Transparent Cylinder Shows You What You Otto Know About 4 Cycle Engines

When we think of a typical four stroke internal combustion engine, we think of metal. And for any type of longevity or performance, that’s certainly the right choice. But [Integza] wanted to see what happens inside a 4 stroke engine, and it wasn’t enough to see it from a transparent cylinder head. No, he wanted to see it in the cylinder itself. Thanks to advances in material sciences, he got his wish as seen in the video below the break.

While researching possible transparent materials to use as a cylinder on his model engine, he learned about resin polishing. Combining his newly learned resin polishing knowledge with his knowledge of 3D printing, [Integza] printed a new cylinder and polished the resin until it was transparent. The engine ran, but misfired terribly.

The experiment progressed into trying different fuels and learning the differences between them, as well as uncovering a new-to-him mystery: Why was the engine misfiring, and why did the different fuels act so dramatically different? Indeed, more learning and more experimenting is needed. But if you want to see the great sight of watching combustion take place in slo-mo, you have to check out the video below.

3D printing has come a long way in a short time, and may even hold the key to practical scramjets for hypersonic aircraft.

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3D Printing A Water-Cooled Jet Engine?

Everybody knows the trick to holding a candle flame to a balloon without it bursting — that of adding a little water before the air to absorb the heat from the relatively cool flame. So [Integza], in his quest to 3D print a jet engine wondered if the same principle could applied to a 3D printed combustion chamber. First things first, the little puddle of water was replaced with a pumped flow, from an external reservoir, giving the thin plastic inner surface at least a vague chance of survival. Whilst this whole plan might seem pretty bonkers (although we admit, not so much if you’ve seen any of other videos in the channel lately) the idea has some merit. Liquid cooling the combustion jacket is used in a great many rocket engine designs, we note, the German WWII V2 rocket used this idea with great success, along with many others. After all, some materials will only soften and become structurally weak if they get hot enough in any spot, so if it is sufficiently conductive, then the excess heat can be removed from the outer surface and keep the surface temperature within sensible bounds. Since resin is a thermoset plastic, and will burn, rather than melt, this behaviour will be different, but not necessarily better for this application.

The combustion chamber itself didn’t burn

The issue we can see, is balancing the thermal conductivity of the resin wall, with the rate of cooling from the water flow, whilst making it thick enough to withstand the pressure of combustion, and any shock components. Quite a complicated task if you ask us. Is resin the right material for the job? Probably not, but it’s fun finding out anyway! In the end [Integza] managed to come up with a design, that with the help of a metal injector separator plate, survived long enough to maintain some sort of combustion, until the plate overheated and burned the resin around its support. Better luck next time!

This isn’t the first time attempting to use 3D printed resin for such an application, here’s an attempt to use the air-multiplier type setup with a combustion chamber. Of course making a combustion chamber from a toilet roll holder is far more sensible, just as [colinfurze] will attest, don’t try this at home folks!

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Open Database Shares Resin 3D Printing Settings

3D printing is much like CNC milling or welding or just about any physical manufacturing process, in that good results fundamentally come down to having the right settings. In an effort to aid those working in the resin printing space, [Adam Bute] has put together a community database of resin printing settings.

The site has sections relevant to a variety of resin 3D printers, sorted by manufacturer. Those eager to find the right settings for their given resin and printer merely need to click through and look up the appropriate data. The settings are crowdsourced, provided by manufacturers, community members, and users of [Adam]’s Maker Trainer website.

While it’s still important to run validation tests on a resin printer to get the best results, having a community-sourced list of settings can help users get up and running much more quickly than they otherwise might. It appears that community contributions can’t directly be made yet, but we suspect such a feature is in the works.

We’ve seen similar material databases before for melty-plastic printers, and those have proven to be valuable to the community. We’re sure this resin database will be received in much the same way. If you know about other great resources for printing tips and tricks, do drop us a line!

Super Tough Resin Is Literally As Tough As Nails

Resin printing still seems to polarize opinions amongst hacker types, with some considering such machines a good tool for the right tasks, and some just plain rejecting them outright. There are many arguments for and against, but like fused deposition modeling (FDM) machines, resin printers are improving in leaps and bounds — and so is the liquid resin itself. Nowadays low-odor resins are common, colors and finishes are varied, and now thanks to some dedicated development work, the brittleness that often characterizes such prints it being addressed. [Mayer Makes] has designed a super tough “engineering resin” that he demonstrates is so tough, you can print a nail and hammer it into a block of wood! (Video, embedded below, if you don’t believe it.)

This particular resin is destined for mixing, given its natural cured shade is a kind of greenish-grey, but it does have a neat trick of presenting a definite yellowish hue when not fully cured, which is very helpful. This is particularly useful when removing support structures as you can use the color change during the curing process to judge the right moment to snap off the thicker sections, minimizing the risk of damaging the print. The resulting printed part is also tough enough to withstand subsequent traditional post-processing, such as milling, giving greater final finishing tolerances. Try doing that with an FDM print.

One of the neat things about resin chemistry is that you can simply mix them in their liquid form to tune the resin properties yourself and they can also be colored with specially formulated dyes without affecting the other properties too much, so this new super-tough resin gives prototypers yet another tool in their resin armory.

Thinking of taking the plunge and giving resin printing a try? Checkout our handy guide which may give you a leg up! If that doesn’t swing it for you, you could always use resin to help smooth out your FDM prints. It’ll probably still smell funny, mind.

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3D Printed Parts Hold Up To Steam Heat

Steam turbines are at the heart of all manner of industrial machinery, particularly that used for power generation. [Integza] decided he needed to better understand this technology, and decided to build one himself – using 3D printing, at that. 

First, a steam source was needed, with a pressure cooker on an electric stove pressed into service. The steam was passed out via a nozzle printed in resin, which better resists heat than most FDM-printed parts. Similarly, a turbine wheel was printed in resin as well, with the steam outlet pointed directly at its vanes.

To really stress test the parts, more steam was required.  To achieve this, hydrogen peroxide was pumped through a manganese dioxide catalyst impregnated into steel wool to create steam. This made an absolute mess, but the printed parts nevertheless survived.

The steam turbine didn’t do any useful work, but was able to survive the high temperatures at play. We’d love to see such a device actually used to bear some load, perhaps in some sort of 3D printed power generating turbine design.

Alternatively, if you prefer your steam turbines more classically driven, consider this build. Video after the break.

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Resin Stacking Proves Messy And Difficult

3D printers are typically the tool you use when you want a one-off quick prototype. However, more and more, they’re being used to produce things in quantity. [Uncle Jessy] decided to try out the resin stacking technique in order to quickly produce many figurines on his resin printer. However, not everything went exactly to plan.

The technique is simple. The idea is to produce many copies of an object in a single continuous print on a resin 3D printer. To achieve this, the object is cloned many times, and scaffolding is created to allow the stacking of multiple objects on top of each other. This must be done carefully to avoid ruining the geometry of the object, and similarly to support material, uses more resin in the process.

[Uncle Jessy] experimented several times, but ran into multiple issues with the process when trying to print out some small Magneto figurines. An initial experiment using a raft failed when the print fell off the build plate. With the raft removed, the second print failed as the scaffolding didn’t print quite right. Further tweaks and beefing up the scaffold improved things, and [Jessy] managed to print 93 figurines in a single operation.

It’s a useful technique if you want to print a ton of models on a resin printer in as short a time as possible. However, expect to spend plenty of resin as you refine the technique. You’ll also need a big wash tank to clean the prints during post-processing. Video after the break.

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The Trials And Tribulations Of SLA Printing A Portable Wii Handheld

The G-Boy kit revolutionized the subculture around building portable home consoles, allowing an entire Wii to be crammed into a form factor the size of a original Game Boy. [Chris Downing] is no stranger to the field, and sourced a G-Boy kit of his own to build it to the best of his abilities. (Video embedded after the break.)

However, he wanted to step up above the FDM-printed parts of the original kit. Thus, he contacted the kit developer Gman, who provided him with the 3D model files so he could attempt a higher-quality SLA print himself. [Downing] had some experience with SLA printing in the past with the Form 2, but found some unique challenges on this build with the Form 3.

The benefits of SLA printing are the finer detail and surface finish it delivers. This is particularly nice on things like enclosures and buttons which are handled regularly by the user. However, the standard resin that ships with the Form 3 had issues with warping, particularly on thin flat walls which make up the majority of the G-Boy case.

Other issues included the fact that the standard cured SLA resin is much harder to thread screws into than softer FDM plastic, something which frustrated assembly of the design. It’s also brittle, too, which leads to easy breakages.

As a fan of a properly finished product, [Downing] decided to sand and paint the enclosure regardless. Tragedy struck when the spray cans started to spit chunks due to being over a year old. However, it serendipitously turned into a win, producing an attractive granite stone-like finish which actually looks pretty good.

The G-Boy kit took Wii portable builds mainstream, and drew many new builders into the subculture. [Downing] may be a stalwart of the scene, but still learned new skills along the way of the build.

We can’t wait to see what happens next in the scene, though we’d suspect someone’s already out there chopping up a rare PlayStation 5 as we speak.

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