Need Many Thin Parts? Try Multi-material Stack Printing

Admittedly it’s a bit of a niche application, but if you need lots of flat 3D printed objects, one way to go about it is to print them in a stack and separate them somehow. An old(er) solution is to use a non-extruding “ironing” step between each layer, which makes them easier to pull apart. But another trick is to use the fact that PLA and PETG don’t stick well to each other to your advantage. And thus is born multi-material stack printing. (Video, embedded below the break.)

[Jonathan] wants to print out multiples of his fun Multiboard mounting system backplates, and these are the ideal candidate for stack printing: they’re thin, but otherwise take up the entire build plate. As you’d expect, the main trick is to print thin layers of PETG between the PLA plate layers that you do want. He demonstrates that you can then simply pull them apart.

There are some tricks, though. First is to make two pillars in addition to the plates, which apparently convinces the slicer to not flatten all the layers together. (We don’t really understand why, honestly, but we don’t use Bambu slicer for multi-materials.) The other trick that we expect to be more widely applicable, is that [Jonathan] extrudes the PETG interlayers a little thicker than normally. Because the PETG overflows the lower PLA layer, it physically locks on even though it chemically doesn’t. This probably requires some experimentation.

As multi-material printers get cheaper, we’ve seen a lot more innovative uses for them popping up. And we wouldn’t be so stoked about the topic if there weren’t a variety of hacker projects to make it possible. Most recently, the impressive system from [Armored_Turtle] has caught our eye. Who knows what kind of crazy applications we’ll see in the future? Are you doing multi-material yet?

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Print-in-Place Engine Aims To Be The Next Benchy

While there are many in the 3D-printing community who loudly and proudly proclaim never to have stooped to printing a 3DBenchy, there are far more who have turned a new printer loose on the venerable test model, just to see what it can do. But Benchy is getting a little long in the tooth, and with 3D-printers getting better and better, perhaps a better benchmarking model is in order.

Knocking Benchy off its perch is the idea behind this print-in-place engine benchmark, at least according to [SunShine]. And we have to say that he’s come up with an impressive model. It’s a cutaway of a three-cylinder reciprocating engine, complete with crankshaft, connecting rods, pistons, and engine block. It’s designed to print all in one go, with only a little cleanup needed after printing before the model is ready to go. The print-in-place aspect seems to be the main test of a printer — if you can get this engine to actually spin, you’re probably set up pretty well. [SunShine] shares a few tips to get your printer dialed in, and shows a few examples of what can happen when things go wrong. In addition to the complexities of the print-in-place mechanism, the model has a few Easter eggs to really challenge your printer, like the tiny oil channel running the length of the crankshaft.

Whether this model supplants Benchy is up for debate, but even if it doesn’t, it’s still a cool design that would be fun to play with. Either way, as [SunShine] points out, you’ll need a really flat bed to print this one; luckily, he recently came up with a compliant mechanism dial indicator to help with that job.

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These Gorgeous Robot Parts Are Hand-Made

[Dickel]’s robot MDi #4 has been in progress for several years, but what we wanted to draw your attention to is the way the parts have been fabricated and what kind of remarkable results are possible with careful design, measurement, cutting, and finishing. Much of MDi #4 was made by hand-cutting and drilling sheets of high impact polystyrene (HIPS) with a utility knife and layering them as needed. Epoxy and aluminum provide gap filling and reinforcement of key sections, and fiberglass took care of one of the larger sections.

The process [Dickel] follows is to prototype using cardboard first. Parts are then designed carefully in CAD, and printed out at a 1:1 scale and glued to sheets of polystyrene. Each sheet is cut and drilled by hand as necessary. Layers are stacked and epoxied, embedding any hardware needed in the process. Two examples of embedding hardware include sealing captive nuts into parts with epoxy, or using aluminum to add reinforcement. After some careful sanding, the pieces look amazing.

Scroll down a bit on that project page and you’ll see plenty of great photos of the process [Dickel] used. A video highlighting the head and a video showing the careful work that goes into making each part are embedded below.

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