Printing Miniatures

Printing miniatures is a popular topic for 3D printing. If you play something like D&D, you never have enough of the right miniature. "I need 20 goblins." "I need some plant-tree creature, small-size, on a base." Thingiverse has a ton of models. Hero Forge lets people design figures, then buy the figure's stl. (And then send the .stl to a friend of theirs to print, if they can.) My friend's Starfinder figure will be an example further down.

My Lulzbot Mini is a workhorse, but uses a stock .5mm nozzle. This means it prints faster than smaller nozzles, as it can push through more melted plastic.  A lot of other printers use .4mm as their standard nozzle...and people generally stop designing a "successful" print when they get it right...which means sometimes I'll get a model that doesn't print well on my bigger nozzle diameter.

A Finer Nozzle

Maybe you have a collection of nozzles, or you buy an extra nozzle off of Amazon for $15. (I've bought some Microswiss ones in the past.)

[The next paragraph will be something specific to a Lulzbot printer...]

Enter...the "Aerostruder .25mm SL Micro" tool head. It's released through the Lulzbot site for $250, needs a $50 converter to fit my Lulzbot Mini 1.3/1.4. You can guess it's a .25mm diameter nozzle, which allows for higher resolution. It also has a custom fan shroud to blow in air from more angles...allowing for better cooling and better resolution.

[...back to the regular broadcast...]

I swapped the new toolhead on one of my 1.4 Mini's, as a long-term switch out. You also need to flash the firmware so it recognizes to print with a smaller nozzle, which is a little bit of an effort. Once you load the default .25mm Micro profile, do NOT change the e-steps. The documentation and Cura is a little wonky....it tells you to copy your e-steps when you change your nozzle...don't. The new profile will have different e-steps, and it should. Imagine that you are shoving filament through at the same rate as before...but you have a smaller nozzle. It won't go through, and you'll have problems.

In Cura, I set up a new printer profile for this "new" printer. It makes it easier in the future if I swap back to a different toolhead. I went to my Octoprint instance, and changed the nozzle size there — if you extrude 30mm, you want that based on the smaller nozzle...

New Layer Heights

It also took some new habits, when it came to printing miniatures. You now have much finer detail available to you...I started printing at .05mm height, which was always so difficult with a bigger nozzle to do it right. (Fine detail for a .5mm nozzle profile was usually .15mm.) Honestly, a .1mm layer height is completely fine - you won't notice much of a difference. I'd recommend starting with .1mm, and seeing how you like it. (My experience is usually about 2 hours at .1mm layer height, including the trees listed below.)

Meshmixer

Miniatures typically have dynamic poses — pointing their sword, or a spell shooting out from their outstretched hand, which means supports. Normal supports can be okay, but sometimes you're missing details in key spots. I started playing around with Meshmixer - a free-to-hobby software released by Autodesk, which can allow for a lot of leeway when it comes to adding tree supports. I'll be talking about my experience in 3.3.15, in case you're reading this in a future that my assistance does not make sense.

A couple of tips...first, when you import an .stl in, first step is Edit>Align [Accept]. This will bump your miniature up into the correct plane. If you don't do this, it sometimes cuts off the lowest part of your model. Next, try letting Meshmixer do the orientation (Analysis/Orientation [Accept].). Hopefully it'll preserve your details better than the stock "as the figure stands".

The real work is Analysis>Overhangs>Generate Support. You may want to try Meshmixer's baseline attempt, before you do a deep dive. Some key settings: Density (how much tree support you want), and Post Diameter (how thick the tree posts are). More density = more support...but it can also introduce more scarring as well as make the support more difficult to pop off. Less support means that parts can droop. A thicker post can be useful - if you print a bunch of really tiny posts, it increases the chances of some getting loose and gumming up the whole print job. The adverse effect — you can't print the posts as closely together, regardless of density...which means you risk more droop between supports.

With a difficult miniature, I was running a density of 80 (a bit high), post diameter of 2mm (a bit thin)...and the Starfinder miniature looked a bit like this:

Export your figure. Now, keep in mind, this is no longer a normal .stl. Don't use supports - you've already added supports. If you generate supports in your slicer....it will not know that your tree supports are anything separate from the figure. It will add more, which defeats the purpose of tree supports.

Finally, I'd urge you to use a "raft" when printing. Usually when I print with Cura, I do a quick skirt. The drawback of trees is you're going to be printing a lot of small support bases onto the bed, and if any of them come loose....not good. The typical 'bad' aspect of a raft is that it needs to be pulled off of whatever model you're making...but that's great for these tree supports. It makes removing them that much easier, beyond making it reliable for the support's bases to stick to the raft.


Good luck!

Blender Gears

I've been using gears for a couple of different projects.

My first foray into gears using Blender, was using the Add Mesh: Extra Objects plug-in. It opens up another "base" object in the Add Mesh > Gears > Gear options. It creates a gear without the faces connecting the inside of the center hole (a non-manifold model). It's easy enough to create these faces - alt-shift each inside ring, the bridge the edge loops (through Control-E for the edge menu, then Bridge Edge Loops, or spacebar-find Bridge Edge Loops).

Breaking it down

• Teeth is...teeth - the distance from the inside ring to the outside tooth tip is Base+Dedendum+Addendum
• Radius is the distance from the middle of a tooth, to the opposing side's middle tooth
• Width is the z-axis height
• Base is the inside of the ring to the outside of the ring
• Dedendum - the distance from the "middle" of a tooth, to the outside ring (increasing it, also shrinks the hole in the center)
• Addendum is the tip of the tooth, distance is figured again from the middle of the tooth to the tip
• Pressure angle is going to the slant of the tips of each tooth - anywhere from 0 degrees (square), to a maximum of 45 degrees (if your addendum is a larger value than your overall size, you'll need to reduce the pressure angle to avoid bad topology)
• Skewness is used for helical and herringbone gears - also known as a helix angle
• Conical angle has one end shrink to a cone - 45 degrees leads to a tip, where 0 is no cone, and 90 is flat (practical uses - 0 to 45)
• Crown makes a crown by elevating the tips and mid-points of each tooth - a measurement of the z-axis difference between the base of a tooth to the connected top of tooth (not a hypotenuse, which would be longer)

Woodgears

That's just how to lay out the gear, once you get your gear designed! I used this perfectly fine option from a site called Woodgears...he does a lot of great woodworking, and the gear tool is useful.

Otvinta's Instant Gear

My current gear-making assistant is Otvinta's Instant Gear. Their branding is "A collection of tutorials & resources for 3D modeling and 3D printing enthusiasts". The useful part, is how it generates a python script to create the gears.

You can then go into a Text Editor window in Blender (usually on the 3D View, lower left hand corner), click on the "+ New" button, to create a new text data block...paste that code, and the press the "Run Script" button. You have the outside outline of two gears, both preset as meshes (back in the 3D View).