Beautiful DIY Spot Welder Reminds Us We Love 3D Printing

[Jim Conner]’s DIY tab spot welder is the sweetest spot welder we’ve ever seen. And we’re not ashamed to admit that we’ve said that before.

The essence of a spot welder is nothing more than a microwave oven transformer rewound to produce low voltage and high current instead of vice-versa. Some people control the pulse-length during the weld with nothing more than their bare hands, while others feel that it’s better implemented with a 555 timer circuit. [Jim]’s version uses a NodeMCU board, which is desperately overkill, but it was on his desk at the time. His comments in GitHub about coding in Lua are all too familiar — how do arrays work again?

Using the fancier microcontroller means that he can do fancy things, like double-pulse welding and so on. He’s not even touching the WiFi features, but whatever. The OLED and rotary encoder system are sweet, but the star of the show here is the 3D printed case, complete with soft parts where [Jim]’s hand rests when he’s using the welder. It looks like he could have bought this thing.
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Customize Forstner Bits For Fidget Spinner Explosions

[Matthias Wandel] is a woodworker par excellence. He’s the guy behind all those wooden gear contraptions, he made cove molding on a table saw, and if the phrase, ‘don’t do this unless you know what you’re doing’ applies to anyone, it applies to [Matthias]. Now he’s getting into the fidget spinner craze, but there’s a problem in the workshop: [Matthias] couldn’t find the right sized drill bit, so he modified a Forstner bit to contain the heart of a spinner.

[Matthias] has a few roller skate bearings, which are 22mm in diameter. However, the closest drill to this size was 7/8″, or 22.23mm. A drill can be ground down, so the bit was chucked into a hand drill and taken over to the bench grinder. As with most things [Matthias] demonstrates, you shouldn’t do this unless you know what you’re doing. [Matthias] does.

With the bit ground down to 22mm, [Matthias] drilled a hole in a piece of wood, inserted the bearing, and completed an epic quest that was his destiny. There is no use for fidget spinners, so [Matthias] decided to make this one explode. After cutting several notches in this wooden spinner, [Matthias] applied shop air liberally and spun the spinner up until it fell apart.

You can check out the video of the fidget spinner carnage below, or check out [Matthias]’ write-up here.

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Dual Trace Scope 1939 Style

If you buy a serious scope these days, it is a good bet it will have at least two channels. There is a lot of value to being able to see two signals in relation to one another at one time. Even though the dual-trace oscilloscope goes back to 1938, they were uncommon and expensive for many years. [Mr. Carlson] found a device from 1939 that would turn a single channel scope into a dual trace scope. In 1939, that was quite the engineering feat.

Today, a dual trace scope is very likely to be digital. But some analog scopes used CRTs with multiple beams to actually draw two traces on the same screen. Most, however, would draw either one trace followed by the other (alternate mode) or rapidly switch between channels (chopper mode). This Sylvania type 104 electronic switch looks like it takes the alternate approach, switching between signals on each sweep using vacuum tubes. You can see the device in action in the video, below.

The inputs and outputs of the device are just simple binding posts, but the unit looked to be in good shape except for the power cord. [Mr. Carlson] does a teardown and he even traced out a hand-drawn schematic. Fair warning. The video is pretty long. If you want to get right to the switch actually driving a scope, that’s at about one hour and seven minutes in.

We doubt we’ll see a tube-based Quake game anytime soon. If you want to get into restoring old tube-based gear yourself, you could do worse than read about radio restoration.

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Overhead Trolley Helps Clear The Air Over CNC Router

[Frank Howarth] has a shop most woodworkers would kill for, stuffed with enough tools to equip multiple hackspaces — four radial-arm saws alone! But while the CNC router in the middle of the shop, large enough to work on an entire sheet of plywood, is a gem of a machine, it was proving to be a dusty nightmare. [Frank]’s solution was as unique as his workspace — this swiveling overhead dust extraction system.

The two-part video below shows how he dealt with the dual problems of collection and removal. The former was a fairly simple brush-bristle shroud of the type we’ve featured before. The latter was a challenge in that the size of the router’s bed — currently 8′ but soon to be extended to 12′ — and the diameter of the hoses needed to move enough air made a fixed overhead feed impractical. [Frank]’s solution is an overhead trolley to support the hoses more or less vertically over the router while letting the duct swivel as the gantry moves around the work surface. There were a few pitfalls along the way, like hoses that shorten and stiffen when air flows through them, but in the end the system works great.

Chances are your shop is smaller than [Frank]’s, but you still need to control the dust. This dust collector for a more modest CNC router might help, as would this DIY cyclonic chip separator.

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Drill Press To Mill Conversion

Every time we look at the little short Z axis of our CNC mill, we think about converting a drill press to a mill. In theory, it seems like it ought to be easy, but we never quite get around to it. [AvE] did get around to it and made his usual entertaining video about it that you can see below. If you haven’t seen any of [AvE’s] videos before, be warned: there is a little colorful language in a spot or two.

This isn’t a CNC mill, by the way, although we suspect you could convert it. Essentially, he adds a spindle and an XY table to a Ryobi drill press. It sounds simple, but getting everything to work did take a few tricks, including a blow torch.

Actually, turns out the blow torch didn’t really do it, but we won’t spoil the final resolution to the problem. Once it was resolved, though, he did manage to do some actual milling, accompanied by some music we wouldn’t associate with [AvE].

Although billed as a “poor man’s” build, the XY table alone was about $200. So add in the cost of the drill press, the spindle, and the mill and this is still a fair chunk of cash. We’d love to see it compared to a Harbor Freight milling vise. We suspect the Harbor Freight vise might not be as good, but is the difference worth the $130 difference in price?

We’ve seen this kind of conversion done before without the colorful language. If you do this conversion and want some practice, why not build a magnetic carabiner?

3D-Printed Turbine Rotary Tool Tops 40,000 RPM

For your high speed, low torque needs, few things beat a rotary tool like a Dremel. The electric motor has its limits, though, they generally peak out at 35,000 rpm or so. Plus there’s the dust and the chips to deal with from whatever you’re Dremeling, so why not kill two birds with one stone and build a turbine-driven rotary tool attachment for your shop vac?

Another serious shortcoming of the electric Dremels that is addressed by [johnnyq90]’s 3D-printed turbine is the lack of that dentist’s office whine. His tool provides enough of that sound to trigger an attack of odontophobia as it tops out at 43,000 rpm. The turbine’s stator and rotors are 3D-printed, as is the body, inlet scoop, and adapter for the vacuum line. A shaft from an old rotary tool is reused, but a new one could be turned pretty easily. The video below shows the finished tool in action; there’ll no doubt be objections in the comments to ingesting dust, chips, and incandescent bits of metal, but our feeling is that the turbine will hold up to these challenges pretty well. Until it doesn’t, that is.

We like [johnnyq90]’s design style, which you may recall from his micro Tesla turbine or nitro-powered rotary tool. He sure likes things that spin fast.

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Custom Aluminum Wheels Teach A Thing Or Two About Casting

For some mobile projects like small carts or rolling cabinets, your standard casters from Harbor Freight will do just fine. But some projects need big, beefy wheels, and these custom cast aluminum wheels certainly make a statement. Mostly, “Watch your toes!”

To be honest, [Brian Oltrogge]’s wheels are an accessory in search of a project, and won’t be crushing feet anytime soon. He made them just to make them, but we have no beef with that. They’ve got a great look that hearkens back to a time when heavy metal meant something else entirely, and things were made to last. Of course, being cast from aluminum sort of works against that, but there are practical limits to what can be done in the home foundry. [Brian] started with a session of CAD witchcraft followed by machining the cores for his molds. Rather than doing this as lost foam or PLA, he milled the cores from poplar wood. His sand mix is a cut above what we usually see in home-brew sand casting — sodium silicate sand that can be cured with carbon dioxide. All his careful preparation meant the pour went off without a hitch, and the wheels look great.

We’ve featured quite a few metal casting projects recently, some that went well and some that didn’t. [Brian] looks like he knows what he’s doing, and we appreciate the workmanship that he puts on display here.

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