Variable Thickness Slicing For 3D Printers

With proper tuning, any 3D printer can create exceptionally detailed physical replicas of digital files. The time it takes for a printer to print an object at very high detail is another matter entirely. The lower the layer height, the more layers must be printed, and the longer a print takes to print.

Thanks to [Steve Kranz] at Autodesk’s Integrated Additive Manufacturing Team, there’s now a solution to the problem of very long, very high-quality prints. It’s called VariSlice, and it slices 3D in a way that’s only high quality where it needs to be.

The basic idea behind VariSlice is to print vertical walls at a maximum layer height, while very shallow angles – the top of a sphere, for example – are printed at a very low layer height. That’s simple and obvious; you will never need to print a vertical wall at ten micron resolution, and fine details will always look terrible with a high layer height.

The trick, as in everything with 3D printing, is the implementation. In the Instructable for VariSlice, it appears that the algorithm considers the entire layer of an object at a time, taking the maximum slope over the entire perimeter and refining the layer height if it’s necessary. There’s no weird stair stepping, overlapping layers of different thicknesses, or interleaving here. It’s doing automatically what you’d normally have to do manually.

Nevertheless, the VariSlice algorithm is now one of Autodesk’s open source efforts, just like the Ember resin printer used in the example below. The application for this algorithm in filament-based printers is obvious, though. The speed increase for the same level of quality is variable, but the time it takes to print some very specific objects can be up to ten times faster. Whether or not this algorithm can be integrated into Cura or Slic3r is another matter entirely, but we can only hope so.

Continue reading “Variable Thickness Slicing For 3D Printers”

3D Internal Structure For Better 3D Printed Objects

Makerbot is in the gutter, 3D Systems and Stratasys stock is only a shadow of their 2014 glory, but this is the best year 3D printing has ever had. Machines are now good and cheap, there’s a variety of various thermoplastic filaments, and printing useful objects – instead of just plastic trinkets – is becoming commonplace.

Gradient-Grid
The standard rectilinear infill from Slic3r

There’s one area of 3D printing that hasn’t seen as much progress, and it’s the software stack. Slicing, the process of turning a 3D object into a Gcode file for a printer has been basically the same for the last few years. Dual extrusion is still a mess, and automated bed leveling is still in its infancy.

One aspect of slicing that has been severely overlooked is infill. Obviously, you don’t want to print plastic trinkets completely solid – only the outside surface matters, and a part with 100% infill is just a waste of plastic. Different slicers have come up with different ways of filling the inside of a print, usually with a grid of squares, triangles, or hexagons.

While the most popular methods of filling in a 3D printed objects do the job of adding a little bit of strength to a print and supporting the top layers of a print, it’s not an ideal solution. The desired strength of the finished part is never taken into account, print artifacts are sometimes visible through the side of a print, and the spacing of the infill grid is completely arbitrary. You can only set a percentage of infill, and telling a slicer to make an internal support grid with 10mm spacing is impossible.

Type A Machines just changed all of this. With the release of their public beta of Cura Type A, the infill for a 3D printed part is also 3D. The dimensions of the infill are predictable, opening the door to stronger and better looking parts.

From the Type A press literature and white paper, this new type of ‘infill’ isn’t; it’s more properly referred to as ‘internal structure’, with proper dimensions between infill features. Instead of a grid of squares or triangles stacked one layer on top of each other, it’s a true structure, with the infill following the perimeter of the 3D printed object.

Generating 3D Infill

3D
Infill generated from Type A Machine’s Cura beta. Note the 3D structure of the infill.

Right now, infill is generated in a slicer by specifying a percentage. Zero percent infill means a hollow object, and 100% infill is a completely solid part. These two edge cases are easy, but anything else means the slicer must fill the part with filament in a grid of tessellating shapes, either rectangles, triangles, or hexagons. With current slicers, the dimensions of this internal structure are, for all practical purposes, random. Printing an object with 20% infill might mean a grid of squares with 5mm or 2mm spacing. Telling the slicer to infill a part with a grid of squares spaced 10mm apart is impossible.

Type A Machine’s latest Cura release changes all of this, allowing a designer to set a precise distance between rows and columns of infill. By defining infill in absolute dimensions, this allows for stronger parts using less infill.

Absolute dimensioning is only one feature of the Type A Machine’s latest release of Cura. Even more exciting is the development of 3D internal structure. Instead of stacking layers of squares, triangles, or hexagons on top of each other, Type A Machine’s Cura uses an infill of cubes turned on their side. While each individual layer of infill looks like a series of triangles and irregular hexagons, when assembled into a printed 3D object, this infill forms a true 3D structure.

The closest comparison to this sort of structure is the difference between graphite and diamond. Both of these materials are made out of the same element, carbon. The physical structure of graphite is just, 1-atom-thick layers of graphene, producing a relatively weak material. Diamond, on the other hand, has a true 3D structure and is one of the hardest materials known to man. While adding 3D structure to the infill of 3D printed objects won’t make the objects any stronger, it will drastically reduce delamination, and be much more resistant to stresses in all three dimensions.

While Type A Machines has done some great work here, it does mean there’s yet another version of Cura to deal with. Type A Machine’s Cura, in addition to the LulzBot edition and the original are now the defacto standard for turning 3D objects into printed parts. Having an open source solution is great, but forking the development this much surely can’t be ideal.

Hackaday Links: March 28, 2016

[Tom] sent this in to be filed under the ‘not a hack’ category, but it’s actually very interesting. It’s the User’s Guide for the Falcon 9 rocket. It includes all the data necessary to put your payload on a Falcon 9 and send it into space. It’s a freakin’ datasheet for a rocket.

A year ago in Japan (and last week worldwide), Nintendo released Pokkén Tournament, a Pokemon fighting game. This game has a new controller, the Pokkén Tournament Pro Pad. There were a few cost-cutting measures in the production of this game pad, and it looks like this controller was supposed to have force feedback and LEDs. If any Pokemon fans want to take this controller apart and install some LEDs and motors just to see what happens, there’s a Hackaday write up in it for you.

There are a lot of options for slicing 3D objects for filament-based 3D printers. Cura, Slic3r, and MatterControl are easily capable of handing all the slicing needs you’ll ever have for a filament 3D printer. For sterolithography (resin) printers, the options for slicing are limited. [skarab] just put together a new slicer for SLA that runs entirely in JavaScript. If anyone wants to turn a Raspi or BeagleBone into a network controller for a resin printer, here’s your starting point. [skarab] will be working on smoothieboard integration soon.

The STM32F4 is an extremely capable ARM microcontroller. It can do VGA at relatively high resolutions, emulate a Game Boy cartridge, and can serve as the engine control unit in a 1996 Ford Aspire. There’s a lot of computing power here, but only one true litmus test: the STM32F4 can run Doom. [floppes] built this implementation of Doom on the STM32F429 Discovery board to run off of an external USB memory stick. The frame rate is at least as good as what it was back in 1993.

The Oculus Rift has just come to pass, but one lucky consumer got his early. The first person to preorder the Rift, [Ross Martin] of Anchorage, Alaska, got his facehugger directly from [Palmer Luckey] in a PR stunt on Saturday afternoon. Guess what [Ross] is doing with his Rift?

rift

WirePrint is a Physical ‘Print Preview’ for 3D Printers

3D printers may be old news to most of us, but that’s not stopping creative individuals from finding new ways to improve on the technology. Your average consumer budget 3D printer uses an extrusion technology, whereby plastic is melted and extruded onto a platform. The printer draws a single two-dimensional image of the print and then moves up layer by layer. It’s an effective and inexpensive method for turning a computer design into a physical object. Unfortunately, it’s also very slow.

That’s why Hasso Plattner Institute and Cornell University teamed up to develop WirePrint. WirePrint can slice your three-dimensional model into a wire frame version that is capable of being printed on an extrusion printer. You won’t end up with a strong final product, but WirePrint will help you get a feel for the overall size and shape of your print. The best part is it will do it in a fraction of the time it would take to print the actual object.

This is a similar idea to reducing the amount of fill that your print has, only WirePrint takes it a step further. The software tells your printer to extrude plastic in vertical lines, then pauses for just enough time for it to cool and harden in that vertical position. The result is much cleaner than if this same wire frame model were printed layer by layer. It also requires less overall movement of the print head and is therefore faster.

The best part about this project is that it’s a software hack. This means that it can likely be used on any 3D printers that use extrusion technology. Check out a video of the process below to see how it works. Continue reading “WirePrint is a Physical ‘Print Preview’ for 3D Printers”

Opening up the settings in MakerWare

ProfTweak

[Rich Olson] really likes MakerWare and the Makerbot slicer – the software package that comes with every Makerbot – but sometimes he needs to change a few settings. Makerware doesn’t allow the user access to 90% of the setting for slicing and printing, so [Rich] did something about that. He came up with ProfTweak, a tool to change all the MakerWare slicing and printing parameters, giving him precise control over every print.

ProfTweak handles common settings changes such as turning the fan on or off, adjusting the filament diameter, changing feed rate options, and turning your infills into cats. It’s a handy GUI app that should work under Windows, OS X, and Linux, so if you’re running MakerWare right now, you can get up and running with this easily.

One thing [Rich] has been using his new software for is experimenting with alternative filaments. With his Makerbot, he’s able to print in nylon, the wood and stone PLAs, flex PLA, and PET. That’s a lot more material than what the Makerbot natively supports, so we have to give [Rich] some credit for that.

An interview with [David] of Ultimaker

cura

After interviewing the creator of Slic3r and the folks at Shapeways, [Andrew] is back again with his adventures in 3D printer videography and an interview with [David Braam] of Ultimaker

About a year ago, [David] looked at the state of the art in 3D printer control and Replicator G. While Replicator G, along with Pronterface and Repetier-Host both convert 3D models into G-code files as well as control the printer while its squeezing plastic out onto a bed. [David] thought the current state of these RepRap host programs were janky at best, and certainly not the best user experience for any home fabricator. This lead him to create Cura, a very slick and vastly improved piece of host software for the Ultimaker.

Cura isn’t just a fancy front end on an already existing slicer engine; [David] created his own slicing algorithm to turn .STL files into G-code that’s immensely faster than skeinforge. Where skeinforge could take an hour to slice a complex model, Cura does the same job in minutes.

There are also a bunch of cool features available in Cura: you can rotate any part before sending it to the printer, as well as pulling voxels directly from your Minecraft world and sending them to your printer. Very, very cool stuff, and if you’re running a Ultimaker or any other RepRap, you might want to check it out.

Continue reading “An interview with [David] of Ultimaker”