Tips and tricks for printing minis

daishi

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Apr 14, 2011
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Hi everyone!

A little history: Me being a big Fallout fan I just had to try out the new Fallout based Board and war games that came out last year, one of them being Fallout Wasteland Warfare. The game I liked, I don't get to play it often, but it did get me infected with collecting minis and making terrain. The thing being, those things are expensive for something I barely get to play, BUT around the same time my co-workers got into 3D printing, and after I asked them to please print a few small tokens and generally talking about 3D printing I decided this sounds Intriguing.
I purchased a Creality Ender 3 printer spent a few weeks upgrading it (you can read about it here). And after a while started printing proxies for the game itself. I am now about the point where I have proxies for most of the officially released figurines, which comes up to about 104 minis +11 tokens printed (from that about 28 waiting to be painted), not to count the big pile of failed prints I have in addition. and some 10cm figurines and terrain pieces. So yeah my printer is running almost continuously since I bought it.

Purpose: I'd like to share some of the things I found really useful or things I've picked up or got from experience.
A Disclaimer though: I'm kind of lazy about the minis so the things I write here might not be the Latest and Greatest techniques, or might not even the ones that give the best result, they are the ones that gave me "good enough" result relatively fast. :cool:

So let's start with some basics:

Printer and workflow: As I wrote above I fave an Ender 3 which is considered one of the best FDM printers under $200 (or under $500 for that matter).
FDM printers in a nutshell (this is enough for our purposes):
- Melts a plastic filament
- Pumps out the melted plastic trough a nozzle
- The nozzle is moving on 3 Axis relative to the build plate (or heated bed)
- Builds a 3D object from the bottom up layer by layer, each layer is "drawn" by the nozzle.

Now the typical workflow is something like this:
- You get a 3D model from somewhere*
- Edit/repair/customize the model*
- Load it into a Slicer
- Position/scale/slice the model*
- Feed the output .gcode file into the printer
- Wait a few hours/days/weeks for the print job to finish
- Getting the print ready for priming/painting*
* I will have some tips for these steps

Software:
I'm using Ultimaker Cura 3.6 as the slicer, and will most likely illustrate most thing with screenshots from that, with some actual prints to show how some things will look IRL.
Windows 10 comes with a great app called 3D Builder, It has some really useful features. If you use a different OS there is no problem the best feature we will need is available as an online service as well.
Meshmixer is a free tool specially made for editing 3D models for printing. To tell the truth I found the controls kind of unintuitive, so I generally do not use it, but I will share some YT tutorials, for those folks who do not have the know-how for 3D editors like Blender/Max/Maya.

This post is getting long so I will start with getting/making models and preparing them for the slicer next time... stay tuned ;)
 
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daishi

Member
Apr 14, 2011
300
411
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Hungary
Getting models:
With more and more usable 3D printers on the market, there is an ever-growing community online. There are sites that are dedicated to sharing or even selling printable 3D models. I usually browse the Thingiverse for cool looking models as well as for upgrades for my printer. All the custom parts currently on my printer came from there, so It is a good place to start. But be aware there are some things that they, coming from a free community, might need some touch up before a decent print can be made.
Making models:
If someone has the skills to create 3D models from scratch, there is the option to create things to print. Basically, every 3D creator program can be used under the sun, to create printable meshes, as long as it can output the file as one of the more widely used polygonal formats e.g. .obj works great.

Editing models:
For the most part, I adapt existing meshes for 3D printing, and I have some tips on what to look out for when doing so.
  • One shell (to rule them all):
    The slicers generally work best if the mesh is one closed-shell, so there are no intersecting shapes, no holes, and preferable the normals are not inverted on half of the mesh (did that once it was not pretty).
    There are quite a few video tutorials on how to join two shapes into one shell online.... don't bother with them. Most of those techniques give really good results but take a lot of work, and the slicer will not care much. If you read my previous post you will remember the 3D Builder app that comes with Windows 10 has a really useful feature, that is also available as an online service? Well, this is where it comes handy. It can "repair" meshes, which amongst other things will create a single shell from a bunch of intersecting shapes automatically. Will it be the most optimal model? Most likely not. ... Will it bother the slicer? Definitely not. If you dont use Windows 10 the service is available online, and I'm sure there are alternatives for it as well
    3Dbuilder1.jpg
  • Being thick is not (always) bad:
    One thing is needed to be kept in mind when creating models for printing, especially minis. The slicer will basically do a "walkaround" on the inner side of the shell. What this means it will calculate how it needs to move the nozzle and pump the molten plastic to get the same appearance of the shell it needs to slice. there will be multiple layers and infill on the inside but for the actual appearance, this outer layer is key. The nozzle diameter and thus the "sting" coming out of it is fixed as well. If there are thinner parts of the mesh than the actual nozzle diameter, the slicer will not be able to find a path through it for the filament and those parts will not get printed, leaving gaps in the model. Think cape of superhero figurine, or any other hanging cloth, strap, etc.
    Some slicers have special settings that will force at least one layer to be printed, but as far as I tested it in Cura it not always works And I could tell without printing that it would have been so brittle it would have not survived the printing itself not to mention sanding and painting.
    But I digress, the point is Any place that is too thin: make it thicker. If you check most minis have really exaggerated details on them, it makes them easier to paint, and in our case also makes the slicer easier to make them printable. take the laser rifle on this mini, the fins near the nozzle and the underbarrel pipe, as well the straps on the armor itself are all much thicker than the original mesh in the video game.
    PA32.jpg
  • Gaps are there to be filled:
    When working with models that were game assets originally (quite a few of them on print resource pages), there are a lot of internal "gaps" on the model. For example big gaps between the armor plates and the body/clothing under it. This has the potential to cause quite a few headaches.
    - Depending on the model orientation during printing might need supports (will go into those later). supports are supposed to be removed after the print finishes, but if they are between hard to reach parts, it can be quite hard to properly remove them.
    - The slicer will have to create a wall for both sides of the gap (multiple passes for both), as well as complicating the path of the nozzle for everything else as well.
    - In the case of armor pieces, the previous problem of the too-thin armor plates can also happen.
    So fill in those gaps whenever possible. (It was not fully possible for the Radroaches below ... had a fun time removing the supports, with tweezers barely fitting into the gaps)
    In the case of the armors, I usually extrude or move the inner face into the body, and let the repair tool sort it out later.
    RadRoach.jpg

Next up: some more model editing tips...
Also If you think this is too vague to be useful, or any other issue you can see let me know. ;)
 
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daishi

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Apr 14, 2011
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Editing models part 2:
FDM printers print bottom-top with each successive layer put on top of the next. Given this limitation, there are a few things to keep in mind while editing models.
  • Flattops are not always cool:
    In general, surfaces that are not perfectly parallel with the print bed, and have a low gradient can come out quite ugly, thi depends on the layer height the print job is set up for, but I found that this is the case with even a 0.08mm layer height. (My printer should be able to do 0.04mm but It has some additional problems so I never tried it). The result can be mitigated with fillers and sanding, but it might result in losing detail. e.g. using filler on a cracked asphalt mini base will most likely fill up the cracks as well. Depending on the model this can be mitigated with print orientation (later) as well, but If the mini is posed with this in mind in the first place a lot of extra work can be sidestepped.
    Check the base this Radscorpion for example, It is one of my first minis, I did a little sanding on the base but realized after the first wash that it was not enough. The subsequent dry brushing made it worse. :hammerhead:
    The other base is fresh out of the printer, As you can see I printed it basically standing on its side, that way the ugly part is on the side, which can be filled and sanded with abandon, also will be painted black. You can see it painted under the Raider Psycho below.
    Clipboard01.jpg 1572905341040.png
  • Careful with overhangs:
    Since the filament is put on top of the previous layers, if the surface gradient is bigger than 90 degrees, the filament starts to be put partially over empty air. de bigger the overhang the more this happens. One of the main jobs of the Part cooler is to cool the extruded filament fast enough so it won't droop down, but this has some limitations.
    What degree of overhang a printer can handle depends on a lot of things: nozzle temperature, nozzle diameter, environment temperature, distance from the heated bed, part cooler airflow, filament type, etc. So the fastest way to print one of the test objects, and modify print settings accordingly.
    If you check this early test print of a Security bot. (0.4mm nozzle) The lower torso was printed upside down, and the top of the back leg looks quite bad due to it being printed as a big overhang. And as a great example for the previous point: the base is totally flat, and came out great.
    Clipboard02.jpg
  • Mid-air is a bad place to start from
    Since the filament needs something to hold it in place obviously no hanging part can be printed properly. e.g. a standing humanoid figure will have problems when the arm gets started with the fingertips mid-air. That's what supports (later) can help with, but I found that with 0.2mm nozzle they not always give enough stability for a flawless print. Typically what I have problems with is the chins and necks of minis, bulky breastplates or torso armors make it really hard to print them correctly.
    This can be mitigated by using poses that do not have "hanging" parts. Adding things that touch the "ground", using supports work most of the time. The Raider Psycho below needed remarkably few supports to come out good looking, while the pistol arm of Sturges come out not so great even with thick supporst
    Clipboard04.jpg Clipboard03.jpg
  • Rest in pieces:
    Cutting up the model in strategical places is one of the things that can greatly improve the quality of the print.
    basically, it makes it possible to orient parts of the model with ideal for just part only, avoid overhanging, midair started limbs. Separated heads will result in much better chins. And low gradient surfaces can be minimized as well. The only problem with this is that it results in multiple parts to be printed, and the assembly can be tricky.
    This is where I'd like to bring up MeshMixer. It is a free software that was made mainly for model manipulation for 3D printing. It does have some great features, I don't really use it because I didn't feel like learning a new control scheme again thou.
    Warning about the aligning pins: As I mentioned previously the slicer will go an inner walkaround of the surfaces, the aligning pins might not fit perfectly, with my profile they are usally need considerable filing before i can assemble the model.

    I generally try to cut my models on places where there is a hard border on a model e.g. the end of a glove or boot. or on big open places where it is easy to sand or use filler. The Nuka-girl below has both gloves printed separately, and the Super Mutant Behemoth has a filled in and sanded glue line in the middle of the upper arm. The Raider woman has a separately printed head, and the chin is superb (the neck is not but don't mind that :p )
    Clipboard05.jpg Clipboard06.jpg Clipboard07.jpg

...Next up the (hopefully) last part of modeling, some useful modeling techniques, and time savers.
 
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daishi

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Apr 14, 2011
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Editing models part 3
As the final part on model editing, here are a few techniques I use a lot. For creating new meshes my skills are fairly limited, but I do quite a lot of editing, both for my paper models and my prints as well, on existing meshes.
  • Look at the pretty patterns:
    A lot of meshes are available on the Internet, but only a fraction of them is intended for 3D printers. This is apparent at first glance since most of them are textured. The slicer will totally ignore anything that comes from textures. This does not only mean the coloring (diffuse map) but the shininess (specular map) and what is the greater problem the bump/normal/displacement maps as well. This latest is the greatest problem because a LOT of detail is created with these on "regular" 3D models. the actual mesh is ofter really low poly and does not look too good when printed as is. It is possible to "bake" these texture-based details onto the mesh. The poly count will skyrocket because of it, but it is possible.
    I know of 2 programs that can do this one if (ofc) Blender, the other is ZBrush. Basically the mesh needs to be subdivided to make add more polygons to work with then the normal map can be used to modify the mesh, adding texture-based details to it, that will actually show up on the print.
    Since Zbrush is not free Ill only put in the Blender video that shows how to do it.

    The muscles on these Super mutants mostly came from the normal maps, the original models were really low poly, Also the shopping carts on the Super mutant's back were totally flat.
    Clipboard01.jpg Clipboard02.jpg
  • Normal is overrated
    In a polygon-based 3D model each verticle usually has a normal. These normals (and the ones coming from a normal map as well) are used by the renderer to calculate a surface gradient I think it is called .... nevermind it involves a lot of math and I'm not sure my English is up to explaining it, and basically beside the point. The reason normals are important right now is that they are used to display meshes, and the slicer will ignore any smoothing that is done with them, similarly how normal maps will not be considered either. For any curved surface, an appropriately high polygon count is needed for any decent 3D prints. Or it will be chunky.
    Subdividing a mesh in any editor usually offers a function to smooth the mesh at the same time. Don't be afraid to use it, a high-poly count is usually beneficial in this case. And just be aware that if it looks smooth on the monitor It might be smoothed by the renderer and will look bad after printing.

  • Mixing is not only for bartenders and DJs
    I regularly check the Thingiverse for cool looking models, but it is quite rare that I print them as is. I usually use a lot of them as parts for my minis or more often my bases. I have touched this under One shell (to rule them all), for the slicer to not freak out and always do a good job the model should be one closed shell. Now when I get a bunch of really high poly stuff from online and try to put them together to make things, joining the meshes can range from "pain in the neck" to "this is impossibe". Fortunately, the repair function 3D Builder is really really really good.
    Not the most optimal solution, but works every time, and the slicer won't care much. (Cura is pretty good at figuring out intersecting objects as well but not as good as the mesh 3D Builder creates)
    What I tend to do is just this:
    1. Put the objects in the correct position, not caring about intersections
    2. Delete what I don't need, and what pokes out in inappropriate places.
    3. If I have big gaps either extrude something or just use a primitive object to plug it.
    4. If I have visible holes try to plug them (not always needed*)
    5. Save the whole thing as an .obj
    6. Load it in 3D Builder
    7. Let the repair run its course
    8. Check the final mesh (if any holes were left, check how they were filled by the repair tool)
    9. Voila! Feed it into the Slicer
If you check these 40k helmets, I rather liked parts of them for my Fallout Raiders :D but most of the Maxims for the Raider Power Armor came from a different model as well.​
Clipboard03.jpgClipboard04.jpg

  • We are pinned down
    I've already mentioned aligning pins in Rest in pieces they are good to have on the feet of the minis as well. If the printer puts them there is no need to drill the feet afterward, and they are great to stick into the Blue-tack during priming/painting.
    But they can have detrimental effects as well. There will be a much smaller contact surface to the heated bed (supposing the mini gets printed standing). The lesser surface means less stability as the nozzle deposits layer after layer on top of the part. So just be aware that this is one of those that is sometimes good to have, but sometimes it is not.
    This is a render from my Goris mini, you can see the pins under its feet.
    Goris2.png
  • I feel hollow inside
    Sometimes models can have a second inner layer inside, basically making the mesh to resemble a chocolate bunny. This usually makes the model less robust complicates/slows printing, And at times even 3D builder won't fix it until I delete most of it manually. I found that editing this hollow out saves a lot of printing time ... usually.
That's about all I could come up with on model editing. It's definitely different from making papercraft templates. :D
Next time I will go into Slicer (Cura) settings.
 
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daishi

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So far I just wrote about preparing models in any 3D editor. I mostly concentrated on steps that I found I either use often and/or had some problems because of them. The internet is a great resource and there is a great community there. For the next part, I will be going through the slicer settings I either change a lot depending on the model or had great results after changing them.

The slicer:
I am using Utimaker Cura 3.6 at the moment. The latest version is 4.3 but I had problems with 4.0 and 4.2 so I started following the "If it ain't broke, don't fix it." principle.
Cura has tons of settings, especially if it is set to expert mode, which I tend to do and use the search option for features I want to tweak. But first things first Id advise to get a few profiles from the hivemind called the Internet and test those out. Most of them have a lot of trial and error behind them, so they are a great starting point.
I got the one I'm more or less using from here: www.3dprintedtabletop.com

Clipboard01.jpg

The basics:
These are mostly self-explanatory so I will only highlight some. Cura will highlight settings invalid looking settings automatically.
  • Quality
    • Layer height: this is basically the height of each layer on the print. Every printer has "Magic Numbers" on these, basically, it depends on the stepper motor and the lifting rod (I think its called that) of the printer. On Creality printers, 0.4mm is the base "Magic Number" for the Z-axis. Getting these smaller will increase the number of layers and consequently the print time. I personally almost always use 0.8mm, with that a 32mm mini is printed in 3-4.5 hours and a 32 mm base for it is another ~3hours.
    • Line width: This is basically the nozzle diameter. I use 0.2mm nozzles so this is set to that as well.
  • Shell
    These settings control how the outer shell of the print should be made.
    • Print thin line: This setting enables the slicer to create at least one wall on parts that are thinner than the nozzle diameter (too thin capes, hanging straps, pipes etc.). Really useful when it works, sometimes It does not seem todo so for me
    • Ironing: This is a great feature to have on If the model has horizontal planes, it is nice to have on other models too but has limited results on those. What this does is basically uses the still heated nozzle on the top layers to smooth out the top surface. Her is a bit old but still great video on ironing:
  • Infill
    Above I mentioned that shell is the outermost part of any print. All internal volume inside the shell is controlled by these settings. normally FDM printed models are hollow with an internal structure printed into them for more strength.
    • Infill density: This setting tells the slicer what percentage of the internal volume should be filled with plastic. It is possible to set it 100% for a solid model. I have never tried it but It is said it leads to a lot of oozing, as in extra plastic on the outer shell. I usually use 20-35% depending on the model.
    • Infill Pattern: This is the setting that controls the geometry of the internal structure, I usually stick to Grid, never had a reason to try anything else, but I am not rally printing anything that experiences great forces or stresses.
  • Material
    These are the settings that change with the kind of filaments used in the actual print. I use a metallic grey PLA filament almost exclusively so I generally don't change anything here. (One of my problems with Cura 4.X was that it did not import some of my settings correctly)
    • Printing Temperatures: These depend on the material used, for the PLA usually 195-205C is sufficient, but It can depend on a lot of factors, the actual filament, the ambient temperature, the print speeds, the humidity, etc. Speaking of humidity, PLA will absorb some water from the humidity in the air over time, the slow speeds that are required for a small nozzle, small layer height and the general small material need of minis, will easily lead to the spool lasting months. the increased water content can lead to decreased print quality. Fortunately, a few degrees increase on the nozzle will fix that, just a good thing to keep in mind.
    • Build Plate Temperature: Similarly to the nozzle the bed on which the print is built upon is heated too. It helps with adhesion. (It is also really important for ABS but I don't use that so cannot elaborate.)
    • Retraction: Now This one is one a great one to keep in mind. When the nozzle is repositioned between points without actually printing. the filament is pulled back by the Extruder if this is enabled. And that is really-really-really useful because it prevents a print artifact called stringing (will go into it later). So Enabling it and setting Retraction Distance from the default 0.3mm (I think) up to 3-5mm is advised, especially if there is stringing. the Extruder stepper will work more from this but totally worth it.
  • Speed
    This setting is one that is really important to get right once, then forget this exists, and never, ever change it EVER for that nozzle diameter.
    There is a good guide that actually explains a lot about this here: toms3d.org (also embedded just the video below)
    There are 3 main groups of settings here:
    • Speed (normally around 40mm/s for defaults, I print on 25mm/s)
    • Acceleration
    • Jerk
  • Travel
    Some really useful, albeit for me rarely used setting, that controls the nozzle movements during repositioning.
    • Combing mode: this tells the slicer how the nozzle should be moved when repositioning between print points. IT can be set to avoid already printed parts move on the shortest straight line, or just avoid the outer skin (that will be visible. I leave this on "Within Infill"
    • Z hop: with this on the nozzle will be elevated a little when the head is repositioning, Better for the print, also moves the Z stepper a LOT more, and slows down the print a bunch.
  • Cooling
    Controls for the blower fan of the Part Cooler. I usually blast at the top RPM. It gives good results for me so I did not tinker with this.
That's it for today I need sleep, next up the remainder of the Cura settings like Supports. That is the part I tweak a lot usually, so I promise I will actually make screenshots for that. ;)
 
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