A very interesting project indeed!
I am not too sure of how one has to go about doing this, but I sure would like to buy one if its put up on sale!
If someone can take of converting the image into data points I am willing to work on the 3D model.
Is your facrication process as following:
- Create a Rapid Prototyped part of the moon.
- Use it as a mold to create a die.
- Cast Aluminum in the die.
Thanks for the reply!
The process you outline is exactly what we have in mind. (See more details in my comment below). I'm still working to figure out how the raw data will get translated into a 3D model. The data sets are beyond me and the JPL/NASA people I've spoken with have conflicting opinions about how to make this happen.
We're working on it though and if we get that resolved we'd love to have your help on the 3d model.
Is this just as a for fun kind of thing or does it need to be accurate?
In order to even see them I think you'd have to exaggerate the heck out of the crater sizes or at least only focus on the largest. That's such a small model I wonder if you could wrap the face of a sphere with the maps and have it laser etched.
You could manually model the whole moon as close to full scale as possible and then just shrink it down. Sounds like a lot of effort. Though I doubt you'd have to be very accurate since the moons face is constantly changing anyway, at least with the smaller craters.
It seams like a very fun idea but a pretty big task at the same time. Good luck, please keep us posted how you progress with it.
I also responded to you over on Renderosity (site Mail).
You were asked for a nurbs model (sldprt, igs, stp) by the metal fabrication companies presumably because they intend to CNC mill a mold. Basically, they won't talk to you until you have a model in that format. However, none of the data for the lunar surface will be in nurbs format. It can be converted, but that will be an additional expense.
It may be possible to 3d print a model (no nurbs or milling required) and use it as a master in some type of casting.
The first step in any machining or molding process would be to construct a polygonal model based on the data.
If it turns out you must have a nurbs model, that would have to be converted from the polygonal model.
At the size you indicate, the height of the surface detail will have to be exaggerated quite a bit in order for it to show up, so that might require a bit of testing on small sections to find out what the best vertical scale multiplier would be for the intended diameter.
I would like to discuss this with you.
Thanks for the response. The metal fab company I've been talking with recently is planning to do a 3D printed model and then make silicone molds from that. They'll then do a lost wax casting.
The general thinking of everyone involved, especially the JPL and NASA folks I've been talking with, is to do something as accurate as possible. The original idea was to use the new altimiter datat from the Luner Reconnaissance Orbiter to make the most accurate model of the moon ever produced. And unless that's simply infeasible that's the direction I'd like to continue working in.
that said, I've run some of the numbers in terms of scale and I do have some concerns that the features of the moon will not show up well on a ~9" globe. There are more than 1 million craters on the moon, 11,000+ are larger than 20km in size, but even a 20km crater will be less than 0.5mm on a 24cm moon. So the resolution would either have to be very high (I'm not sure if 0.1mm is sufficient but I'm also not sure how much more detailed we could go because I don't know what level of detail a high-end 3D printer can faithfully render) or the size of the moon would need to be increased.
I've reached out the metal fab team on these points and they're going to get back to me. That said, here are the estimates they've given me so far:
- $4,000 for the initial physical 3D model
- $1,500 for the original silicone mold (which will do a run of 10-50 moons) and $700 for each subsequent mold
- and a unit cost of $275 for each 9" aluminum moon if we do a run of 100 or more.
So about $350 a unit (run of 100), not including the cost of getting the 3D CAD drawing done. I approached them about doing a 14 or 16" version and they gave me a ballpark quote of $600-700 for the 14" version. $750 per moon starts to be expensive enough that I'm not sure we could sell 50 or 100 units via a kickstarter.
I appreciate any input that you might have on all this. I think it would be a great object to produce and there is nothing like it on the market right now.
I just spoke with the guy at the fab company:
1. Resolution: He said he has access to two 3d printing options (a) Stereolithography (SLA) and (b) Polyjet. Resolutions for SLA max out at 0.010 inches / 0.254mm and Polyjet runs 0.007 inches / 0.1778mm. So .1mm in terms of the 3D model should be fine.
2. Process: He suggested doing a series of sample runs. First step would be producing a 3D drawing of a small section of the moon and then we'd print that on both machines (SLA and polyjet) at various scales - 9", 12", 14" and 16" and see which option looks the best. Given the limits of the 3d printers I think we'll need to go larger.
That's it for now. Thanks in advance for any input.
I'm curious if this is the same metal fab company you mentioned previously. ... Have they changed their minds on needing a nurbs based file (sldprt, igs, stp) ?
One unfortunate side effect of converting to nurbs is that it will smooth out the surfaces somewhat, which could work against you for preserving the fine details.
Different company. The first couple of companies I was talking with suggested the listed file types. Then I began discussions with Masters In Metal (www.mastersinmetal.com), they're local (for me) and have been very responsive. So I switched to their specs.
Sorry for the confusion on that.
All that said, the end goal of the project is a very hi-fidelity final product. If nurbs is necessary to achieve that, then we can go with that (assuming it's not cost prohibitive). Not sure how detailed a CNC machine can get though (0.1mm engraving bits are the smallest I see, which would probably work just fine).
Actually, I think it would be preferable to keep it as a triangulated mesh for a few reasons.
FYI, cnc milling machines can do very high precision work. The industry is driven by nurbs models as most CAM software is unable to program a toolpath efficiently from a triangulated model. At some point there is a trade off in the faithfulness of the nurbs representation to the original triangles.
The 3d printer I have access to cannot print as large as you would need, but it should handle smaller test sections just fine.
Can you send me your contact info, and I will pass it along to my superior and he can work up some pricing for you to provide an STL based on the lunar data and some 3d printed test sections.
Thanks for that, I have passed your info along for a quote. The quote will be coming from Lanny Smith at Arrival3D.
hei'ya Chris, lurv the sound of the project
and on the positive side- it's not Jupiter
on the practical side to get a minds picture,
as stated earlier, the moon is quite flat and
the scale is approx.- 1:15,000,000 I think-
this puts the deepest feature (South Pole Crater? 13.5km) at 0.9mm-ish
and the highest mountain(? 5.5km) standing 0.36mm-ish proud
and a feature limit of 0.1mm
would render 1.5km> differances invisible,
and the nurbs will only reduce the other features- too
but hey. love it, and I would be happy to contribute if I can
- go dude, have a good'n kelef
Thanks for helping to think this through.
There's nothing quite as inspiring as the sight of Mons Huygens at 0.36mm!
Even if we scale it up to 16" / 40cm, that still yeilds a height of 0.575mm. I have real concerns that this kind of detail can't be faithfully rendered by even the highest end 3D printers. But I'm no expert and it seems like it's worth printing a sample or two at various scales to see what we get.
And, we could always exaggerate the features, maybe 2-3x? I didn't want to go there, but it may be better to do that than to end the project.
Have you considered doing a model of the Mun instead. It is already digitized, and I beleive the features on it are much more extreme. See Kerbal Space Program if none of this makes sense.
Kelef and Chris,
The good news is that the vertical resolution of the Objet 3D printers is much finer than the horizontal resolution. On the one that we just bought, they claim 600 dpi horizontal and 1600 dpi vertical. That gives you 0.016 mm steps vertically. If you're right about the 1/15,000,000 scale, you would have 240 m steps vertically. Your horizontal resolution would be 635 m. You probably couldn't resolve features finer than a km or two or three in diameter.
The bad news is that you will have to build your model up out of sectors to keep the vertical more or less vertical, but you would probably have to make it in sections anyway.
The next question is how would you get the light and dark coloring on your cast model?
Coming at this from a different perspective - could earth-globe makers' techniques enlighten the process?