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  1. #1

    Scanning "transparent" parts

    I am helping a company in South India purchase a 3D printer and scanner. Some of the parts they would like to scan are an inch or so in size, and made from clear material. Is this going to be a problem in scanning those parts, and if so, are there any solutions?

    I can post a photo of one of the parts if that would help, but I'd rather this be a "generic" question, as other parts might look very different in shape.


    Possible solutions I am thinking of include using some kind of dye to make the part surface opaque.

  2. #2
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    The Capture Mini scanner from 3D Systems would be able to get enough detail - of the outside of it, anyway. White spray paint would work better than dye, since white generally is most reflective of light. As I said in my other post, it would take some reverse engineering to construct the interior volumes, but Wrap could probably deal with that. The only other alternative would be CT-scanning, which might capture the interior volumes as well, but how well that worked would depend on the material these things are made of; some things work better than others in that process.

    Andrew Werby
    www.computersculpture.com

  3. #3
    Thank you 'awerby' again. I will need to get the engineer, Rajasekar, to review this thread. I'm not sure what you mean by "interior volume". I thought all that was just part of the shape? I'm not sure if this is something they need, but since I don't yet know what "this" is, it may well be something they do need, which I don't yet understand.

    Thanks for the info about using white paint. I didn't realize that the color would make a difference. If I understand you correctly, it would be best to color our parts white before scanning?

    Would a scanner cover a range such as 1" to 6" in measurements, or would a smaller scanner be better for small parts?

  4. #4
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    Quote Originally Posted by mike@aravind.org View Post
    Thank you 'awerby' again. I will need to get the engineer, Rajasekar, to review this thread. I'm not sure what you mean by "interior volume". I thought all that was just part of the shape? I'm not sure if this is something they need, but since I don't yet know what "this" is, it may well be something they do need, which I don't yet understand.

    [That looked like a hollow part. The interior volume is the part that's inside; an optical scanner won't pick it up, because they only capture data that's in their line of sight. If the configuration of the interior isn't critical, you can approximate it by specifying a wall thickness when you shell the scanned model, but if it is then you'd need to model it separately and subtract it from the exterior solid.]

    Thanks for the info about using white paint. I didn't realize that the color would make a difference. If I understand you correctly, it would be best to color our parts white before scanning?

    [Usually that's recommended, particularly if they're clear, black, and/or shiny, all of which can confuse a scanner.]

    Would a scanner cover a range such as 1" to 6" in measurements, or would a smaller scanner be better for small parts?
    [It really depends on the particular scanner. There's no absolute relationship between the size of a random scanner and the size of the objects it will scan. There are relatively small scanners that can capture a whole room, and some large ones that are intended for small objects.]

    Andrew Werby
    www.computersculpture.com

  5. #5
    I wrote up a list of what I think their requirements are, intending to post it here. I had second thoughts, and sent it off to Rajasekar, to make any changes he thinks are necessary. One way or another, I'll try to post it here by the end of the day tomorrow.

    From what you're writing here, I'm both learning a lot of new things, and realizing how ignorant I was. So much of what you say I never even considered before reading your responses. When I entered the post, we were only concerned about it being "transparent". Apparently there's a lot more to it. I don't see that as a problem - whatever color works best with the scanner, I'm thinking we could put a think coat of paint on it of that color.

    One of the people who has the best overview of what is going on suggested a while back that we buy a 3D printer to learn 3D printing. Depending on the cost, the same might apply to a 3D scanner. I know from my photographic experience that I don't really know what I want or need until I start "doing".

    Next thing for tonight is to check out "The Capture Mini scanner from 3D Systems".

  6. #6

  7. #7
    Thank you Wendy. I went to their page, and watched the video on YouTube. The cost is only $1,300. The Capture Mini Scanner from 3D systems "seems" much more professional, but it costs almost $15,000 including the accessory package.

    I just had a wonderful phone conversation with Tracy at "Geomagic" (1 800 251 5551). She will be sending me more information on the Capture Mini, and will find out if 3D Systems has a support system in India.

    It's too early to say for sure, but I get the impression that their scanner (suggested by 'awerby') will not only work for parts I originally described, but also for scanning a mold of the socket that supports a prosthetic eye. That would allow us to print a complete prosthetic eye that would look natural, and fit properly into the socket.

  8. #8
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    To me, that application (scanning the mold for the eye socket) seems more appropriate for a scan-to-print process than the more mechanical parts, which probably should just be modeled from scratch, or reverse-engineered. Scanning works great on organic sorts of things that are hard to model, which makes them especially suited to medical applications like this, where manufactured devices need to interface with variable human anatomy.

    Andrew Werby
    www.computersculpture.com

  9. #9
    'awerby', I'm now home in Miami Beach, the other side of the planet away from where all this is happening. I felt like I was in kindergarten, trying to learn enough about "what" the group wanted to do with a 3D printer and scanner, and never got around to the "why". I'm sure there is a lot more to it than the small amount I've been able to learn so far - and there are others in the group who are trying to document the "why" before they buy anything. I'm not sorry about this - I've learned a lot more about this in the past two weeks than the past two years!

    Regarding the scan and mold and print for the prosthetic eye, I spent a couple of weeks with the person at Aravind Eye Hospital who does all this work manually, making a mold from the eye, then making casts and more molds, and so on until they get the final result, which is made in a way to look as normal as possible. I spent most of my time learning about how they made the "front" of the eye, the eyeball, and how it was made to look realistic. I didn't yet know enough to even start to understand how technology would help.

    I can already see how the hospital can make a mold of the "socket", and get from that to everything needed for a prosthetic eye. When I get back to India, I can apply what I've learned to what they do now, and find out if what we're trying to do is reasonable based on today's technology.

    It's more science fiction than science fact, but I also keep wondering of the patient could be held in a fixed position, and the 3D scanner could create a realistic representation of the patient's face, eye socket, and the surrounding tissue, and if that would help create a better prosthetic eye. Maybe in a year or two I can ask that question here.


    Back to reality - what I think I've learned, very much thanks to your help, is that the hospital can continue to make a mold of the socket the way they do now, that mold could be scanned with the scanner you suggested ($15,000 or so), the part could then be replicated in resin using the high resolution resin scanner, an a mold could be made from that, to cast a "body part" that would fit perfectly into the eye socket. From what I learned two years ago, a Stratasys Mojo printer could create the "front" part of the eye. .........all this was my project long ago, but it came to a dead end because we couldn't find an appropriate scanner for a reasonable price.


    Thanks once again - I will try to get the people in India to read both these discussions completely. I will try to get them to explain the "why" in addition to the "what".

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