Tips on Getting Started, Part 1 - Cura

Getting Started with Cura

My coworker from the first post suggested that I print existing models to learn what to expect.

I printed 8 cookie cutters from Thingiverse, then started printing the Pip-Boy pieces (also mentioned in the first post). Later on, I downloaded things like Open Forge terrain for D&D, D&D figures from Shapeways, and watch stands from Thingiverse.

After the first couple of items printed, I probably could have moved onto the "difficult" pieces. But as a caution: just because it was modeled in 3D, doesn't mean it will print well.

Profiles in Cura

Cura has a "basic" setting that didn't work for my first print - I ended up jumping straight into "Expert mode". Expert mode uses Profiles to manage general settings for what material you are using, and how fine you want the details. This is primarily addressing extruder temperature (melting the plastic), the bed temperature (so there's a consistent temperature once the plastic has been "printed" - allowing for regular adhesion)...and then Layer Height for detail (the smaller the number, the finer the detail). A distant fourth quality is "in-fill" - if you have 100% in-fill, it will be a solid object. More plastic, longer printing, heavier...20% is considered "enough", but if you want additional heft or strength...

If you need to use gcode to print, these profiles will be included in the gcode instructions.

Standard profiles can be found on the lulzbot website, and probably anywhere you downloaded Cura from. (I did fast printing for a long time. It's rare that I use "fine" printing.)

Adding Useful Information

You bought some PLA/HIPS? Great. In File>Preferences>, you can put the Cost/kg. This will give you an idea on the cost of your model - it's probably cheaper than you think. My current standard price is about $25-30 / kg.

Rules for 3D printing

It's ridiculous to have rules for this, right?

1. The object needs to be small enough to fit on the printer bed. (I think the Lulzbot Mini has a 6" x 6" x 6" area.) One of my early-modelling projects was designing a 9" diameter braiding wheel. I cut it apart in quarters in Blender, then printed the 4 pieces in Cura.
2. The printer can only reasonably handle 45 degree angles as it builds vertical layers. Beyond that, the plastic has nothing to layer on top of. If your object has overhang issues, Cura's answer is "Support: Everything". It will leave some rough parts where you remove the support, but it doesn't use a lot of plastic - and doesn't cause your model to collapse as it would without the supports. (I've aborted a half-dozen printings because of not having support turned on.) Cura is an all-or-nothing choice, when it comes to supports.

Slightly Advanced Choices

Rotating the Model

Sometimes I'll change the model's orientation to the printer bed. Usually so there's less support needed, or so that the smooth surface from the bed. Cura's generous with rotating (and bringing in models) - it will always bring the object up into the printing area. This is nice if you don't create your objects above the origin point in Blender.

Scaling the Model

Ugh. I think my biggest issue with Blender is scaling, due to its use of "Blender Units" or BU. They actually export as millimeters. I'll talk more about the measurements once I talk about Blender in-depth. Fortunately, Cura is good about scaling your models. My initial braiding wheel was usually boosted by 28:1 scale in each axis.

Printing Multiple Objects

When I'm printing multiple small objects, it's convenient to load them all onto the platform in Cura. This reduces the start-up time for the printer - the Lulzbot Mini needs to scrub off the plastic on the extruder from last printing session, and auto-level the bed again. This tacks on 3-5 minutes, which becomes a more onerous task if you're printing things one after another. Under Tools, you can choose to print all at once or one at a time - I recommend one at a time, so that the temperature is consistent for adhesion.