Apple’s newest Mac Pro with its distinctive machined grille continues to excite interest, but until now there has been one question on the lips of nobody. It’s acquired the moniker “Cheese grater”, but can it grate cheese? [Winston Moy] set out to test its effectiveness in the kitchen with a piece of Pecorino Romano, a great cheese.
Of course, the video is not really about cheese grating, but about the machining process to create that distinctive pattern of intersecting spherical holes. He doesn’t have a real Mac Pro because nobody does as yet, so like others his approach was to reverse engineer the manufacturing process. He takes us through the entire thing and the rationale behind his decisions as he makes a 13-hole piece of Mac Pro-like grill from a billet of aluminium. It’s first roughly cut with a pair of decreasing-size end mills, then finished with a ball mill. He’s added an extra cut to round off the sharp edge of the hole that isn’t there on the Mac.
An unexpected problem came when he machined the bottom and the holes began to intersect, it was clear that they were doing so wrongly. Turning the piece over must be done in the correct orientation, one to note for any other would-be cheese-grater manufacturers. Finally the piece is blasted for a satin finish, and then anodised for scratch-resistance.
So, the important question must be answered: does it grate? The answer’s no, the best it can manage is something close to a crumble. He doesn’t seem bothered though, we get the impression he likes eating cheese whatever its form. The whole process is in the video below the break.
Apple released a monitor stand not so long ago with an eye-watering price tag, and in the resulting fuss you might almost be forgiven for missing the news that they also released a new computer. The distinctive grille on the new Mac Pro caused some interest among Hackaday editors, with speculation rife as to how it had been machined. It seems we’re not alone in this, because [J. Peterson] sent us a link to his own detailed analysis.
The key to the pattern lies in hemispherical holes milled part-way-through a piece of metal on a triangular tessellation, and intersecting with an identical set of holes milled at an offset from the other side. The analysis was done purely from online information as he doesn’t have a real Mac Pro, but using some clever trigonometry he is able to calculate the required offset as well as the hole depth. There are some STL files on Thingiverse, for the curious.
Should you wish to make your own copy of a Mac Pro grille you should therefore be able to use this information in programming a CNC mill to carve it from a piece of alloy plate. The interesting side of it from a manufacturing perspective though is that this is a complex shape that would be difficult to produce in numbers without either CNC or a very specialist one-off machine tool for this single purpose, and neither is a normal expenditure for a mere grille. Perhaps you might come close by rolling alloy plate between rollers whose profile matched the hole pattern, but in that event you would not equal the finish that they have achieved. Apple’s choice to use a relatively time-intensive CNC process in mass-production of a cosmetic part is probably in a large part a quality statement for their particular brand of consumer, but also sets a high bar to any would-be imitators. We applaud it for its engineering, even if we won’t be shelling out for that monitor stand.
People making videos about machining have a problem: the coolant gets everywhere. When you take a video to show the process of creating a device, the milky gunk that keeps everything cool gets all over your camera lens. AvE is experimenting with an interesting fix for this problem, with a self-cleaning camera lens. (Video embedded below, some salty language.) His prototype uses a spinning piece of clear PVC mounted on BB gun pellets, driven by compressed air. The camera can see through this spinning piece, but when the coolant hits the spinning piece, it is thrown off.
If you want a big CNC machine you need a strong, vibration-resistant base. They build bells out of metal, so that might not be the best if you want something that doesn’t shake. Epoxy granite is your best bet, but what epoxy granite is the best? That’s the question [Adam Bender] answered in a series of experiments that resulted in a great-looking CNC machine.
While this is a project that resulted in a completed base for a CNC machine, this is also an experiment to determine the best formula for creating your own epoxy granite. The purpose of the experiment is effectively to determine the best-looking epoxy granite and uses four variables in the composition of this composite. Play sand, gravel, dye (in the form of iron oxide and liquid epoxy dye), and two-part epoxy were used to create seven different samples. Samples using rock didn’t turn out that great and still had trapped air. This was true even if the epoxy was put in a vacuum chamber for degassing. The winning combination turned out to be a mix of 80% sand and 20% epoxy with a bit of black dye, vibrated for 30 minutes on a DIY shaker table.
With the correct formula for epoxy granite, [Adam] set up his mold and waxed everything liberally. The internal skeleton, or what the CNC machine will be bolted to, is assembled inside the mold and the epoxy is poured in. The result is fantastic, and an excellent base for a machine that turns metal into chips. You can check out the video below.
Here at Hackaday, we thought we’d seen every method of making PCBs: CNC machining, masking and etching with a variety of chemicals, laser engraving, or even the crude but effective method of scratching away the copper with a utility knife. Whatever works is fine with us, really, but there still does seem to be room for improvement in the DIY PCB field. To whit, we present rapid PCB prototyping with electrical discharge machining.
Using an electric arc to selectively ablate the copper cladding on a PCB seems like a great idea. At least that’s how it seemed to [Jake Wachlin] when he realized that the old trick of cutting a sheet of aluminum foil using a nine-volt battery and a pencil lead is really just a form of EDM, and that the layer of copper on a PCB is not a million miles different from foil. A few experiments with a bench power supply and a mechanical pencil lead showed that it’s relatively easy to blast the copper from a blank board, so [Jake] took the next logical step and rigged up an old 3D-printer to move the tool. The video below shows the setup and some early tests; it’s not perfect by a long shot, but it has a lot of promise. If he can control the arc better, this homebrew EDM looks like it could very rapidly produce prototype boards.
[Jake] posted this project in its current state in the hopes of stimulating a discussion and further experimentation. That’s commendable, and we’d really love to see this one move along rapidly. You might start your brainstorming by looking at this somewhat sketchy mains-powered EDM, or look into the whole field in a little more detail.
Light painting is the process of moving a light while taking a long-exposure photograph, which creates a sort of drawing from the path of the light source. It’s been done in one way or another since at least the early-to-mid 1900s, but modern hardware and methods have allowed for all kinds of new spins on this old idea. [Josh Sheldon] demonstrates just how true this is with the light painting he did for a gum ad, showing what’s possible with a single multicolor LED under CNC control combined with stop-motion animation techniques. The rest of the magic comes from the software. [Josh] designs the animations in Blender, and the paths are then exported and used as the instructions for his self-made Light Painting Machine. The machine therefore recreates the original animation with lights and camera and not a single computer-generated graphic.
For those of you who would like to know more, there are plenty of details on [Josh]’s Light Painting Machine on GitHub along with a more in-depth description of the workflow and software, so check it out.
The build gains X and Y axes by virtue of two salvaged DVD drives. The tray mechanisms come ready to go with stepper motors and lead screws already assembled, and make a great basis for a compact plotter. A wooden frame is constructed to hold everything together. The pen is held against the paper with a rubber band which helps the ballpoint to draw a nice dark line, with a servo used as a pen retract mechanism. An Arduino Uno with a stepper driver shield is then employed to run the show.