Creating Lookalike Valves With Resin Casting

Valves (tubes) certainly have a die hard fan base in the electronic community, praised for their warm sound, desirable distortion characteristics and attractive aesthetic. However, sometimes you just want the look of a valve for a prop or a toy, without actually needing the functionality. For those cases, this project from [Ajaxjones] might be just the ticket.

The build consists of taking an existing valve, combining it with a 3D printed base, and using this to create a silicone mould. 3D printed parts and dressmaker’s pins are then used to create the internal parts of the valve, and are inserted into the mould. Clear resin is then degassed, and poured into the mould to create the part. Once cured, the part is removed and the base painted to complete the look. An LED is then installed into a void in the base to give the piece a warm glow as you’d expect.

It’s a simple tutorial to producing high-quality clear plastic parts, and one that should prove useful to many prop builders and cosplayers alike. If you’re wanting to take your resin game to the next level, consider trying some overmolded parts. Video after the break.

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Stereolithography Goes Big

When it comes to hobby-level 3D printing, most of us use plastic filament deposited by a hot end. Nearly all the rest are using stereolithography — projecting light into a photosensitive resin. Filament printers have typical build volumes ranging from 1,000 to 10,000 cubic centimeters and even larger isn’t unusual. By contrast, SLA printers are often much smaller. A 1,200 CC SLA printer is typical and the cheaper printers are sometimes as little as 800 CCs. Perhaps that’s why [3D Printing Nerd] (otherwise known as [Joel]) was excited to get his hands on a Peopoly Phenom which has a build area of over 17,000 CCs. You can see the video review, below.

He claims that it is even bigger than a Formilab 3L, although by our math that has a build volume of around 20,000 CCs. On the other hand, the longest dimension on the Peopoly is 40 cm which is 6.5 cm longer than the 3L, so maybe that’s what he means. Either way, the printer is huge. That’s nearly 16 inches which is big even for a filament printer. Regardless of which one is bigger, the Peopoly is certainly much less expensive coming in at around $1,800 versus the 3L’s almost $10,000 price tag.

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When Does Moving To Resin 3D Printing Make Sense?

An Elegoo Mars DLP resin 3D printer, straight to my doorstep for a few hundred bucks. What a time to be alive.

Resin-based 3D printers using stereolithography (SLA) and especially digital light processing (DLP) are getting more common and much more affordable. Prosumer-level options like Formlabs and the Prusa SL1 exist, but more economical printers like the Elegoo Mars, Anycubic Photon, and more can be had for a few hundred bucks. Many printers and resin types can even be ordered directly from Amazon, right at this moment.

Resin prints can look fantastic, so when does it make sense to move to one of these cheap DLP printers? To know that, consider the following things:

  • The printing process and output of resin printers is not the same as for filament-based printers. Design considerations, pre-processing, and post-processing are very different.
  • Resin printing has a different workflow, with consumables and hidden costs beyond the price of resin refills.

Things may not be quite where fused deposition modeling (FDM) printers were just a few short years ago when we were extremely impressed with the quality of printer one could get for about $200, but it is undoubtedly far more accessible than ever before. Let’s look at how to inform a decision about whether to take the plunge. Continue reading “When Does Moving To Resin 3D Printing Make Sense?”

Resin Printers Are Now Cheaper, Still Kind Of A Hassle

Your run-of-the-mill desktop 3D printer is based on a technology known as Fused Deposition Modeling (FDM), where the machine squirts out layers of hot plastic that stick to each other. But that’s not the only way to print a Benchy. One of the more exotic alternative techniques uses a photosensitive resin that gets hardened layer by layer. The results are impressive, but historically the printers have been very expensive.

But it looks like that’s finally about to change. The [3D Printing Nerd] recently did a review of the Longer3D Orange 10 which costs about $230, less than many FDM printers. It isn’t alone, either. Monoprice has a $200 resin printer, assuming you can find it in stock.

The resin isn’t cheap and it’s harder to handle than filament. Why is it harder to handle? For one is smells, but more importantly, you aren’t supposed to get it on your skin. The trade off is that the resulting printed parts look fantastic, with fine detail that isn’t readily possible with traditional 3D printing techniques.

Some resin printers use a laser to cure resin at particular coordinates. This printer uses an LCD to produce an image that creates each layer. Because the LCD exposes all the resin at one time, each layer takes a fixed amount of time no matter how big or detailed the layer is. Unfortunately, using these displays means the build area isn’t very large: the manufacturer says it’s 98 by 55 millimeters with a height of up to 140mm. The claimed resolution, though, is 10 microns on the Z-axis and 115 microns on the LCD surface.

Getting the prints out of the printer requires you to remove the uncured resin. In the video, they used a playing card and two alcohol baths. After you remove the uncured resin, you’ll want to do a final curing step. More expensive printers have dedicated curing stations but on this budget printer, you have to cure the parts separately. How? By leaving them out in the sun. Presumably, you could use any suitable UV light source.

There are a few other similar-priced options out there. Sparkmaker, Wanhao (resold by Monoprice). If you’re willing to spend more, Prusa has even thrown their orange hat into the ring. If you were wondering if you could use the LCD in your phone to do this, the answer is sort of.

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Making Flexible Overmolded Parts With Urethane Resin

Resin casting videos have taken social media by storm of late. Everything from inlaid driftwood tables to fancy pens are getting the treatment. Pouring some nicely colored epoxy is straightforward enough, but it’s just the tip of the iceberg. [Eric Strebel] has some serious skills in resin casting, and has lately been working on some overmolded electroniics with urethane resin (Youtube link, embedded below).

The build starts with the creation of a silicone mold, using a 3D printed SLA master. The part in question is for a prototype medical device, and requires overmolding, in which a flexible PCB is covered in flexible urethane. Wooden pins are used to allow the flexible PCB to clip into the mold for accurate location, and a small shield is placed over the metal contacts of the PCB to avoid them being covered in silicone.

Initial tests are done with an empty mold to determine the correct material to use, before the actual parts are ready to produce. [Eric] takes great care with the final production, as any mistakes would waste the expensive prototype PCBs provided to him by the client. With the electronics placed in the mold, the resin is degassed and carefully injected, using a syringe to minimise the chance of any air bubbles. With some delicate cleanup by hand, the completed parts are ready for delivery.

It’s a process that covers the basics of overmolding for a prototype part, as well as showing off [Eric]’s skill at producing quality prototype parts. We’ve seen [Eric]’s work before, too – like his discussion of the value of cardboard in product design. Video after the break.

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Epoxy LED Cube Looks Sleek, And Flashes To The Beat

If there’s one thing that’s universally popular in these polarizing times, it’s colorful glowing objects. LEDs reign supreme in this area, and we’re accustomed to seeing all manner of fun flashy devices hit the tips line. Today is no different, and we’ve been looking at [Modustrial Maker]’s stylish epoxy LED cube.

The build starts with the casting of a black epoxy cube, with a cutout near the top in which the LEDs will be installed. A melamine form is used, with aluminium foil tape, caulk and paste wax to help seal it up. After releasing the cast from the form, there were some unsightly voids which were swiftly dispatched, by trimming the block down with a table saw. With the block cut to size, LED strips were installed, and the light cavity sealed with hot glue before white epoxy was poured in as a diffuser. All that’s left was a simple matter of polishing the cube and installing electronics.

The cube runs from a single-cell LiPo battery, and there’s a wireless power receiver and charging module to keep the power flowing. The cube can be used on most wireless phone chargers, as well as its own dedicated charging base. The LEDs are controlled by an off-the-shelf module, which offers a variety of flashing displays as well as a music-reactive mode.

While the electronics side is done with off-the-shelf parts, the real art in this piece is in the build of the cube. Its glossy, attractive form would look stunning on any coffee table or bedside shelf.

LED cubes are a great rabbit hole to go down on your lunch break. This OpenGL-enabled build is particularly impressive. Video after the break.

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Transparent And Flexible Circuits

German researchers have a line on 3D printed circuitry, but with a twist. Using silver nanowires and a polymer, they’ve created flexible and transparent circuits. Nanowires in this context are only 20 nanometers long and only a few nanometers thick. The research hopes to print things like LEDs and solar cells.

Of course, nothing is perfect. The material has a sheet resistance as low as 13Ω/sq and the optical transmission was as high as 90%. That sounds good until you remember the sheet resistance of copper foil on a PCB is about 0.0005Ω.

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