Homebrew space exploration program

Description

This project documents my hope for a better future. All of these ideas are sincere, although in order for one man to have time for so many projects perhaps more than one lifetime is needed. Fortunately, the medical sciences are promising exactly this.

Before I could read I had a children's book about the history of space exploration where at the end artists also illustrated their vision of the future. I was greatly impressed by these ideas and contemplated the vastness of space.
I feel that I have a duty to try to make visions like those of that artist in that book, and others, and my own, come true.

Perhaps by sharing these visions of the future we can coalesce and accumulate a multiple of productive lifetimes. This site can help us do that.

Details

Purpose & Design goals

The purpose of this system is to enable efficient selective sintering of transparent and reflective materials such as glass and steel. To reach this goal I'm designing a compact, high-efficiency, powerful and affordable gas laser which can operate in the mid-IR region.

State-of-the-Art and Theory

Usually in gas lasers most of the input energy is lost from the system in the form of heat conduction through the walls of the optical resonator. The existing designs of especially HeNe lasers seem to use an approach of dumping ever more energy in the system and removing the heat in a controlled manner to achieve temperature stability and beam power. These designs expose the hot lasing gas to very large surface areas compared to effective beam volume, making them inefficient.

According to the art of building gas lasers, you get very little power increase when you make the laser beam wider. This is because the atoms spend a long continuous time in the active lasing region so they get little opportunity to reset their energy levels, which is needed to ready them for emitting more photons. Using a thin beam and a very long waveguide is the efficient approach, but folding the laser beam in a zig-zag pattern inside the optical resonator through various topological means has not given as much space saving as one might expect. These existing solutions are brilliant in their own right, with very robust geometry often involving convex mirrors, so that when the device undergoes thermal expansion the beam does not attenuate.

Home-built CO2 lasers often have a beam which fades in and out because of this. To get a stable beam you need to de-couple the mirrors. Desktop HeNe devices used for education tend to use an elaborate and very costly rig of machined parts to do this.

This project will hack high-voltage amplifiers to drive common piezoelectric discs as actuators, and mount the mirrors to the actuators. There are two pairs of parallel mirrors at a diagonal to the other pair, with one pair kept at nλ and another at nλ ± ½λ (The latter is also referred to as 'half-wavelength mirrors' in this document.). This creates a tightly-folded beam path which yields high efficiency and high beam power since the ratio lasing region volume vs. resonator surface area is large. This configuration also reduces device size vs. beam power. The solid medium version of this laser is called total-internal-reflection face-pumped laser (TIR-FPL), where the laser is confined to the medium by angle and index of refraction, similar to how an optical fiber works. In TIR-FPL the parallel surfaces are still a problem because even though the index of refraction lets light perpendicular to the surfaces pass right through and no mirrors are used along that path, some of the light is still reflected. These reflections are called 'parasitic oscillations' in slab lasers. The patent US7505499 assigned to Panasonic Corporation postulates no parallel polished surfaces to address this issue. We of course solve the same problem by keeping the parallel mirrors and detuning them.

If you put two mechanically coupled end mirrors in parallel against each other, making an 'infinity mirror', then thermal effects will make them sometimes lase and sometimes not as the optical resonator heats up and expands. This happens because the light as they constructively interferes and destructively interfere since this effect is controlled by the distance between the mirrors. Mirrors separated by nλ ± ½λ, meaning a length of any number of full laser light wavelengths with a half-wavelength either added to subtracted to its length, will always destructively interfere and cancel light amplification. Mirrors separated by a number of full wavelengths, eg. for HeNe 632.8 nm x some large number, will always increase light amplification, adding more and more intensity to the laser beam as the process of Light Amplification through Stimulated Emission of Radiation does its thing.

Stimulated Emission...

Lasmix plasma pump for cooling. Career change
ganzuul • 06/23/2017 at 14:26 • 1 comment

There exists a type of gas laser which achieves much higher power densities at the cost of destroying its own lasmix. It vents the lasmix from a bottle, though the optic cavity, and from there presumably into the atmosphere. It does this for the sake of cooling.
I have been mulling on how to implement a plasma pump inside the cavity for about two years now, and just connected the dots with just enough rigor to blog about.
If the floor and ceiling of the cavity is coated with a dielectric material and the RF wave powering the thing is a phase modulated standing wave (Like an IQ modulator.), then the dielectric barrier discharge should, I hope, favor certain locations along the length of the cavity. If the glow discharge further is able to exert pressure, then what we should have is a pump with no moving parts and potential for extremely fast flow. - This ought to enable the high cooling rates needed for adding another power output multiplier to the original house-of-mirrors design I have spoken about.
(Just 16 hours ago W2AEW uploaded a video explaining how IQ modulators work, and together with my study of variable capacitance diode tuners over the past month, these were the last pieces of the puzzle. Thank you Alan, I wish you and you ankle all the best. 73 :)
p.s. If the phase modulation scheme does not work, then an array of addressable dielectric sections should. This seems inelegant by comparison though.
Since the last time I posted I have been very busy! I have completed one year of basic metalworking studies and gotten a diploma for that, and now I'm half a year in on getting one as a CNC machinist / programmer. The mystery box picture I posted almost two years ago contained a tiny lathe, and obviously I have moved on to bigger machines now. Much bigger. I have nascent plans on starting a business selling shiny consumer goods mostly made out of electroplated aluminum, so I may fund my robot army.
Mystery box arrives
ganzuul • 09/21/2015 at 21:36 • 0 comments
Fused metal deposition
ganzuul • 12/19/2014 at 22:48 • 0 comments

At 6:15 they tell of a camera that looks through the same optics that the laser beam passes. It's very impressive to see the molten area getting bombarded by rapidly heating titanium granules. The deposition rate of this method is also very impressive.
For accuracy, the other method has a clear advantage.
Well that was unexpected
ganzuul • 11/25/2014 at 16:36 • 0 comments

This circuit on page 15 of AN-106 by Analog Devices mentions sub-micron movement. I had browsed this document before during the hectic days of the HaD space race, but somehow I had missed this. The OP-77 is less than half the price of the LTC6090 and there appears to be nothing magical about it, at all.
I'm a little unsure of what the voltage drop across that 2M resistor at the top is supposed to be. - I didn't blow up my uC when I powered the LTC6090 with 24V volts and in a similar strategy sprinked resistors over the high voltage bits. - Instead I get exactly the performance I thought I might get. Together with this circuit I found earlier I have a pretty good refrence on how to do this without the LTC6090.
It is time to move on, and design a test jig to calibrate the movement of the piezo membrane... A laser oscilloscope, perhaps?
Ball mill, 405nm, Jim Williams
ganzuul • 07/24/2014 at 10:45 • 0 comments

Making glass frit by hand is labor intensive. A machine should do it. This is perhaps the simplest machine which will do the job:

In want of steel balls, cut-up lengths of rebar should work too. That steel is very hard. (If anybody can get the original I'd be much obliged. I'm storing a copy of this on my server in case it gets deleted.)
I might postulate a cyclone separator to get the right sized grains under the laser for sintering. It adds complexity but Hackaday readers are already familiar with those. In industry the combination ball mill and cyclone separator is commonly used in for example coal-fired power plants, which burn powdered coal.
[ED 23.08.2015 - Removed competition-specific and import-related speculation.]
It's a 405nm, violet 10mW laser. I ordered two. After a bunch of research I determined that I need at least 10^2 voltages on the piezo discs to control a CO2 laser like I imagined. The short 405nm wavelength will let me use the 30Vmax voltage regulators to demonstrate destructive interference and also characterize the voltage/amplitude response of the piezo discs through the same mechanism.
I'll probably aim for a maximum voltage of 10^3. 1kV. This high voltage, low current has me researching CCFL tube drivers as I expect the volume they're made in to make their components cheap. Turns out that Jim Williams spent 10 years working on these things, to the point he was fed up with them. I'd very much like to stick one of his designs verbatim on an Arduino shield so I've been getting deeper, much deeper into electronics than I have been before. Current mirrors, totem poles, Darlingtons, the different breeds of TTL and the protocols I2C and SPI... Fortunately I have found a teacher who seems to know what he's talking about, presenting simple things as simple as they are. Too bad he's no longer taking phone calls...
http://cds.linear.com/docs/en/application-note/an25fa.pdf
http://cds.linear.com/docs/en/application-note/an65fa.pdf
http://cds.linear.com/docs/en/application-note/an70.pdf
http://cds.linear.com/docs/en/application-note/an118fa.pdf
Perhaps I can just refer to his documentation for this part of the project? Hmmm!
Novel approach to laser waveguide design
ganzuul • 06/19/2014 at 22:06 • 5 comments

Since I could be on to something here the following maybe-formal text describes what I believe really is a new invention:
Background:
Inside a laser waveguide where laser light is 'folded' in a zig-zag pattern using mirrors, the intensity of the beam is increased by effectively lengthening the optical resonator with the mirrors. This is commonly done with multiple mirrors where the beam bounces once per mirror, which results in a requirement to align a multitude of mirrors to a high degree of accuracy. Even in large industrial lasers this alignment is done manually, often by a man with a wrench, which is costly and time-consuming.
Invention and some theory:
None of the patents for waveguide lasers I have reviewed mention that; putting one pair of parallel mirrors at nλ ± ½λ and at a small angle to them another pair of parallel mirrors at nλ means that only the nλ pair causes light amplification, as the other pair interferes destructively. This lets the beam that is stabilized by the nλ pair of mirrors be folded a large number of times between the pair of mirrors at nλ ± ½λ.
Prior art, and such:
I assume that the reason the industry has not adopted this approach lies in the perceived difficulty of maintaining a pair of mirrors at a set half-wavelength from each other while the entire device flexes, expands and contracts from thermal expansion. It is however possible to have this degree of accuracy and control for laser light; which is especially true at the longer, mid-infrared wavelength of the CO2 laser where it can be done cheaply.
Piezoelectric devices respond with small movement to high voltage, which translates to a ultra-fine precision when the voltage is well-behaved. Usually piezoelectric actuators built for the purpose cost hundreds of dollars, but according to my interpretation of https://www.comsol.com/offers/conference2012papers/papers/file/id/13148/file/13943_garcia_paper.pdf the degree of control needed for laser mirror alignment of a CO2 laser can be had for a mere pittance.
Conclusion / claims:
My plan, (should some soulless greyface attempt to claim this invention as their own...) is to actuate the mirrors of a CO2 laser with piezo disks and to drive the actuators with e.g. a 8051 microcontroller. To alleviate friction the mirrors can be mounted on an air cushion. The distance between the mirrors is constantly monitored,e.g. by a laser beam power meter, and the output of the sensor is fed back through the automation system to adjust the voltage of the actuators and keep the laser's power at the desired power level.

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Discussions

PointyOintment wrote 11/27/2017 at 06:35

Hold on… terraform Venus by HEATING its atmosphere? Isn't it hot enough already?

Are you sure? yes | no

ganzuul wrote 11/27/2017 at 17:49

Spot heating. But I do see the irony.

A solar reflector made out of mylar could also work.

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ganzuul wrote 06/03/2016 at 05:30

Almost half a year into the vocational training programme, this project is far from dead!

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Albert Latham wrote 07/29/2015 at 07:17

...its quiet. Too quiet.

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ganzuul wrote 07/29/2015 at 09:56

I have applied for an education program for adults in CNC machining. :)

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Albert Latham wrote 07/29/2015 at 22:35

Oh! Excellent! Perhaps we might be able to collaborate in the future.

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ganzuul wrote 07/30/2015 at 11:02

I'd like that! I have so many ideas I can start to realize once I can cut metal. :D

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Albert Latham wrote 08/02/2015 at 00:13

I'm super interested in your manufacturing ideas, especially some of the laser sintering and deposition stuff. It is way out of my league, but still very interesting to read through and struggle with.

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PointyOintment wrote 08/03/2014 at 07:20

I just had an idea for how to make the metal evaporation easier. Put electric heaters below the samples and heat them up before shooting them with the electron beam. Heat makes electron emission easier (as seen in vacuum tubes), so it may do the same for emission of atoms. Then you might be able to get away with your relatively low-current e-beam.

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ganzuul wrote 08/03/2014 at 21:33

That is a quite compelling idea. It could perhaps offset heat-dissipation in larger samples and generally make the process more controllable too, like how a crystal oscillator is stabilized with a built-in heater.

Googling thermal evaporation, I found a Wikipedia jump-page which lists a lot of the common terms: https://en.wikipedia.org/wiki/Evaporation_(deposition)
I now suspect that the industrial name for sublimating with an e-beam is EBPVD, while the academic term is molecular beam epitaxy. No doubt the MBE keyword will yield better documentation in the form of research papers. If I find any that mention your idea I'll inform you.

In the long term I hope to sinter custom radiation-hardened vacuum vessels out of PbO and SrO, by pulverizing CRTs with a ball mill, which would accommodate for stronger electron guns or for other higher-energy processes which produce more intense radiation. Once you're done with the equipment you could just re-pulverize it to save precious space in the lab and in storage.

There is also https://en.wikipedia.org/wiki/Pulsed_laser_deposition which seems to be used for modern semiconductors. Hmm..!

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PointyOintment wrote 08/03/2014 at 22:44

I looked up MBE on Wikipedia and it looks like it's designed for exactly what you want to do, but it also looks much more complicated. Also, when I looked up EBPVD, the diagram in that article has the e-beam curving around so that the electron gun is behind the target, so you might want to turn the target sideways in your machine so the evaporated atoms don't coat your electron gun.
https://en.wikipedia.org/wiki/Electron_beam_physical_vapor_deposition

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ganzuul wrote 08/03/2014 at 23:29

Yup, that's exactly it. The yoke on the CRT lets you steer the e-beam so you could potentially have many materials mounted on the side of the chamber, all pointed at a target on the other side of the chamber.
Apparently MBE uses shadow masks on actuators to make patters on the substrate. I suspect it might be a complete silicon fab in a box...

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Jerry Biehler wrote 07/10/2014 at 04:30

For a filament to last very long you need to be at least into the 10e-3 to 10e-4 torr range. At 1 torr your filament will last probably a matter of minutes.

Even low power research size ebeam guns like the one I am going to build use about 3kw, 10kw is more common. The small ones run somewhere around 3kv to 4kv at 750ma to 1A, large ones at 10kv at an amp and 20-30 amps on the filament. You will never get enough power out of a crt e-gun to do what you want to do.

As for your laser, well... I am just going to be blunt and say you need to learn a lot more about lasers.

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ganzuul wrote 07/10/2014 at 20:02

The CRT tube is rated for 30kV at 10mA. With ions you start embedding your atoms after about 5kV, which is why you use those field intensities for eg. doping silicon.
I'm entirely uncertain if I'll be able to knock off gold or copper with a high-speed, low intensity e-beam. That is an experiment to satisfy the 8 year-old in me. If I can't get a deep vacuum or if the e-beam just doesn't ablate then I'll use the CRT as an x-ray proof Bell jar for simple sputtering. No harm, no foul.

It's unfortunate, but your very bluntness is uninformative...
It should placate you to know that I'm not immediately trying to build a wear-resistant industrial solution but instead check if I really did understand Bose-Einstein statistics correctly. The people I have spoken to say that I got the theory right. One of them recommended me this book, which I have been making my way through: http://www.amazon.com/Lasers-Anthony-E-Siegman/dp/0935702113
The past few days I have found out that the electrical equipment available to me should actually suffice to test destructive interference with the shorter wavelength of a red diode laser, without having to involve any high voltage. Right now I'm stuck dog-sitting far from home, so I can't build but I can study, reiterate on my plans as the deadline for submissions draws near, and wait for parts to arrive from China.

I'm attempting to build something of real hack-value which deserves winning a trip to space, and perhaps back again. Failure is absolutely an option. I have no desire to play it safe with Arduinos and LEDs. This project is a moon-shot which might only come to fruition if provided good vibes, well-wishes and generous helping of good luck.

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Jerry Biehler wrote 07/11/2014 at 07:58

10ma? Are you sure that is not 10ua? 10ma beam current is insanely high for a crt. A power supply that can supply that much voltage is much bigger than any tv flyback I have ever seen. Even assuming that it is 10ma of beam current that is still only 300 watts of energy, that is pretty low.

You seem to have your technologies confused. You talk about embedding atoms (ion implantation?), knocking off gold and copper (sputtering?) and e-beam PVD. These are three different processes. Sputtering uses ions to knock particles off the target to be deposited on the surface of the substrate to be coated. e-beam uses the electron beam to evaporate the target and thermally deposit on the substrate. Ion implantation uses a stream of ions that are embedded in the substrate.

You dont need to worry about x-rays from sputtering, it is done at a relatively low voltage and does not generate any. DC sputtering is the easiest, there are a lot of designs used for sample coating for electron microscopes. You will need a better vacuum pump, you need to get down to around 50 millitorr for most sputtering. I would highly not recommend using a CRT as a bell jar, the thin neck is an implosion hazard. You can pick up smaller jars off ebay pretty cheap. If you do get a glass jar, make sure you build a shatter guard. A friend has seen bell jar implosions send glass through a car door.

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ganzuul wrote 07/24/2014 at 16:07

I feel a bit offended at you calling me confused and I suspect you might be talking down to me. Since this page is the public face of my project I have to confront you on this. If you read what I actually wrote a bit more carefully, I said that you start to embed atoms, not electrons. I don't explain the nomenclature because I expect that I'm talking to one of my peers, who doesn't need hand-holding.

You can get vacuum deep enough for sputtering with two air-conditioning compressors in series. See here if you still won't believe me: https://www.youtube.com/watch?v=KsBXixItlAI

I checked the label on the CRT and it says 1mA, 30kV... That's still 10^2 over 10uA. 30W of energy isn't in my opinion low, but if you disagree then I would like to hear why.

I think I've written about coating the CRT with epoxy because of the implosion hazard, since I took off the implosion band due to lessons learned. The fact that the neck is fragile is obvious... A few minutes of research on the subject drives this home. Of course this is not the only precaution I'll take. The 1mA CRT is a lot bigger than the cracked one in the project picture.

X-ray emission in sputtering isn't a yes-or-no issue, but it depends on the elements that you put in the jar and the associated material-specific voltages.

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Jerry Biehler wrote 07/26/2014 at 04:03

I never said anything about implanting electrons.

Yes, you can use two refrigeration compressors in series. That has been shown in the old back issues of Scientific American: Amateur Scientist. You do need to watch out when using these compressors as vacuum pumps. They can run dry of oil pretty easy and seize up. When installed in a refrigeration system the oil circulates with the freon and keeps the pump lubricated. When they are run open ended they can just pump out their oil if you are not careful. At this point is is usually easier and cheaper to get a refrigeration service vacuum pump at harbor freight. Or look for a nice two stage rotary pump on craigslist or something. This especially holds true if you want to use a diffusion or turbo pump which you will need if you want to do any work with electron beams, a fridge compressor does not have the throughput necessary to back one of these pumps unless the chamber is very small.

30w is nothing. It can effect the material the beam is hitting, I have seen it happen at lower powers while using a SEM. But to expect to do thermal deposition is asking a lot.

I would not use epoxy on the neck, at least not the most common hard epoxies. They usually have poor adhesion to the glass and would not stop glass flying during an implosion, in fact it might just add more shrapnel. If you muse use something maybe a silicone might be better. It adheres well to glass and is flexible which might stop glass from flying.

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PointyOintment wrote 07/28/2014 at 18:31

You might want to look into rear-view mirror glue. It's one of the few glues that adheres well to glass.

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PointyOintment wrote 07/03/2014 at 03:59

You said you wanted to do EBPVD because it would allow you to alternate between two materials. Could you not do the same using sputtering and a mechanical system (which could be as simple as a wheel) to alternately put the thing you're sputtering onto in front of each material?

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ganzuul wrote 07/06/2014 at 13:08

Yes, but I wanted to try something new first. If I can't get the e-beam to work as intended with this CRT then I'll sputter since I still have the laser project.

I'm also curious about electron microscopy and lithography. This could be an early, tentative step towards a DIY ion beam workstation.

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PointyOintment wrote 07/07/2014 at 04:11

Awesome; I'll look forward to that!

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tqfvm wrote 06/30/2014 at 04:07

I've been working on a different project that uses vacuum.

Once you get below 1 Torr, you can calculate the "mean free path", which is the distance something travels in your vacuum before it hits an atom of the remaining atmosphere. See here: http://en.wikipedia.org/wiki/Mean_free_path, and for reference values see here (3rd page in): http://www.colorado.edu/physics/phys3340/phys3340_sp07/Lectures/AdvLab-Vacuum07.pdf

The rule of thumb is this: at .001 Torr (1 millitorr) the mean free path is 1mm, and goes up or down by a factor of 10. The mean free path at 1 Torr is therefore .001 mm, and the mean free path at 1 uTorr is 1 meter. This can be used to calculate the amount of vacuum you need for your application. For example, if an electron microscope has a 1 meter stack, at 1 uTorr on average 50% of the electrons will be deflected the beam reaches the target. For proper operation the microscope will need a shorter stack or more vacuum.

At 1 Torr, each electron in your beam will be deflected on average each .001 of travel, so you'll need better vacuum. Assuming the CRT is 1/2 meter long, you will need at least 1 uTorr in order to have proper beam control.

This is not a critique of your project (!), I'm just saying that you will need higher vacuum. Hobbyists can achieve vacuum in this range, so you should plan accordingly. You will need a roughing pump *and* a diffusion pump, these are available used on eBay for not much money.

Regular sputtering is optimal at the 200 mTorr range (.200 Torr or thereabouts). It doesn't use an electron beam per se, it relies on the remaining atmosphere to knock off particles of one electrode and accelerate them towards another. More vacuum is less effective because there isn't enough remaining atmosphere to knock off particles, less vacuum is less effective because more atmosphere causes more collisions. See "Procedures in Experimental Physics" by John Strong for a really good explanation of home-built sputtering systems and vacuum technique. It's written with the hobbyist in mind.

For electron beam anything, you will need much more vacuum than your pump will allow.

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ganzuul wrote 07/05/2014 at 17:07

It's not a critique! In my mind you just told me I can roughly gauge how deep a vacuum I have through electron deflection! ;D

I'm going to try a vacuum cleaner motor/turbine before I get a diffusion pump, you know, just because! I'll be able to see if it helps at all at the very least and I will document the experiment here.
Right now, dog-sitting for two weeks. Fortunately I found an old piezo buzzer that I made in shop some 15 years ago to examine.

Thanks for the reference. The illustrations in that book are gorgeous. =O

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Jerry Biehler wrote 07/11/2014 at 08:05

Putting an average vacuum cleaner motor in a vacuum would not turn out well. Most vacuum motors are air cooled and will burn up without air flowing over the windings. Plus it will not run fast enough, my little turbos run anywhere from 72000 to 90000 rpm. Basically the vanes velocity is greater than the speed of the molecules in the chamber and acts like a check valve. Multiple stages of vanes knock the molecules though successive stages of stators "pumping" the gas though. With a turbo-drag pump you *might* be able to get away with your vacuum pump, some can tolerate up to 2 torr on the fore line. Diffusion pumps usually need 500 millitorr or lower on the fore line to operate. Check the fusor.net forums, there are a lot of people there putting together vacuum systems on the cheap.

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ganzuul wrote 07/24/2014 at 16:00

I knew that but thank you for the reference...

If there is a way to strongly cool the gas so that the molecules are slow enough for a cheaper motor, this could get interesting. A gas mixture here, such as back-filling with helium and then pumping down again, could help in the cooling scheme.
If the bearings in the vacuum cleaner are are good enough then you should be able to spin it at a high rate with little energy input, meaning little heating.

It's something that _just_ _might_ _work_, which is why I think it deserves a test.

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Jerry Biehler wrote 07/26/2014 at 04:19

You could cool it down with liquid nitrogen, but by the time you are doing that you could just get a sorption pump and use that with the LN2 to create a high vacuum,. Trying to cool an entire system to temps low enough would be an engineering mess.

You really want to avoid helium in a vacuum system. It is great for checking for leaks with a mass spec but it is really hard to pump compared to heavier molecules. If you look at the specs on most high vacuum pumps the pumping speed for Helium is listed separately from the Nitrogen speed due to the relative difficulty of pumping it. On the other hand, big heavy atoms like argon are easy to pump. There is also economy, helium is expensive, the little bottles you see at the store are only a percentage of helium and mostly air, and they still charge $20 for it!

You would have to use ceramic bearings at a minimum and find a grease that can handle being run at that speed and not outgas into the chamber. Most turbo pump designs that use ball bearings have the bearings and motor in a section of the pump that is not exposed to high vacuum, just the roughing vacuum side which has a much, much higher relative pressure. This way there is no possibility of the varnish on the motor or grease contaminating the chamber.

Vacuum an insulator so even with little current draw there is no convection to remove heat from the coils. This heat will build up and eventually break down the varnish on the coils and short the motor out. You would be limited to radiative cooling to the walls of the pump and conduction through the mounts.

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tqfvm wrote 06/30/2014 at 03:46

I've been doing a similar project that works with vacuum.

Once you get down to 1 Torr or less, you get to calculate the "mean free path" of things. This is the distance something will travel before it bumps into an atom in the remaining atmosphere. (See <a href="http://en.wikipedia.org/wiki/Mean_free_path

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tobias.kornmayer wrote 06/27/2014 at 08:33

Please, make a 3D metal printer out of it ;)

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ganzuul wrote 06/27/2014 at 13:45

That should be easy once I can do glass. I'll start with glass since it should let me gauge the internal structure of what I've melted by just looking at it, so I don't require any kind of x-ray imaging to know that.
I'm especially interested in trying to make alloy mixtures of very finely powdered pure elements which form directly into specific kinds of crystal structure when melted. Getting a wide selection of elements in specific grains is not going to be very easy though.

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Mike Szczys wrote 06/05/2014 at 15:55

Thanks for submitting this one to The Hackaday Prize. I'm not familiar with laser additive techniques that use glass. Do you feed it a filament or is it like SLS with powder? If so, how do you make the glass powder?

Should be really awesome. Don't forget to touch on the "connected" judging preference as you continue to document your project.

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ganzuul wrote 06/19/2014 at 23:40

There has been a few tentative research papers which conclude that glass is a promising material for additive manufacturing. There is also Markus Kayser who built a solar-powered machine that melted sand into traditional 3D printing shapes in the Sahara.

SLS-like seems to be the simplest for this application, but glass fibers could certainly be considered!
Crushed glass is called frit. Traditionally it is made with crude implements, but it can be bought commercially too at various grain and with many colors. I haven't come around to improving on any existing technique yet.

I picked glass because since I popped my first CRT I have some crystal glass (lead oxide) which is easier to melt than SiO, and powdering metal seems like hard work.

Didn't know about the "connected" thing. Thanks! =)

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Homebrew space exploration program

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Lasmix plasma pump for cooling. Career change

Mystery box arrives

Fused metal deposition

Well that was unexpected

Ball mill, 405nm, Jim Williams

Novel approach to laser waveguide design

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