Casting A Cannon Is A Lot Harder Than You Think

We’ve seen backyard casting, and for the most part, we know what’s going on. You make a frame out of plywood or two by fours, get some sand, pack it down, and very carefully make a mold around a pattern. This is something else entirely. [FarmCraft101] is casting a bronze cannon. Sure, it’s scaled down a bit, but this is the very limit of what sanity would dictate a single person can cast out of molten metal.

This attempt at casting a cannon is more or less what you would expect from a backyard bronze casting experiment. There’s a wooden flask and a greensand mold, everything is tamped down well and there’s a liberal coating of talcum powder inside. This is a large casting, though, and this presented a problem: during the pour, the halves of the flask were only held together with a few c-clamps. This ended poorly, with molten bronze pushing against the mold and eventually flowing onto the garage floor. Doing this alone was perhaps a bad idea.

The failure of the mold meant some math was necessary, and after some quick calculations it was found that more than 300 pounds pushing the sides of the mold apart. A second pour, with the sides of the flask bound together with nylon straps, was much more successful with a good looking bronze cannon ready for some abuse with a wire wheel.

This is only the first video in the series, with the next videos covering the machining and boring out of the barrel. That’s some serious craft right there.

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Casting CNC Parts In Aluminium

When it comes to machining, particularly in metal, rigidity is everything. [Tailortech] had a homebuilt CNC machine with a spindle held in place by a plastic bracket. This just wasn’t up to the job, so the decision was made to cast a replacement.

[Tailortech] decided to use the lost PLA process – a popular choice amongst the maker crowd. The spindle holder was first sketched out, then modeled in Fusion 3D 360. This was then printed in PLA slightly oversized to account for shrinkage in the casting process.

The PLA part was then used to make a plaster mold. [Tailortech] explains the process, and how to avoid common pitfalls that can lead to problems. It’s important to properly heat the mold once the plaster has set to remove moisture, but care must be taken to avoid cracking or wall calcination. It’s then necessary to slowly heat the mold to even higher temperatures to melt out the PLA prior to casting. With the mold completed, it can be filled with molten aluminium to produce the final part. When it’s cooled off, it’s then machined to final tolerances and installed on the machine.

Lost PLA casting is a versatile process, and goes to show that not everything has to be CNC machined out of billet to do the job. It’s also readily accessible to any maker with a furnace and a 3D printer. If you’ve got a casting project of your own, be sure to let us know. Video after the break.

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How 5G Is Likely To Put Weather Forecasting At Risk

If the great Samuel Clemens were alive today, he might modify the famous meteorological quip often attributed to him to read, “Everyone complains about weather forecasts, but I can’t for the life of me see why!” In his day, weather forecasting was as much guesswork as anything else, reading the clouds and the winds to see what was likely to happen in the next few hours, and being wrong as often as right. Telegraphy and better instrumentation made forecasting more scientific and improved accuracy steadily over the decades, to the point where we now enjoy 10-day forecasts that are at least good for planning purposes and three-day outlooks that are right about 90% of the time.

What made this increase in accuracy possible is supercomputers running sophisticated weather modeling software. But models are only as good as the raw data that they use as input, and increasingly that data comes from on high. A constellation of satellites with extremely sensitive sensors watches the planet, detecting changes in winds and water vapor in near real-time. But if the people tasked with running these systems are to be believed, the quality of that data faces a mortal threat from an unlikely foe: the rollout of 5G cellular networks.

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Casting Car Emblems Via 3D Printing

Casting is a process that can be quite demanding for the first timer, but highly rewarding once the basic techniques are mastered. It then becomes possible to quickly and reliably produce metal parts en masse, and with impressive tolerances if the right method is chosen. [VegOilGuy] has been experimenting with lost PLA casting, and decided to see if it could be applied to car emblems. 

The process begins with 3D models of various car emblems, primarily sourced from Thingiverse. These are printed in PLA, with sprues added to assist with the casting process. The parts are sanded to avoid unsightly print lines on the finished product, and any voids filled with wax. The various emblems are then assembled onto a casting tree, with extra sprues added to improve metal flow with wax and further PLA parts.

The investment mold is then created with plaster, and baked to remove water and melt out the PLA. This is crucial, as any water left in the mold can react explosively with the molten aluminium bronze.  The mold is then filled with metal and then allowed to cool. The plaster mold is destroyed, and the parts can then be removed. Final processing involves a trip through a rock tumbler before final polish with sandpaper.

[VegOilGuy] gets impressive results, with the parts looking excellent in their bronze colour. This is an unconventional color for a car emblem, but it’s noted that this material is an excellent candidate for chrome plating to get a more OEM finish.

You might find your lost PLA casting experiments could benefit from the help of a microwave, too. Video after the break.

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Casting The Bed Of A CNC Machine In Granite

If you’re looking at CNC machines, or machine tools in general, heavier is better. That old drill press or mill made of a few hundred pounds of cast iron isn’t just better because it’s stood the test of time for a hundred years — greater mass equals less vibration. Thanks to modern epoxy resins, we now have a replacement for tons and tons of iron. Epoxy granite, or chips of granite bound together with epoxy resin, is a viable and very good base for CNC machines, mills, and other tools that are served well with a ton of mass. [Joerg Beigang] is building his own CNC router, and he’s building the base out of epoxy granite. Here’s how he’s doing it.

Before you pour epoxy into a mold, you’ll need to figure out how you’re going to attach your ways, linear rails, and ball screws. [Joreg] is bolting these parts to pieces of aluminum he cut on his home made panel saw before carefully drilling and tapping them to accept the linear rails. These aluminum plates were then mounted to the bottom panel of the mold, in this case melamine-coated plywood.

As you would expect, the most intricate part of this build isn’t globbing up a mold with epoxy resin. No, the real trick here is making sure the rails of the CNC are aligned perfectly before the epoxy goes in. This was done by bolting the linear rails to the mold box and checking everything with a dial indicator. Once that was done it was time to pour.

The bed itself is made of 18kg of epoxy granite, with the entire pour done in four batches. The best way to settle a big pour of epoxy granite is through vibration, just like concrete, but it looks as though [Joreg] is getting some good results by tamping it down with a few sticks. You can check out the first part of this build series below.

If we’ve captured your interest, it’s worth reminding you that this isn’t the first epoxy granite CNC machine we’ve featured.

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Casting Concrete With 3D Printed Molds

[Thomas Sanladerer] wanted to create some molds using 3D printing for concrete and plaster. He used a delta printer with flexible filament and documented his process in the video below.

If you’ve printed with flexible filaments before, you know you need an extruder that has a contained path. [Tom] borrowed a printer, but it didn’t have that kind of set up. The first step was to swap extruders with another printer.

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Weather Forecasting Clock Makes An Almighty Racket

The old-fashioned alarm clock was a staple of cartoons in years past, with loud clanging bells and slap-to-shutoff functionality. Despite being an excellent dramatic device, these classic timepieces began to lose favor to the digital clock radio, and, in more recent times, the smartphone alarm. However, [LenkaDesign] has come up with this excellent build that combines the best of the old and the new.

The build starts with an old alarm clock. The clockwork internals are removed, but the bells remain, powered instead by a brushed DC motor. An Arduino Nano is the brains of the operation, interfacing with the now-ubiquitous temperature, humidity and barometric pressure sensors. Time is displayed on a Nokia 5110 LCD screen of the type popular a decade ago when options for small hobby project displays were significantly more limited then they are today.

As a nice touch, an old circuit board lends a new face to this clock, with a trio of big chunky buttons to act as controls. The LCD uses attractive icons to help convey information, making the most of the graphical capabilities available. There’s even a rudimentary weather forecasting algorithm that uses barometric pressure changes to predict the likelihood of rain.

Overall, it’s a tidy build that promises to serve as a great alarm clock, given the high volume of the original bells. Alarm clocks have always been a hacker staple, but if you’re still struggling to get out of bed this fire bell build should rattle your fillings loose on a daily basis. Video after the break.

[Thanks to Baldpower for the tip!]

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