Machine Shop Soaps Are Good, Clean Learning Fun

At first glance, it’s easy to dismiss the creation of custom bath soaps as far outside the usual Hackaday subject matter, and we fully expect a torrent of “not a hack” derision in the comments. But to be able to build something from nothing, a hacker needs to be able to learn something from nothing, and there is plenty to learn from this hack.

On the face of it, [Gord] is just making kitschy custom bath soaps for branding and promotion. Cool soaps, to be sure, and the drop or two of motor oil and cutting fluid added to each batch give them a little machine shop flair. [Gord] experimented with different dyes and additives over multiple batches to come up with a soap that looked like machined aluminum; it turns out, though, that adding actual aluminum to a mixture containing lye is not a good idea. Inadvertent chemical reactions excepted, [Gord]’s soaps and custom wrappers came out great.

So where’s the hack? In stepping way outside his comfort zone of machining and metalwork, [Gord] exposed himself to new materials, new techniques, and new failure modes. He taught himself the basics of mold making and casting, how to deal with ultra-soft materials, the chemistry of the soap-making process, working out packaging and labeling issues, and how to deal with the problems that come from scaling up from prototype to production. It may have been “just soap”, but hacks favor the prepared mind.

How a Professional Resin Caster Duplicates Parts

[Gregg Eshelman] reproduces plastic parts for antique car restorations for a living; likewise, he’s very good at it. Greg always chimes in with helpful hints whenever we post about resin casting. Shown above is a lens for a car turn signal. Manufactured in 1941, having [Gregg] cast a few copies is an easy option for replacing the rare part.

[Gregg] uses a similar method to us, but it is easy to see that he has done it more and his process has been refined by lots of experience. We really liked how he avoids using expensive foam core by wrapping cardboard in packing tape, or using the kind that has a plastic coating on it; the kind most retail packaging is made out of. He also has better techniques for keying the part to be manufactured, and prepping difficult geometry between different mold halves. It also never would have occurred to us to use Dremel cutting disks to cut the sprues and air vents in the silicone, a surprisingly tricky material to cut precisely with a knife.

It’s always nice when a professional takes time to write about their processes for the hobbyist trying to emulate it. We hope [Gregg] writes more tutorials, and continues to contribute in the comment section. If you have your own fabrication techniques to share we’d love to hear about it on the tips line.

Learn Resin Casting Techniques: Duplicating Plastic Parts

Resin casting lets you produce parts that would be otherwise impossible to make without a full CNC and injection molding set-up. It costs about as much as a 3d printer, 300 to 600 US dollars, to get a good set-up going. This is for raw material, resin, dye, pressure chamber, and an optional vacuum degassing set-up. A good resin casting set-up will let you produce parts which are stronger than injection molding, and with phenomenal accuracy, temperature resistance, and strength. I will be covering various techniques from the simple to advanced for using resin casting from a hacker’s perspective.

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An Introduction to Casting With Nuka Cola

There’s less than a month until the next Star Wars is released, and consequently a few weeks until amateur propmakers and cosplayers go insane fabricating their own lightsabers with lightsaber cross guards and rolling robots. Until then, Fallout is pretty cool and [Bill] is here to give us an introduction to prop making with one of the defining objects of this post-apocalyptic universe. He created a real life copy of a Nuka Cola bottle and created a great introduction to resin casting in the process.

As with all proper part making endeavours, this project began with getting reasonably accurate models of the object to be copied. In Fallout, we’re lucky enough to have a way to look at a specific object while zooming and spinning around it, giving [Bill] the basic shape. The size was rather easy as well: all bottlecaps are the same size, so [Bill] just scaled the model to that.

With the model created and the part printed out, assembled, and finished, it was time to create the mold. [Bill] used a two-part silicone mold for the basic shape. The actual casting was done by rolling around a little resin on the inside of the mold. There’s no need for a solid, bottle-shaped block of resin; bottles are hollow anyway.

There are a few neat tricks [Bill] has up his sleeve, including coating the inside of the mold with aluminum powder and using a vinyl cutter to get the labels and logos exactly right. The finished product turns out great, perfect for leaving in the Wasteland for 200 years until the Sole Survivor stumbles upon it.

Video below.

Continue reading “An Introduction to Casting With Nuka Cola”

3D Printed Eyeglasses, VR Lenses

[Florian] is hyped for Google Cardboard, Oculus Rifts, and other head mounted displays, and with that comes an interest in lenses. [Floian] wanted to know if it was possible to create these lenses with a 3D printer. Why would anyone want to do this when these lenses can be had from dozens of online retailers for a few dollars? The phrase, ‘because I can’ comes to mind.

The starting point for the lens was a CAD model, a 3D printer, and silicone mold material. Clear casting resin fills the mold, cures, and turns into a translucent lens-shaped blob. This is the process of creating all lenses, and by finely sanding, polishing, and buffing this lens with grits ranging from 200 to 7000, this bit of resin slowly takes on an optically clear shine.

Do these lenses work? Yes, and [Florian] managed to build a head mounted display that can hold an iPhone up to his face for viewing 3D images and movies. The next goal is printing prescription glasses, and [Florian] seems very close to achieving that dream.

The last time we saw home lens making was more than a year ago. Is anyone else dabbling in this dark art? Let us know in the comments below and send in a tip if you have a favorite lens hack in mind.

MRRF: Flexible 3D Printing

The concession stand at the Midwest Rep Rap Festival did not disappoint when it came to the expected fare: hot dogs, walking tacos, and bananas for scale. But the yummiest things there could not be bought—the Nutella prints coming off the Ultimaker² at the structur3D booth.

3D printed gasket
Flexible gasket printed in silicone atop a rigid 3D printed engine block.

Hey, what? Yes, an Ultimaker² that can print in Nutella, icing sugar, silicone, latex, wood filler, conductive ink, polyurethane, peanut butter, and a growing list to which you should contribute. This is possible because of their Discov3ry Universal Paste Extruder add-on, which is compatible with most filament printers, especially those that use a RAMPs or Arduino control board.

A large syringe containing the substance of your choice is loaded business end up in the Discov3ry. It gets pushed through tubing that runs to the print head and out through one of many commonly available polypropylene or stainless steel tips. The structur3D team has found that printing on waxed paper works best for the materials they’ve proven out. Each syringe holds 60cc of stuff, and the Discov3ry comes with three of them. They are currently available for pre-order, with a shipping forecast of early summer.

Fail of the Week: Silicone Molding That Won’t Cure

fotw-uncured-silicone

Mold making is a hacking skill we see pop up around here from time to time. But rarely do we hear about problems in the process, and they must happen. Here’s proof. This Fail of the Week focuses on [Michael’s] unfortunate experience with failed mold making due to uncured silicone around the master mold. It’s worse than it may sound, since he lost about a pound of silicone to the fail, and we’re unsure of whether he can even use the master again (how do you clean uncured silicone off of something?). Not to mention the time lost from setting up the pour and waiting 20 hours for it to cure.

Soon after the issue presented itself [Michael] started researching to see what had gone awry and noticed that the master should have been sealed with acrylic lacquer. This gave him the opportunity to test several different finishes before making a run at the full mold once again. He picked up a variety of the paint products he could find locally, used them to coat some scraps, and globbed on some silicone to see which worked the best.  He found a couple of different primers worked well, as did both glossy and matte acrylic coatings.

If you’ve never had a reason for mold making before, keep it in mind. You’d be surprised what kind of factory-production-type things can be pulled off by 3D printing a master, and casting a silicone mold of it.


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.