Fridge Compressor Turned Into Capable Little Four-Stroke Engine

December 2, 2020 by Dan Maloney 18 Comments

Never underestimate the power of a well-stocked junk bin. Along with a TIG welder and mechanical ingenuity bordering on genius-level, all of which come to bear on this fridge compressor to four-stroke engine build.

The video posted by [Let’s Learn Something] is long, but watching it at double speed doesn’t take away much from the enjoyment. By using a piston-type compressor, a lot of the precision machining is already taken care of here. Adding the intake and exhaust valves, camshaft, timing chain, carburetor, and ignition system are still pretty challenging tasks, though. We loved the home-made timing chain sprockets, made with nothing more than a drill and an angle grinder. In a truly inspired moment, flat-head screws are turned into valves, rocker arms are fabricated from bits of scrap, and a bolt becomes a camshaft with built-up TIG filler. Ignition and carburetion are cobbled together from more bits of scrap, resulting in an engine that fired up the first time — and promptly melted the epoxy holding the exhaust header to the cylinder head.

Now, compressor-to-engine conversions aren’t exactly new territory. We’ve seen both fridge compressors and automotive AC compressors turned into engines before. But most of what we’ve seen has been simple two-stroke engines. We’re really impressed with the skill needed to bring off a four-stroke engine like this, and we feel like we picked up quite a few junk-box tips from this one.

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Manual To Hydraulic Press, With A Paint Sprayer

March 14, 2020 by Jenny List 11 Comments

A press can be one of the most useful additions to a workshop, once you have one you will wonder how you ever coped beforehand when it came to all manner of pressing in and pushing out tasks. An arbor press with a big lever and ratchet is very quick to use, while a hydraulic press gives much higher pressure but is extremely slow. [The Buildist] missed out on an arbor press, so turned his eye to improving the speed of his hydraulic one. The solution came from an unexpected source, an airless paint sprayer that had come his way because its valves were gummed up with paint.

An airless paint sprayer is simply a high pressure pump that supplies paint to a nozzle, and that pump is easily repurposed to pump oil instead of paint. Testing revealed it could produce a pressure of 3000 PSI, which would be plenty to move the hydraulic jack even if the hand pump would be needed to finish the job when higher force was required.

What follows over two videos is a masterclass in hydraulic jacks, as he strips down the jack from his press, and modifies it not only to take an input from the pump, but also to run inverted by the addition of an oil reservoir pick-up pipe. Along the way we learn a few useful gems such as the fact that a grease gun pipe is the same as a hydraulic pipe, but much cheaper.

The result is a jack that extends quickly, and has the pressure to do most pressing tasks without the hand assistance. He crushes a drinks can for effect, then pinches the end of a piece of pipe, because given a press, why wouldn’t you! Take a look at both videos below the break.

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See How Wildly Different Air Conditioners Can Be (On The Inside)

December 15, 2019 by Donald Papp 16 Comments

Air conditioners are easy to take for granted. From refrigerators to climate control, most of us would miss them dearly if they disappeared. That’s part of what draws [Josh Levine]’s interest in air conditioners, and he has provided an interesting tour of several different units and how different they can be, despite all working in basically the same way.

That white PCB is crucial (for running the bluetooth speaker and LED flashlight, that is.)

One way that air conditioners try to stand out is by being quiet, and the bulk of noise comes from the fans and the compressor. One unit (the Haier Serenity) aimed to be the quietest unit possible, but while this effort had mixed results at best it is still interesting to see [Josh] give a tour of the different ways they tried to reduce noise (YouTube, embedded below). Noise-limiting elements include the unusual step of using separate motors for the indoor and outdoor fans, and even little counterweights to ensure they are perfectly balanced, just like wheel weights on automobile tires.

Another notable air conditioner is the Zero Breeze, a portable unit that was the product of a Kickstarter campaign. Features included (either bizarrely or predictably, you be the judge) a bluetooth speaker and an LED flashlight. [Josh] more than half suspected the product would never actually ship, but was pleasantly surprised. Not only did it deliver, it turned out to be a pretty nice design with only a couple of mildly head scratching moments (YouTube, also embedded below).

There are a few more to check out in the roundup on [Josh]’s web site, which he also compares and contrasts with his own DIY unit which we featured in the past.

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Building An Engine With An A/C Compressor

December 4, 2019 by Lewin Day 38 Comments

Air conditioning compressors aren’t exactly a mainstay of the average hacker’s junk box. Typically, they’re either fitted to a car to do their original job, or they’re on the bench getting refurbished. However, with the right mods, it’s possible to turn one into a functioning internal combustion engine.

The build starts by disassembling the compressor, which contains three double-sided pistons. The housing is drilled with ports to allow gas to flow into and out of the cylinders, as well as to transfer from one side of the piston to the other. Acrylic end plates are fitted to the assembly. One end acts as an intake manifold, delivering air and fuel to the cylinders. The other side acts as the cylinder head, mounting the sparkplugs. Everything is then connected with acrylic tubing and a small square section of acrylic is turned into a carburetor to supply the air-fuel mix. Ignition is handled by coils triggered by the movement of the flywheel.

After an initial failure due to the acrylic manifold cracking, a stronger part is fabricated, and the engine bursts into life. The acrylic end caps give a great view of the combustion process in action. We’d love to see the a dyno graph on how much power and torque the unit puts out, or to see it hooked up to a bicycle or cart.

We’ve seen others attempt their own engine builds, too. If you’ve got an unconventional engine build of your own, be sure to let us know. Video after the break.

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Air Compressor From Fridge Parts Gets An Upgrade

May 15, 2019 by Lewin Day 21 Comments

Air compressors are often loud, raucous machines – but they don’t have to be. [Eric Strebel] built a remarkably quiet compressor using parts salvaged from an old fridge. After several years of use, it was due for an upgrade (Youtube link, embedded below}.

While performance of the original setup was good, [Eric] desired a compressor with more capacity for his resin casting activities. A 15 gallon air tank was sourced from a damaged Craftsman brand compressor, and pressed into service. The build involved plenty of sheet metal work to mount the various components, as well as an upgrade to the pressure regulator.

During the refit, [Eric] takes the time to answer questions from the audience about his original build. He notes that the fridge compressor has worked well without using any noticeable amount of oil, and that there was a problem with water build up in the original tank which has been solved in the new rig.

It’s a great example of building your own tools, which can provide years of service if done right. Check out our write up on [Eric]’s first build, or his work on photogrammetry. Video after the break.

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DIY Air Conditioner Built From Weird Donor Appliance

April 7, 2019 by Al Williams 64 Comments

There are some parts of the world where living without air conditioning borders on unthinkable. But in more moderate climates, it isn’t all that unusual. [Josh’s] apartment doesn’t have central air conditioning — the kind that connects to a forced-air heating/cooling system. It does, though, have a water circuit for air conditioning, so he decided to hack a few experimental air conditioners.

He’s not starting completely from scratch. The two attempts he made at building his AC came from donor parts. The successful one started out as a hot water heater. The very first attempt didn’t quite work as well, using a refrigerator compressor and an evaporator from a baseboard heater. The flow control through the heat exchanger turns out to be very tricky, so [Josh] claims he mostly got ice right at the inlet and minimal cooling through the evaporator.

The more successful one works better but still has a problem with the evaporator freezing that he’s trying to solve. He’s looking for suggestions on how to make it work better. As much as we like a good hack, our advice is to move to a different apartment building.

We’ve seen other homemade coolers, but they are more like swamp coolers. If you just need to cool your desk, you might just get some ice in a metal can.

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Hacked Vacuum Chamber Won’t Suck A Hole In Your Budget

August 4, 2018 by Dan Maloney 38 Comments

There’s nothing like a true hack, where something useful is concocted from bits of scrap and bargain store finds. Builds like these are much more than the sum of their parts, especially when they result in a useful tool, like this DIY vacuum chamber that’s good for all sorts of jobs.

Everything [Black Beard Projects] used to accomplish this build is readily available almost everywhere in the world, although we have to note that appliance recycling efforts and refrigerant recovery programs have made it somewhat harder to lay hands on things like the old fridge compressor used here. The big steel cooking pot is an easy thrift store find, though, and while [Black Beard] used high-quality stainless fittings and valves to plumb the chamber, pretty much any cheap fittings will do.

The one sketchy area of the build is the plexiglass sheet used for the chamber top, which seems a little on the thin side to us. You can see it flexing in the video below as vacuum is pulled; it survived, but we can see it failing catastrophically at some point. We stand ready to be reassured in the comments. Still, it’s a tidy build with a few nice details, like wiring a switch into the old start capacitor box and using car door edge protector as a gasket on the chamber.

Fridge compressor hacks are standard fare, of course, being used to make everything from air compressors to two-stroke engines. Sometimes they’re even used to keep things cool too.

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