The Cheese Grater In Fusion 360

By now you will all have heard so much about the grille on Apple’s new “Cheese grater” Mac Pro that you might think there was nothing more to say. Before we move on though there’s one final piece of work to bring to your attention, and it comes from [Andy Pugh]. He’s replicated the design in Fusion 360, and used it to produce rather an attractive Raspberry Pi case.

It seems that for Fusion 360 users the problem lies in that package’s method of placing spheres which differs from that of some other CAD software. Using the page linked in our previous coverage of the grille he’s taken its geometry information and produced a video detailing every step in recreating it for Fusion 360. This is where following someone who really knows your CAD package pays dividends, because we suspect it would take us days to figure out some of the tricks he shows us.

The result is the Raspberry Pi case, which is for the Pi 3 and others like it. Sadly we couldn’t break our embargo and tell him about the Pi 4 and its different connector layout, but we’re guessing a halfway competent CAD operator could put together a Pi 4 case. Andy’s files can be found on Thingiverse, so you can all make one for yourselves.

Andy’s appeared here before a few times, not least for his Ner-A-Car motorcycle, and for designing a Robot Wars robot.

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Does The Cheese Grater Do A Great Grate Of Cheese?

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.

For more Apple grille examination, take a look at this mathematical analysis.

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This Upgraded Power Wheels Toy Is Powerful Enough To Need Traction Control

A Lamborghini Aventador Is beyond the budget of all but the most well-heeled fathers, but [CodeMakesItGo] came pretty close with a gift for his young son. It was a Lamborghini Aventador all right, but only the 6V Power Wheels ride-on version. As such it was laclustre even for a youngster in its performance, so he decided to give it a 12V upgrade. This proved to have enough grunt to cause wheelspin on those hard plastic wheels, so a further upgrade was a traction control system featuring a NodeMCU. No other child has such a conveyance!

Veterans of the Power Racing Series or Hacky Racers might have expected to see a Chinese motor controller in the mix, but instead he’s used a set of relays for simple on-off control. The traction control has a pair of 3D-printed sensor wheels that operate upon a corresponding  pair of optocouplers to provide feedback to the NodeMCU. A set of different drive options were tried, with finally an H-bridge board being found to be most reliable.

The video below the break shows the hardware, and goes into some detail on the software. The NodeMCU’s WiFi is used to provide some tweakability to the system on the go. The traction control turns out to lower the standing start speed a little, but makes the machine more controllable by its driver. he certainly seems happy with his toy!

Long-time readers will know this isn’t the first Power Wheels upgrade we’ve shown you.

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A TTL CPU, Minimising Its Chip Count

By now we should all be used to the astonishing variety of CPUs that have come our way created from discrete logic chips. We’ve seen everything from the familiar Von Neumann architectures to RISC and ever transport-triggered architecture done in 74 TTL derivatives, and fresh designs remain a popular project for many people with an interest in the inner workings of a computer.

[Warren Toomey]’s CSCvon8 is an interesting machine that implements an 8-bit computer with a 64-bit address space using only 17 chips, and without resorting to any tricks involving microcontrollers. It implements a fairly conventional Von Neumann architecture using TTL with a couple of tricks that use modern chips but could have been done in the same way in decades past. Instruction microcode is stored in an EEPROM, and the ALU is implemented in a very large EPROM that would probably once have been eye-wateringly expensive. This in particular removes many discrete TTL chips from the total count, in the absence of the classic 74181 single-chip part. To make it useful there is 32k each of RAM and EEPROM, and also a UART for serial access. The whole is brought together on a neat PCB, and there is a pile of demo code to get started with. Everything can be found in the project’s GitHub repository.

At the start of this article we mentioned a couple of unconventional TTL CPUs. The transport triggered one we featured in 2017, and the RISC one is the Gigatron which has appeared here more than once.

Home Made Gears Save This Shredder

It’s very likely that a majority of readers will have had a gear fail in a piece of equipment, causing it to be unrepairable. This is a problem particularly with plastic gears, which shed teeth faster than a child who has discovered the financial returns of the Tooth Fairy.

[BcastLar] has a shredder with a gear that has, well, shredded. He’s posted a video series over three parts that while ostensibly about fixing his shredder, is in reality a three-part tutorial on how to create custom gears using FreeCAD. While the principles of a gear are readily apparent to most observers their intricacies hide significant complexity which he does a great job of explaining. How to measure the parameters of a given gear, explaining mysteries such as pitch angle or beta, he breaks everything down in easy to understand steps.

His tool of choice is FreeCAD, and while he explains that FreeCAD has the ability to make gears from scratch the tool employed in the videos is the Gear Workbench plugin. He shows how this software removes the complexity of creating a gear, and shows the process on his screen as he creates the custom shredder part.

Finally, the process of 3D printing the gear is explained. You might ask why not machine it, to which he responds that tooling for non-standard gear profiles is prohibitively expensive. We’ve placed all three videos below the break, and we think you might want to make yourself a cup of tea or something and work through them.

Thanks [Andy Pugh] for the tip.

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A Two Metre Bridge Across The Atlantic For The First Time

Amateur radio is a pursuit with many facets, some of which hold more attention than others for the hacker. Though there have been radio amateurs for a century it still has boundaries that are being tested, and sometimes they come in surprising places.

A recent first involved something you might consider a done deal, a transatlantic radio contact. On June 16th, for the first time ever a contact was made between the operators [D41CV] and [FG8OJ] at 3867 km across the Atlantic ocean from the Cape Verde Islands to Guadeloupe, on the 2 metre (144 MHz) band. If this means little to you it’s worth explaining that the 2 m band is a VHF band, with a range normally similar to that you’d expect from an FM broadcast station. Nobody has ever done this before, so it’s a significantly big deal.

Before you dismiss this as merely some radio amateur chasing grid squares and thus not particularly impressive, it’s worth talking about both the radio mode used and the unusual atmospheric conditions that were carefully sought for the achievement. The attempt was made to coincide with a prediction of transatlantic tropospheric ducting, and the mode employed was [Joe Taylor K1JT]’s FT8. This is a digital mode designed especially for weak-signal and long-distance work. It is theorised that the propagation was so-called surface ducting, in which the signal travels and is reflected between the surface of the sea and a relatively low-level reflective layer of atmosphere. The contact really pushed the limit of what is possible with radio, and while you wouldn’t use it for a voice conversation, proves that there are new tricks in an old hobby for the hardcore experimenter.

We’ve talked about [K1JT] modes crossing the Atlantic before, but of course not at such a high frequency.

Coffee Tables, Computers, And Railways

If you were a British kid at any time from the 1950s to the 1980s, the chances are that your toy shop had a train set in it. Not just any train set, but a full model railway layout in a glass case roughly the size of a pool table, with a button that when pressed started a timer and set a little tank engine off on a circuit with a pair of coaches. Magical for a generation raised on black-and-white TV, but probably not something that would cut it with today’s youth. A modern take on the glass-case layout comes from [Jack Flynn], who has created a coffee table with an automated and computerised N-gauge railway layout inside it. And this is definitely a railway rather than a railroad, the main locomotive is a Brush Type 4, a British Rail Class 47 diesel.

The modelling is a work of art, with a slightly idealised British street scene in an oval of double track against a backdrop of a rocky hillside. In the hill is an unexpected surprise which you can see on the video we’ve  placed below the break, and beneath it lie the electronics. A Teensy handles the track switching and all the various LED lights around the board, a Sprog DCC controller takes care of the trains, and overseeing everything is a Raspberry Pi running some custom software in Python with a web interface for control. We probably wouldn’t be able to resist a bit of remote-control railway action if our coffee table had a layout like this one!

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