Defective 3D Printing For Great Strength

Most of us want our 3D prints to be perfect. But at Cornell University, they’ve been experimenting with deliberately introducing defects into printed titanium. Why? Because using a post-print treatment of heat and pressure they can turn those defects into assets, leading to a stronger and more ductile printed part.

The most common ways to print metal use powders melted together, and these lead to tiny pores in the material that weaken the final product. Using Ti-6Al-4V, the researchers deliberately made a poor print that had more than the usual amount of defects. Then they applied extreme heat and pressure to the resulting piece. The pressure caused the pores to close up, and changed the material’s internal structure to be more like a composite.

Reports are that the pieces treated in this way have superior properties to parts made by casting and forging, much less 3D printed parts. In addition, the printing process usually creates parts that are stronger in some directions than others. The post processing breaks that directionality and the finished parts have equal strength in all directions.

The hot isostatic pressing (HIP) process isn’t new — it is commonly used in metal and ceramic processing — so this method shouldn’t require anything more exotic than that. Granted, even cheap presses from China start around $7,000 and go way up from there, but if you are 3D printing titanium, that might not be such a big expenditure. The only downside seems to be that if the process leaves any defects partially processed, it can lead to fatigue failures later.

We wonder if this development will impact all the car parts being printed in titanium lately. If you need something to print in titanium, consider hacking your rib cage.

World’s Largest Super Soaker Is Dangerously Good Clean Fun

Running around while dousing each other with Super Soakers and screaming in delight is de rigueur on suburban lawns on hot summer days, but if you build this giant replica of a Super Soaker that can double as a pressure washer, you might have the upper edge on the neighborhood gang.

You may remember [Mark Rober] from such projects as his bullseye-catching dart board and his previous entry in the awesome uncle of the year awards, the fully automatic snowball gun. We’re not entirely sure that this seven-foot long replica of the original Super Soaker will win him any uncle or neighbor plaudits, given that it the stream it produces is not far off of what a pressure washer can manage and can literally slice a watermelon in half. Fortunately, [Mark] included swappable nozzles to reduce the pressure enough that relatively safe dousing is still on the table. The housing is a pretty accurate plywood and foam replica of the original toy, but the mechanism is beefed up considerably — a pair of nitrogen tanks, some regulators, and a solenoid valve. See the gun in all its window-smashing, kid-soaking glory in the video after the break.

We realize [Mark]’s build is just a fun way to beat the heat, but it gives us a few ideas for more practical uses. Maybe a DIY water-jet cutter that’s not built around a pressure washer?

Continue reading “World’s Largest Super Soaker Is Dangerously Good Clean Fun”