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  1. #1
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    How to shop for a 3-D printer

    How many different basic types of 3-D printers are out there now, and where do you find them to compare & decide which to buy?

    What materials can you print with them, and what are the physical characteristics of the resulting objects?

    Do some manufacturers have better options than others for designing the shapes to print?

    Do they come in different resolutions so some would make rough surfaces and some would make smooth surfaces?

  2. #2
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    Hello Delvo,

    You could inform yourself at Reprap.org.

    You can build your own with much their help. They also have user forums discussing most of the commercial machines.

    Cheers,

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    Going to assume you are talking about a home printer on a budget of order hundreds rather than thousands of dollars. Because there are more options once you get to a budget of tens of thousands!

    Basically the home market is dominated by two technologies at the moment. FDM, which is the classic moving print head laying down molten plastic, and SLA which is UV cured resin. I've run both for a few years and there are pros and cons for each. It's very much about level of effort and your goal.

    FDM printers are much easier to use and can print a range of materials. PLA is the workhorse which makes reasonably tough plastic objects cheaply. There are loads of alternatives if you need certain properties though. All of them, however, are thermoplastics so don't have good heat resistance. The new printers are pretty good but all FDM outputs I've seen do have a slightly rough, layered look to them. A bit of post processing (sandpaper and paint, basically) can reduce that, though. When picking one do look at the advertised resolution. It varies a lot on these. There are lots of 3D print sites out there that offer reviews too. Strongly advise browsing them, I found them really useful (especially all3dp which has regular wrap ups of the current best printers for different budgets).

    SLA is a different beast. These are temperamental, use some smelly and irritant chemicals - generally much harder to use. And I love them. Mainly because they make incredible, high resolution outputs that are smooth and tough (although they get brittle with exposure to the sun for too long, paint is your friend). Getting them to work reliably is an art form. Can't stress that enough. With these things I've found it's a rollercoaster of amazing results followed by disappointment. The material is a resin, there isn't much choice about it's properties. Again, review sites are your friend.

    Slicing software does vary by manufacturer but most people I know use a third party app anyway so I wouldn't worry too much about that. Ultimate Cura (FDM) and Chitubox (SLA) are common tools, if your printer is supported by them then you don't have to worry about the default software.

    I've not made much practical with the printers but in general I've found FDM rules for larger objects (>10cm) and bulky things. Because it is cheap and tough I've used it for things like boxes, war game terrain, replacement bits for plastic things I broke. SLA rules for small, detailed things. I've made board game pieces, war game miniatures and stuff like that with it. A word on models. It's not hard to make your own, but quite time consuming. But there are loads online you can get free or buy. Modifying them is often much faster.

    Happy to discuss any specific uses you are thinking about. I'm no expert though, just an enthusiastic amateur. Which probably comes across in this wall of text...

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    Quote Originally Posted by Shaula View Post
    ...war game terrain...
    War game terrain? Why didn't I know about you doing this? Do you have website or images? Please?
    Solfe

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    Quote Originally Posted by Solfe View Post
    War game terrain? Why didn't I know about you doing this? Do you have website or images? Please?
    This is going to sound like a terrible series of excuses but I just checked my phone and I don't have any pictures to hand. And I'm moving, so all my stuff has just been sent to storage! If this had come up a month ago I'd have been able to post something. Sorry about that... I'll try to remember this when I get myself set back up but it might be a few months now.

    And to temper expectations all I've done is a few buildings (adobe village style and corrugated iron sheds) plus some scatter terrain (crates, storage units). I had grand plans for some gothic sci fi stuff I bought on Kickstarter but ran out of time. My biggest problem is I'm stuck on what game system I want to make it for. My favourites are currently a 28mm and a 6mm scale and I've not had time to support both. Which has meant I've not really done either!

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    Quote Originally Posted by Shaula View Post
    This is going to sound like a terrible series of excuses but I just checked my phone and I don't have any pictures to hand. And I'm moving, so all my stuff has just been sent to storage! If this had come up a month ago I'd have been able to post something. Sorry about that... I'll try to remember this when I get myself set back up but it might be a few months now.

    And to temper expectations all I've done is a few buildings (adobe village style and corrugated iron sheds) plus some scatter terrain (crates, storage units). I had grand plans for some gothic sci fi stuff I bought on Kickstarter but ran out of time. My biggest problem is I'm stuck on what game system I want to make it for. My favourites are currently a 28mm and a 6mm scale and I've not had time to support both. Which has meant I've not really done either!
    Aw!

    But I have a question about this. A few years back, I set up a couple of 3D printers (Cubify machines, they wanted several of them and that's what the budget said) for the local science museum. In doing a couple of test prints, I noticed that a model tended to "drift" in scale. I printed a 500mm tall pawn on three identical printers using PLA and they all came out 3 differents sizes. It was odd, because when we did it again, the same thing happened but the differences didn't correspond to specific machines. One day, we'd get a 499mm print and on the next day the same product was 502mm. I was a volunteer so I didn't stick around to troubleshoot such a small variance but I still wonder about it.

    More recently, I ordered some 25mm printed figures and they seemed to be about 35mm. Is 25 or 28 mm too small for most machines?
    Solfe

  7. #7
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    Quote Originally Posted by Solfe View Post
    Aw!

    But I have a question about this. A few years back, I set up a couple of 3D printers (Cubify machines, they wanted several of them and that's what the budget said) for the local science museum. In doing a couple of test prints, I noticed that a model tended to "drift" in scale. I printed a 500mm tall pawn on three identical printers using PLA and they all came out 3 differents sizes. It was odd, because when we did it again, the same thing happened but the differences didn't correspond to specific machines. One day, we'd get a 499mm print and on the next day the same product was 502mm. I was a volunteer so I didn't stick around to troubleshoot such a small variance but I still wonder about it.

    More recently, I ordered some 25mm printed figures and they seemed to be about 35mm. Is 25 or 28 mm too small for most machines?
    For the pawn, the "bead" of plastic gets squashed flat as it is deposited, and there's residual stresses after it solidifies. There might have been some rebound afterward as the plastic relaxed into a final shape. It could possibly depend on bed heating, fan cooling, drafts, etc.

    A 25 mm part coming out 35 mm is something else entirely though. That's not warping plastic, and if the machine was that far off dimensionally, it wouldn't be laying down enough plastic to successfully print. It sounds like it was scaled up at some point in the printing process. And no, 25 mm is not too small.

  8. #8
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    Quote Originally Posted by Shaula View Post
    FDM printers are much easier to use and can print a range of materials. PLA is the workhorse which makes reasonably tough plastic objects cheaply. There are loads of alternatives if you need certain properties though. All of them, however, are thermoplastics so don't have good heat resistance. The new printers are pretty good but all FDM outputs I've seen do have a slightly rough, layered look to them. A bit of post processing (sandpaper and paint, basically) can reduce that, though. When picking one do look at the advertised resolution. It varies a lot on these.
    How much heat is a problem for them? One of the projects I've imagined making would be the things that go around the light bulb in a small light fixture like a wall sconce or pendant light or some kinds of vanity lights, about 15cm wide and usually 12-20cm tall, usually made of glass. The bulbs are LED, not incandescent, so they're safe to touch even after being on for a while, but they do still feel warm.

    I've seen pictures of things being printed in various colors of plastic, but it always looks like it's one color per project. So you can't print something with different parts already in different colors? And what form is the stock material in before you use it? A big solid block? Beads? Liquid? And how tough is "tough"?

    Quote Originally Posted by Shaula View Post
    There are lots of 3D print sites out there that offer reviews too... Again, review sites are your friend.
    Where?

    Quote Originally Posted by Shaula View Post
    SLA... I love them. Mainly because they make incredible, high resolution outputs that are smooth and tough (although they get brittle with exposure to the sun for too long, paint is your friend).
    If sunlight is bad for the products, doesn't that mean they'll suffer anywhere that isn't completely windowless, just over different lengths of time? (For example, some rooms in my home have shades/blinds on the windows so nothing is ever directly sunlit in there, but enough light does come through the shades/blinds to light up everything in the room just as much as artificial lights would at night. And that would presumably still include UV coming through the shades/blinds along with the visible.)

    Also, although this might not matter if the plan is always to paint the anyway: does this stuff come in different colors? Do people who use this kind just not care what color it is because they'll paint it anyway? Can it be transparent/translucent? (Aside from the light fixture things, another thing I've imagined printing is transparent or translucent items of various shapes to be lit up with LEDs. The need for transparency/translucency alone could force me into one printer type if the other can't do that.)

    Quote Originally Posted by Shaula View Post
    SLA is a different beast. These are temperamental, use some smelly and irritant chemicals - generally much harder to use... Getting them to work reliably is an art form. Can't stress that enough. With these things I've found it's a rollercoaster of amazing results followed by disappointment.
    What kinds of things go wrong with them when you try? I'm interested mainly in the results I can get, not starting a new hobby of lots of work just for the sake of working on it, but the smoother surfaces (and maybe greater toughness, until the UV gets to them?) might compel me to go this route anyway if the struggle isn't too horrible.

    Quote Originally Posted by Shaula View Post
    I've not made much practical with the printers but in general I've found FDM rules for larger objects (>10cm) and bulky things... SLA rules for small, detailed things.
    That reminds me of another problem I'm likely to run into. Another project I've imagined would be a set of skinny pedestal-like tables, about the same height as most other tables & desks but less than 30cm across for the top surface and footprint. From what I've seen in pictures of these things mid-job, there's got to be a maximum height, either because it's the depth of the pool of starting material, or the distance from the bottom of the work area to a working part of the machine above, or because adding more height would mean adding more weight and it can't hold up too much weight while it's still fresh & hot. So would the tables be something I need to just give up on or find a way to separate into smaller pieces to be combined later?

    * * *

    No metal options, apparently

  9. #9
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    Quote Originally Posted by Delvo View Post
    How much heat is a problem for them? One of the projects I've imagined making would be the things that go around the light bulb in a small light fixture like a wall sconce or pendant light or some kinds of vanity lights, about 15cm wide and usually 12-20cm tall, usually made of glass. The bulbs are LED, not incandescent, so they're safe to touch even after being on for a while, but they do still feel warm.
    Guideline I have seen is >60C and you start to weaken it (PLA has a phase transition around there). I have made lithophanes for use around LEDs and they didn't have issues. Cjameshuff has mentioned some other materials - I don't have experience with them, so I will leave it to them to talk about.

    Quote Originally Posted by Delvo View Post
    I've seen pictures of things being printed in various colors of plastic, but it always looks like it's one color per project. So you can't print something with different parts already in different colors? And what form is the stock material in before you use it? A big solid block? Beads? Liquid? And how tough is "tough"?
    Cjameshuff mentioned that for FDMs the stock is a spool of filament. For SLAs it is a bottle of gloop. You can get dual extruder machines (FDM) that let you print two materials (and hence colours) at once, not sure if there are more than that. SLA it is really one material only. If you need many colours it is easier to print the parts seperately and join them later. Lots of colours is getting into industrial machines which are expensive and I don't have any experience of.

    Quote Originally Posted by Delvo View Post
    Where?
    https://all3dp.com/
    https://reprap.org/wiki/RepRap
    https://www.techradar.com/uk/best/best-3d-printers
    If you search for "best 3d printer 2020" you will find llists

    Quote Originally Posted by Delvo View Post
    If sunlight is bad for the products, doesn't that mean they'll suffer anywhere that isn't completely windowless, just over different lengths of time? (For example, some rooms in my home have shades/blinds on the windows so nothing is ever directly sunlit in there, but enough light does come through the shades/blinds to light up everything in the room just as much as artificial lights would at night. And that would presumably still include UV coming through the shades/blinds along with the visible.)
    Yep, although it is a slow process. And all that happens is that the reson becomes more glass like and less flexible which means that small pieces/details are easier to break off. It takes days in full sun to really see this though (at least at 50N). For your goals I don't think it is an issue. Plus you can use something like polyurethane varish (clear) to help with this problem and protect the piece.

    Quote Originally Posted by Delvo View Post
    Also, although this might not matter if the plan is always to paint the anyway: does this stuff come in different colors? Do people who use this kind just not care what color it is because they'll paint it anyway? Can it be transparent/translucent? (Aside from the light fixture things, another thing I've imagined printing is transparent or translucent items of various shapes to be lit up with LEDs. The need for transparency/translucency alone could force me into one printer type if the other can't do that.)
    The resins and filaments are interoperable so manufacturer doesn't matter and there are a lot to choose from. For example:
    https://www.amazon.co.uk/AmazonBasic...t-1-75mm-Spool - Amazon own brand (I am not recommending this one, by the way, it is just an example) with 20 colours including glowing and translucent.
    https://www.amazon.co.uk/ELEGOO-405n...r-Photopolymer - Elego resins, 18 colours including transparent.
    My experience is that (especially with SLA) anything is translucent if printed thinly enough. FDMs can struggle with that thought (very thin films distort and show up structure). I'd prefer SLA for translucent stuff as it doesn't show the print structure. Look up lithphanes - there is a community out there that does this who can probably get around some of these issues.

    Quote Originally Posted by Delvo View Post
    What kinds of things go wrong with them when you try? I'm interested mainly in the results I can get, not starting a new hobby of lots of work just for the sake of working on it, but the smoother surfaces (and maybe greater toughness, until the UV gets to them?) might compel me to go this route anyway if the struggle isn't too horrible.
    I will caveat this with the fact that I had very little trouble out of the box - my issues came later after the machine got worn. Other people have had more problems.

    Basically it is down to plate adhesion. The way an SLA works is usually a build plate is dipped into a tray of liquid and the UV light is shone upwards. So the object has to stick to the plate really well throughout the process to print properly. The issue is that every time the build plate moves up there is strong suction from the layer sticking to the bottom of the tank. So often you have to tweak the build or alignment to avoid this and have a model that is cleanly built and not warped by this force. I think that it is mostly about experience. That said when my build plate got old I hit a wall and nothing I did worked. I've replaced it and hopefully this will fix it.

    The other issue is (and I'm probably a bit cavalier about this) that the resins are irritants and quite unpleasant. Gloves, ventilation and washing the object are vital. You also have to cure it in the sun for enough but too much time (1-2 hours on a sunny day is fine, its not a precise thing). I didn't find any of this particularly an issue, but compared to the very safe and simple FDM it can put some people off. Oh. And thanks to people stockpiling Isopropanol washing them is more expensive than it should be...

    FDMs are much easier in that they are not fighting gravity and suction. I found them easier to troubleshoot and work out.

    Quote Originally Posted by Delvo View Post
    That reminds me of another problem I'm likely to run into. Another project I've imagined would be a set of skinny pedestal-like tables, about the same height as most other tables & desks but less than 30cm across for the top surface and footprint. From what I've seen in pictures of these things mid-job, there's got to be a maximum height, either because it's the depth of the pool of starting material, or the distance from the bottom of the work area to a working part of the machine above, or because adding more height would mean adding more weight and it can't hold up too much weight while it's still fresh & hot. So would the tables be something I need to just give up on or find a way to separate into smaller pieces to be combined later?
    Max build height for most printers is 20-50cm, so you would have to do them in pieces. It is not hard - Blender or other tools lets you chop stuff up. I will say that larger projects take a long time to print. I would not be shocked if you were looking at 18-24hr per print (and 4-6 prints) for something that big. Home 3D printers are optimised for smaller things. And you would never do this with an SLA. Not only would it be prohibitively expensive but it would take forever. Big projects are FDM all the way. Nice thing with that is that you can get very strong plastic glues that cold weld the pieces together.

    Biggest things I've printed are game box organisers at 40x40x15cm or so and they took an age and had to be done in bits.

    Quote Originally Posted by Delvo View Post
    No metal options, apparently
    I focused on home machines from 100s to 1000s of dollars.
    https://m.all3dp.com/1/3d-metal-3d-p...l-3d-printing/

    If you have $50,000 - $250,000 to spare there are solutions. Most cheap ones are not great resolution and the one cheap option requries you to pay for every piece you make (it is an FDM printer that prints metal rich plastic, they they debind and sinter it for you). You also may need inert gas supplies.

  10. #10
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    Quote Originally Posted by Delvo View Post
    How much heat is a problem for them? One of the projects I've imagined making would be the things that go around the light bulb in a small light fixture like a wall sconce or pendant light or some kinds of vanity lights, about 15cm wide and usually 12-20cm tall, usually made of glass. The bulbs are LED, not incandescent, so they're safe to touch even after being on for a while, but they do still feel warm.
    That would probably be fine. It's more of an issue for things that might get left in the car, for example. I've printed a lid for an electric kettle that softens when it's been heated and has severely warped, but still fits. (Actually, I haven't yet gotten around to modeling the actual lid, this was just run off as a fit check to make sure the dimensions were right...but it works.)


    Quote Originally Posted by Delvo View Post
    I've seen pictures of things being printed in various colors of plastic, but it always looks like it's one color per project. So you can't print something with different parts already in different colors? And what form is the stock material in before you use it? A big solid block? Beads? Liquid? And how tough is "tough"?
    The FDM machines take plastic filament. Some have multiple heads, some can change the filament on the fly to do multiple colors/materials, but multi-material printing is generally more complex and finicky. FDM machines can do translucent parts, but they can't do high optical quality, parts look a bit like they were formed out of ice.

    Toughness depends on material (and even on the particular blend produced by a given manufacturer). PETG can be extremely tough, bending and stretching quite a bit without breaking. Same goes for nylon and various other materials.

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    Quote Originally Posted by Delvo View Post
    How much heat is a problem for them?

    If sunlight is bad for the products, doesn't that mean they'll suffer anywhere that isn't completely windowless, just over different lengths of time? (For example, some rooms in my home have shades/blinds on the windows so nothing is ever directly sunlit in there, but enough light does come through the shades/blinds to light up everything in the room just as much as artificial lights would at night. And that would presumably still include UV coming through the shades/blinds along with the visible.

    No metal options, apparently
    I don’t have the wealth of experience of other posters here but a few pointers:
    Normal window glass will shut out the UV so your plastic should be perfectly safe indoors.
    The toughness of those fibre printed models can be greatly increased by using Super glues which wick into the porous nature.
    The metal 3-D printers are in a different price class.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    Quote Originally Posted by profloater View Post
    I don’t have the wealth of experience of other posters here but a few pointers:
    Normal window glass will shut out the UV so your plastic should be perfectly safe indoors.
    The toughness of those fibre printed models can be greatly increased by using Super glues which wick into the porous nature.
    The metal 3-D printers are in a different price class.
    Glass greatly reduces UV, but enough still gets through to fade pigments and dyes and make plastics go brittle. And even if they were total protection, it'd only work if you never opened a window.

    The prints are not particularly porous, they just have rough surfaces. And I think even PLA is less brittle than cyanoacrylate glue.

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    Quote Originally Posted by cjameshuff View Post
    Glass greatly reduces UV, but enough still gets through to fade pigments and dyes and make plastics go brittle. And even if they were total protection, it'd only work if you never opened a window.

    The prints are not particularly porous, they just have rough surfaces. And I think even PLA is less brittle than cyanoacrylate glue.
    Thanks for that, the pieces I made were used in water and it got through, superglue solved that and made it a composite material. But it would depend on the print parameters. I have also made custom fine porosity filters, rather like sintered material, but in useful shapes. But i did not have my own printer, I had access to one. So I escaped much of the trial and error. I think there are more factors in post moulding changes than a little UV. I imagine the process leaves a matrix of build in stresses and all unreinforced plastics creep. It is not something I considered for 3D printing but it is a big factor in other processes. I hope to experiment with a 3D printer of my own next year.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

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    Quote Originally Posted by Delvo View Post
    How many different basic types of 3-D printers are out there now, and where do you find them to compare & decide which to buy?
    As Shaula said, there's basically filament deposition printers that lay down layer after layer of molten plastic, with several different mechanisms for moving the print head, delivering plastic, etc, and a few different variations of printers that selectively cure UV-sensitive resin.


    Quote Originally Posted by Delvo View Post
    What materials can you print with them, and what are the physical characteristics of the resulting objects?
    The FDM machines take spools of plastic filament as an input material. There's some gotchas, like problems that can arise if the filament absorbs moisture (which can be remedied by baking the moisture out, preferably in something like a food dehydrator that isn't used for food). Some materials take particular care to get to adhere to the bed, or require a heated enclosure to print well. If a print fails you can end up with a pile of spaghetti, or a blob of death encasing your hot end. If it goes well, depending on the material you can pop a usable print off the bed.

    The SLA machines take some expensive and noxious resins, and more solvents for cleaning the prints afterward. You may also need to expose them to more UV in a postprocessing step to fully harden them. The resin obviously can't be UV-stable, so it'll degrade if not protected. Material selection is limited by the fact that it has to start out liquid and harden when exposed to moderate levels of UV.

    Some FDM machines can use multiple materials, for example using soluble support material, or mixing colors. SLA machines are pretty much limited to a single material at a time, at most you might change the resin mid-print.

    FDM materials include PLA (a biodegradable, temperature-sensitive plastic that's somewhat brittle but rigid and cheap), PETG (tough but a bit less rigid), nylon (tough and self lubricating), polycarbonate (very strong and temperature resistant, but hard to work with and requires high printing temperatures), PEEK (an aerospace engineering plastic that is very strong, tough, and stable, but requires even higher printing temperatures and is very expensive), flexible thermoplastic polyurethane, PVA (water soluble, a removable support material), and many others. There's also versions of the above that are strengthened with glass or carbon fiber, versions that are somewhat electrically conductive for ESD suppression, etc. Some incorporate wood fibers or metal powders.

    FDM prints generally have an interior fill pattern that is mostly empty space. Physically, they're a bit like a hard shell around a regular geometric foam. The layered structure shows in the surface finish, but can be smoothed out by sanding, tumbling with abrasives, applying coatings, and with some materials by using solvents.


    Quote Originally Posted by Delvo View Post
    Do some manufacturers have better options than others for designing the shapes to print?
    Technically, but I wouldn't use any manufacturer-provided software for designing shapes, there's going to be better-developed alternatives like Blender, FreeCAD, OpenSCAD, etc. Prusa maintains their own fork of the slicer software for generating the actual control files for the printer, but you could use something else (or use theirs with a different printer, or modify their version and build your own).


    Quote Originally Posted by Delvo View Post
    Do they come in different resolutions so some would make rough surfaces and some would make smooth surfaces?
    Different printers will achieve different resolutions. SLA printers are better at fine details. FDM printers can use nozzles of different sizes, so you can use a small nozzle for extra detail or a large one for extra print speed (or for printing some materials that don't work well with small nozzles, like the wood-filled filaments). I upgraded mine to a Mosquito hot end largely to make nozzle swapping easier. (...and have not changed the nozzle since.)

    Some example FDM prints:
    Gale Crater in PLA (Martian cacti sprouted all over it for some reason, need to tune some print settings):
    https://i.imgur.com/LT6haWq.jpg
    https://i.imgur.com/VGBrxlr.jpg

    A treefrog (a standard benchmark model) in black and marble PETG:
    https://i.imgur.com/fNHQBdL.jpg
    https://i.imgur.com/JEN8ctV.jpg

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    Once you buy your 3-D printer, make a copy of this miniature "Mars rover" which uses robotics to drive over rough terrain.

    https://phys.org/news/2020-12-d-mars-rover-exomy.html
    Do good work. —Virgil Ivan "Gus" Grissom

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    Quote Originally Posted by Roger E. Moore View Post
    Once you buy your 3-D printer, make a copy of this miniature "Mars rover" which uses robotics to drive over rough terrain.

    https://phys.org/news/2020-12-d-mars-rover-exomy.html
    That's over a hundred dollars in servos alone. Why do people keep using expensive servos modified for continuous rotation when cheap gearmotors are widely available? I mean, here's a pack of 6 for $12: https://www.amazon.com/Antrader-Moto...dp/B07DDC3ZBK/

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    Quote Originally Posted by Roger E. Moore View Post
    Once you buy your 3-D printer, make a copy of this miniature "Mars rover" which uses robotics to drive over rough terrain.

    https://phys.org/news/2020-12-d-mars-rover-exomy.html
    I see the Borg got Gumby

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    What does "support material" mean?

    Did the description of nylon as "self-lubricating" mean "very low friction"? I can't believe any of these things actually ooze liquid.
    Last edited by Delvo; 2020-Dec-14 at 12:06 AM.

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    Quote Originally Posted by Delvo View Post
    What odes "support material" mean?

    Did the description of nylon as "self-lubricating" mean "very low friction"? I can't believe any of these things actually ooze liquid.
    Support material is temporary material laid down to support parts of the print when they aren't self-supporting. It can be the same material as the print, printed so it (hopefully) doesn't adhere very well, or it can be a different material, like water-soluble PVA.

    Some nylon blends actually do, others incorporate dry lubricants, and you can find self-lubricating plastic filament for printing (https://www.igus.com/info/3d-printing-materials has some, but I'm not sure if they specifically have nylon), but you'll have to hunt them down and pay extra. I wouldn't expect it of normal nylon filament.

    I've seen the "nylon is self-lubricating" claim but nothing to support it as a general trait of nylon, I suspect it's confusion about nylon's low-friction nature or not understanding that it was a feature of a specific blend. A lot of materials experience high friction when you have surfaces of the same material rubbing against each other, sometimes making squeaking and creaking noises, while nylon slides with relatively low friction and wear.

  20. #20
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    Now that I've got the basic background on how this stuff works, I've started making a list of printers to compare features of (and find out what some of those differences even are/mean). This one here is an example of two different issues I've had on my mind:
    https://artillery3d.com/products/art...t-touch-screen

    For one thing, it's a kit. And another manufacturer gives two separate prices for most or all models, less for the kit and more for the fully assembled one. How bad is the process for getting a kit to work?

    Also, the model they're showing there looks like somebody either printed it on another printer, or printed it on this one & painted it with lots of fading between the color zones, and put it back on the platform for the picture. Everything else I've gathered about colors tells me it couldn't have been printed the way it looks, at least not on the shown printer. Maybe I got some of this wrong, so here's my double-check. Printing multiple colors in one job would require multiple spools on the machine at once and a machine that can use them. Also, I'm fairly sure I ran across a model somewhere along the way that specified that it's capable blending/mixing, which must mean that some other models can't; if they can take more than one spool they'd need to print strictly one at a time even if they switch back & forth in a single job. Also, I get the impression that most machines can only take one or two spools, not three or more. So printing Groot as we see him there would require a printer with special abilities (taking at least three spools and blending them) which most printers don't have and this one seems not to have, since its web page only shows one gray spool on it and doesn't trumpet having those abilities (and it isn't especially expensive). So if I wanted to print multiple (or even just two) colors with blending like this, I'd need to narrow my search to only printers that can handle it and thus are probably the most expensive; it's either that or just accept printing monochrome or maybe dichrome and then either leaving things that way or learning to paint them. Did I take any wrong turns in there?

  21. #21
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    To get it to print like that you would probably use a filament with a graded colour - like this one https://www.amazon.co.uk/Zi-Rui-Fila.../dp/B07GTH4666 . You don't get to control the colour there, it just changes slowly as you go through the print. So it can only vary vertically, not horzontally. And it changes based on the volume of filament used so small things won't have much of a gradient.

    If you wanted to accurately control the colour, rather than just have a gradient, then yes, you would need a different printer. I think there are only a couple of hobbyist ones that do full colour printing (that I've seen advertised). Otherwise you are limited to the number of spools/extruders the machine has (which is one for that model, so yes, only one material at a time there). So most of what you said was right - but there is the option of a graded filament.

    Can't help you on kits I am afraid, I just bought assembled.

  22. #22
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    OK, I've pretty much settled on which printer to get, so at this point I'm really just picking up stray details I've noticed along the way...

    Some printing materials are gluable, but the descriptions always specify to use an "acrylic" glue. I remember from building a plastic model ages ago that there was a particular kind of glue at art supply stores for gluing plastics, called "cement" at the time. Is that the same stuff? I also have a container of "superglue" right here and see that "acryl" is part of the name of its active ingredient. Is superglue an acrylic glue?

    I've noticed that the only context in which people seem to talk about the possibility of a printing material (other than PVA) absorbing moisture is while it's still a filament. Once it's been printed, nobody seems to be concerned with having the object in a humid climate or letting rain hit it or even letting water sit touching it for a long time (like in a printed plant pot). And they'll deliberately dunk it for a while at least once just to get rid of attached PVA. So it seems as if the printing process prevents subsequent water problems by putting the plastic in a state that doesn't absorb water anymore. Is that right? (Otherwise maybe people are just figuring they can just print a new one whenever the old one gets ruined by humidity.) (The light-fixture project I mentioned before is in a bathroom that gets foggy during showers.)

    Also, what is the purpose of heating the platform that the object sits on while it's still being printed? Some manufacturers' websites show that thing's temperature for each model in a way that's easier to spot than nozzle temperature, and one YouTube review said the printer he was reviewing was limited to 80° so it can't print ABS. Why not? And what other cutoffs apply to other materials? Is there a list of what minimum platform & nozzle temperatures are needed for which materials?

    * * *

    (The one I'm almost certainly going to get is an Ender-5 Pro by Creality. My main point of hesitation about it was that it has one nozzle & extruder and I really wanted a dual system of some kind, but the ones that come that way from the start are more expensive by a wide margin, even wider if we eliminate Creality's CR-X based on frustrated reviews of it even by people who are happy with other Creality products like Ender-5 Pro. I have some stuff in mind that ideally calls for dual extrusion, but there are other workarounds for those, like accepting breaking off same-material supports, learning to paint, and/or even just not ever making one or two specific items that can't be done any other way. But I also discovered along the way that, instead of adding hundreds of dollars to the price just for that one feature, I can get a separate 2-in-1-out or mixing hot-end to replace the original one with, for under $25.)

  23. #23
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    Quote Originally Posted by Delvo View Post
    I've noticed that the only context in which people seem to talk about the possibility of a printing material (other than PVA) absorbing moisture is while it's still a filament. Once it's been printed, nobody seems to be concerned with having the object in a humid climate or letting rain hit it or even letting water sit touching it for a long time (like in a printed plant pot). And they'll deliberately dunk it for a while at least once just to get rid of attached PVA. So it seems as if the printing process prevents subsequent water problems by putting the plastic in a state that doesn't absorb water anymore. Is that right? (Otherwise maybe people are just figuring they can just print a new one whenever the old one gets ruined by humidity.) (The light-fixture project I mentioned before is in a bathroom that gets foggy during showers.)
    It's mainly an issue for the filament because printing involves melting it at temperatures well above the boiling point of water, obviously not conditions you can use the printed objects at. Some plastics do also swell noticeably when they absorb moisture.


    Quote Originally Posted by Delvo View Post
    Also, what is the purpose of heating the platform that the object sits on while it's still being printed? Some manufacturers' websites show that thing's temperature for each model in a way that's easier to spot than nozzle temperature, and one YouTube review said the printer he was reviewing was limited to 80° so it can't print ABS. Why not? And what other cutoffs apply to other materials? Is there a list of what minimum platform & nozzle temperatures are needed for which materials?
    Bed heating is mainly to prevent the part from warping. ABS is particularly bad because of its high thermal coefficient of expansion.

  24. #24
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    Quote Originally Posted by Delvo View Post
    Some printing materials are gluable, but the descriptions always specify to use an "acrylic" glue. I remember from building a plastic model ages ago that there was a particular kind of glue at art supply stores for gluing plastics, called "cement" at the time. Is that the same stuff? I also have a container of "superglue" right here and see that "acryl" is part of the name of its active ingredient. Is superglue an acrylic glue?
    No, superglue is not an acrylic glue. It does work (really quite well) on most printed materials but it is a different mechanism of action. Superglue is a rapid setting polymerisation of a cyanoacrylate whereas acrylic glues (or plastic cements) rely on solvents to soften the plastic and 'weld' the pieces together. I use both - superglue is a bit more brittle a join but fast whereas the plastic cements tend to need to be clamped or held lest they slip but tend to give a more flexible, stronger bond when used properly. I don't know which alternative plastics the plastic cement works on though - I've only used PLA.

    Quote Originally Posted by Delvo View Post
    I've noticed that the only context in which people seem to talk about the possibility of a printing material (other than PVA) absorbing moisture is while it's still a filament. Once it's been printed, nobody seems to be concerned with having the object in a humid climate or letting rain hit it or even letting water sit touching it for a long time (like in a printed plant pot). And they'll deliberately dunk it for a while at least once just to get rid of attached PVA. So it seems as if the printing process prevents subsequent water problems by putting the plastic in a state that doesn't absorb water anymore. Is that right? (Otherwise maybe people are just figuring they can just print a new one whenever the old one gets ruined by humidity.) (The light-fixture project I mentioned before is in a bathroom that gets foggy during showers.)
    Water ingress can accelerate the biodegredation of the plastic. There is a whole community who care about this in the form of 3D printers for fish tanks. ABS is bad as it poisons fish, PLA is biodegradable so has to be carefully treated lest it fall apart after a length of time (I have seen claims of months)

    And I hope you enjoy your Ender! Good luck with it, I found 3D printing a bit of an adventure at first but very rewarding in the longer term.

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