A man in a red plaid shirt draped over an olive t-shirt holds sandpaper in one hand an an aluminum tube filled with white beads in the other over a wooden table.

Activated Alumina For Desiccating Your Filament

When you first unwrap a shiny new roll of filament for your FDM printer, it typically has a bag of silica gel inside. While great for keeping costs low on the manufacturing side, is silica gel the best solution to keep your filament dry at home?

Frustrated with the consumable nature and fussy handling of silica gel beads, [Build It Make It] sought a more permanent way to keep his filament dry. Already familiar with activated alumina beads, he crafted a desiccant cylinder that can be popped into the oven all at once instead of all that tedious mucking about with emptying and refilling plastic capsules.

A length of aluminum intake pipe, some high temperature epoxy, and aluminum mesh are all combined to make a simple, sealed cylinder. During the process, he found that using a syringe filled with the epoxy led to a much more precise application to the aluminum cylinder, so he recommends starting out that way if you make these for yourself.

We suspect something with a less permanent attachment at one end would let you periodically swap out the beads if you wanted to try this hack with the silica beads you already had. Perhaps some kind of threaded pipe fitting? If you want a more active dryer, try making one with a Peltier. If you want to know just how dry your filament is getting, you could also put in a sensor. You might also wonder, do you really need to dry filament at all?

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DIY Tube Oven Brings The Heat To Homebrew Semiconductor Fab

Specialized processes require specialized tools and instruments, and processes don’t get much more specialized than the making of semiconductors. There’s a huge industry devoted to making the equipment needed for semiconductor fabrication plants, but most of it is fabulously expensive and out of reach to the home gamer. Besides, where’s the fun in buying when you can build your own fab lab stuff, like this DIY tube oven?

A tube oven isn’t much more complicated than it sounds — it’s just a tube that gets hot. Really, really hot — [Nixie] is shooting for 1,200 °C. Not just any materials will do for such an oven, of course, and this one is built out of blocks of fused alumina ceramic. The cavity for the tube was machined with a hole saw and a homebrew jig that keeps everything aligned; at first we wondered why he didn’t use his lathe, but then we realized that chucking a brittle block of ceramic would probably not end well. A smaller hole saw was used to make trenches for the Kanthal heating element and the whole thing was put in a custom stainless enclosure. A second post covers the control electronics and test runs up to 1,000°C, which ends up looking a little like the Eye of Sauron.

We’ve been following [Nixie]’s home semiconductor fab buildout for a while now, starting with a sputtering rig for thin-film deposition. It’s been interesting to watch the progress, and we’re eager to see where this all leads.