In advanced engineering circles, the finite element method — or, more commonly, finite element analysis — is a real staple. With the advent of more powerful home computers, though, even your home projects can benefit. The technique itself is very general, but you usually see it used for structural analysis. However, you might wonder how well it corresponds to reality. That is if analysis shows a segment of your part is weak (or strong) does that hold true when you actually build the part? [Fiveohno] wondered the same thing and decided to do some testing, which you can see in the video below.
Of course, like any simulation, the accuracy will only be as good as your data input and model. But if you work carefully, it should match up pretty well to the real world, so it is interesting to see the results of a real-world test. In fact, a video from Solidworks that shows a similar part points out — inadvertently — what not to do. For example, the force used in that analysis was too low and at a point where the part was at relatively low stress instead of at the maximum stress.
Being a bit shocked at the prices of articulating arm microscope mounts, not to mention the shipping fees to the UK, [CapTec] realized they looked substantially similar to your typical computer monitor arm mount. Thinking he could adapt a monitor arm for much less money, he fired up FreeCAD and started designing.
[CapTec] is using this to support his Amscope / Eakins camera-equipped trinocular microscope, but notes that the same mechanical bracket / focus rack interface is found on binocular ‘scopes as well. He observes that the mount is no more stable than your desk or lab bench, so keep that in mind.
Ultimately the monitor arm set him back less than $40, and all told he reckons the whole thing was under $55. Based on prices he’s been researching online, this represents a savings of well over $200. In his calculations, the shipping fee comprised quite a hefty percentage of the total cost. We wonder if they are artificially high due to coronavirus — if so, the make / buy price comparison might yield different results in the future.
This type of project is a perfect use-case for a home 3D printer — making your own parts when the normal supply channels are unavailable or overpriced. Are articulating arms that are purpose-built for microscopes significantly different than those designed for big computer monitors? If you know, please comment down below.
A great addition to a home shop is a bandsaw, but when [Design Prototype Test] got a well-used one, he found it wasn’t in very good shape. The previous owner put in an underpowered motor and made some modifications to accommodate the odd-sized blade. Luckily, 3D printing allowed him to restore the old saw to good working order.
There were several 3D printed additions. A pulley, a strain relief, and even an emergency stop switch. Honestly, none of this stuff was something you couldn’t buy, but as he points out, it was cheaper and faster than shipping things in from China. He did wind up replacing the initial pulley with a commercial variant and he explains why.
Desiccant is common in 3D printing because the drier plastic filament is, the better it prints. Beads of silica gel are great for controlling humidity, but finding a porous container for them that is a convenient size is a little harder. 3D printing is a generally useful solution for custom containers, but suffers from a slight drawback in this case: printing dense grills or hole patterns is not very efficient for filament-based printers. Dense hole patterns means lots of stopping and starting for the extruder, which means a lot of filament retractions and longer print times in general.
The green model is used as a modifier to the orange container (of which only the corners are left visible here)
[The_Redcoat]’s solution to this is to avoid hole patterns or grills altogether, and instead print large wall sections of the container as infill-only, with no perimeter layers at all. The exposed infill pattern is dense enough to prevent small beads of desiccant from falling through, while allowing ample airflow at the same time. The big advantage here is that infill patterns are also quite efficient for the printer to lay down. Instead of the loads of stops and starts and retractions needed to print a network of holes, infill patterns are mostly extruded in layers of unbroken lines. This translates to faster print speeds and an overall more reliable outcome, even on printers that might not be as well tuned or calibrated as they could be.
To get this result, [The_Redcoat] modeled a normal, flat-walled container then used OpenSCAD to create a stack of segments to use as a modifier in PrusaSlicer. The container is printed as normal, except where it intersects with the modifier, in which case those areas get printed with infill only and no walls. The result is what you see here: enough airflow for the desiccant to do its job, while not allowing any of the beads to escape. It’s a clever use of both a high infill as well as the ability to use a 3D model as a slicing modifier.
There’s also another approach to avoiding having to print a dense pattern of holes, though it is for light-duty applications only: embedding a material like tulle into a 3D print, for example, can make a pretty great fan filter.
Inductors are not the most common component these days and variable ones seem even less common. However, with a ferrite rod and some 3D printing, [drjaynes] shows how to make your own variable inductor. You can see him show the device off in the video below.
The coil itself is just some wire, but the trick is moving the ferrite core in and out of the core. The first version used some very thick wire and produced an inductor that varied from 6 to 22 microhenrys. Switching to 22 gauge wire allowed more wire on the form. That pushed the value range to 2 to 12 millihenrys.
OpenSCAD is a fantastic free tool for 3D modeling, but it’s far less intuitive to use for non-programmers than mouse-driven programs such as Tinkercad. Powerful as it may be, the learning curve is pretty steep. OpenSCAD’s own clickable cheat sheet and manual comes in handy all the time, but those are really more of a reference than anything else. Never fear, because [Jochen Kerdels] had quite the productive lockdown and wrote a free comprehensive guide to mastering OpenSCAD.
[Jochen]’s book opens with a nice introduction to OpenSCAD and it’s user environment and quickly moves into 10 useful projects of increasing complexity that start with simple stuff like wall anchors and shelf brackets and ends with recursive trees.
There are plenty of printing tips along the way to help realize these projects with minimum frustration, and the book wraps up by covering extra functions not expressly used in the projects.
Of course, you could always support [Jochen]’s Herculean effort by buying the print edition and forcing yourself to type everything in instead of copy/pasting, or give it to someone to introduce them to all the program has to offer.
Need help mastering OpenSCAD workflow? We’ve got that. Just want to make some boxes or airfoils? We have those in stock, too.
Over the years, artists have been creating art depicting weapons of mass destruction, war and human conflict. But the weapons of war, and the theatres of operation are changing in the 21st century. The outcome of many future conflicts will surely depend on digital warriors, huddled over their computer screens, punching on their keyboards and maneuvering joysticks, or using devious methods to infect computers to disable or destroy infrastructure. How does an artist give physical form to an unseen, virtual digital weapon? That is the question which inspired [Mac Pierce] to create his latest Portrait of a Digital Weapon.
[Mac]’s art piece is a physical depiction of a virtual digital weapon, a nation-state cyber attack. When activated, this piece displays the full code of the Stuxnet virus, a worm that partially disabled Iran’s nuclear fuel production facility at Natanz around 2008. Continue reading “Portrait Of A Digital Weapon”→
