Author: me@jacobchiu.com
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I recently found the need to sift store-bought sand to separate out the finer particles, with a targeted particle size of <0.4–0.5 mm (< 35–40 mesh). I considered using a kitchen sieve or a piece of window-screen, but found that they both had a hole size of about 1.5 mm (14 mesh), making them too coarse for my purposes. Since I couldn’t find any other easily-available sieves or meshes that were fine enough, I decided to 3D-print my own. I printed circular sieves 150 mm in diameter, with a rim that was 2 mm thick and 40 mm high. The…
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Here’s an essay I wrote in my 12th-grade English class about David Macaulay and Neil Ardley’s The Way Things Work. The Way The Way Things Work Works As anyone who has ever done so can testify, reading textbooks is really boring. Often one finds themself going over the same paragraph over and over, reading but not comprehending anything. But in The Way Things Work (TWTW), illustrator David Macaulay shows the power of illustrations over text in creating the mental image that leads to true understanding, rather than documenting someone else’s line of reasoning. For this purpose, …
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Abstract My goal was to measure the resistance of a dilute solution using tools available to me, and relate it to the solution’s concentration. A resistor was wired in series with the solution, and a DC power supply and a multimeter were used to measure the relative changes in input voltage and voltage across the resistor. This allowed the solution’s resistance to be calculated. I found a strong linear relationship between calculated resistance, and solution concentration. Introduction I was recently doing some more experiments with clay, which involved rinsing dissolved salts from a clay-water slurry. I wanted some way of…
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Are you working on a project consisting of FEM simulations done in FreeCAD? Are you using trial-and-error to converge your models? Or perhaps just running simulations on variations of the same basic geometry? Are you getting brain damage from the tedious and repetitive work of setting up simulations, and then babysitting them as they run??!! Well — fret no more! Introducing: an Automatic FreeCAD FEM Library! It contains functions designed to run without user input, almost as though it’s intelligent… but artificially. Using this library is free for one month, and then you’ll be automatically charged our monthly subscription fee…
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I recently needed to filter water out of a clay slurry for one of my projects. Since laboratory filter-paper wasn’t available, I had to try some common household filtration materials. Requirements for Filter Paper In Chemical Manipulation, Michael Faraday writes, 487. […] Unsized paper, cloth, flannel, tow, sponge, sand, pulverized glass, flints, porous stones, and earthenware, with many other substances, are used on different occasions, but the first is almost exclusivey resorted to in the laboratory, a few of the others now and then being resorted to only on particular occasions. […] 501. It is no easy matter for …
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Introduction An essential idea in finite element modelling (FEM) is convergence, the idea that as you make the simulation more and more lifelike, its results will converge to the real-life stress state. In most simulations, which mainly use single-point or rigid-body constraints, the main variable that must be converged is element size: as you make the elements smaller and smaller, the simulation will become truer and truer to reality. In this case, the procedure to obtain convergence is fairly simple: run successive simulations reducing the element size each time — for example, by halving it until the results — …
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I’ve been wanting to make a die filer for some time now. It is a power-driven file that allows you to easily cut complex shapes. Die filers are not meant for a very high material-removal rate; rotary files and cold-chisels exist for that purpose. Design Parts of the Die Filer The file is run up and down on a “filing shaft”, which is supported by a “top bushing” and a “bottom bushing”. A “chuck”, consisting of a steel sleeve and set screws, couples the file and filing shaft. The filing shaft is driven up and down with a scotch-yoke mechanism,…
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This Repair Café took place from 11:00 AM to 3:00 PM at the Tzu Chi’s Northwest Region Office. Tzu Chi is a humanitarian organization whose members are Buddhist, but who do not preach to those they aid. I worked first on a Panasonic toaster oven. It had 5 heating elements: 1 clear quartz element and 2 diffuse quartz elements on top, and 2 tubular elements on the bottom. The diffuse quartz element consisted of a nichrome wire in a translucent quartz tube, emitting IR at a longer wavelength and lower intensity than the clear element, which had a tungsten wire…
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I’d previously done some experiments trying to anodize aluminium with household chemicals, avoiding the need to buy sulfuric acid. The only process that succeeded was to make sulfuric acid by the electrolysis of Epsom salt (magnesium sulfate) in a partitioned electrochemical cell, and then use the sulfuric acid for anodization in the usual way. However, the electrolysis was very inefficient and slow, and is not really applicable for anodizing any appreciable quantity of parts. So when I was recently given the opportunity to anodize and dye some parts for my school’s robotics team, I abandoned my initial goal of …
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With only a center punch and drill press, it can be very difficult to drill small, straight holes. Though medium-sized drills can self-center parts by shifting them around till the center-punch mark is exactly aligned with the spindle, smaller drills tend to just deflect and drill an angled hole. To overcome this, a short, stiff “spot drill” is used before drilling to create a new divot, exactly aligned with the spindle, obliterating the old center-punch divot and taking out any misalignment it might have had. Locating large holes accurately can also be difficult, since the large chisel-shaped tip of the…
