Making Custom Curved Mirrors At Home

Generally speaking, creating custom mirrors is a complex task that involves a lot of careful grinding, and isn’t something to be taken lightly if you need precision results. Just ask the folks who provided NASA with a wonky mirror for the Hubble. But assuming you’re not working on an orbital space telescope (or even a ground based one, for that matter), [volzo] has recently documented some techniques for producing single and double curved mirrors of reasonable quality using common workshop tools.

The first step is finding something that’s a bit easier to work with than glass. After testing various reflective materials such as PVC foil and painted PETG sheets by comparing the reflections of projected test patterns, [volzo] found that laminated polystyrene gave the most accurate results. If you just want to make a simple bent mirror, he shows how you can pop one of these sheets on a CNC router, make the appropriate cuts, and fold them into shape.

That part might seem a bit obvious, but what about a more complex shape? Here, [volzo] points to how the thin sheets of polystyrene also lend themselves to vacuum forming. As demonstrated in the video below, all it takes is a 3D printed plug and some basic equipment to rapidly produce mirrors in arbitrary shapes.

Now obviously the optical properties of such mirrors will leave something to be desired, but depending on your application, that might not be such a big deal. As examples [volzo] shows off a few projects using these custom mirrors, such as a tabletop camera that captures both sides of the table simultaneously and a circular projector. Laminated polystyrene could potentially even be used to create low-cost variable mirrors.

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How To Make A Collapsible Container Without Breaking Down

How hard could it be to make a collapsible silicone container? Turns out, it’s really, really hard — collapsible containers have rigid guidelines. Just ask [Eric Strebel], who failed dozens of times before finally getting it right (video, embedded below).

[Eric] started with an SLA-printed two-part mold and a silicone formulation with a Shore durometer of A 40 — this is the measure of hardness for silicone, polymers, and elastomers in the sense that the piece will resist indentation. The first twenty-four attempts all came out looking great, but not a single one of them would collapse and stay collapsed.

Eventually, [Eric] went back to the drawing board and played with the angles of the flex points, the thickness of the living hinges, and the wall thicknesses, which have to be strong enough to stay collapsed.

For attempt #25, [Eric] took the part out of the mold about three hours in and tried curing it in the collapsed state. Persistence paid off, and the part finally collapses and stays that way. Get yourself some popcorn and check out the fail-fest after the break. You know what we always say — fail fast, fail often.

[Eric] has made many molds both from silicone and for silicone. Some of them are really big!

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An Impressive Modular Mold Box

Prolific maker and product designer [Eric Strebel] has years of experience making reusable mold boxes for silicone and resin casting. He’s always used 3/4″ plywood before, but it comes with some problems such as inaccuracy, screws that eventually slip out, and no room at all for expansion. Now [Eric] has decided to devise a modular mold box system that’s so awesome, it’s even stack-able. Check out the design and build process in the video after the break.

[Eric] took advantage of additive manufacturing and made fancy trapezoidal walls with recessed bits that allow for the magic that this modular system hinges on — a handful of M6 socket cap screws and matching nuts for tensioning. Once the prints were ready, [Eric] pounded the nuts captive into the walls and marked fill lines every 10mm. As usual, [Eric]’s video comes with bonus nuggets of knowledge, like his use of a simple card scraper to clean up prints, smooth the sides, and chamfer all the edges.

If you want to mold stuff like concrete and plaster, you may be better off using flexible filament.

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Something’s Brewing Up In The Woods – And It Looks Stunning

Caffeine fuels the hacker, and there are plenty of options to get it into your system, from guzzling energy drinks to chewing instant coffee pellets. But let’s take a nice cup of coffee as input source, which itself can be prepared in many ways using all kinds of techniques. In its simplest form, you won’t need any fancy equipment or even electricity, just heat up some water over a fire and add your ground beans to it. This comes in handy if you’re camping out in the woods or find yourself in a post-apocalyptic world, and in case you still prefer a stylish coffee maker in such a situation — why let an apocalypse ruin having nice things? — you’re in luck, because [Andreas Herz] designed this nifty looking off-the-grid coffee maker.

The design somewhat resembles a certain high-end precision coffee maker that even fictional billionaires approve of, which [Andreas] created in Fusion 360 and is available online. The device base is made from brass, wood, and silicone he cast from a 3D printed mold, while the glass and ceramic parts — i.e. the water tank and coffee pot — are simply store bought. [Andreas] opted for fuel gel as heat source, which burns under a copper coil that acts as heat exchanger and starts the actual brewing process. It took him a few attempts to get it right, and in the end, a coat of black exhaust paint did the trick to get the temperatures high enough.

This may not be the fastest coffee maker, as you will see in the video after the break, but choosing a different fuel source might fix that — [Andreas] just went the safe(r) way by using fuel gel here. But hey, why rush things when you’re camping or having a cozy time in a cabin anyway. Now all you need is the right blend, maybe even your own, made with a camp stove coffee roaster. Of course, in case of an actual apocalypse, you may not have easy access to a CNC router or 3D printer, but then there’s always the option to build an espresso machine from salvaged motorcycle parts.

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Silicone Injector Gives Parts Production A Shot In The Arm

Many of us are happy to spend hours cooking up a solution that saves us seconds, if success means never having to do a hated task again. [frankensteinhadason] molds enough silicone parts that he grew tired of all the manual labor involved, so he built a silicone injector to do it for him. Now, all he has to do is push the handle in notch by notch, until silicone starts oozing from the vent holes in the mold.

The mold pictured above is designed to make little shrouds for helicopter communications connections like this one. His friends in the industry like them so much that he decided to sell them, and needed to scale up production as a result. Now he can make six at once.

He designed brackets to hold a pair of syringes side by side against a backplane. There’s a lever that pushes both plungers simultaneously, and adapters that keep the tubing secured to the syringe nozzles. Ejected two-part silicone travels down to a double-barrel mixing nozzle, which extrudes silicone into the top of the mold.

Naturally, we were going to suggest automating the lever operation, but [frankensteinhadason] is already scheming to do that with steppers and an Arduino. Right now he’s working on increasing the hose diameter for faster flow, which will mean changes to the adapter. Once that is sorted, he plans to post the STLs and a video of it pumping silicone.

Ever thought about doing the reverse, and using silicone to mold hot plastic? Yeah, that’s a thing.

Via r/functionalprint

3D Printing With Multiple Soluble Filaments

Complex 3D-printed designs often require the use of an automatically generated support structure around them for stability. While this enables some truly incredible results, it adds considerable time and cost to the printing process. Plus there’s the painstaking process of removing all the support material without damaging the object itself. If you’ve got a suitably high-end 3D printer, one solution to this problem is doing the supports in a water soluble filament; just toss the print into a bath and wait for the support to dissolve away.

But what if you’re trying to print something that’s complex and also needs to be soluble? That’s precisely what [Jacob Blitzer] has been experimenting with recently. The trick is finding two filaments that can be printed at the same time but are dissolved with two different solutions. His experimentation has proved it’s possible to do with consumer-level hardware, but it isn’t easy and it’s definitely not cheap.

You might be wondering what the possible application for this technique is. For [Jacob], he wanted to be able to print hollow molds in complex geometric shapes that would ultimately be filled with concrete. The molds required extensive internal supports that would have been all but impossible to remove if they weren’t printed in a soluble filament. But he also wanted to be able to dissolve the mold once the concrete inside had cured. So he needed one easy to dissolve filament for the supports, and a harder to dissolve one for the actual mold.

For the mold itself, [Jacob] went with High Impact Polystyrene (HIPS) which can be dissolved with an industrial degreaser called Limonene. It’s expensive, and rather nasty to work with, but it does an excellent job of eating away the HIPS so that’s one problem solved. Finding a water-soluble filament for the supports that could be printed at similar temperatures to the HIPS took months of research, but eventually he found one called HyroFill that fit the bill. Unfortunately, it costs an eye-watering $175 USD per kilogram.

So you have the filaments, but what can actually print them at the same time? Multi-material 3D printing is a tricky topic, and there’s a few different approaches that have been developed over the years. In the end, [Jacob] opted to go with the FORMBOT T-Rex that uses the old-school method of having two individual hotends and extruders. It’s the simplest method conceptually, but calibrating such a machine is notoriously difficult. Running two exotic and temperamental filaments at the same time certainly doesn’t help matters.

After all the time, money, and effort put into the project (he also had to write the software that would create the 3D models in the first place) [Jacob] says he’s not exactly thrilled with the results. He’s produced some undeniably stunning pieces, but the failure rate is very high. Still, it’s fascinating research that appears to be the first of its kind, so we’re glad that he’s shared it for the benefit of the community and look forward to seeing where it goes from here.

3D Printed Wheels Get Some Much Needed Grip

You’d be hard-pressed to find more ardent supporters of 3D printing then we here at Hackaday; the sound of NEMA 17 steppers pushing an i3 through its motions sounds like a choir of angels to our ears. But we have to admit that the hard plastic components produced by desktop 3D printers aren’t ideal for a number of applications. For example, the slick plastic is useless for all but the most rudimentary of wheels. Sure there are flexible filaments that can give a printed wheel a bit of grip, but they came with their own set of problems (not to mention, cost).

In the video after the break, [Design/Forge] demonstrates a clever method for fitting polyurethane rubber “tires” onto 3D printed hubs which is sure to be of interest to anyone who’s in the market for high quality bespoke wheels for their project. The final result looks extremely professional, and while there’s a considerable amount of preparation that goes into it, once you’re set up you should be able to pump these out quickly and cheaply.

The process begins with a 3D printed mold pattern, which includes the final tire tread texture. This means you can create tire treads of any design you wish, which should have some creative as well as practical applications. The printed part is then submerged in silicone rubber and allowed to cure for 8 hours. Once solidified, the silicone rubber becomes the mold used for the next steps, and the original printed part is no longer needed.

The second half of the process is 3D printing the wheels to which the tires will be attached. These will be much smaller than the original 3D printed component, and fit inside of the silicone mold. The outside diameter of the printed wheel is slightly smaller than the inside diameter of the mold, which gives [Design/Forge] the space to pour in the pigmented polyurethane rubber. The attentive viewer will note that the 3D printed wheel has a slight ribbed texture designed into it, so that there will be more surface area for the polyurethane to adhere to. Once removed from the mold and cleaned up a bit, the final product really does look fantastic; and reminds us of a giant scale LEGO wheel.

Whether you’re casting metal parts or just want a pair of truly custom earbuds, creating silicone molds from 3D printed parts is an extremely useful skill to familiarize yourself with. Though even if you don’t have a 3D printer, there’s something to be said for knowing how to mold and cast real-world objects as well.

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