Help designing CNC machines for MARS

[MarsMaker]

I am interested in space exploration and eventually machining in outer space on Mars or the moon.

I am an electrical engineer but I am not particularly mechanically inclined so I am starting from the VERY beginning.

My Shapeoko 3 XXL will be delivered on Monday its my first CNC or milling machine. Originally, I wanted to machine aluminum for CubeSat sized spacecraft and was considering the PocketNC or Nomad machines but I think the Shapeoko is a good hobby level aluminum routing machine for the price as a learning tool for my basic education in CNC. I understand its primarily a 33" by 33" wood cutting machine but I will be stretching it to mill aluminum and am looking on any advice to mill aluminum and brass to the best possible tolerances.


So my goal is to construct machines on Mars that will be able to construct slightly more precise machines which will then construct more precise.....
This is a very large goal and I will nearly certainly fail but I think I may be able to push the ball forward so that others can succeed and I would like to ask your help with this.


This is how I currently envision building a prototype machine shop for less money while also learning how to build one from scratch which will be a necessary skill on Mars where from scratch includes mining the metal.

1) Buy the first generation machine. In my case Shapeoko 3 XXL but I may need to modify it back to the Shapeoko 3 for better resolution on aluminum/brass. I picked the shapeoko because it is up and running in an hour and allows me to be using a machine rather than trying to build a machine. Shapeoko is more rigid than X-carve from what I have read and more reliable than the chinese 3040 which is probably more rigid but has a much smaller travel. Mars may start with heavier machines but the cost of mass at Mars is likely to be 5-10 times the cost of Gold so its unlikely that it will be much more expensive.

2) I am interested in professional level 5 Axis for cheap and I found a project that seems to have a design for that its a 4th/5th axis made mostly from purchased parts for around $3000 in parts.

http://digitalcommons.calpoly.edu/cg...2&context=mesp

I am interested in comments on how "professional" this build is and how badly messed up it would be for me to try and build it using hobby equipment and aluminum for the steel parts.
I plan on making it several times as I don't have access to "professional" milling equipment for steel and will need to improve gradually.

3) For CAM software I plan on writing my own for the 4th/5th axis. This is a massive undertaking but for simple machining it may be possible to build a 5-axis light that is mostly 3 axis with limited 5th axis capabilities. I don't need the tool path to be the shortest and am willing to sacrifice some capability for simpler operation. For CNC I will use either linuxCNC or fork the code and use a custom version that doesn't run in linux as a native Martian CPU will be very different from Earth CPUs and far less capable.

4) In order to build with steel using a shapeoko I would need to build a home made EDM machine and etch an aluminum/brass/copper pattern into a steel work piece. This would allow tolerances worse than Shapeoko can do which would need to be improved upon in the future. I am interested in which type of EDM is best to achieve the highest precision/resolution etc. Also any modifications to the Shapeoko that have improved tolerances.

5) A rough 4th axis build would allow me to use photometry to produce a 3D image of the work surface and determine where the table is not accurate. I would use open source software at this point to create the 3d images. Kinect is listed at 0.05 mm in an article which if true may allow the entire machining process to be closed loop instead of open loop which would allow inferior machines to perform above their capacity with optical feedback.

6) I am very interested in using Laser cutting of steel for CNC scrubbing of a nearly finished steel work piece. Laser is attractive because laser optics allows large movements to be focused down into smaller movements allowing non precise machines to make more precise machines. Personally having a laser picture etcher is attractive but for mars having the ability to CNC etch very thin layers and CNC mill very small detail is very attractive.

7) I have a Kiln and am considering casting my own aluminum metal parts but at the moment the risk associated with home casting is not something I want to jump into. Mars metals are probably not going to be pure so aluminum may be a suitable analog for what a Martian metal would look like on the first pass. I currently know nothing about ceramics and the building of the crucible that would be needed to forge aluminum or iron.

8) At some point Extrusion seems to be the best technology for taking a small precise thing and making a large precise thing from it. I know nothing about extrusion and this may be a fun project for far in the future for me or someone else. The only alternative I see is sand casting with a finish to provide the precision.

9) I own most of the Gingerly do it yourself books and I like very much his way of approaching machines form the bottom up. I believe this is the method that will be necessary on Mars.

10) at some point wire winding and stepper motor construction will be required but for now I am assuming that stepper motors will be manufactured on earth for some time after Mars has its own machine shop.


I am interested in any helpful comments you may have on what technology I have skipped over or what tooling would be required and how to build it.
I know I will be initially far below the capabilities of large expensive machines but currently Mars has even less capacity that I do and it will take a layered approach to build up to precision machining on Mars.
I want to emphasize again that I am just starting out with zero experience in mechanical engineering or machining and even very trivial things are probably new to me so be patient =)

Thanks for your help,
MarsMaker

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[Jim Dawson]

An ambitious project. And I think completely doable with enough time and money.

One of the problems that I see is that before any mining or machining is possible, there will have to be sufficient infrastructure on Mars to support these activities. That is not going to happen in my lifetime, but it's possible that it may occur in yours. I may live long enough to see human footprints on Mars, but not much else. Having said that, I see additive manufacturing overtaking subtractive manufacturing in the not too distant future. By the time humans are able to colonize Mars, 3D printing will be a mature technology and have capabilities that we can only dream about today.

Is it possible to build a machine to build a larger and more accurate machine ad infinitum? Yes, at least to the practical limits of physics. I'm not going to try to address much of your points in this post, I don't have the time to write a book right now. But I will in subsequent posts.

One note to get you started, use BLDC motors and close the loop for maximum accuracy. Secondly, mass is your friend for machining accuracy, but not so much for space travel. You have to find a happy medium.

Looking forward to reading comments from others.

[samco]

Maybe a Stewart Platform? (Hexapod)

Linuxcnc can handle the kins - and you should be able to get rigidity with less weight..

sam

[CNCMAN172]

MarsMaker,
Interesting project. I would think the team going to Mars could bring a small machine completely assembled, which could be used to make bigger machines like you said. The biggest issue will be having the power required to power the machine. I guess initially they will have batteries and who knows maybe a nuclear reactor to generate power. Become any of that happens they are going to need a way to make oxygen, clearly they can all some with them, but that along with Water and Food will be the biggest challenges. Like Jim Dawson said don't think this will happen in my lifetime, but at some point in the future with the right group of people and enough financial backing this might all happen. I watched the television series on colonizing Mars which was interesting. You will also need to bring a hardware store to Mars,

Russ