3D Print Springs With Hacked GCode

November 14, 2018 by Tom Nardi 36 Comments

If you’ve used a desktop 3D printer in the past, you’re almost certainly done battle with “strings”. These are the wispy bits of filament that harden in the air, usually as the printer’s nozzle moves quickly between points in open air. Depending on the severity and the material you’re printing with, these stringy interlopers can range from being an unsightly annoyance to triggering a heartbreaking failed print. But where most see an annoying reality of pushing melted plastic around, [Adam Kumpf] of Makefast Workshop sees inspiration.

Noticing that the nozzle of their printer left strings behind, [Adam] wondered if it would be possible to induce these mid-air printing artifacts on demand. Even better, would it be possible to tame them into producing a useful object? As it turns out it is, and now we’ve got the web-based tool to prove it.

As [Adam] explains, you can’t just load up a 3D model of a spring in your normal slicer and expect your printer to churn out a useful object. The software will, as it’s designed to do, recognize the object can’t be printed without extensive support material. Now you could in theory go ahead and print such a spring, but good luck getting the support material out.

The trick is to throw away the traditional slicer entirely, as the layer-by-layer approach simply won’t work here. By manually creating GCode using carefully tuned parameters, [Adam] found it was possible to get the printer to extrude plastic at the precise rate at which the part cooling fan would instantly solidify it. Then it was just a matter of taking that concept and applying it to a slow spiral motion. The end result are functional, albeit not very strong, helical compression springs.

But you don’t have to take their word for it. This research has lead to the creation of an online tool that allows you to plug in the variables for your desired spring (pitch, radius, revolutions, etc), as well as details about your printer such as nozzle diameter and temperature. The result is a custom GCode that (hopefully) will produce the desired spring when loaded up on your printer. We’d love to hear if any readers manage to replicate the effect on their own printers, but we should mention fiddling with your printer’s GCode directly isn’t without its risks: from skipping steps to stripped filament to head crashes.

The results remind us somewhat of the 3D lattice printer we featured a couple of years back, but even that machine didn’t use standard FDM technology. It will be interesting to see what other applications could be found for this particular technique.

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Mastering OpenSCAD Workflow

November 14, 2018 by Tom Nardi 33 Comments

As you may have noticed in our coverage, we’re big fans of OpenSCAD around these parts. The fact that several of the Hackaday writers organically found and started using the parametric CAD package on their own is not only a testament to our carefully cultivated hive mind but also to the type of people it appeals to. Hackers love it because it allows you to model physical objects as if you were writing software: models are expressed in code, and its plain text source files can be managed with tools like git and make. If you’re a real Pinball Wizard you could design objects and export them to STL without ever using a graphical interface.

But as you might expect, with such power comes a considerable learning curve. OpenSCAD devotee [Uri Shaked] recently wrote in to share with us his workflow for designing complex interacting mechanisms, which serves as an excellent primer to the world of parametric design. From animating your models to recreating the “vitamins” of your build, his post contains plenty of tips that can help both new and veteran OpenSCAD users alike.

Perhaps the biggest takeaway from his post is that you should be thinking of your projects as a whole, rather than as individual models. [Uri] recalls his early attempts at designing mechanisms: designing each component individually, printing it out, and only then finding out if it fits together with the other pieces. This method of trial and error is probably familiar to anyone who’s designed their own 3D printed parts — but it’s slow and wastes materials. The alternative, as he explains it, is to design all of the pieces at the same time and “assemble” them virtually. This will allow you to check clearances and fitment without dedicating the time and materials to test it in the real world.

In fact, as [Uri] explains, you’re better off spending your time bringing real-world parts into OpenSCAD. By carefully measuring the hardware components you want to interact with (servos, gears, switches, etc), you can create facsimiles of them to use as a reference in your OpenSCAD project. As time goes on, you can build up your own library of drop-in reference models which will accelerate future designs.

He also spends a little time talking about something that doesn’t seem to be terribly well known even among the OpenSCAD converts: you don’t have to use the built-in editor if you don’t want to. Since OpenSCAD source code files are plain text, you can write them in whatever editor you like. The OpenSCAD model viewer even has an option specifically for this scenario, which will cause it to update the rendered preview as soon as it detects the source has been updated. For [Uri] this means he can create his designs in Visual Studio Code with a constantly updating preview in another window.

If you’re looking for examples of what the parametric capabilities of OpenSCAD can do for you, we’ve got no shortage of excellent examples. From creating customized computer cases to saving time by using mathematically derived components. Our very own [Elliot Williams] even has a write up about that most glorious of OpenSCAD commands: hull().

3D Printering: Blender Tips For Printable Objects

November 14, 2018 by Steven Dufresne 20 Comments

3D models drawn in Blender work great in a computer animated virtual world but don’t always when brought into a slicer for 3D printing. Slicers require something which makes sense in the real world. And the real world is far less forgiving, as I’ve found out with my own projects which use 3D printed parts.

Our [Brian Benchoff] already talked about making parts in Blender with his two-part series (here and here) so consider this the next step. These are the techniques I’ve come up with for preparing parts for 3D printing before handing them off to a slicer program. Note that the same may apply to other mesh-type modeling programs too, but as Blender is the only one I’ve used, please share your experiences with other programs in the comments below.

I’ll be using the latest version of Blender at this time, version 2.79b. My printer is the Crealty CR-10 and my slicer is Cura 3.1.0. Some of these steps may vary depending on your slicer or if you’re using a printing service. For example, Shapeways has instructions for people creating STLs from Blender for uploading to them.

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Friday Hack Chat: All About Crypto

November 14, 2018 by Brian Benchoff 15 Comments

What is crypto? Crypto means ‘hidden’, and it’s meant ‘hidden’ since before the Greek alphabet was written, but don’t let that stop you from arguing. For this week’s Hack Chat, we’re going to be talking all about cryptography, a medium of exchange for secrets. If you need confidentiality, integrity, or authenticity, you need cryptography.

Our guest for this week’s Hack Chat will be none other than Nick Sayer. Nick is a frequent attendee of the Hackaday meetups and he’s been building gadgets and gizmos and selling them on Tindie for years now. He’s given talks on design for manufacturing. This year, he designed and developed the Orthrus, an appliance that creates a cryptographically secured USB volume from two microSD cards. Basically, it’s like the Captain Planet team, only instead of rings, you need all the SD cards, and instead of Captain Planet, you summon your data.

For this week’s Hack Chat, we’re going to sit down with and talk about all things cryptography, including understanding what you need, what you don’t, and picking the correct tools. Items of interest will include:

When cryptography is needed
Cryptography tools
The best practices for cryptography

You are, of course, encouraged to add your own questions to the discussion. You can do that by leaving a comment on the Cryptography Hack Chat and we’ll put that in the queue for the Hack Chat discussion.

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Friday, November 16th, at noon, Pacific time. If time zones got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.

The Value Of Cardboard In Product Design

November 14, 2018 by Brian Benchoff 23 Comments

A while ago, [Eric Strebel] created a backpack hanger. The result was great — by just bolting this backpack hanger to the wall, he kept his backpack off the floor and out of the way. There was even a place for him to set his phone to charge. [Eric] is thinking about turning this idea into a product, and just posted a video on his process of making a cardboard mockup.

Since this is a study in industrial design, any mockup will need to keep in mind how the finished article will be constructed. In this case, [Eric] is going to use 4-5mm thick aluminum, cut on a water jet, bent into place, and finally anodized. The finished product will be made out of bent sheet aluminum, so this little bit of product design will use Matboard — a thick, heavy cardboard often used for mounting pictures in frames. The Matboard will substitute for the aluminum, as it is carefully cut, bent, and glued into shape.

The tools for this build are simple, just a hobby knife, razor blade, ruler, and a pen. But there are a few tricks to working with Matboard. To bend these pieces perfectly, [Eric] is painting one side with water. This loosens the fibers in the Matboard, allowing for perfect creases before one layer of the build is glued together.

Once a few layers of this Matboard are glued together, the finished product becomes less like cardboard and more like a very soft wood. This allows [Eric] to use belt sanders and countersink drill bits to give a little bit of polish to this one-off prototype. This finished article works great, and now [Eric] is looking at taking this idea into production.

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Hack My House: Opening Raspberry Pi To The Internet, But Not The Whole World

November 14, 2018 by Jonathan Bennett 29 Comments

If you’ve followed along with our series so far, you know we’ve set up a network of Raspberry Pis that PXE boot off a central server, and then used Zoneminder to run a network of IP cameras. Now that some useful services are running in our smart house, how do we access those services when away from home, and how do we keep the rest of the world from spying on our cameras?

Before we get to VPNs and port forwarding, there is a more fundamental issue: Do you trust your devices? What exactly is the firmware on those cheap cameras really doing? You could use Wireshark and a smart switch with port mirroring to audit the camera’s traffic. How much traffic would you need to inspect to feel confident the camera never sends your data off somewhere else?

Thankfully, there’s a better way. One of the major features of surveillance software like Zoneminder is that it aggregates the feeds from the cameras. This process also has the effect of proxying the video feeds: We don’t connect directly to the cameras in order to view them, we connect to the surveillance software. If you don’t completely trust those cameras, then don’t give them internet access. You can make the cameras a physically separate network, only connected to the surveillance machine, or just set their IP addresses manually, and don’t fill in the default route or DNS. Whichever way you set it up, the goal is the same: let your surveillance software talk to the cameras, but don’t let the cameras talk to the outside world.

Edit: As has been pointed out in the comments, leaving off a default route is significantly less effective than separate networks. A truly malicious peice of hardware could easily probe for the gateway.

This idea applies to more than cameras. Any device that doesn’t need internet access to function, can be isolated in this way. While this could be considered paranoia, I consider it simple good practice. Join me after the break to discuss port forwarding vs. VPNs.

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Memory Mapping Methods In The Super Nintendo

November 14, 2018 by Bryan Cockfield 6 Comments

Not only is the Super Nintendo an all-around great platform, both during its prime in the 90s and now during the nostalgia craze, but its relative simplicity compared to modern systems makes it a lot more accessible from a computer science point-of-view. That means that we can get some in-depth discussion on how the Super Nintendo actually does what it does, and understand most of it, like this video from [Retro Game Mechanics Explained] which goes into an incredible amount of detail on the mechanics of the SNES’s memory system.

Two of the interesting memory systems the SNES uses are called DMA and HDMA. DMA stands for direct memory access, and is a way for the Super Nintendo to access memory independently of the CPU. The advantages to this are that it’s incredibly fast compared to more typical methods of accessing memory. This isn’t particulalry unique, but the HDMA system is. It allows the SNES to do all kinds of interesting tricks with its video output display like changing color gradients and doing all kinds of masking effects.

If you’re interested in the inner workings of classic consoles like the SNES, this video gets way down in the weeds in the system itself. It’s interesting to see how programmers were able to squeeze more capability from these limited (by modern standards) systems by manipulating memory like the DMA and HDMA systems do. [Retro Game Mechanics Explained] is a great resource for exploring in-depth aspects of lots of classic games, like how speedrunners can execute arbitrary code in old Mario games.

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