To Ferrule or Not to Ferrule?

We recently posted about a spectacular 3D-printer fire that was thankfully caught and extinguished before spreading to the hacker’s house or injuring his family. Analyzing the remains of the printer, the hacker determined that the fire was caused when a loose grub screw let the extruder’s heater cartridge fall out and touch the ABS fan shroud. It ran full-on and set things on fire.

A number of us have similar 3D printers, so the comments for this article were understandably lively, but one comment stood out by listing a number of best practices for wiring, including the use of ferrules. In particular, many 3D printers connect the heated bed, which draws a lot of current, with screw terminals to the motherboard. While not the cause of the fire in the original post, melted terminal blocks are a common complaint with many DIY 3D printer kits, and one reason is that simply jamming thick stranded wire into a screw terminal and hoping for the best can result in increased resistance, and heat, at the joint. In such situations, the absolutely right thing to do is to crimp on a ferrule. So let’s talk about that.

 

Continue reading “To Ferrule or Not to Ferrule?”

Mechanisms: Couplings

I was splitting wood one day a few years back, getting next winter’s firewood ready on my hydraulic splitter. It normally handled my ash and oak with ease, but I had a particularly gnarly piece of birch queued up, and the splitter was struggling. The 20-ton cylinder slowed as the wedge jammed in the twisted grain, the engine started to bog down, then BANG! I jumped back as something gave way and the engine revved out of control; I figured a hydraulic hose gave out. Whatever it was, I was done for the day.

I later discovered that a coupler between the engine shaft and the hydraulic pump failed dramatically. It was an easy fix once I ordered the right part, and I’ve since learned to keep extras in stock. Couplings are useful things, and they’re the next up in our series on mechanisms.

Continue reading “Mechanisms: Couplings”

Sensor sleeve makes tablet use easier and benefitial for disabled children

tablet-accessiblity-hack

Pinch-zoom is a godsend (and shouldn’t be patent-able) and although we mourn the loss of a physical keyboard on a lot of device we use a tablet nearly as often as we do a full computer. But the touch screen interface is not open to everyone. Those who lack full dexterity of their digits will find the interface frustrating at best or completely unusable at worst. A team of researchers from the Atlanta Pediatric Device Consortium came up with a way to control touch-screen tablets with a sensor array that mounts on your arm.

The project — called Access4Kids — looks not only to make tablet use possible, but to use it as a means of rehabilitation. The iPad seen above is running a custom app designed for use with the sensor sleeve. The interface is explained in the video after the break. Each sensor can serve as an individual button, but the hardware can also process sequential input from all three as a swipe in one direction or the other. If they can get the kids interested in the game it ends up being its own physical therapy coach by encouraging them to practice their upper body motor skills.

Continue reading “Sensor sleeve makes tablet use easier and benefitial for disabled children”