Engine Turning Aluminum The Easy Way

Engine turning, or jeweling, or guilloché, or a whole host of other names, is the art of polishing a pattern of circles on a piece of metal. You see it on fine watches, and you’ll see it on art-deco metal enclosures. [Ariel] decided to explore this technique and ended up getting good results with a pencil eraser and toothpaste.

The process begins with a piece of aluminum, in this case an aluminum Open Source Hardware logo. The only other required components are a number 2 pencil, some toothpaste, and any sort of rotary tool, in this case a drill press. Toothpaste is spread over the piece to be turned, and a pencil is put in the chuck. It’s just a matter of putting circles on the aluminum after that.

This is, incidentally, exactly how engine turning and jeweling are done in the real world. Yes, the tools are a bit more expensive, but you’re still looking at a somewhat soft tool scraping a fine abrasive into a piece of metal. The trick to engine turning comes in getting a consistent pattern on the piece, something that could easily be done with a CNC machine. If anyone out there feels like putting a pencil in the collet of a CNC router, we’d love to see the results.

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Anodize Aluminum Easily

We’ve all seen brightly-colored pieces of aluminum and can identify them as anodized. But what does that mean, exactly? A recent video from [Ariel Yahni] starring [Wawa] — a four-legged assistant — shows how to create pieces like this yourself. You can see [Wawa’s] new dog tag, below.

[Ariel] found a lot of how to information on using sulphuric acid, but that’s dangerous stuff. One web page we covered years ago, though, discussed a safer chemistry. The process requires lye and a common pool chemical used to decrease pH. Sodium hydroxide isn’t super safe, but it is much less problem to buy, store, and use than battery acid.

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Art Deco Control Panel Looks Out of Metropolis

Bakelite, hammertone gray finish, big chunky toggle switches, jeweled pilot lights – these are a few of [Wesley Treat]’s favorite retro electronics things. And he’ll get no argument from us, as old gear is one of our many weak spots. So when he was tasked by a friend to come up with some chaser lights for an Art Deco-themed bar, [Wesley] jumped at the chance to go overboard with this retro-style control panel.

Granted, the video below pays short shrift to the electronics side of this build in favor of concentrating on the woodworking and metalworking aspects of making the control panel. We’re OK with that, too, as we picked up a ton of design tips along the way. The control panel is all custom, with a chassis bent from sheet aluminum. The sides of the console are laminated walnut and brushed aluminum, which looks very chic. We really like the recessed labels for the switches and indicators on the front panel, although we’d have preferred them to be backlighted. And that bent aluminum badge really lends a Chrysler Building flair that ties the whole project together.

All in all, a really nice job, and another in a long string of retro cool projects from [Wesley]. We recently featured his cloning of vintage knobs for an old Philo tube tester, and we’ll be looking for more great projects from him in the future.

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Super Magnesium: Lighter Than Aluminum, Cheaper Than Carbon Fiber

We think of high tech materials as the purview of the space program, or of high-performance aircraft. But there are other niche applications that foster super materials, for example the world of cycling. Magnesium is one such material as it is strong and light, but it has the annoying property of burning in its pure state. Alloys of magnesium meanwhile generally don’t combust unless they are ground fine or exposed to high temperatures. Allite is introducing a new line known as “super magnesium” which is in reality three distinct alloys that they claim are 30% lighter than aluminum, as well as stronger and stiffer than the equivalent mass of that metal. They also claim the material will melt at 1200F instead of burning. To lend an air of mystique, this material was once only available for defense applications but now is open to everyone.

It’s a material that comes in three grades. AE81 is optimized for welding, ZE62 is better suited for forging, while WE54 is made for casting processes. Those names might sound like made up stock numbers, but they aren’t, as magnesium allows typically have names that indicate the material used to mix with the magnesium. A stands for aluminum, Z is for zirconium zinc, W is for yttrium, and E stands for rare earths. So AE81 is a mix of magnesium, aluminum, and some rare earth material. The numbers indicate the approximate amount of each addition, so AE81 is 8% aluminum and 1% rare earth.

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Sharpies and Glue Sticks Fight the Gummy Metal Machining Blues

“Gummy” might not be an adjective that springs to mind when describing metals, but anyone who has had the flutes of a drill bit or end mill jammed with aluminum will tell you that certain metals do indeed behave in unhelpful ways. But a new research paper seeks to shed light on the gummy metal phenomenon, and may just have machinists stocking up on office supplies.

It’s a bit counterintuitive that harder metals like steel are often easier to cut than softer metals; especially aluminum but also copper, nickel alloys, and some stainless steel alloys. But it happens, and [Srinivasan Chandrasekar] and his colleagues at Purdue University wanted to find out why, and what can be done about it. So the first job was to get up close and personal with the interface between a cutting tool and metal stock, to observe the dynamics of cutting. In a fascinating bit of video, they saw that softer metals tend to fold in sinuous patterns rather than breaking on defined shear planes.

Source: American Physical Society.

Having previously noted that cutting through Dykem, a common machinist’s marking fluid, changes chip formation in soft metals, the researchers tested everything from Sharpies to adhesive tape and even correction fluid, and found that they all helped to reduce the gumming action to some degree. Under their microscope they can clearly see that chips form differently once the cutting edge hits the treated surface, tending to act more brittle and ejecting rather than folding. They also noted a marked decrease in cutting force for the treated metal, and much-improved surface finish to boot.

Will Sharpies and glue sticks enter the book of old machinist’s tricks like gauge-block wringing? Only time will tell. But for now, this is a pretty fascinating bit of research that you might be able to put to the test in your shop. Let us know what you find in the comments.

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Fail of the Week: When Good Foundries Go Bad

Like many of us, [Tony] was entranced by the idea of casting metal, and set about building the tools he’d need to melt aluminum for lost-PLA casting. Little did he know that he was about to exceed the limits of his system and melt a hole in his patio.

[Tony]’s tale of woe begins innocently enough, and where it usually begins for wannabe metal casters: with [The King of Random]’s homemade foundry-in-a-bucket. It’s just a steel pail with a homebrew refractory lining poured in place, with a hole near the bottom to act as a nozzle for forced air, or tuyère. [Tony]’s build followed the plans pretty faithfully, but lacking the spent fire extinguisher [The King] used for a crucible in the original build, he improvised and used the bottom of an old propane cylinder. A test firing with barbecue charcoal sort of worked, but it was clear that more heat was needed. So [Tony] got hold of some fine Welsh anthracite coal, which is where the fun began. With the extra heat, the foundry became a mini-blast furnace that melted the thin steel crucible, dumping the molten aluminum into the raging coal fire. The video below shows the near catastrophe, and we hope that once [Tony] changed his pants, he hustled off to buy a cheap graphite or ceramic crucible for the next firing.

All kidding aside, this is a vivid reminder of the stakes when something unexpected (or entirely predictable) goes wrong, and the need to be prepared to deal with it. A bucket of dry sand to smother a fire might be a good idea, and protective clothing is a must. And it pays to manage your work area to minimize potential collateral damage, too — we doubt that patio will ever be the same again.

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Cheap Front Panels with Dibond Aluminium

The production capability available to the individual hacker today is really quite incredible. Even a low-end laser engraver can etch your PCBs, and it doesn’t take a top of the line 3D printer to knock out a nice looking enclosure. With the wide availability of these (relatively) cheap machines, the home builder can churn out a very impressive one-off device on a fairly meager budget. Even low volume production isn’t entirely out of the question. But there’s still one element to a professional looking device that remains frustratingly difficult: a good looking front panel.

Now if your laser is strong enough to engrave (and ideally cut) aluminum sheets, then you’ve largely solved this problem. But for those of us who are plodding along with a cheap imported diode laser, getting text and images onto a piece of metal can be rather tricky. On Hackaday.io, [oaox] has demonstrated a cost effective way to create metal front panels for your devices using a print service that offers Dibond aluminum. Consisting of two thin layers of aluminum with a solid polyethylene core, this composite material was designed specifically for signage. Through various online services, you can have whatever you wish printed on a sheet of pre-cut Dibond without spending a lot of money.

As explained by [oaox], the first step is putting together the image you’ll send off to the printer using a software package like Inkscape. The key is to properly define the size of the Dibond plate in your software and work within those confines, otherwise the layout might not look how you expected once the finish piece gets back to you. It’s also important to avoid lossy compression formats like JPEG when sending the file out for production, as it can turn text into a mushy mess.

When you get the sheet back, all you need to do is put your holes in it. Thanks to the plastic core, Dibond is fairly easy to cut and drill as long as you take your time. [oaox] used a step drill for the holes, and a small coping saw for the larger openings. The final result looks great, and required very little effort in the grand scheme of things.

But how much does it cost? Looking around online, we were quoted prices as low as $7 USD to do a full-color 4×4 inch Dibond panel, and one site offered a 12×12 panel for $20. For a small production run, you could fit several copies of the graphics onto one larger panel and cut them out with a bandsaw; that could drop the per-unit price to only a couple bucks.

We’ve seen some clever attempts at professional looking front panels, from inkjet printing on transparencies to taking the nuclear option and laser cutting thin plywood. This is one of those issues the community has been struggling with for years, but at least it looks like we’re finally getting some decent options.