Learn How Impossibly Close-fitting Parts Are Actually Made

May 17, 2023 by Donald Papp 15 Comments

Most of us have seen those demonstrations of metal parts that mate together so finely that, once together, they have no visible seam at all. But how, exactly, is this done? [Steve Mould] has a video that shows and explains all, and we’ve never seen the process explained quite like he does.

The secret ingredient is wire EDM, or Electrical Discharge Machining, but that’s only one part of the whole. Wire EDM works a bit like a hot-wire cutter slicing through foam, but all by itself that’s not enough to produce those impossibly close-fitting parts we love to see.

EDM is capable of astounding precision in part because — unlike a cutting tool — nothing physically contacts the material. Also, there isn’t a lot of friction and heat causing small distortions of the material during the machining process. EDM is as a result capable of fantastically-precise cuts, but not invisible ones.

It’s pretty neat to see a water jet used to thread the fine wire through the workpiece.

In all good manufacturing, the capabilities (and limitations) of the tool are taken into account, and this is also true for making those close-fitting pieces. The hole and plug are actually made in two separate stages.

The hole is cut separately from the plug, and because EDM is capable of such finesse, the cuts can be made in such a way that they complement one another with near-perfection. After that, grinding and polishing takes care of the surface finish. The result is the fantastically-smooth and apparently seamless fitment we like so much.

The video is embedded below, and there are some great details about EDM and how it actually works in there. For example, we see how a wire EDM machine can use a jet of water to help thread the wire through a hole in the part to start a job, and we learn that the wire is constantly moving during the process.

As cool as wire EDM is, it is not magic and we’ve seen some pretty remarkable efforts at bringing the technology into the home workshop.
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DIY Adjustable Wrench? Nuts!

February 1, 2023 by Al Williams 12 Comments

What do you do if you want a tiny little adjustable wrench? If you’re [my mechanics] you build your own. Where do you get the stock metal? Well, he started with an M20 nut. A few milling operations, a torch, some pliers, and work with a vice resulted in a nice metal blank just the right size to make each part of the wrench, including a new nut for the adjustment.

Want to do this yourself? If you do, we hope you have a well-equipped machine shop. You should also be comfortable working with red-hot metal. Overall, it is an amazing piece of work, and you can watch the whole process in the video below.

Honestly, precision metalworking is a little out of our comfort zone. Like the recent wood bending we’ve seen, we always think, “Yeah, I could so do that!” Then we realize that we really couldn’t. But still fun to watch and maybe a few ideas we might be able to apply next time we have to bend a little metal.

The wrench is a scale model of a larger one, and it looks great. We would have liked to see it in use with a tiny nut, but we imagine it would work just fine. If you get excited about making things from a single piece of metal, may we suggest a nutcracker?

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Old Ham Wisdom Leads To Better Aluminum Painting

January 24, 2023 by Al Williams 50 Comments

When [bdk6] tried painting aluminum for electronic projects, he found it didn’t tend to stay painted. It would easily scratch off or, eventually, even flake off. The problem is the paint doesn’t want to adhere to the aluminum oxide coating around the metal. Research ensued, and he found an article in an old ham radio magazine about a technique that he could adapt to get good results painting aluminum.

Actually, paint apparently adheres poorly, even to non-oxidized aluminum. So the plan is to clean and remove as much aluminum oxide as possible. Then the process will convert the aluminum surface to something the paint sticks to better. Of course, you also need the right kind of paint.

The key ingredients are phosphoric acid and zinc phosphate. Phosphoric acid is found in soft drinks, but is also sold as a concrete and metal prep for painting. The zinc phosphate is part of a special paint known as a self-etching primer.

Cleaning takes soap, elbow grease, and sandpaper. The next step is a long soak in the phosphoric acid. Then you apply a few coats of self-etching primer and sand. Once it is all set, you can paint with your normal paint. That’s usually epoxy-based paint for [bdk6].

Of course, you can also dye aluminum while anodizing it. Soldering aluminum also has its challenges.

How To Achieve Knurling On A Flat Surface

October 15, 2022 by Lewin Day 20 Comments

Knurling is a popular way to finish handles of tools and other hardware, with a pattern of crossed lines rolled into metal to provide better grip and an attractive finish. It’s most commonly done on a lathe to round stock, but it can also be achieved on flat surfaces if you have the right tool. Of course, you can make one yourself.

The build is simple, and is based around by creating a special carrier out of a solid piece of steel. It’s a long bar has a space milled out to hold two wheels in the middle. A pair of off-the-shelf knurling wheels are then installed in the bar, with socket head bolts serving as axles.

With the tooling complete, it’s then a simple matter of installing the carrier bar in a lathe and running it back and forth over a flat workpiece. The workpiece is rolled back and forth to allow the wheels to do their work, while also being shifted horizontally to allow the entire flat surface to be worked over.

A nice knurled finish really can elevate the form and function of any tool or other piece of metal craftsmanship. We’ve explored how to create your own knurled knobs before, too.

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3D Printing Aids Metal Polishing

September 20, 2022 by Jenny List 9 Comments

While a machinist can put a beautiful finish on a piece of metal with their lathe or mill, to achieve the ultimate finish, a further set of polishing procedures are necessary. Successively finer abrasives are used in a process called lapping, which removes as far as possible any imperfections and leaves eventually a mirrored smoothness. It’s not without problems though, particularly at the edge of a piece it can result in rounded-off corners as the abrasive rubs over them. [Adam the machinist] has a solution, and he’s found it with a 3D printer.

To avoid the rounded edges, the solution involves fitting a piece of metal or wood flush with the surface to be lapped, such that the pressure doesn’t act upon the corner. This can be inconvenient, and the solution avoids it by 3D printing a custom piece that fits over the entire machined object providing a flat surface surrounding the edges. We see it being used with a demonstration piece that has three separate surfaces in the same plane to lap,something that would have been challenging without the 3D printed aid.

Lapping isn’t a process we see too often here. But it has cropped up as an extreme overclocking technique.

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Watching A Boat Get Welded Together Is Workshop ASMR

July 11, 2022 by Tom Nardi 33 Comments

If you’ve been on the Internet long enough to know about Hackaday, we’ll wager you’re familiar with the concept of autonomous sensory meridian response (ASMR) — a tingling sensation in the scalp that’s said to be triggered by certain auditory stimuli. There are countless videos on YouTube that promise to give you “the tingles” using everything from feather dusters to overly starched shirts, but for us, the tool of choice is apparently a Lincoln Electric Magnum PRO 100SG spool gun in the hands of [Bob].

You’ll want a friend to help wrangle the panels.

Admittedly we can’t promise the latest Making Stuff video will induce a euphoric physical sensation for all viewers, but at the very least, we think you’ll agree that watching [Bob] and his brother methodically welding together the twelve foot hull of what will eventually be a custom jet boat is strangely relaxing.

While we usually associate [Bob] with scratch builds, this time he’s actually working his way through a commercial kit. Sold by Jet Stream Adventure Boats, the kit includes the pre-cut aluminum panels that make up the hull, stringers, and top deck — niceties like a windshield and seats are offered as extras. The engine and jet drive need to be salvaged from an existing personal watercraft (PWC), but that will have to wait for a future video. For now, there’s a boat-load (get it?) of tack welding to be done.

The build process looks to go pretty smoothly, except for when they attempt to put the bow of the boat together. Unable to get the two side panels to meet properly, [Bob] eventually has to contact the manufacturer. After some back and forth, it turns out that a bit must have broken on the CNC when the hull panel went through, as a key cut was made nearly 8 inches (20 cm) too short. He was able to complete the cut with a jigsaw and continue on with the build, but we’re still scratching our heads at how this wasn’t caught before it got shipped out.

It won’t be the first homemade boat we’ve covered, but given [Bob]’s attention to detail, we’re particularly excited to see how this one develops in future videos. Especially since he’s ~~foolishly~~ bravely asked the commenters to come up with a name for his new craft.

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Hand-Built Metal Mouse Is Beautifully Engraved

April 26, 2022 by Lewin Day 19 Comments

Computer mice, like computers themselves, used to be built almost solely in hideous beige designs. These days, things are a bit more stylish, but they’re still largely following a simple plastic formula. [Uri Tuchman] decided to build a fancy metal engraved computer mouse for a little more style on the desktop.

The build starts by gutting a simple three-button scroll mouse, as there’s really no sense in reinventing the wheel where the electronics is concerned. The PCB inside is pulled out and assembled on a brass baseplate, along with standoffs and supports for the mouse wheel as needed. It’s paired with a hefty brass enclosure with a nice gentle slope to sit well in the hand. Or, as well as it can, given the square metal edges of the finished product.

The build is full of fun details, like [Uri] trying to form a hex shaft by hand, and the work that goes into the engraving is similarly impressive. In any case, it’s a build that would pair wonderfully with a proper steampunk keyboard. Alternatively, if you hate the idea of having to do all that engraving by hand, think about building your own CNC machine. Video after the break.

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