To entangle the qubits, the device uses 50 to 100 laser pulses on individual or pairs of ions. The pulse shape determines the actual function performed, which is how the device is programmable. The operations depend on the sequence of laser pulses that activate it. Continue reading “Ion Trap Makes Programmable Quantum Computer”→
[Scott Harden] is working on a research project involving optogenetics. From what we were able to piece together optogenetics is like this: someone genetically modifies a mouse to have cell behaviors which can activated by light sensitive proteins. The mice then have a frikin’ lasers mounted on their heads, but pointing inwards towards their brains not out towards Mr. Bond’s.
Naturally, to make any guesses about the resulting output behavior from the mouse the input light has to be very controlled and exact. [Scott] had a laser and he had a driver, but he didn’t have a controller to fire the pulses. To make things more difficult, the research was already underway and the controller had to be built
The expensive laser driver had a bizarre output of maybe positive 28 volts or, perhaps, negative 28 volts… at eight amps. It was an industry standard in a very small industry. He didn’t have a really good way to measure or verify this without either destroying his measuring equipment or the laser driver. So he decided to just build a voltage-agnostic input on his controller. As a bonus the opto-isolated input would protect the expensive controller.
The output is handled by an ATtiny85. He admits that a 555 circuit could generate the signal he needed, but to get a precision pulse it was easier to just hook up a microcontroller to a crystal and know that it’s 100% correct. Otherwise he’d have to spend all day with an oscilloscope fiddling with potentiometers. Only a few Hackaday readers relish the thought as a relaxing Sunday afternoon.
He packaged everything in a nice project box. He keeps them on hand to prevent him from building circuits on whatever he can find. Adding some tricks from the ham-radio hobby made the box look very professional. He was pleased and surprised to find that the box worked on his first try.
Laser-cut plywood boxes are cool. Don’t believe me? Take a look at the free projects out there for people to get started with when they get a laser cutter – it’s obviously a popular genre of project. Laser cut plywood boxes with combination locks are even cooler, especially when the combination is entered on four separate number selectors, on four sides of the very same box.
The LaserWeb project recently released version 3, with many new features and improvements ready to give your laser cutter or engraver a serious boost in capabilities! On top of that, new 3-axis CNC support means that the door is open to having LaserWeb do for other CNC tools what it has already done for laser cutting and engraving.
LaserWeb3 supports different controllers and the machines they might be connected to – whether they are home-made systems, CNC frames equipped with laser diode emitters (such as retrofitted 3D printers), or one of those affordable blue-box 40W Chinese lasers with the proprietary controller replaced by something like a SmoothieBoard.
We’ve covered the LaserWeb project in the past but since then a whole lot of new development has been contributed, resulting in better performance with new features (like CNC mode) and a new UI. The newest version includes not only an improved ability to import multiple files and formats into single multi-layered jobs, but also Smoothieware Ethernet support and a job cost estimator. Performance in LaserWeb3 is currently best with Smoothieware, but you can still save and export GCODE to use it with Grbl, Marlin, EMC2, or Mach3.
We recently shared a lot of great information on safe homebrew laser cutter design. Are you making your own laser cutting machine, or retrofitting an existing one? Let us know about it in the comments!
We weren’t going to run this one, because, well, it’s just ridiculous. But enough of you have browbeat us by sending in tips to the tipline that we’re going to capitulate. We’re not going to name you all by name, because really, you should be ashamed of yourselves. But you know who you are!
[Styropyro] does a lot of crazy things on YouTube. We really liked his “stuff in a microwave oven” series. He’s also obsessed with lasers and popping black balloons. So he took the laser heads out of four DLP computer projectors (the ones with 24 of those 1.5W Nichia diodes) and combined them. Yup, 200W of 405 445nm blue.
Then he just straps them together and passes them through a lens. It’s not a tight beam, but this thing is really bright. Even though the beam is very loosely focused, it burns stuff. That’s about all you can say. Lots of laser. Boy Howdy!
OK, there, we ran it. Don’t do this at home. It doesn’t require much finesse, and it’s going to get someone blind. Much better to expend your efforts on something more civilized like a projector. At least then you can play vector games on the wall. And stay off my lawn!!! (Kids these days…)
For those that do want to burn stuff, [Joshua Vasquez] published an article yesterday about building a safe laser cutter… much more worth your energy than anything billed as a laser bazooka.