Hackaday Podcast 045: Raspberry Pi Bug, Rapidly Aging Vodka, Raining On The Cloud, And This Wasn’t A Supercon Episode

Hackaday editors Mike Szczys and Elliot Williams talk over the last three weeks full of hacks. Our first “back to normal” podcast after Supercon turns out to still have a lot of Supercon references in it. We discuss Raspberry Pi 4’s HDMI interfering with its WiFi, learn the differences between CoreXY/Delta/Cartesian printers, sip on Whiskey aged in an ultrasonic jewelry cleaner, and set up cloud printing that’s already scheduled for the chopping block. Along the way, you’ll hear hints of what happened at Supercon, from the definitive guide to designing LEDs for iron-clad performance to the projects people hauled along with them.

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

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Core XY Explained

If you are building a CNC machine, a 3D printer, or even a plotter, you have a need for motion in both the X and Y directions. There are many ways to accomplish this, for example, some printers move the tool in the X direction and the bed in the Y direction while others move the entire X carriage in the Y direction and yet more use a delta mechanism. However, one of the oldest means of doing this is the Core XY method. It is interesting because both motors remain stationary and the business end moves entirely on belts or cords. This is similar to the H-Bot technique, but with some differences. [Michael Laws] has a video (see below) that explains how two stationary motors can move a tool anywhere in an XY region.

The idea behind Core XY goes back to at least old drafting tables. You can think of it as an object held by two ends of the same belt. As one end of the belt gets shorter the other end gets longer. The belts are arranged so that motion of one motor causes the tool to move at a 45 degree angle. That means you have to move both motors to go in a straight line.

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Watch A 3D Printer Get Designed From The Ground Up

Too often when you see a build video, you only get to see the final product. Even if there’s footage of the build itself, it’s usually only the highlights as a major component is completed. But thankfully that’s not the case with the “V-Baby” CoreXY 3D printer that [Roy Berntsen] has been working on.

Watching through his playlist of videos, you’re able to see him tackle his various design goals. For example he’d like the final design to be both machinable and printable, which is possible, but it certainly adds complexity and time. He also transitions from a triangular base to a rectangular one at some point. These decisions, and the reasons behind them, are all documented and discussed.

Towards the end of the series we can see the final testing and torturing process as he ramps up to a final design release. This should definitely demystify the process for anyone attempting their first 3D printer design from scratch.

X-Printer Fits In A Backpack

3D printers are great for rapid prototyping, but they’re not usually what you’d call… portable. For [Malte Schrader], that simply wouldn’t do – thus, the X-printer was born!

The X-printer is a fused-deposition printer built around a CoreXY design. Its party piece is its folding concertina-style Z-axis, which allows the printer to have a build volume of 160x220x150mm, while measuring just 300x330x105mm when folded. That’s small enough to fit in a backpack!

Getting the folding mechanism to work took some extra effort, with the non-linear Z-axis requiring special attention in the firmware. The printer runs Marlin 1, chosen for its faster compile time over Marlin 2. Other design choices are made with an eye to ruggedness. The aluminium frame isn’t as light as it could be, but adds much needed rigidity and strength. We’d love to see a custom case that you could slide the printer into so it would be protected while stowed.

It’s a build that shows there’s still plenty to be gained from homebrewing your own printer, even in the face of unprecedented options on the market today. We’ve seen other unique takes on the portable printer concept before, too. Video after the break.

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Classy CoreXY Build Breaks Down The Design Pinchpoints

Ever since [Ilan Moyer] published the design, CoreXYs have been exploding in the homebrew 3D Printer community. Nevertheless, not all designs are created equal, and a solid design means adhering to some unspoken constraints. Fear not, though. [Mark Rehorst’s] blog post pulls the lid off these constraints and puts them up-front-and-center.  For anyone looking to succeed with their own CoreXY build, this thoughtful critique will keep us away from stray design paths.

[Mark’s] blogpost centers around the xy-stage of his UMMD printer. Here, he walks through the constraints of where belts should be located to guarantee dimensional accuracy of parts. Engineering doesn’t always result in designing the parts ourselves, but rather picking them from a list of options. This geometry-constraint breakdown gives us a more acute set of eyes the next time we pick a CoreXY frame to download and clone off of a place like Thingiverse.

What’s more, for all the antagonizing forces acting on our xy-stage like thermal expansion and frame flexing, [Mark] comes in with a countermeasure. Belts are thickened. Moving stages are constrained correctly, and pulley blocks are reinforced for a stage that is both precise and accurate. Given that it’s so easy to get another printer to start producing parts, lessons learned here will guide us on what underlying measures they need to counteract for a successful print stage.

It’s hard not to love [Mark Rehorst’s] foray into at-home printer builds. Not only do we see new ideas that constantly reinvent how we design printers, each build comes bundled with a wealth of tips and drawbacks. [Mark] gives us a tested design and a critical set of eyes on it that better helps us explore the space if we so choose. For more thoughtful additions to your next 3D printer, check out [Mark’s] CPAP-style remote cooling fan and belt-driven z axis.

Sexiest Tiny Metal Core-XY 3D Printer

That’s a lot of qualifications, but we’re pretty sure that you can’t accuse us of hyperbole in the title: this is one of the tightest little 3D printer builds we’ve ever seen. Add in the slightly esoteric CoreXY kinematics and the thick aluminum frame, and it’s a speed demon in addition to being a looker.

[René] had built a few 3D printers before, so he had a good feel for the parameters and design tradeoffs before he embarked on the DICE project. Making a small print volume, for instance, means that the frame can be smaller and thus exponentially more rigid. This means that it’s capable of very fast movements — 833 mm/s is no joke! It also looks to make very precise little prints. What could make it even more awesome? Water-cooled stepper motors, magnetic interchangeable printheads, and in-built lighting.

The build looks amazing, and there is video documentation of the whole thing on [René]’s site, including a full bill of materials and designs. It’s certainly not the cheapest 3D printer we’ve ever seen, and the tiny build platform makes it a bad choice for a general-purpose machine, but if you need a second printer and you want one with style, the DICE looks hard to beat.

Thanks [Laimonus Mockus] for the tip!

Design Analysis: Core XY Vs H-Bot

Hackaday writer [Joshua Vasquez] wrote about the mechanical difference between the Core-XY and H-Bot movements commonly used in 3D printers on his personal website. There are so many things a beginning mechanical designer can overlook when setting out to make a movement. Sometimes,in the case of these movements, they aren’t readily apparent, and like finding a troublesome pattern in code; have to be shown before the mind picks them up in future designs.

[Joshua] starts by describing how each movement works. At first glance, the H-Bot movement seems simpler and more effective than the Core-XY.  The Core-XY uses more belting, and some of the pulleys are out of plane with each other. However, this is done to eliminate a moment put on the frame in the H-Bot design. This moment can throw off the accuracy of the movement in unpredictable ways.

The Core-XY movement is one of our favorites. It keeps the motors stationary. It’s compact, precise, repeatable, and linear. It’s good to understand the mechanical reasons for this. Just like learning the SQL database calls a library has been obfuscating for you lets you write better code.