[thisoldtony] has a nice shop in need of a CNC. We’re not certain what he does exactly, but we think he might be a machinist or an engineer. Regardless, he sure does build a nice CNC. Many home-built CNCs are neat, but lacking. Even popular kits ignore fundamental machine design principles. This is alright for the kind of work they will typically be used for, but it’s nice to see one done right.
Most home-built machines are hard or impossible to square. That is, to make each axis move exactly perpendicular to the others. They also neglect to design for the loads the machine will see, or adjusting for deviation across the whole movement. There’s also bearing pre-loads, backlash, and more to worry about. [thisoldtony] has taken all these into consideration.
The series is a long one, but it is fun to watch and we picked up a few tricks along the way. The resulting CNC is very attractive, and performs well after some tuning. In the final video he builds a stunning rubber band gun for his son. You can also download a STEP file of the machine if you’d like. Videos after the break.
You may think you’ve built a power supply for your bench. Heck, we all do. But until you check out [Denis]’s bench power supply build, you may not even know what you’re missing.
[Denis]’s design is nearly entirely modular and targeted to the intermediate builder. It’s built on easily available parts and through-hole components. It’s got an Arduino running as the brains, so you’re going to be able to hack on the code when you feel like tweaking it. But easy doesn’t mean light on features. Let’s walk through the build together.
It starts off with a pre-regulator: a switching MOSFET that gets the voltage down to just a couple volts above the target value. Then it’s off to the post-regulator that includes all of the fine adjustments, the DAC and ADC interfacing to the microcontroller, and some fancy features like a “down-programmer” that turns the output off extra quickly.
On the user end of things, [Denis] made a very sleek board that incorporates a TFT touchscreen for the controls, Arduino connections, and the obligatory banana plug outputs. There’s opto-isolation on the SPI bus, a real-time clock, and a bunch more goodies on board. He’s in his third revision of this module, and that level of refinement shows. It’s even SCPI compliant, meaning you can control remotely using an industry-standard protocol.
So what would you do with a ridiculously fancy power supply under microcontroller control? Test out battery charging algorithms? Program test routines to see how your devices will work as their batteries drain out? We have no idea, but we know we want one!
I have an old Prusa i2 that, like an old car, has been getting some major part replacements lately after many many hours of service. Recently both the extruder and the extruder motor died. The extruder died of brass fill filament sintering to the inside of the nozzle (always flush your extruder of exotic filaments). The motor died at the wires of constant flexing. Regardless, I replaced the motors and found myself with an issue; the new motor and hotend (junk motor from the junk bin, and an E3D v6, which is fantastic) worked way better and was pushing out too much filament.
The hotend, driver gear, extruder mechanics, back pressure, motor, and plastic type all work together to set how much plastic you can push through the nozzle at once. Even the speed at which the plastic is going through the nozzle can change how much friction that plastic experiences. Most of these effects are somewhat negligible. The printer does, however, have a sort of baseline steps per mm of plastic you can set.
The goal is to have a steps per mm that is exactly matched to how much plastic the printer pushes out. If you say 10mm, 10mm of filament should be eaten by the extruder. This setting is the “steps per mm” in the firmware configuration. This number should be close to perfect. Once it is, you can tune it by setting the “extrusion multiplier” setting in most slicers when you switch materials, or have environmental differences to compensate for.
The problem comes in measuring the filament that is extruded. Filament comes off a spool and is pulled through an imprecisely held nozzle in an imprecisely made extruder assembly. On top of all that, the filament twists and curves. This makes it difficult to hold against a ruler or caliper and get a trustworthy measurement.
I have come up with a little measuring device you can make with some brass tubing, sandpaper, a saw (or pipe cutter), a pencil torch, solder, and some calipers. To start with, find two pieces of tubing. The first’s ID must fit closely with the filament size you use. The second tube must allow the inside tubing to slide inside of it closely. A close fit is essential.
Robots and DIY electronics kits have a long history together. There probably isn’t anyone under the age of forty that hasn’t had some experience with kit-based robots like wall-hugging mouse robots, a weird walking robot on stilts, or something else from the 1987 American Science and Surplus catalog. DIY robot kits are still big business, and walking through the sales booths of any big Maker Faire will show the same ideas reinvented again and again.
[demux] got his hands on what is possibly the worst DIY electronics kit in existence. It’s so incredibly bad that it ends up being extremely educational; pick up one of these ‘introduction to electronics’ kits, and you’ll end up learning advanced concepts like PCB rework, reverse engineering, and Mandarin.
There’s so many ways to skin the home-fabrication-of-PCBs cat! Here’s yet another. [Nuri Erginer] had a DLP projector on hand, and with the addition of some reducing optics, managed to turn it into a one-shot PCB exposer.
If you’ve ever used photo-resist PCB material before, you know the drill: print out your circuit onto transparency film, layer the transparency with the sensitized PCB, expose with a UV light for a while, dissolve away the unexposed resist, and then etch. Here, [Nuri] combines the first three steps in one by exposing the board directly from a DLP projector.
The catch is that the projector’s resolution limits the size of the board that you can make. To fab a board that’s 10cm x 10cm, at XGA resolution (1024×768), you’ll end up with a feature size of around 0.004″ in the good direction and 0.005″ in the other.
For DIP parts, that’s marginal, but for fine-pitch or small SMT parts, that won’t do. On the other hand, for a smaller board, optimally one in the same 4:3 ratio, it could work. And because it exposes in one shot, you can’t beat the speed. Cool hack, [Nuri]!
Heathkit, the storied purveyor of high-quality DIY electronics kits that inspired a generation of enthusiasts and launched the careers of many engineers, has returned from the dead. We think. At least it seems that way from this build log by [Spritle], an early adopter of the rebooted company’s first offering. But if [Spritle]’s experience is any indication, Heathkit has a long way to go to recreating its glory days. Continue reading “Heathkit’s Triumphant Return?”→
My first job out of high school was in a TV shop. I was hired mainly for muscle; this was the early 1980s and we sold a lot of console TVs that always seemed to need to be delivered to the third floor of a walk up. But I also got to do repair work on TVs and stereos, and I loved it. Old TVs from the 60s and 70s would come in, with their pre-PCB construction and hand-wired chassis full of terminal strips and point to point wiring that must have been an absolute nightmare to manufacture. We’d replace dodgy caps, swap out tubes, clean the mechanical tuners, and sometimes put a new picture tube in – always the diagnosis that customers dreaded the most, like being told they’d need a heart transplant. We kept those old sets alive, and our customers felt like they were protecting their investment in their magnificent Admiral or Magnavox console with the genuine – and very, very heavy – walnut cabinet.
I managed to learn a lot from my time as a TV repairman, and I got the bug for keeping things working well past the point which a reasonable person would recognize as the time to go shopping for a new one. Fixing stuff is where I really shine, and my house is full of epic (in my mind, at least) repairs that have saved the family tens of thousands of dollars over the years. Dishwasher making a funny noise? I’ll just pull it out to take a look. You say there’s a little shimmy in the front end when you brake? Pull the car into the garage and we’ll yank the wheels off. There’s basically nothing I won’t at least try to fix, and more often than not, I succeed.
I assumed that my fix-it bug made me part of a dying breed of cheapskates and skinflints, but it appears that I was wrong. The fix-it movement seems to be pretty healthy right now, fueled in part by the explosion in information that’s available to anyone with basic internet skills.