3D Printing Hack Leverages Vase Mode Structurally

Conceptually, FDM 3D printing is quite a simple process: you define a set of volumes in 3D space, then the slicing software takes a cut through the model at ever-increasing heights, works out where the inner and outer walls are, and then fills in the inside volume sparsely in order to tie the walls together and support the top layers that are added at the end.

But as you will find quite quickly, when models get larger and more complex, printing times can quickly explode. One trick for large models with simple shapes but very low structural needs is to use so-called ‘vase mode’, which traces the outline of the object in a thin, vertical spiral. But this is a weak construction scheme and allows only limited modelling complexity. With that in mind, here’s [Ben Eadie] with a kind-of halfway house technique (video, embedded below) that some might find useful for saving on printing time and material.

This solid shape is mostly cut-through to make supporting ribs between the walls of the shell

The idea is to use vase mode printing, but by manipulating the shell of the model, adding partially cut-through slots around the perimeter, and critically, adding one slot that goes all the way.

First you need a model that has an inner shell that follows the approximate shape of the outer, which you could produce by hollowing out a solid, leaving a little thickness. By making the slot width equal to half the thickness of the nozzle size and stopping the slots the same distance from the outer shell, vase mode can be used to trace the outline of shape, complete with supporting ribs in between the inner and outer walls of the shell.

Because the slot is narrower than the extrudate, the slot walls will merge together into one solid rib, tying the objects’ walls to each other, but critically, still allowing it to be printed in a continuous spiral without any traditional infill. It’s an interesting idea, that could have some merit.

There are other ways to stiffen up thing printed parts, such as using surface textures, But if you’re fine with the thin shell, but want to have a little fun with it, you can hack the g-code to make some really interesting shapes.

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Mechanical Engineering Hack Chat

Join us on Wednesday, September 30 at noon Pacific for the Mechanical Engineering Hack Chat with Adam Zeloof!

Almost every non-trivial project involves some level of cross-discipline work. If you build a robot, for instance, you need to worry not just about the electronics but also the mechanical design. You need to make sure that the parts you use will be strong enough to deal with the forces that it’ll face, you have to know how much power it’ll take to move your bot, and you have to deal with a thousand details, from heat flow to frictional losses to keeping things moving with bearing and seals.

Unfortunately for many of us, the mechanical engineering aspects of a project are foreign territory. We lack the skills to properly design mechanical systems, and so resort to seat-of-the-pants decisions on materials and fasteners, or over-engineering in the extreme — the bigger the bolt, the better. Right?

Some of us, though, like Adam Zeloof, actually know a thing or two about proper mechanical engineering. Strength of materials, finite element analysis, thermodynamics — all that stuff that most of us just wing are Adam’s stock in trade. Adam brings a trained mechanical engineer’s skillset to his multi-discipline projects, like the Rotomill or his reverse-engineered ride-share scooter. And many of you will have been lucky enough to see Adam’s excellent 2019 Superconference talk on thermal design for PCBs.

Adam joins us on the Hack Chat to talk about anything and everything to do with mechanical engineering. Join us with your burning — sometimes literally — questions on how to make your designs survive the real world, where things break and air resistance can’t be ignored.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, September 30 at 12:00 PM Pacific time. If time zones baffle you as much as us, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

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