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.

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Hackaday Prize Entry: A Big, Inexpensive 3D Printer

When it comes to 3D printers, most machines you’ll see are pretty small. The Ultimaker, Prusa, Lulzbot, and the Rostock Max are desktop devices. While they have entirely usable build volumes, you’re not printing furniture with these machines. Yes, large format 3D printers exist, like the SeeMeCNC Part Daddy (they’ll build you one for ~$90,000, IIRC), a house printer that uses concrete, and a number of very large printers from various other manufacturers with very high price tags.

There is no 3D printer designed to print large objects without spending tens of thousands of dollars on a machine. That’s the focus of this Hackaday Prize entry. [RigTig]’s Big 3D Printer is designed to be big, but also inexpensive.

A big, inexpensive 3D printer can’t use the usual machine setups seen in other large format printers. Big machines with traditional kinematics demand big pieces of aluminum, counterweights, and a design that might spiral out of control. Instead of a thousand pounds of metal, [RigTig] is using something like the Skycam system seen at every NFL game; put a few towers up at the corners of a triangle, run some string or cable through some pulleys, and you have a simple, light movement platform.

With the machine side of the problem figured out, the next question is what material to use. [RigTig] has decided plastic filament is impractical because of cost. A clay extrusion system has a lot of problems. Concrete is a good idea, but the prints would weigh several tons. Right now, [RigTig] is planning on using dirt with a polymer binder. It’s an interesting idea, and one we haven’t seen elsewhere.

Building a 3D printer from scratch is easy. Building a huge 3D printer is one of the most interesting engineering challenges out there. Not only do you need a motion platform that can make it work, but you also need to print in a material that is cheap enough and prints fast enough for the printer to make sense. We don’t know if [RigTig] is on the right track yet, but we’re glad to see him put in the effort for this excellent addition to the Hackaday Prize.

3D Printed Electric Longboard Courtesy Of Stratasys

[Tallaustin] worked at Stratasys as an intern this past summer. They let him know that he was welcome to use their fancy industrial printers as much as he’d like. Not to waste such an opportunity he promptly got to work and designed an electric longboard, printable for a mere $8,000.

Just in case the idea of a 3D printer that can print a whole longboard was causing envy. Here's a photo of a print delaminating inside of it half way. Just in case the idea of a 3D printer that can print a whole longboard was causing envy. Here's a photo of a print delaminating inside of it half way.
Just in case the idea of a 3D printer that can print a whole longboard was inducing acute envy. Here’s a photo of a print delaminating inside of it half way through.

[Tallaustin] is presumably tall, and confided to Reddit that he weighs in at 210 lbs. For those of us who have had the pleasure of designing for FDM 3D printing, we know that getting a skateboard one can actually skate on without it delaminating somewhere unexpected is pretty difficult if you weigh 80 lbs, 200+  is another category entirely. So it’s not surprising that his first version shattered within in moments of testing.

So, he went back to the drawing board. Since he had his pick of all of Stratasys’s most expensive and fine spools of plastic, he picked one of the expensivest and finest, Ultem 1010. Aside from adding a lot of ribbing and plastic, he also gave it a full rundown with some of SolidWorks’s simulation tools to see if there were any obvious weak points.

Six days of exceedingly expensive printing later, he had a working long board. The base holds some batteries, an ESC, and a 2.4 GHz transceiver. The back has a brushless motor that drives a pulley slotted into one of the wheels. The rest is standard skateboard hardware.

If you’d like to build it yourself he’s posted the design on Thingiverse. He was even nice enough to put together a version that’s printable on a plebeian printer, for a hundredth of the price.

DIY Nozzle Socks For Your 3D Printer

If you have a 3D printer, your nozzle and heater block are invariably covered in a weird goo consisting of decomposed and burnt plastic. There’s only one way around this – a nozzle sock, or a silicone boot that wraps around the heater block and stops all that goo from accumulating.

Right now, E3D sells silicone nozzle socks for their normal-sized heater blocks, with a release for their maxi-sized Volcano blocks coming shortly. [Ubermeisters] couldn’t wait, so he designed a 3D printed mold to cast as many Volcano nozzle socks as he could ever need.

The mold itself is taken from the mechanical drawings of the E3D Volcano hotend, printed in Proto Pasta HTPLA. To create the nozzle sock, this mold is filled with a goo made from GE Silicone I, mineral spirits, plaster of Paris, carbon powder, aluminum powder, titanium microspheres, and bronze powder colorant from Alumalite.

The mold is sprayed with release, filled with silicone goo, and slowly brought together. After a few hours, the silicone has cured, can be removed from the mold, and the flash can be cut away from the finished part. The end result is great — it fits the Volcano hotend well, and shouldn’t be covered in melted, burnt plastic in a week’s time.

All the files for the Volcano nozzle sock mold can be found on YouMagine. Alternatively, you could wait another month or two for E3D to release their ‘official’ Volcano nozzle sock.

The Tiny 3D Printers Of Maker Faire

Building a big 3D printer has its own challenges. The strength of materials does not scale linearly, of course, and long axes have a tendency to wobble. That said, building a bigbot isn’t hard – stepper motors and aluminum extrusion are made for industry, and you can always get a larger beam or a more powerful motor. [James] is going in the opposite direction. He’s building tiny, half-scale printers. They’re small, they’re adorable, and they have design challenges all their own.

At this year’s New York Maker Faire, [James] is showing off his continuing project of building baby 3D printers. He has a half-scale wooden Printrbot, a half-ish scale Mendel Max, a tiny Makerbot Replicator, and a baby delta and baby Ultimaker in the works.

Click past the break for a gallery, and more info on [James’s] tiny creations.

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Riding Rollercoasters with 3D Printed Kidneys, Passing Stones

Citizen science isn’t limited to the nerd community. When medical professionals get a crazy idea, their options include filling out endless paperwork for human consent forms and grant applications, or hacking something together themselves. When [David Wartinger] noticed that far too many of his patients passed kidney stones while on vacation, riding rollercoasters, he had to test it out.

Without the benefit of his own kidney stones, he did the next best thing: 3D printed a model kidney, collected some urine, and tossed a few stones that he’d collected from patients into the trap. Then he and a colleague rode Big Thunder Mountain Railroad sixty times, holding the model in a backpack at kidney height.

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Putting Sand, Water, and Metal into A 3D Print

[Adam] over at Makefast Workshop writes about some of the tests they’ve been running on their 3D printer. They experimented with pausing a 3D print midway and inserting various materials into the print. In this case, sand, water, and metal BBs.

The first experiment was a mixture of salt and water used to make a can chiller for soda or beer (the blue thing in the upper right). It took some experimentation to get a print that didn’t leak and was strong. For example, if the water was too cold the print could come off the plate or delaminate. If there was too much water it would splash up while the printer was running and cause bad layer adhesion.

They used what they learned to build on their next experiment, which was filling the print with sand to give it more heft. This is actually a common manufacturing process — for instance, hollow-handled cutlery often has clay, sand, or cement for heft. They eventually found that they had to preheat the sand to get the results they wanted and managed to produce a fairly passable maraca.

The final experiment was a variation on the popular ball bearing prints. Rather than printing plastic balls they designed the print to be paused midway and then placed warmed copper BBs in the print. The printer finished its work and then they spun the BB. It worked pretty well! All in all an interesting read.