Lessons Learned: Plastic Injection Molding For Products

October 14, 2023 by Donald Papp 19 Comments

Injection molding is one of the technologies that makes the world go round. But what does it actually look like to go through the whole process to get a part made? [Achim Haug] wrote up a blog post that does a fantastic job of explaining what to expect when getting plastic enclosures injection molded in China.

These air quality monitors required a two-part enclosure.

Injection molding a part requires making a custom mold, which is then used by an injection molding machine in a shop to crank out parts. These are two separate jobs, but in China the typical business model is for a supplier to quote a price for both the mold as well as the part production. [Achim] describes not only what navigating that whole process was like, but also goes into detail on what important lessons were learned and shares important tips.

One of the biggest takeaways is to design the part with injection molding in mind right from the start. That means things like avoiding undercuts and changes in part thickness, as well as thinking about where the inevitable mold line will end up.

[Achim] found that hiring a been-there-done-that mold expert as a consultant to review things was a huge help, and well worth the money. As with any serious engineering undertaking, apparently small features or changes can have an outsized impact on costs, and an expert can recognize and navigate those.

In the end, [Achim] says that getting their air quality monitor enclosures injection molded was a great experience and they are very happy with the results, so long as one is willing to put the work in up front. Once the mold has been made, downstream changes can be very costly to make.

[Achim]’s beginning-to-end overview is bound to be useful to anyone looking to actually navigate the process, and we have a few other resources to point you to if you’re curious to learn more. There are basic design concerns to keep in mind when designing parts to make moving to injection molding easier. Some injection molding techniques have even proven useful for 3D printing, such as using crush ribs to accommodate inserted hardware like bearings. Finally, shadow lines can help give an enclosure a consistent look, while helping to conceal mold lines.

Making A Concrete Sign

October 14, 2023 by Jenny List 16 Comments

While paging through the feed a few days ago our attention was caught by something a little away from the ordinary in Hackaday terms, a DIY video about creating cast concrete signage from [Proper DIY] which we’ve placed below the break. A deceptively easy-looking mould-making process has a few tricks that will make the difference between a hard-wearing sign that lasts for years, and a lump of concrete.

So, to make a cast concrete sign, you throw together a mould with some letters, and chuck in some concrete? Not so fast, because the key appears to be preparation, and ensuring that there are no 90-degree corners on the mould parts. The letters are carefully shaped and sealed with varnish before being attached to the mould with silicone adhesive, and all the corners are beveled. Finally a light oil is used as a release agent, and hefty vibration takes care of any air bubbles.

The result is a set of signs, but we can see these techniques finding uses outside signage. For example, how about casting using a 3D printed mould?

Continue reading “Making A Concrete Sign” →

A Buzzing, Flashing Phone Ringer For The Elderly

October 11, 2023 by Kristina Panos 8 Comments

For a lonely person, elderly or otherwise, the sound of a ringing phone can be music to the ears, unless of course it’s another spam call. But what good is a phone when you can’t hear it well enough to answer?

[Giovanni Aggiustatutto] was tasked with building an additional ringer for a set of cordless landline phones belonging to an elderly friend. Rather than try to intercept the signal, [Giovanni] chose to simply mic up the phone base that’s connected to the phone port on the router and send a signal over Wi-Fi to a second box which has a loud piezo buzzer and a handful of LEDs.

At the heart of this build is a pair of ESP8266 Wemos D1 minis and an Arduino sound sensor module inside a pair of really nice-looking 3D printed boxen that may or may not have been inspired by an IKEA air quality sensor. On the receiving side, a green LED indicates the system is working, and the red LEDs flash as soon as a call comes in.

All the code, schematics, and STL files are available for this build, and between the Instructable and the build video after the break, you should have no trouble replicating it for the hard-of-hearing in your life.

Continue reading “A Buzzing, Flashing Phone Ringer For The Elderly” →

Polish Up Your Product With Graphic Overlays

October 8, 2023 by Donald Papp 17 Comments

[Kevin Hunckler] recently did some in-house manufacturing for a product and shared his experiences in adding high-quality custom graphic overlays or acrylic panels to give the finished units a professional look. The results look great and were easy to apply, making his product more attractive without needing much assembly work.

A graphic overlay with transparent areas, a cutout, and adhesive backing to fit an off-the-shelf Hammond enclosure.

Sadly, when doing initial research he was disappointed to find very little information on the whole process. While in the end it isn’t terribly complex, it still involved a lot of trial and error before he zeroed in on what the suppliers in the industry expect. Fortunately, everything can be done with tools most hackers probably already have access to.

The process seems to us somewhat reminiscent of having PCBs manufactured. One defines the product housing, outlines the overlay, creates the artwork, defines an adhesive layer, and makes a design document explaining each layer and important feature. [Kevin] provides examples of his work, one of which fits an off-the-shelf Hammond enclosure.

Professionally-made acrylic panels or graphic overlays is something worth keeping in mind for hobbyists and those who might engage in desktop manufacturing, as long as the costs are acceptable. Rather like PCBs, costs go down as quantities go up. [Kevin]’s 50 mm x 50 mm overlay cost about 1 USD each in quantity 200, but only 0.50 USD each when buying 500.

These may be great for low or middling quantities, but that doesn’t mean one is out of options for prototypes or micro quantities. We have seen fantastic results adding full-color images to 3D prints, and even using a 3D printer to draw labels directly onto prints.

2023 Halloween Hackfest: Treat Trough Of Terror Is Actually Pretty Cute

October 3, 2023 by Kristina Panos 7 Comments

Even though it seems the worst of COVID has passed, October generally kicks off cold and flu season, so why not continue to pass out Halloween treats in a socially-distanced fashion?

That is, of course the idea behind [Gord Payne]’s Halloween Treat Trough of Terror. Lay a treat at the top of the trough and it will activate the LED strips that follow the treat down to the end, as well as some spooky sounds. The treat in question is detected by an SR-04 ultrasonic distance sensor connected to an Arduino Nano.

All in all this was a highly successful build as far as neighborhood entertainment value goes. Toddlers stared in awe at the blinkenlights, teenagers proclaimed it ‘sick’, and we can only assume that the adults were likely happy to see something aimed at kids that’s not scary.

[Gord] has a nice how-to if you want to build your own, and of course, the Arduino sketch is available. Be sure to check it out in action after the break.

Don’t have room to build a treat slide? Here’s a socially-distanced dispenser that lets them stomp a giant button.

Continue reading “2023 Halloween Hackfest: Treat Trough Of Terror Is Actually Pretty Cute” →

These DIY Super Headphones Take Sound Seriously

October 1, 2023 by Donald Papp 23 Comments

[Pete Lewis] from SparkFun takes audio and comfort seriously, and recently shared details on making a customized set of Super Headphones, granting quality sound and stereo ambient passthrough, while providing hearing protection at the same time by isolating the wearer from the environment.

Such products can be purchased off the shelf (usually called some variant of “electronic hearing protection”), but every hacker knows nothing beats some DIY to get exactly the features one wants. After all, off-the-shelf solutions are focused on hearing protection, not sound quality. [Pete] also wanted features like the ability to freely adjust how much ambient sound was mixed in, as well as the ability to integrate a line-level audio source or Bluetooth input.

Early prototype of Super Headphones (click to enlarge)

On the surface the required components are straightforward, but as usual, the devil is in the details. Microphone selection, for example, required a lot of testing. A good microphone needed to be able to deal with extremely loud ambient sounds without distortion, yet still be sensitive enough to be useful. [Pete] found a good solution, but also muses that two sets of microphones (one for loud environments, and one for quieter) might be worth a try.

After several prototypes, the result is headphones that allow safe and loud band practice in a basement as easily as they provide high-quality music and situational awareness while mowing the lawn. Even so, [Pete]’s not done yet. He’s working on improving comfort by using photogrammetry to help design and 3D print custom-fitted components.

Powder Your Prints For Baby-Smoothness

September 24, 2023 by Kristina Panos 46 Comments

Layer lines are a dead giveaway to non-normies that a thing was 3D printed. There are things you can do to smooth them — sanding, chemical smoothing, and fillers come to mind. Although this technique technically uses all three, it starts with something very simple.

In the video after the break, [DaveRig] gets right to the point: baby powder and resin mixed together make a fine smoothing agent when cured. Having read about it online, he decided to give it a try.

Starting with a half sphere that had admittedly pretty big layer lines, [DaveRig] mixed up enough resin and baby powder to make the consistency of milk or cream. Then he put five coats on, curing and sanding with 120 in between each one.

Then it’s on to standard post-processing stuff. You know, wipe it down with alcohol, sand it a little more, wet sand, and then it’s on to the airbrush and clear-coat. The end result looks to be as smooth as your average bowling ball, as you can see in the main photo.

What’s your favorite post-processing method? Have you tried annealing them in salt?

Continue reading “Powder Your Prints For Baby-Smoothness” →