Recently for my job, we've been developing some 3-D stimuli for children's psychology experiments. We found a 3-D printing service for rent at the university, and it works great, but the texture on the finished pieces is a bit distracting. In our case in particular, weird object textures might actually affect experimental results. We want to make the texture smoother, but without spending hours with sandpaper. So we decided to try out an acetone vapor bath solution.
This is what the initial texture looks like from my university 3-D printing service. It holds decent detail, but the lines of plastic laid down are still visible, and that texture is going to show through even if painted.
We can address this by exposing the piece to acetone vapor, which melts / reacts with the ABS plastic the 3-D printer uses, leaving a glassy finish. You can see the basic setup below. A large mason jar has a couple of tablespoons of acetone in the bottom of it. It is then also sitting in a hot water bath, which inceases the vapor pressure and speeds the reaction. I microwaved my water until it was boiling. The piece was then suspended from the lid inside the jar to bathe in the acetone vapors without touching the liquid directly:
It is very important that an airtight seal be achieved, one that is strong enough to withstand pressure inside the jar. In the above images, I was trying to use some paint to seal the gap where the screw goes through, but that didn't really work. Later I tried a similar setup with clay as a sealant, and it worked perfectly. This following setup also worked, using super glue, although I don't know how it will stand up long term to the acetone (I switched to clay after just two runs):
The yarn here is wool. If it were acrylic yarn, there's a pretty good chance it would have melted in the acetone fumes and dropped my piece into the drink. Paper clip chains would have worked, too. Double check that everything in your jar is acetone-proof, or test it with a junk piece (which you should probably do anyway), before you rely on it for something you care about.
When the seal is air tight and the water is hot enough, you should see acetone condensation on the side of the jar. That's an indication things are going quickly enough and that the seal is good. If the seal is leaking, you should be able to actually hear hissing if you listen closely, and won't see much condensation.
Here you can see it melting the surface. In the first image, notice that the bottom portion is smoothed out, but texture remains on top. In the second image, there is still some texture on the very inside top, but even that is looking glassy, and all the edges are done:
When the piece looks sufficiently smooth to you (up to an hour for me, and maybe a change of re-heated water bath), take the jar out of the bath and place it in a sink. Now, fill up a glass of water, and have it ready (or the faucet), THEN remove the lid just enough to be able to douse the piece in water.
Don't let it touch the sides of the jar yet, until it is doused. The plastic with acetone still on it is very sticky, like warm caramel, and it will stick to the walls and leave ugly marks on your piece. After dousing with water, it's much more resilient. Enough so to pull out and hang somewhere to dry.
The piece will also attract dust while it is "curing." If you have a spare jar available, you might want to reserve one for drying purposes, to cut down on dust that permanently sticks to the surface. I hung my pieces from the corner of the drop ceiling in my office, and they avoided dust pretty well.
Below is the finished piece. For about another day or so, it will be soft and easily damaged. Not so soft that you will leave fingerprints, but enough for a nail to easily scratch it. The dotted line I drew here was from minimal pressure with a bic pen. If you can, it's best to just leave it hanging somewhere and not touch it at all for a full day.
Notice that the corners definitely get gooey and rounded, so if you need precision, this is not for you. It's an aesthetic thing, like if you're 3D printing a piece of an artwork or similar. (Note: the side corners near the slots in the photo here were actually damaged by the piece being slightly too big for the jar, not by the process).
Here's another piece that shows how easily blemished fresh plastic is out of the bath - I was hanging it by the eye socket there, and just the weight of the piece itself pressing against a metal screw left that gouge mark. So be careful how you hang your piece!
If you prefer, and if you have a big enough glass container, you can also lay the piece into a platform in the bottom instead of hanging it. A piece of wood with nails works well - balance the piece on the tips of 3 nails, and the marks left behind will be minimal. Keep two things in mind, though:
The distance from the piece to the acetone will affect how quickly it melts the top versus bottom relative to one another, because fumes are thicker near the liquid and the water bath.
Try not to leave any large surface flat on top. Tilt it slightly instead. This prevents acetone pooling from condensation and leaving blisters on your piece. You can also do this when hanging the piece, by hanging it slightly off center if possible.
In this post, I'll go step by step through my process for creating an (unpainted) PVC organ pipe! An organ pipe has two parts: the resonator, which is most of the length of the pipe as a simple empty tube, and the fipple, which creates oscillations.
THE RESONATOR
The resonator takes vibrations (or perhaps more accurately, oscillating air vortices that I don't entirely understand) from the fipple and resonates at a fixed, controllable wavelength, allowing specific tones for music. Each pipe is going to produce one fundamental tone, just like individual strings in a piano. A single pipe will create several other tones at once when sounded, equaling integer multiples of the fundamental frequency (harmonics). The smaller the pipe, the more prominent the harmonics, but the fundamental is always the strongest.
Here are some different harmonics fitting into a single pipe (top three waves) and a fundamental of a longer pipe (bottom), with distance from midline being relative min and max pressure for each one:
However, less so than composers, we don't need to concern ourselves much with harmonics for building the organ. The pipe will sound like the fundamental frequency when you play it. So what matters more for us is the bottom of the image above: When you make a longer pipe, it will naturally resonate at a longer fundamental frequency. Longer waves are heard as lower tones. So by making different length pipes, we make different notes. One half the length of pipe = one octave lower, and other notes vary by even logarithmic steps in between. In other words, human perception varies logarithmically with frequency.
So the resonator, at the end of the day, is just an empty tube of the correctly calculated length. I'm making mine out of PVC pipe. For tuning purposes, I also have slightly larger pieces of pipe on top that can slide up or down to make fine adjustments to the lengths for tuning.
Middle C is an open pipe of about 2 feet in length, as a point of reference. A concert tuner of the A above middle C at 440Hz is about 1.28 feet long.
Closed pipes (with a stopper at the end) have twice as long of waves, roughly, because the wave has to "reflect" the length of the tube then back again from the fipple. A closed pipe sounds one octave lower than it normally would, so middle C would be about a 1 foot long closed pipe. This is useful if you want to fit big pipes in an apartment building.
THE FIPPLE
The fipple is the vibration producing part of the pipe. I'm going to be routing air to my pipes by plastic tubing, so it needs to convert a stream of pressurized air from a circular tube into a consistent vibration. The fipple is much harder to make than the resonator.
Briefly, the concept of a basic flue pipe fipple (meant to sound something like a flute) is:
You somehow shape incoming air into a laminar air flow (a flat, non turbulent sheet of air).
You get that flow to pass right into a thin knife of rigid material, which will then vibrate.
The vibration resonates in the resonating chamber.
The way we make those things happen is by building something like this:
The pipe (red) has a cap on the end (black) with a hole for the air hose (green). There's also a plug in the pipe (orange). Air comes into the cavity in the back and has nowhere to go, except for a narrow section of pipe cut away at the top. This forces the air into a sheet, which passes over and under a knife shape cut in the pipe (red also). This vibrates, which then causes resonation in the pipe (left off the edge of this image). Again, I think it is more like oscillations of swirling air systems in a much more complicated way than just vibrating, but that's close enough for me to build it.
So without further ado, let's build it! We begin with a PVC plumbing pipe:
First, we need to cut a notch out of the end. The width of the notch is related to the diameter of the pipe, something around 2/5 the diameter. The depth of the notch depends on the system you're using for a cap. I used this tool here, a dremel with a grinding fiber/ceramic/something wheel:
Here's the notch cut out:
Then I used a much wider grinding stone (seen below), 100 grit sanding drum (not shown) and finally manual 220 grit sandpaper (not shown) to grind a sharp, gradual "knife edge" on the inside of the notch. Grinding stone:
Knife edge after all the dremeling work:
Knife edge after hand sanding:
We need a laminar sheet of air now. I achieved this by using the thickness of the PVC pipe wall itself as a guide for a sheet of air. So I need to block off the inside diameter, AND the outside diameter. The inner diameter is blocked using this section of a solid plastic dowel rod:
The corner is sanded down to aid aerodynamics (the air needs to be smoothly guided toward the knife). The plug fits into the pipe snugly. Notice how the pipe walls stick above the plug, so that when the cap goes on later, there will be a thin slice of opening:
A hole is drilled in the middle of the pipe cap. This is where plastic tubing will go to deliver the air supply:
And finally, the cap is attached. If you look closely, you will be able to see the thin slice of empty black space in between the plug and the cap nearest the camera. This is the guide for the airflow to make it into a sheet of air. It will then pass right into the knife edge, creating the musical vibrations, which resonate in the remainder of the organ pipe:
Again, here's the schematic now that you've seen the real thing:
NEXT TIME
In the next installment of this series, I will explain how the air system works, and I think I'm going to actually try out a new idea, different than my original plan, for how to activate air flow to individual pipes. I will try experimenting with homemade electric solenoids, versus the alternative of manual springs and levers and things. If the electric version works, then the whole organ could be played either manually OR by computer program, potentially!
It's time to talk about everybody's two favorite cocktail party conversation topics: plate tectonics and mantle convection currents. I'll also get to our first specific geology algorithm that simulates the planet's dynamic core and source of plate movement, as well as some basic methods of plate formation in the model.
Coding-wise, I've been busy in the meantime with some underlying framework: file input, graphics output, setting up utility functions, classes to store data on plates and columns, considering whether multithreading makes sense or not, etc. I won't bore you with those details right now, though. I'll get straight to the first interesting bits. We need to answer some basic questions about the simulation world:
Why do the tectonic plates in our world move?
What happens at the boundaries of plates?
How do we start building our earliest continents?
The most logical place to begin is by looking for the answers to these same question when it comes to our very own, real-life Earth.
CRASH COURSE ON TERRESTRIAL PLATE TECTONICS
WHAT MOVES THE CRUST?
The Earth is divided into several layers. The inner core is solid, as is the very outermost few miles of rock (crust). The rest ranges from sort-of-maybe-kind-of solid (very outer mantle/asthenosphere) to pretty much flat out liquid (middle portions), and so the outermost parts, to varying degrees, "float" around on top.
Why does it move around, though, instead of just floating perfectly still? Well, primarily because of convection: the natural cycling pattern formed by fluids of different densities -- most commonly because of uneven heating. Take a look at this cartoon beaker of water on a stove top:
The hot fluid expands and become less dense, so it floats upward on top of the colder liquid above. The cold, dense fluid sinks to fill in its place nearby. The cold fluid then heats up closer to the source of heat, and the hot fluid cools off at the surface, so they begin cycling in orderly patterns. Depending on the shape of container, the rates of cooling and heating, etc., the cycles can take many shapes, from 3-D donuts to columns to rolling cylinders. A single modular pattern, whatever the shape, is called a "convection cell."
The Earth is heated from below, too. And I do mean actively HEATED: most of the Earth's internal temperature is from ongoing radioactivity converting nuclear bond energy to new thermal energy. It is also cooled on top as heat is lost to space. Since it is also partially liquid, it has convection currents.
Now imagine a skin on the surface of the beaker above: the currents from the convection would pull it apart and push it off toward the side walls. Sort of like these chia seed continents in my kitchen:
The plates on Earth move much like that, except there are no sides of the beaker or pot in a round world, so things are less static. I.e., instead of hitting the wall and staying, plates wrap around the planet and tend to keep bumping around and re-jostling into new positions continuously.
PLATE BOUNDARIES AND MANTLE / CRUST ALIGNMENT
It is often assumed that convection cells in the Earth's mantle line up with the joints between tectonic plates. Where plumes of heat are rising up in the convection cells, one theory suggests that that's where (and why) the new crust is forming, swelling, and sliding "downhill" away from the heat, usually in the sea floor. This is called a ridge or rift zone:
Notice those light blue / yellow lines in the middles of the oceans? Those at the mid-ocean ridges and their elevation swells, where most new crust is formed. This might reasonably line up with the rising heat side of a convection cell.
On the other hand, where plates meet, usually one will "subduct" under the other one. Some of the higher-silica-content material will bubble back up through volcanoes, but a lot of the material will sink and remelt into the mantle. In the Earth map above, you can (just barely) see dark blue lines where subducting plates plunge under deep ocean trenches. Japan is an example where two ocean plates meet, one subducts, and volcanic islands and a trench are formed. Cartoon version:
This subducting rock cools the area of mantle it pushes into, and thus might line up with the other, sinking end of a convection cell. The convection would occur anyway just from losing heat to the crust by direct conduction, but the crust itself recycling from rift to subduction zones might nudge the system into lining up in the same way. So you could get an overall picture something like this:
Things wouldn't be anywhere near that neat and tidy in reality, but it may be a rough approximation. In the following picture and video, you can see two interpretations of what a more realistic mantle convection pattern might look like. One is a bit more... tame than the other. But in both cases, you can see reasonable convection cells where heat travels up and down again in a recognizable pattern. You can also imagine how crust might move on top of the video model.
Shifting gears a bit, it's also worth explaining an important distinction between two major types of crust that affect movement patterns: oceanic and continental. Both can exist together on the same plate. Oceanic crust is made out of denser, silica-poor rock (mainly basalt) and is thin. Continental crust is made out of relatively less dense, silica-rich rock (like granite), and is much thicker.
The continents float better, so when a continent and an ocean collide at a boundary, the ocean inevitably subducts under the continent. And when continents collide, sometimes one subducts, but sometimes they just crumple together like a car wreck. Since continents rarely subduct, they tend to stick around, and have been getting bigger over the ages as more of the silicon and lighter elements have settled out toward the surface over time and stayed. Whereas ocean crust comes and goes.
In my program, ocean and continental crust will both be important, but I'm not going to directly code them by fiat -- I hope to instead have these distinctions arise naturally from modeling actual thickness, density, and bouyancy of rock columns.
HOTSPOTS AND SUPERCONTINENT ISSUES
There are a couple problems with the above story so far:
There are places on Earth called hotspots (about 40 "official" ones) where volcanoes or hot thin sections of crust seem to stay in one place for a very long time, ignoring plate movements. Like Hawaii. It doesn't really make sense that hot fluid can travel up in a stationary line AND flow around in circles in the same space at the same time. Something doesn't add up, and there's disagreement among geologists about what that is. Best case scenario, though, this would be a whole extra layer of programming for me on top of the above model. Worst case, it means I have no idea what to program at all.
What happens when a continent gets too large? Remember, continents rarely subduct, so inevitably, they all pile up in a supercontinent. This would be very boring if they don't break up again. They do split, but geologists seem to disagree about what causes the breakup of supercontinents. Everyone agrees it has something to do with heat building up under the insulation, but the details for how this would work in the above model are a bit fuzzy.
Maybe I could soldier on anyway, maybe ignore hotspots entirely (and in fact I tried!). However, I think I may be able to leverage both issues to my advantage instead with a simpler overall system...
What if we theorize that the mantle convection cells essentially "don't care" about the crust? The crust moves and changes (in this theory) more slowly than mantle convection cells. They're rapidly churning away down below, and the crust and it's tiny features are just minor side effects.
This allows for hotspots... of course they ignore plates, because ALL mantle convection does.
This lets me use one of the simpler supercontinent theories -- which is that hotspots cause more damage under supercontinents as they move more slowly, and have time to burn through the thick continental crust. Eventually "unzipping" the supercontinents along the weakened connected dots.
Ridges and subduction zones don't have to line up with convection cells all the time, which removes several awkward implications and restrictions from the basic model. Getting this to all agree was like herding cats or trying to organize bags full of magnets. Whereas plates sliding around semi-freely on top with minimal feedback is much simpler.
This should still allow convincing, normal geology at the end product.
CONVECTION + TECTONICS ALGORITHM
Alright, so let's get down to brass tacks and implement this concept in an actual algorithm! I don't have a working demo yet, but this is the quasi-implemented plan:
1) Hotspots.
First, we generate some random dots on the surface, representing hot convection plumes from the core/deep mantle (how many can be a customizable parameter):
2) Convection Cells.
Next, we simulate what the convection cells for these hotspots might be. I'm going to use Voronoi cells to represent the convection cells. Voronoi cells are shapes drawn between a set of points indicating the regions of space that are closest to each individual point. This makes sense for convection, because these would be the boundaries at which hot fluids sliding along the surface from different plumes would hit each other and stop having anywhere to go but down.
In real life, convection currents often do take on Voronoi cell shapes under the right conditions, which can easily be MY conditions, because I can invoke any depth of planet, any age of planet, any amount of radiation in the core, etc. Here's two actual videos of Voronoi-like cells convecting in a hot fluid, followed by a hand-drawn Voronoi algorithm applied to my hotspot dots above, representing something similar:
(by Jennifer Liang and csegal0)
3) Plate Formation.
These cells radiate heat outward to the shared edges (below, I show this as a circle of heat, but it may actually work better if irregularly shaped due to different speeds of fluid flow within a cell). The heat will change the crust above it: weakening, blistering and thinning the rock, sometimes breaking through like in Hawaii or Yellowstone. These hot, thin, weak areas can rip open into a new crust-producing rift zone.
At the same time, cold (and therefore dense / heavy) crust at the furthest edges of cells wants to sink down. And especially if it happens to be thin crust that can break easily, it might just crack and do so, and one side can begin subducting.
Later, these cracks will be harder to form, but right now the whole world is just brand new, thin basaltic ocean crust everywhere and the first few plates form more easily using some simple pathfinding algorithms that use heat levels and thickness as "pathing costs:"
(red = rift, blue = subduction zone)
4) Plate Drift.
Due to our torus-world, we need at least two cracks to make two plates, since things wrap around. So here we now have two plates. Where do they move? Well, remember the strategy here is that the crust is just a side-effect of a much more powerful mantle. So the mantle convection flows don't care about our new fault lines. They just do their thing, and the plates respond dependently.
Therefore, the movement of each plate will be pretty much purely the resultant vector of the convection currents moving underneath it. So what we do is add up the resultant vectors for all the cells that are part of them:
And so we end up with two overall vectors for plate movement, appropriately moving toward the subduction zone and away from the ridge.
5) New and Old Crust and Continents.
One of the plates will subduct under the other (coin flip at this point, since both are equally thin, cold, and chemically identical. Later, these factors will make one outcome more likely), causing volcanic island chains in the upper plate, which are then lighter weight than basalt and will stick around, forming the nucleus of our very first continents. And of course, where the plates spread apart leaving no data, new crust gets added on in the simulator. In the model for now, this is simply deleting some cells at overlaps, adding others at gapes (after movement), and keeping track of thickness and volcanism changes, etc.
This is hugely simplifying things. But for now, I need to keep things simple until I can get a working model of SOME sort, at least. Later though:
6) Increasing Complexity
Over time and with future features, this picture will get much more interesting:
The plates will slide over the hotspots, which tend to weaken crust above them and maybe even break through, leaving a sort of perforated line of weakness which is then liable to crack to make more plates later, and more interesting dynamics.
At the same time, plates will sometimes fuse if jammed together particularly violently.
The plumes will slowly shift and rearrange.
Continents will build up and alter the patterns of subduction.
Sometimes oceans may get gobbled up entirely.
Thicker plates will be harder to break through for hotspot volcanoes.
And plenty of other geologically-relevant things I haven't talked about at all yet: erosion (waves, wind, rivers), sediment deposition, rock metamorphism from heat and pressure, life forms, changing atmosphere (oxygen rusts minerals...), details of volcanoes, and more.
NEXT TIME
My focus now is on finishing up a few straggling bits of basic engine framework, Then implementing steps 1-5 of the above algorithm. Hopefully I'll have a working demo next time, along with tales to tell about whatever is bound to go wrong along the way! Or I may have to make a short detour into discussing multithreading or simialr. We'll see.
"Refractory" is just a word that means "very resistant to high temperatures." In the context of pottery and glassmaking, I need refractory material for the lining of my kiln(s) I am going to make. Regular, pure clay doesn't cut it. I can also use refractory for making bricks to hold up pieces in the kiln or to use for making the actual walls of a kiln, if I want to make one out of entirely my own materials.
For either of these purposes, I need a substance that is actually not only refractory, but also insulating. That is, it should neither break down at high temperatures nor should it let heat get past it. Tungsten metal is highly refractory but a poor insulator. Cotton is not refractory (will burst into flames at maybe 400 degrees F) but is a great insulator.
Pure earthenware clay by itself is mediocre at both of these things by itself--it will slump and melt at moderately high temperatures, and it isn't actually that great of an insulator (Think about how quickly your mug gets too hot to touch on the outside when you pour coffee in it). So we want to improve these qualities for furnace materials.
Refractory recipes can get very complicated, but for mine, I want only locally available ingredients. I am going to have 3 ingredients: dry grass, quartz sand, and some of the clay I prepared earlier here.
The clay forms the main body of the material and holds everything together. It is also, of course, reasonably heat resistant.
The sand raises the melting point of the material significantly, since quartz melts about 500 degrees celsius higher than earthenware clay does (note: sand is locally available, but this particular batch used hardware store sand just for now).
The oven-dried grass helps hold everything together at first, since the clay mixed with sand is crumblier than pure clay (see here [link]). Later, the grass will burn away in the kiln and leave lots of tiny air pockets that will help insulate against heat transfer.
...another ingredient I could have added is wood ash. WASHED wood ash. I.e. the stuff left over after you have soaked new ashes in water and drained off the potash a few times (this will be the subject of an upcoming blog post, since potash is used for glass making and pottery glazes). Washed ash stuff is much more heat resistant than quartz, so replace a little or a lot of the sand with it, if it's available. It must be washed ash, though: raw ash contains potash, which is a chemical that actually lowers the melting point of quartz, and thus is counterproductive.
The ratio I'm using is about 50/50 clay and sand by volume and then about another equal part as the sum of the first two ingredients in dry grass by volume, loose (not packed!). In reality, it's probably something like 70/27/3 by mass for clay/sand/grass, but I don't know. It's easier for me to measure volume, so I'm just using that. Mix it all together, and you get something like this:
This is essentially adobe in it's raw form. You can build some pretty strong buildings out of this in dry climates if you let it bake in the sun for awhile, although you'd probably want more sand and grass in it.
The adobe is much harder to work with than pure clay, but making things like bricks is still easy. Below are some examples of bricks that I made out of this material and then fired (I'll cover firing in a later post). Click for a larger size. As you can see, the grass has burned away and left them porous. These things are super lightweight and feel like pumice, and their insulation is probably excellent. Unlike the raw adobe, though, the fired bricks are also extremely brittle and easy to break, since the binding strength of the grass has been removed and now actually hurts the strength of the material by leaving air behind instead.
The examples below actually used more like 60/65% sand, 35-40% clay by volume, and the fact that they are so brittle is why I'm now suggesting a 50/50 mixture instead (I also toned down the grass slightly from these bricks):
Notice the gray spots all over -- there was not enough oxygen and/or not enough time during firing. This is the same issue as that cheap hardware store pot I showed in an earlier post. It's not the end of the world, but it does increase brittleness even further, and I need to fix it. I'll discuss this more in my post(s) about firing clay.
You can also see a crack in the middle brick that formed just from roughly piling them in this stack! That's how brittle these are with the sand-heavy recipe... Again, use more clay than this (which I will be doing in the future).
My own version is adapted from commercial versions and the backyard metal casting website, but substituting locally plausible materials (the sand and clay are literally locally gathered) to fill all the same roles in about the same ratios.
One of my long term crafting projects is to build my own working pipe organ. Do I know how to play the organ, you ask? The answer is no. No I do not. Why did you ask that? I hardly see it as relevant.
Moving on, this will be a "positive organ," or in other words, a small desk-sized one. In the layout below, the entire table there is about 4 foot by 2 foot, and the largest pipes are 2" in diameter and would just barely clear a typical apartment ceiling (top pipe in the splash image above). The color coding is for commercially available widths of PVC pipe, my primary building material:
I don't remember at all what made me interested in this project, but hopefully it will be capable of creating wonderful art when it's all done, whether or not I'm the one making art with it!
Overall, a pipe organ requires the following components, and thus these are the major areas of the project:
A frame of some sort -- this can be anything from a modified table to a huge gilded architectural wing of a building. In my case, my most important design consideration is portability - I am keeping the organ small and desk-sized, and I want to be able to break it down for transportation.
A lot of pipes -- My organ has five octaves (61 pipes) in flute-like sound, give or take a few pipes possibly for different harmonies at the end(s). One octave is a 2x difference in pipe length. You can "cheat" your way for one bonus octave without longer pipes by making ones with stoppers in the ends which effectively doubles the virtual length. Thus, my organ will have pipes from about 4 foot to 6 inches. They also get narrower as they get shorter. I am planning 2-3 additional redundant octaves in something much more fun. Tentatively, "bubble" sound. I.e. bubbling water, but in specific pitches. Because reasons.
A keyboard (called a "manual" on an organ). This doesn't have to have a key for every tone, although it is convenient and mine will. The color coded keys above are ones that would be able to play either/both bubble and flute pipes, based on a pull-control knob (a "stop").
A "wind" (air) supply, including some sort of fan or bellows, as well as a regulating reservoir to control for consistent pressure despite however many keys you are playing at once. Without a regulator, an 8-note chord would play 8x more softly than a single note. We want consistency, which requires building up a reserve of air pressure. i will use a squirrel cage electric fan and a box with a rising, weighted lid for a reservoir.
A windchest, which is an interface that takes in the main air supply, and uses linkages from the keys and any number of control stops to distribute wind to the appropriate pipe or pipes.I plan to take advantage of plastic tubing to greatly reduce the mechanical complexity compared to traditional church organs. Basically all I need are some small boxes and flap valves for each key, and some airtight gaskets, and that's it. Possibly one sliding board to convert between flute and bubble pipe voices.
Finish. Most of the pipes in my organ are going to be made out of PVC plastic plumbing pipe, so paint is a high priority to hide that fact. A tentative paint scheme is something like this (the arrangement of pipes here is not realistic, just slapped on the image):
(Possible paint scheme of my organ. An air pressure reservoir is on the floor.
The tube sections on top of the pipes are tuning slides.)
In my next post for this project, I'll dive right into the design and airflow diagrams for individual organ pipes, which are all homemade here, mostly out of PVC.
In the meantime, here's a sound clip of the four pipes from the splash image. In order from the top: 1,2,4,3. Sorry, the highest note is a bit wheezy and cracks its voice--it's not the pipe, it's just that I can't play it as hard as it is designed for without blowing out the audio on my microphone. At normal strength, it is crisp.
HELPFUL LINKS
I'd like to extend deep thanks Raphi Giangiulio, who I have never written or talked to myself, but whose website about homemade organ building has been my #1 go-to resource for this project so far: Mr. Giangiulio's homemade pipe organ. Here's a sound sample using flue pipes similar in construction to what I have planned (mine would be less warm and rich): Giangiulio sound sample
Laptops are for suckers. Why put up with the hassles of a cord and wall outlets, when you can enjoy the unfettered freedom of a 40 pound block of manually operated, electricity free cast iron?! Also, if you start taking mortar fire while typing a memo, this guy's got you covered:
Unfortunately, this circa 1905 Kaiser-approved German desktop typewriter arrived in rough shape fresh from UPS. It needs a lot of TLC before we can even attempt to type with it, let alone rely on it or display it proudly as some beautiful, functional art.
So... let's fix it! Repairing typewriters is a joyful experience in my opinion. Nowadays, most of the machines we use require computer diagnostics, etc. to even attempt to work on them. Even if you understand the mechanics of things like cars, there are fewer and fewer things you can fix or modify yourself as a hobbyist.
With mechanical typewriters, you can fix almost anything with only some screwdrivers, oil, ingenuity, and gumption. I obviously have no formal training on these, but I can still figure it all out, because it's all just levers and springs, and you can reliably follow them around and puzzle it out in the end. It's a sometimes very challenging, yet an almost certainly solvable puzzle, and one that uses your eyes and hands -- the best kind!
First, we begin with just testing the features:
GENERAL CHECK OVER
The keys, of course (A) - What happens when you hit them? Well, what happens is that a couple of them stick ("H" and "^"), and the rest make it about halfway to the platen (the rubberized striking surface at J), before they meet with mysterious bouncey resistance.
The space bar (B) - It snapped in half, but the lever seems to function.
Shifting (C) - The buttons seem to work, but the carriage (the whole top assembly) is jammed or messed up, so they don't really do what they are supposed to. I don't think it's the shift's fault, though, intuitively. This can be revisited later if necessary.
Caps Lock (D) - Same as shifting.
Carriage return lever - It moves the carriage, but it requires a stupid amount of force to do, like there's a lot of friction, about halfway across. It also makes a horrible grinding sound from the teeth skipping on the gears in the back (the rack gear S<->T with the teeth of the escapement mechanism P).
Margin release - It's hard to see, but it's a button that pops out at F, when you hit the right margin. You can push it and give yourself a couple more letters if you need them (shame on you you bad bad typist! *ruler smack*). This doesn't work, because it's not attached to anything in the back (N - see the empty hole at the top of the lever).
Ribbon advancing - The ribbon holder (H) is supposed to move whenever you type a key. The knob at G reverses the direction. Both seem to work.
Platen knobs (I) - This is used for manually turning from line to line. One is missing, the other is horribly deteriorated, but there are no mechanical issues, the parts just need replacing.
The platen itself (J) - The rubber is in good shape!
Lever that lets the carriage slide freely (K) - Has the same friction and grinding issues with the carriage, but I don't think this is a cause, since it's just a minor input.
A bar is missing that is supposed to hold the paper down (based on internet photos of the same typewriter) at (L).
The single/double/triple spacing selector (M) - There was a spring that kept this in place that was out of whack. It took 2 seconds to pop back in position, and this now works.
The backspace function - This is disconnected in back just like the right margin is. It seems to be missing parts (O).
The escapement and main spring assembly (P) - This is grinding against the rack gear above it, but I don't think it is the originator of the problem, because it looks solidly attached and whole, etc.
Arms that hold paper (Q) - These work. There is some gross mildewy felt under them though.
The bell is missing (area below N), but the adjustable clapper that is supposed to hit it works (R).
General aesthetics -- Dusty and dirty. There are a few areas of uncontrollable rust, and a lot of minor rust. It should clean up pretty well, though, with some light abrasion and chemicals and elbow grease. The decals are in good shape (the back one and ribbon spools look awesome), the front one is dim but intact, and it seems to be behind a layer of flaky varnish or something. The side lettering is worn, but very easy to touch up. The paint looks great, I don't see many chips or flaws in the paint job. The keys are in mediocre shape. There's some stubborn tape or something on the top of the case.
CARRIAGE DIAGNOSIS AND REPAIR
Most of these issues can be steadily repaired and cleaned up one at a time. But the carriage issues are by far the highest priority. If they can't be fixed, the whole machine will always be useless, and so would any other repairs.
The symptoms the carriage is exhibiting are increasing friction toward one side and grinding gears. Gradual friction implies that two large moving parts are not properly aligned. Grinding implies that gears are not aligned. My first thought was thus that a major rail somewhere was bent. Thankfully, I couldn't find anything like that!
My next thought was that two or more large rails were just entirely not lined up, even though straight. For example, are screws holding the fram together missing? No. Is the FRAME straight (also not a great question to find yourself asking...). Turns out NO it isn't. The frame has a difficult-to-see but large crack in the back near the foot (somewhat below point N in the above pictures):
This is not good, however typewriters don't actually experiences THAT much stress. The frame can probably be fixed with just a really strong 2 part epoxy (I also considered drilling through and bolting, but the surface area isn't large enough). Before doing that, though, I got a small C-clamp and just dry-clamped the sections together. What happened was that the friction largely disappeared, but the gear grinding didn't, and some parts were still knocking into each other. I futzed around until I found where:
A screwdriver just bent out the middle part by a couple of millimeters and it was fine (hopefully this doesn't mess up typing later! I don't think it will.). Next, the gear issue. Turns out that one of the two screws holding that rack gear on was rotten and the head fell apart when I tried to unscrew it (see points S and T above). Here is an over-dramatization of the rack being misaligned (in this photo it's entirely unattached not just loose) and the gear underneath it's supposed to interface with:
These screws from 1905 Germany aren't exactly standard modern thread sizes. I tried the hardware store, but it seems to be something ridiculous like M3.5 threading x 5mm long?? So instead, I found a random set screw of the same threading that wasn't doing much from elsewhere on the typewriter (see the remaining screw on the other side):
This screw was too long, so I clamped it in some vice grips and used my dremel to cut it down to the right size, then filed down the burrs on the end so it would thread (broken screw on the right):
(in its new home)
After fixing the rack, the carriage now moves smoothly (C-clamp still dry-fitted for now), and doesn't skip teeth. It does still have a couple of issues though. First of all, it's WAY too strong. I assume that somebody working on the typewriter in the past tried to ratchet up the power on the main spring to just FORCE their way past the friction from the broken frame (tsk tsk tsk!). As in, the entire typewriter was vibrating with force every time the rack gear moved at all. So I loosened the tension dramatically to make it safer and less damaging to the machine. I rocked this lever back and forth to slowly release tension one tooth at a time until the carriage was too weak to move forward. Then I re-strengthened it by a few teeth (you can just grab the wheel with your hand and turn it usually):
Finally, the carriage seems to sort of randomly stop partway across, and keys now sometimes work, and sometimes don't. When it does stop, it's a "soft" stop. It's hard to explain, but having used typewriters a lot in the past, it "feels like the typewriter doesn't want me to go further" not that something is broken and binding.
Sure enough, my intuition helped me figure out the problem after a bit of looking in the right places. Remember that margin release that was disconnected? Here's another photo of what should be there:
That missing arm is supposed to help keep the lever to the left UNTIL you hit the actual right side margin. The spring at the bottom helps hold it to the left, but was never designed to do this all by itself. What was happening was that the lever was too weakly held in its current state and was wandering randomly to the right side, then the machine thought that I was at the margin now and then, and it was dutifully stopping anything from working. For now, I just slapped some rubber bands on to hold it to the left.
SO now the carriage works! It moves one spot when you type a key all the way across and returns properly with good tension and no resistance. This is a big relief. The rest of the problems can definitely be addressed and are worth working on, now that the carriage works. I still want to keep it under observation while I fix some other things before I epoxy it, but we can move onto other things.
OILING
At this point, I also oiled the main rails and pulleys of the carriage. Oiling bars is always a good idea. Just be careful to not get oil in the springbox or in any very dense areas of machinery like the big block that holds all the typebars. Oil in hard to reach places can get gummed up and is very difficult to fix later. Getting it inside coiled spring is bad too.
DO NOT use WD-40. Use a proper machine oil. Something like sewing machine oil would be best. I'm a little lazy, and I'm just using basic 3-in-1 oil, but it's still universes better than WD-40, which will seize up in no time and make a huge mess later.
A dab will do you! I prefer to use an old toothbrush with a few drops of oil and not even pour any oil from the bottle directly on the machine at all. It leaves a medium-thin layer everywhere with no dripping into bad places.
The typewriter database provides year of manufacture estimates for most typewriter brand serial numbers and other identification images and resources.
The virtual typewriter museum similarly provides identification resources for a lesser number of machines, and for this one it had some very useful information about how parts are supposed to go together and what was missing on my own model.
NEXT
I need to finish up all the remaining more minor mechanical issues, fixing some linkages and fabricating a part or two (backspace, margins, missing and rusty knobs, making a new space bar, new feet, new ribbon, new bell, unstuck "^" key).
There's also a LOT of cleaning to do - rust removal, cleaning crud and dust and grease in general, dealing with the weird varnish/tobacco mix or whatever is on the front plate, retouching gold lettering, polishing, waxing. At some point, I'll probably have to remove the surface panels and clean up individual typebars underneath too. Also, re-felting.
A couple specific photos of things still left to fix that I didn't include earlier. Top: a super rusted and old rubber platen knob. Middle: A completely missing other platen knob. Bottom: Another view of the remaining knob and a lot of surface rust on other levers and things.
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