Fail Of The Week: Casting A Bolt In A 3D-Printed Mold

Here’s a weird topic as a Fail of the Week. [Pete Prodoehl] set out to make a bolt the wrong way just to see if he could. Good for you [Pete]! This is a great way to learn non-obvious lessons and a wonderful conversation starter which is why we’re featuring it here.

The project starts off great with a model of the bolt being drawn up in OpenSCAD. That’s used to create a void in a block which then becomes two parts with pegs that index the two halves perfectly. Now it’s time to do the casting process and this is where it goes off the rail. [Pete] didn’t have any flexible filament on hand, nor did he have proper mold release compound. Considering those limitations, he still did pretty well, arriving at the plaster bold seen above after a nice coat of red spray paint.

One side of the mold didn’t make it

He lost part of the threads getting the two molds apart, and then needed to sacrifice one half of the mold to extract the thoroughly stuck casting. We’ve seen quite a bit of 3D printed molds here, but they are usually not directly printed. For instance, here’s a beautiful mold for casting metal but it was made using traditional silicon to create molds of the 3D printed prototype.

Thinking back on it, directly 3D printed molds are often sacrificial. This method of pewter casting is a great example. It turns out gorgeous and detailed parts from resin molds that can stand up to the heat but must be destroyed to remove the parts.

So we put it to you: Has anyone out there perfected a method of reusable 3D printed molds? What printing process and materials do you use? How about release agents — we have a guide on resin casting the extols the virtues of release agent but doesn’t have any DIY alternatives. What has worked as a release agent for you? Let us know in the comments below.

When Stirling Engines Meet 3D Printers

Let’s face it, everybody wants to build a Stirling engine. They’re refined, and generally awesome. They’re also a rather involved fabrication project which is why you don’t see a lot of them around.

This doesn’t remove all of the complexity, but by following this example 3D printing a Sterling engine is just about half possible. This one uses 3D printing for the frame, mounting brackets, and flywheel. That wheel gets most of its mass from a set of metal nuts placed around the wheel. This simple proof-of-concept using a candle is shown off in the video after the break, where it also gets an upgrade to an integrated butane flame.

Stirling engines operate on heat, making printed plastic parts a no-go for some aspects of the build. But the non-printed parts in this design are some of the simplest we’ve seen, comprising a glass syringe, a glass cylinder, and silicone tubing to connect them both. The push-pull of the cylinder and syringe are alternating movements caused by heat of air from a candle flame, and natural cooling of the air as it moves away via the tubing.

We’d say this one falls just above mid-way on the excellence scale of these engines (and that’s great considering how approachable it is). On the elite side of things, here’s a 16-cylinder work of art. The other end of the scale may not look as beautiful, but there’s nothing that puts a bigger smile on our faces than clever builds using nothing but junk.

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Up, Up, Up: $2,000 More Seed Funding for Hackaday Prize Entries

Getting a project off the ground often means an up-front investment in parts. Hackaday is upping our efforts to smooth out that obstacle for those who want to Build Something That Matters. Seed funding for the 2018 Hackaday Prize is simple, enter your Open Hardware design, share it far and wide so that a lot of people will show their admiration with a ‘like’ on the project page. If you’re in the Prize competition, you get a dollar for each like to help jump-start the build phase. If you haven’t entered, you get to encourage and reward the projects that inspire you most.

This year has started off like a rocket. We’ve already passed the $4,000 seed funding limit and you still have until a week from Monday to take part in this seed funding. With so much excitement around this first challenge, Supplyframe, Hackaday’s parent company, is raising the pot to a total of $6,000. That means there’s more up for grabs. Enter your project now. If you’ve already done that, polish up your presentation and show it around to your friends and on social media. Entries with the most likes will get a dollar for every like up to $200 max, or until we undoubtedly reach the new limit once again. Don’t delay, it’s time to Build Something that Matters!

Seed funding is a big deal as we found out with Alex Williams, the 2018 Grand Prize Winner. He mentioned that the money really helped him with early build costs, and the interest from the community inspired him to keep up development throughout the contest. Help us give away this extra funding and inspire the next generation of finalists by commenting on and upvoting great entries!

Dublin Knows How to Bring-a-Hack

When on the road, we love to stop by a local hackerspace and connect with the hacker community. On Friday, TOG Hackerspace in Dublin, Ireland opened their doors to host a Bring-a-Hack with Hackaday and Tindie.

The city center of Dublin is anything but a grid. The cobblestone roads meander every which way and are a puzzle of one-way and surprise construction, none of which seemed to faze Google’s navigation algorithms. I was happy to be operating the smartphone instead of the rental vehicle. A big thanks goes to Jenny List for taking on the stress of driving on our refreshments run without coming in contact with people or cars.

You’re likely wondering why the street layout of the city deserves such attention. I’m used to centrally-located Hackerspaces being tight on space, and indeed the members of TOG cautioned us that 50 people would feel cramped. Much the opposite, the pubs, restaurants, hotels, and performing arts centers are not small, nor winding, nor made of cobblestones. Dublin is a fantastic place to party, with plenty of space for us hardware geeks to congregate. TOG itself, which about 20 minutes walk from the central Temple Bar area (where this image was taken), even has a small parking lot which made our beer drop off and pizza delivery a breeze.

A Tour of TOG Hackerspace

TOG is a Gaelic word which loosely translates as “to make”. Declan met us for the beer drop and gave us a tour when we returned for the evening event. The building is divided into several different spaces, starting with an entry area that serves as a meeting space, gaming room, and showcase of projects.

Where you might see prayer flags strung up on an apartment building, we see floppy disks (both the hard and soft variety) strung around the meeting area. Declan has a shamrock of K’nex parts wired up with a microphone controlled RGB LED strip — it’s like a test your strength game to see who can shout the coolest colors.

I also really enjoyed the fabric anatomy display that has snaps on each organ and only lights up the labels if you complete the circuits in the correct locations.

These are just the tip of the iceberg. There’s much more after the break so join me for the rest of the tour, and some of the notable hacks that showed up on Friday evening.

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Ask Hackaday: Is Your Clock Tied to Mains Frequency?

Earlier in March we heard about a quirk of the interconnected continental European electricity grid which caused clocks to lose about six minutes so far this year. This was due to a slight dip in the mains frequency. That dip didn’t put anything out of commission, but clocks that are designed to accumulate the total zero-crossings of the power grid frequency of 50 Hz don’t keep accurate time when that frequency is, say 49.985 Hz for an extended period of time.

An interesting set of conversations popped up from that topic. There were several claims that modern alarm clocks, and most devices connected to mains, no longer get their clock timing from mains frequency. I’ve looked into this a bit which I’ll go into below. But what we really want to know is: are your alarm clocks and other devices keeping time with the grid or with something else?

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We’re Making it Rain Achievements This Year

We just dished out the first round of achievements to a bunch of hardware projects and there’s a lot more to come.

You may have missed it in all the fanfare last week, so today we take a closer look. Achievements are the newest edition to the Hackaday Prize and we’re really excited about them! With so much creativity in the projects we see entered, these achievements recognize a range of different aspects from serious to lighthearted, and even the downright absurd. There can be only 20 finalists in each challenge of the Prize, but there can be dozens of projects that unlock each achievement.

Today we’re taking a look at three of the achievements: Voltron, Pickle Rick, and the League of Extraordinary Cyborgs. You can also pursue the current list of achievements for an idea of what they’re all about.

Voltron Achievement

The five projects that have unlocked the Voltron Achievement aren’t about defending the universe (but if that’s what you’re doing, cool!). What we’re looking for is many things coming together to be greater than the whole. Two great examples are the Hexabitz project which is an edge-soldered modular PCB system, and a project that envisions swarm robotics for construction, inspection, and maintenance.

Pickle Rick Achievement

Does this need explaining? If your brain skips a cycle and your lips utter a halting “What?!” then you’ve unlocked the Pickle Rick Achievement. These are the out-of-the-ordinary hacks borne of the because-I-can mentality and we love them. The first two projects in this group are a neon 7-segment display (complete with bulky toggle switches and mechanical relays) and a robot snake that transforms into a robot car. What?!

League of Extraordinary Cyborgs Achievement

It’s dangerous to go alone. OK, maybe it’s not, but you can get a lot more done as a close-knit team! We’re looking for team entries, which is how you unlock the League of Extraordinary Cyborgs Achievement.

Unlocks and the Achievements We Forgot

These achievements are easy to unlock. Your project needs to be a Hackaday Prize entry, and meet the achievement criteria. They don’t come with a cash prize (and don’t affect your chances of winning one). Achievements are a tip of the hat to the hackers who are passionate about the hardware they’re building.

We’ll be digging through entries, awarding these as we go, but of course we would love your help. When you see projects perfect for an achievement, leave a comment on that page with your support. You can also send a Hackaday.io message to Stephen Tranovich, Technical Community Leader at Hackaday.io and the person most on the lookout for awarding achievements, requesting an achievement unlock.

The currently displayed list doesn’t include all of the achievements. Some of them are secret (we’ll tell you when we start awarding those). We will be adding more along the way. If an idea for an interesting achievement pops into your mind, let us know in the comments below and we might add it!

Hackaday’s Irish Excursion is on 7 April

Try something a bit out of the ordinary with us on 7 April. Spend a Saturday with Hackaday in Dublin without really knowing what to expect. This is the Unconference format, and we’ve fallen in love with the spontaneity and consistently fascinating talks that come out of it.

We’ve booked a fantastic hall in the Temple Bar district of Dublin, lined up snacks throughout the day and dinner for all who attend, plus there’s an after bar and we’ll buy the first round. All of this is yours if you grab one of the rapidly disappearing free tickets.

What we ask of you is to come prepared to give a 7 minute talk on something you’re really excited about right now. This is low-pressure; the point of an Unconference is to learn about what people are working on right now (not to see a 40 minute talk that was polished over several months). There will not be enough time for absolutely everyone to speak but we’ll get through as many as we can and make sure there’s an interesting mash-up of topics throughout the day.

To break the ice, we have a few “ringers” who we’ve asked to lead off each talk session. Beth ‘pidge’ Flanagan is an embedded and Linux expert who is well-known for her work on OpenEmbedded and Yocto and will talk about “how the sausage is made” specifically surrounding some advance metering infrastructure. Rachel “Konichiwakitty” will be speaking. Rachel was at our London Unconference back in September and we’re excited to hear about the stem cell research she’s been doing as part of her Ph.D. work. James Twomey will be on hand to go into some of the craft of stage magic, and also talk about what we can learn from the battery-free magic of crystal set radios like the “foxhole” radios built during WWII.

DesignSpark LogoThere are already enough people to pack the place and we only have about 20 tickets left, so hurry up and grab yours.

This event is made possible, free of charge to the attendees, with generous support from DesignSpark, the innovation arm of RS Components. DesignSpark is the exclusive sponsor of the Hackaday Dublin Unconference.