We’ve all been there: you need a specific tool or gadget to complete a project, but it’s not the kind of thing you necessarily want to fork over normal retail price for. It could be something you’re only going to use once or twice, or maybe you’re not even sure the idea is going to work and don’t want to invest too much money into it. You cast a skeptical towards the ever-growing pile of salvaged parts and wonder…
Inspiration and a dig through the junk bin is precisely how [Nixie] built this very impressive spin coater for use in his ongoing homemade semiconductor project. If you’ve never had first hand experience with a spin coater, don’t worry, not many people have. Put simply, it’s a machine that allows the user to deposit a thin layer of material on a disc by way of centrifugal force. Just place a few drops in the center of the disc, then spin it up fast enough and let physics do the rest.
[Nixie] only needs to spin up a fairly tiny disc, and realized the hub of a 40x40mm brushless case fan was just about the perfect size. A quick pass through the lathe stripped the hub of its blades and faced off the front. Once he found a tube that was the exact same diameter of the fan’s axle, he realized he could even use a small vacuum pump to hold his disc in place. A proper seal is provided by 10 and 16 mm OD o-rings, installed into concentric grooves he machined into the face of the hub.
With a way to draw a vacuum through the hub of the spinner he just needed the pump. As luck would have it, he didn’t have to wait for one to make the journey from China, as he had one of those kicking around his junk bin from a previous project. The only thing he ended up having to buy was the cheap PWM fan controller which he mounted along with the modified fan to a piece of black acrylic; producing a fairly professional looking little piece of lab equipment. Check out the video after the break for a brief demonstration of it in action.
It’s not every project write-up that opens with a sentence like “I had this TURBOVAC 50 turbomolecular pump laying around…”, but then again not every write-up comes from someone with a lab as stuffed full of goodies as that of [Niklas Fauth]. His pump had an expired controller board, so he’s created an open-source controller of his own centred upon an STM32. Intriguingly he mentions its potential use as “I want to do more stuff with sputtering and Ion implantation in the future“, as one does of course.
So given that probably not many Hackaday readers have a turbomolecular pump lying around but quite a few of you will find the subject interesting, what does this project do? Sadly it’s a little more mundane than the pump itself, since a turbomolecular pump is a highly specialised multi-stage turbine, this is a 3-phase motor controller with analogue speed feedback taken from the voltage across a couple of the motor phases. For this reason he makes the point that it’s a fork of his hoverboard motor controller software, the fruits of which we’ve shown you in the past. There isn’t a cut-out timer should the motor not reach full speed in a safe time, but he provides advice as to where to look in the code should that be necessary.
This is by no means the first turbomolecular pump to make it to these pages, in 2016 we brought you one taking inspiration from a Tesla turbine.
What can you do with a very good vacuum pump? You can build an electron microscope, x-ray tubes, particle accelerators, thin films, and it can keep your coffee warm. Of course getting your hands on a good vacuum pump involves expert-level scrounging or a lot of money, leading [DeepSOIC] and [Keegan] to a great entry for this year’s Hackaday Prize. It’s the Everyman’s Turbomolecular Pump, a pump based on one of [Nikola Tesla]’s patents. It sucks, and that’s a good thing.
The usual way of sucking the atmosphere out of electron microscopes and vacuum tubes begins with a piston or diaphragm pump. This gets most of the atmosphere out, but there’s still a little bit left. To get the pressure down even lower, an oil diffusion pump (messy, but somewhat cheap) or a turbomolecular pump (clean, awesome, and expensive) is used to suck the last few molecules of atmosphere out.
The turbomolecular pump [DeepSOIC] and [Keegan] are building use multiple spinning discs just like [Tesla]’s 1909 patent. The problem, it seems, is finding a material that can be made into a disc and can survive tens of thousand of rotations per minute. It’s a very, very difficult build, and a mistake in fabricating any of the parts will result in a spectacular rapid disassembly of this turbomolecular pump. The reward, though, would be great. A cheap turbomolecular pump would be a very useful device in any hackerspace, fab lab, or workshop garage.
If you work with surface mount components, you might want an air pickup tool (sometimes called air or vacuum tweezers). You can find inexpensive ones that use a bulb or spring mechanism (like a solder sucker). While these are cheap, they don’t work very well. [Natsfr] had one of these cheap tools and decided to add a proper pump to make it work like a much more expensive tool.
Experimentation with the unusual nature of things in the world is awesome… especially when the result is smokey glowing plasma. For this relatively simple project, [Peter Zotov] uses the purchase of his new vacuum pump as an excuse to build a mini vacuum chamber and demonstrate the effect his mosfet-based Gouriet-Clapp capacitive three-point oscillator has on it.
In this case, the illumination is caused due to the high-frequency electromagnetic field produced by the Gouriet-Clapp oscillator. [Peter] outlines a build for one of these, consisting of two different wound coils made from coated wire, some capacitors, a mosfet, potentiometer, and heat sink. When the oscillator is placed next to a gas discharge tube, it causes the space to emit light proportionate to the pressure conditions inside.
For his air tight and nearly air free enclosure, [Peter] uses a small glass jar with a latex glove as the fitting between it and a custom cut acrylic flange. With everything sandwiched snugly together, the vacuum hose inserted through the center of the flange should do its job in removing the air to less than 100 Pa. At this point, when the jar is placed next to the oscillator, it will work its physical magic…
[Peter] has his list of materials and schematics used for this project on his blog if you’re interested in taking a look at them yourself. Admittedly, it’d be helpful to hear a physicist chime in to explain with a bit more clarity how this trick is taking place and whether or not there are any risks involved. In any case, it’s quite the interesting experiment.
About a decade ago I started a strange little journey in my free time that cut a path across electronics manufacturing from over the last century. One morning I decided to find out how the little glowing glass bottles we sometimes call electron tubes worked. Not knowing any better I simply picked up an old copy of the Thomas Register. For those of you generally under 40 that was our version of Google, and resembled a set of 10 yellow pages.
I started calling companies listed under “Electron Tube Manufacturers” until I got a voice on the other end. Most of the numbers would ring to the familiar “this number is no longer in service” message, but in one lucky case I found I was talking to a Mrs. Roni Elsbury, nee Ulmer of M.U. Inc. Her company is one of the only remaining firms still engaged in the production of traditional style vacuum tubes in the U.S. Ever since then I have enjoyed occasional journeys down to her facility to assist her in maintenance of the equipment, work on tooling, and help to solve little engineering challenges that keep this very artisanal process alive. It did not take too many of these trips to realize that this could be distilled down to some very basic tools and processes that could be reproduced in your average garage and that positive, all be it rudimentary results could be had with information widely available on the Internet.
If you’re building a pick and place machine, or even just a vacuum pen, you’ll need some way to pick up tiny part. This means something that sucks, aquarium tubing, and everything that goes with that. A few months ago, [Wayne] found an interesting device called a Micro Blower that will blow small amounts of air from a small, lightweight device. A few modifications later, and he had a piezoelectric vacuum pump for picking up tiny parts.
The Micro Blower [Wayne] found is available on Mouser for about $45, but this device blows. To turn it into something that sucks, he would need to find a way to block up the input side of the pump so it could draw a vacuum. Eventually settling on mounting the blower inside a stack of foam board, [Wanye] glued on a 20 gauge needle and was able to suck up 0603 SMD parts.
The new piezoelectric sucker is extremely light, and the power draw is very reasonable: 18V and 20mA. This would be a great device to mount to a certain pick and place machine without having to run vacuum lines through the mechanics of a motion platform. Video below.