pla/abs plastics

Discussion in 'Ancient Coins' started by dougsmit, Feb 8, 2019.

  1. dougsmit

    dougsmit Member

    Does anyone know of a study on the effects on coins of pla or abs plastics commonly used in 3D printers?
     
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  3. furryfrog02

    furryfrog02 Well-Known Member

    In what manner are you thinking of them being used? I'm just curious.
     
  4. desertgem

    desertgem Senior Errer Collecktor

    I couldn't find specific, but since PLA is built from lactic acid monomers in a chain, suspect it would be safe until it decompose. Also it does decompose over time, and the lactic acid components separate. and although its life time varies, it is usually fairly short. I would also expect it's mechanical strength and rigidity would be limited. But easy to work and mold.

    ABS is much stronger, more rigid, higher melting points, reacts more as common plastics such as acrylic ( as in the name).

    Common pocket coins are plentiful to try . I would try PLA first as easiest and easily bought from a Maker machine store or Amazon in many colors.

    Jim
     
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  5. TypeCoin971793

    TypeCoin971793 Just a random guy on the internet

    ABS is what is used in Legos.

    I’ve printed in ABS and PLA before. The ABS seems to be holding its own quite well
     
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  6. furryfrog02

    furryfrog02 Well-Known Member

    If LEGO are made from ABS, that stuff lasts forever. My son is currently playing with LEGO that I had as a kid and that were bought second hand from another kid who probably got them brand new in the early 80s.
     
  7. -jeffB

    -jeffB Greshams LEO Supporter

    Our LEGO from the 1960s is worn down to F or so, no more shiny surfaces, but still shows no sign of getting brittle. Of course, it spent several decades of that time in various dark closets.
     
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  8. Pavlos

    Pavlos You pick out the big men. I'll make them brave!

    I synthesize and work with PLA daily and I got quite some years of experience with it. PLA is a wonderful plastic because there are so many variations of it, all plastics have that but PLA is a little more special because the lactic acid in the chain can be mirrored from eachother. PLLA (100% Levo-lactic acid) is incredibly strong, as it is very crystalline and it won't degrade at all under normal circumstances. However, the most commonly used PLA is 96% Levo-lactic acid and 4% dextro-lactic acid, the one used in 3D printing. It is mechanically weaker but I still doubt it will suddenly degrade, it is always possible under the right temperate and humidity. PLA is incredibly hygroscopic and quickly attracts water so much humidity is not even needed. PLA is definitely safe for coins but the question is, is lactic acid safe for the coins? I don't know what, but it is after all an acid. I still think polypropylene without additives is the most safe for coins.
     
  9. dougsmit

    dougsmit Member

    It would be rather simple to design a custom size/shape coin tray using a 3D printer. Slabbers could even print out a custom shape ring to mount coins and get rid of those ugly tabs that cover the coin. For a display, you could design a copy statue of an emperor with a coin holder sized to a specific coin. You could scan in and enlarge a coin using 3D software and make a placque that could be painted to look like the coin. PLA is not poisonous as far as we know now but I wondered about it toning or cleaning a coin as it deteriorates over time. The field is getting to the point that you can find software for many things but no ancient coins.
     
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  10. Pavlos

    Pavlos You pick out the big men. I'll make them brave!

    PLA itself is not poisonous at all, in fact, my job is to make the ideal PLA for these guys:
    [​IMG]
    Implants that will degrade inside your body, a good replacement of titanium implants and it prevents a second surgery to normally remove these titanium plates. That is however biomedical PLA, technical PLA does have some high content Tin metal (from the catalyst), but if nobody ingests it, it is fine (and even then I do not expect any problems, except if it happens many times).

    It sounds like a really nice idea, but I personally wouldn't put bronze coins in it, I have no idea what possible lactic acid (from degradation over time) might do with bronze, but I am pretty sure the lactic acid might react with copper to cupric lactate over time. Silver coins will be obviously fine, however, I do expect some toning of the silver over a long time, but definitely not in the short time.
     
  11. TypeCoin971793

    TypeCoin971793 Just a random guy on the internet

    From a practical standpoint, you don’t want to do this. 3D printing takes a lot of time, and unless you get a high $$$ or $$$$ printer, large flat plates/bases encourage warping due to uneven heating of the baseplate. If you are going through the trouble of making a CAD/scan of the coin’s exact shape, it would be easier for you to use a laser cutter.

    But if you are wanting to go the 3D printer route, I’ve heard very good things about the Prusa printers. I’ve personally used the MK3 and love it.

    https://www.prusa3d.com/
     
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  12. dougsmit

    dougsmit Member

    Our local public library has four 3D printers which are available to anyone with a library card for free. Currently they don't charge for small projects but only stock a dozen colors of PLA and do a lot of business with Star Wars emblems, custom chess men, figurines for nick-nack shelves etc. but are proud of the 30 plastic safety/training barrels they made for the Sheriff recruit class (trainees get a real Glock with proper weight but no chance of shooting themselves or each other until later in the program). I would not buy a $2k printer for making a coin holder but it seems like something to try for the experience.
     
  13. PeteB

    PeteB Well-Known Member

    I continue to be amazed at the skills and knowledge in non-coin areas of our members!!!
    Humbling!
     
  14. -jeffB

    -jeffB Greshams LEO Supporter

    Don't be humbled -- be challenged and inspired!
     
  15. desertgem

    desertgem Senior Errer Collecktor

    Doug, Congratulations for having a forward looking Library that is bringing learning of all kinds into their areas. It is rare!! I envy the patrons in your area. Jim
     
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  16. dougsmit

    dougsmit Member

    My wife was a librarian until her retirement in 2003. In her time, libraries were selling off their card catalogs and introducing computer circulation systems of books and other formats including VHS tapes. Today libraries are promoters of information but fewer have reference books having embraced online searches in place of books. Today, our local library maintains one set of encyclopedias for the comfort of 80-100 year olds and a 'Makerspace' with 3D printers, power tools and sewing machines and librarians who can help people use them. Currently they have patrons making quilts, robots and a headboard from scrap pallet wood. At my age, I probably will not see the last book in library. VHS tapes and encyclopedias are easier to find in the Friends of the Library book sale.
     
  17. arizonarobin

    arizonarobin Well-Known Member

    Coming out of lurk mode for a minute!
    This is a really cool idea- I like the display idea a lot! I actually have both a filament and resin printer but have never thought about using it for coins. I wonder if the resin would be okay for the coins. I would love to make a Julia Domna coin holder. I guess if it is not- I could always make it to hold the clear circle coin holders.
    Back to lurk mode
     
  18. desertgem

    desertgem Senior Errer Collecktor

    Odd you mention a library book sale. I went to a local one today also. They were discarding some geology and astronomy books from the 60-70 in the lots, so I picked them up along with some Art books, and a couple of popular reading ones. They have 3 a year , mainly donated books . There were about half older people and the other half under 20. What I don't keep , I redonate to other thrift shops. JIm
     
    TIF likes this.
  19. TIF

    TIF Always learning.

    Welcome to the light! Don't fade back into the woodwork :D. Show us your Domna!
     
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  20. -jeffB

    -jeffB Greshams LEO Supporter

    That was a long lurk. :)
     
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  21. arizonarobin

    arizonarobin Well-Known Member

    I excel at lurking, but it was a tiny bit longer than I intended!

    I like the woodwork :joyful:
    But I do have a JD or two- here is one of my favorites:

    [​IMG]
     
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