Integrating sphere test setup

Cannonball Mold Makes A Dandy Integrating Sphere For Laser Measurements

It’s an age-old riddle: if you have a perfect sphere with a perfectly reflective inner surface, will light bounce around inside it forever? The answer is pretty obvious when you think it through, but that doesn’t mean that you can’t put the principle to use, as we see with this homemade Ulbricht sphere for optical measurements.

If you’ve never heard of an Ulbricht sphere, don’t worry — it’s also known as an integrating sphere, and that makes its function a little more apparent. As [Les Wright] explains, an integrating sphere is an optical element with a hollow spherical cavity that’s coated with a diffusely reflective coating. There are two ports in the sphere, one for admitting light — usually from a laser — and one for light to exit. The light bounces around inside the sphere and becomes perfectly diffuse, and creates a uniform beam at the exit port.

[Les]’ need for an integrating sphere comes from the desire to measure the output of some of his lasers with his Raspberry Pi-based PySpectrometer. Rather than shell out for an expensive commercial integrating sphere, or turn one on a lathe, [Les] turned to an unlikely source: cannonball molds. The inside of the mold was painted with an equally unlikely ultra-white paint concocted from barium sulfate and PVA glue. With a few ports machined into the mold, it works perfectly to diffuse the light from his dye lasers for proper measurements.

Lasers can be an expensive hobby, but [Les] always seems to find a way to make things more affordable and just as good. Whether it’s homemade doorknob caps for high-voltage power supplies or blasting the Bayer filter off a cheap CCD camera, he always seems to find a way.

Continue reading “Cannonball Mold Makes A Dandy Integrating Sphere For Laser Measurements”

Hydrodipping 101

Style counts, and sometimes all it takes to jazz up the product of a 3D-printer is a 2D printer and a how-to guide on hydrographic printing.

Hydrographic printing, sometimes called hydrodipping, is a process for transferring graphics onto complex-shaped objects in one simple step. A design is printed on a special film which is then floated on the surface of a tank of water. The object to be decorated is carefully dipped into the water right through the film and the design wraps around all the nooks and crannies in one step.

The video tutorial below details the steps to hydrographic printing and outlines how easy the method has become with the availability of water transfer films for inkjet printers. The film is polyvinyl acetate, which is essentially white glue and hence quite soluble in water. The film dissolves and leaves the ink floating on the surface, ready for dipping.

The video lists quite a few tips for optimizing the process for 3D-printed parts and should let you decorate your parts quickly and easily. And once you master the basics, you might want to look at mathematically warping your design to hydrodip complex surfaces.

Continue reading “Hydrodipping 101”

Decorate Your 3D Prints With Detailed Hydrographic Printing

It’s like the old quip from [Henry Ford]: You can have your 3D prints in any color you want, as long as it’s one. Some strides have been made to bringing more color to your extruded goodies, but for anything beyond a few colors, you’re going to need to look at post-print processing of some sort. For photorealistic 3D prints, you might want to look into a simple hydrographic printing method that can be performed right on a printer.

If some of the prints in the video below look familiar, it’s because we covered the original method when it was presented at SIGGRAPH 2015. [Amos Dudley] was intrigued enough by the method, which uses computational modeling of complex surfaces to compose a distorted image that will be stretched back into shape when the object is dipped, to contact the original authors for permission to use the software. He got a resounding, “Nope!” – it appears that the authors’ institution isn’t big into sharing information. So, [Amos] hacked the method.

In place of the original software, [Amos] used Blender to simulate the hydrographic film as a piece of cloth interacting with the 3D-printed surface. This allowed him to print an image on PVA film that will “un-distort” as the object is dipped. He built a simple tank with overflow for the printer bed, used the Z-axis to dip the print, and viola! Photo-realistic frogs and globes.

[Amos]’ method has its limitations, but the results are pretty satisfying already. With a little more tweaking, we’re sure he’ll get to the point that the original authors did, and without their help, thank you very much.

Continue reading “Decorate Your 3D Prints With Detailed Hydrographic Printing”

Sewbo Robot Sews Up Automated Garment Manufacturing

While robots enter other industries in herds, the assembly of garments has long been a tedious, human privilege. Now, for the first time, a robot has sewn an entire, wearable piece of garment. Sewbo, an industrial robot programmed to tackle the tricky task, assembles clothes and makes it look easy.

Continue reading “Sewbo Robot Sews Up Automated Garment Manufacturing”

Full Color 3D Printer Upgrade Leaves Competition In The Dust

Most hobby 3D printers are based on FDM, extruding a single-color noodle of melted plastic to build up an object. Powder-based inkjet 3D printing allows you to print detailed, full-color models from a plaster-like material. The process uses ink and water droplets, dispensed from an inkjet print head to selectively fuse and color layers of a powdered binder material. When you see an offer for a 3D printed miniature version of yourself (or someone else), they are made with powder. [Aad van der Geest] wants to put this technology on your desktop with ColorPod, a kit that converts your FDM printer into a powder printer.

Continue reading “Full Color 3D Printer Upgrade Leaves Competition In The Dust”

MRRF: Innovating Extruders And Dissolvable Filament

Think laying down molten plastic on a 3D printer is as easy as squeezing plastic filament out of a hot tube? It’s not, and anyone who had a 3D printer in 2009 would tell you as such. There were hobbed bolts that stripped the plastic into a gooey paste, extremely large x carriages that made everything wobbly, and nothing worked as well as it does today.

Technology marches on, and this year’s Midwest RepRap Festival had people showing off the latest advances in pushing plastic, and something that hasn’t seen much use yet – dissolvable filament.

Continue reading “MRRF: Innovating Extruders And Dissolvable Filament”