Lost PLA Casting With a Little Help From Your Microwave

lost-pla

[Julia and Mason] have been perfecting their microwave-based lost PLA casting technique over at Hackaday.io. As the name implies, lost PLA is similar to lost wax casting techniques. We’ve covered lost PLA before, but it always involved forges. [Julia and Mason] have moved the entire process over to a pair of microwaves.

Building on the work of the FOSScar project, the pair needed a way to burn the PLA out of a mold with a microwave. The trick is to use a susceptor. Susceptors convert the microwave’s RF energy into thermal energy exactly where it is needed. If you’ve ever nuked a hot pocket, the crisping sleeve is lined with susceptor material. After trying several materials, [Julia and Mason] settled on a mixture of silicon carbide, sugar, water, and alcohol for their susceptor.

The actual technique is pretty simple. A part printed in PLA is coated with susceptor. The part is then placed in a mold made of plaster of paris and perlite. The entire mold is cooked in an unmodified household microwave to burn out the PLA.

A second microwave with a top emitter is used to melt down aluminum, which is then poured into the prepared mold. When the metal cools, the mold is broken away to reveal a part ready to be machined.

We think this is a heck of a lot of work for a single part. Sometimes you really need a metal piece, though. Until metal 3D printing becomes cheap enough for everyone to do at home, this will work pretty well.

The ChipWhisperer At Defcon

We’ve seen [Colin]’s entry to The Hackaday Prize before. After seeing his lightning talk at Defcon, we had to get an interview with him going over the intricacies of this very impressive piece of hardware.

The ChipWhisperer is a security and research platform for embedded devices that exploits the fact that all security measures must run on real hardware. If you glitch a clock when a microcontroller is processing an instruction, there’s a good probability something will go wrong. If you’re very good at what you do, you can simply route around the code that makes up the important bits of a security system. Power analysis is another trick up the ChipWhisperer’s sleeve, analyzing the power consumption of a microcontroller when it’s running a bit of code to glean a little information on the keys required to access the system. It’s black magic and dark arts, but it does work, and it’s a real threat to embedded security that hasn’t had an open source toolset before now.

Before our interview, [Colin] did a few short and sweet demos of the ChipWhisperer. They were extraordinarily simple demos; glitching the clock when a microcontroller was iterating through nested loops resulted in what can only be described as ‘counter weirdness’. More advanced applications of the ChipWhisperer can supposedly break perfectly implemented security, something we’re sure [Colin] is saving for a followup video.

You can check out [Colin]’s 2-minute video for his Hackaday Prize entry below.

Continue reading “The ChipWhisperer At Defcon”