Smithsonian Institution Digitized Artifacts

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Dave K
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Smithsonian Institution Digitized Artifacts

Post by Dave K » Sun Apr 13, 2014 5:40 am

If you haven't seen this Smithsonian Institution website, take a look. It is fascinating on many levels. I think this is the future of online museum access for researchers and, hopefully, the general public.

https://3d.si.edu/

The photo is a small version of a digitized life mask of Abraham Lincoln. The 1:1 scaled version is too big for the M2, but I think a 0.8 scale will just fit. I wanted to try a small version before going whole hog. When I think about the fact that we can print Lincoln's face in 3D, digitized from an actual cast of his face, it just boggled my mind.

I have to say, the lighting and the close-up photo really brings out the flaws in this print. I may be having an extrusion motor problem I've been trying to work out with Josh's guidance, but I think I also need to work on the retraction settings. Any suggestions appreciated!
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Toby
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Re: Smithsonian Institution Digitized Artifacts

Post by Toby » Sun Apr 13, 2014 8:18 pm

Very appropriate size cue in the pic.

I downloaded Abe (the 15 mb version) and am printing him now at 30% scale.

Toby
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Re: Smithsonian Institution Digitized Artifacts

Post by Toby » Sun Apr 13, 2014 10:35 pm

Abe just finished- about 4 hours for this print at .2 mm layer height. My longest print so far.
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The biggest defects occurred on the parts that are at a shallow pitch relative to the bed. Because of the way the model is angled, this is the bridge of the nose and the top of the head. What I think is happening there is that the perimeters aren't overlapping enough to give a solid surface, so you see through to the sparse infill. It might help to bump up the extrusion multiplier and/or print more outline perimeters. I had 2. If I did it again I'd go to 3 or 4.
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Toby
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Re: Smithsonian Institution Digitized Artifacts

Post by Toby » Sun Apr 13, 2014 11:10 pm

Dave, comparing our two prints I'm thinking I might be under-extruding and you might be over-extruding. My retraction is set at 1.1 with no coast or extra restart. there are tiny blobs here and there but they are all but invisible. lincoln had a blobby face but there are blobs on yours that aren't in mine, which i'm guessing is too much plastic in your case. on the other hand the top of the head in yours is much better than mine. I show gaps between the layer perimeters.

What we really need is a slicer that allows us to graphically set parameters on different parts of the model. That shouldn't be that hard to implement once the geometry is all sliced up. It's sort of like when you edit text and select a portion and make it italic or bold. We should be able to select a port of the slicing and say "increased extrusion here."

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Dave K
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Re: Smithsonian Institution Digitized Artifacts

Post by Dave K » Sun Apr 13, 2014 11:36 pm

Toby, I've got some experimentation to do with extrusion to try and get it right. I noticed, with this print in PLA and with prints using PET+, I get blobs right where a new layer starts. It looks as if it is over extruding right at the starting point. I think setting the Extra Restart Distance (in Simplify3D) to a negative value will help keep initial blobs from forming, but I need to play with that.

I've had some possible extrusion problems with the hardware at the same time. The extruder gear set screw became loose, so the gear slipped when retracting. I've got it tightened and loctited again now. And I think the extruder motor needed higher current, because it wasn't moving when I used Viki to jog it unless I had the current set higher (M907 setting) than the default of 135 (I set it at 175 for this print). I'm still confused about that one, and I'm working with MG customer support. I think you're right about my extrusion, but I should get other unknowns resolved before I'm going to start playing with extrusion settings, I guess.

Your print is definitely cleaner than mine. It looks pretty good to me, aside from the top which you mentioned. There have been times I've set up Simplify3d to use a different Process file depending on what layer it's at, and I wonder if you could make use of that to change your process when you're printing the top of the head, if you're using Simplify.

Every time I think I'm getting a handle on 3D printing, something else comes up that makes me realize how much I don't know. That's part of the frustration and the fun :)

jsc
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Re: Smithsonian Institution Digitized Artifacts

Post by jsc » Mon Apr 14, 2014 1:11 am

As Dave notes, you can use Processes to set up different extrusion parameters for different heights of your model. It is not as simple as drawing an outline around the part you want changed, but you can use the Cross Section View (third button up from the bottom on the right side of the preview window) to see at what height you want to use different processes at.

Toby
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Re: Smithsonian Institution Digitized Artifacts

Post by Toby » Mon Apr 14, 2014 5:46 am

that's a good point about using separate processes in the same model. it also suggests doing test prints of layer ranges rather than test printing the whole thing with a single setting. like use the trick of positioning the model partly under the bed and only printing to a certain height from there. If I'd taken 3 or 4 sample ranges and printed a few millimeters of each one I might have found the problem areas for my settings much sooner.

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Tim
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Re: Smithsonian Institution Digitized Artifacts

Post by Tim » Tue Apr 15, 2014 2:15 am

The Smithsonian guys showed up at the Silver Spring Maker Faire this past autumn and were showing off their Lincoln mask print and a few others. I guess being just a few miles away, they didn't mind hauling out the printers and doing the setup and tear-down. I'm glad to see that all of that is publicly available for download. That's your tax dollars at work, after all.

Still, most of those objects are good for 3D viewing but a long, long way from being printable!

There are various museum pieces available on Thingiverse, too, which looks like a legal disaster waiting to happen. Probably will get shut down by lawyers hired by all the companies MakerBot sued for infringement of the enclosed printer patent.

Toby
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Re: Smithsonian Institution Digitized Artifacts

Post by Toby » Tue Apr 15, 2014 3:09 am

A long time ago Bill Gates tried to buy exclusive rights to digital reproductions of art from various famous museums around the world. In fact, he did buy them. I think the Vatican sold out, but it was a long time ago so my memory could be wrong.

Unfortunately for Bill, this was later struck down in court, if I remember correctly because a faithful reproduction of a non-copyrighted work can't be copyrighted.

For statues it's different though. A picture of a statue can be copyrighted because it's considered a different form of art from the statue. But then, anyone else can take a different picture and publish that with or without a copyright.

Enter 3D printing. What status does a faithful digital reproduction of a statue have? No clue. Is there even such a thing as a faithful digital reproduction of an object?

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Tim
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Re: Smithsonian Institution Digitized Artifacts

Post by Tim » Tue Apr 15, 2014 1:12 pm

Hmm, that's a good point. I guess I'll keep donating to the Electronic Freedom Foundation and hope for the best.

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