A Few More Kind-of-Boring-But-Necessary Details

This is not going to be the most riveting post, but read it anyway. There are some important things in here.

When I left off with the ring from the first tutorial, it was basically just a bunch of shapes.

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But now we have to make it into something we can print, or at least THINK about printing. The first thing we’ll want to do is turn it into a single body.

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You’ll find the Combine Tool in the modify menu. You’ll choose one body to be the “target body” – or the thing the other things will attach themselves to. The tool bodies are all the other ones. Select them all, make sure your operation is set to “Join,” and click OK.

Now you have a single body- you won’t be able to select individual components and edit them anymore, unless you roll back your design history. Your ring is now officially a ring.

Now, I think this design can be improved a bit – both in terms of aesthetics and comfort – if I round out the edges of of the ring. We’ll do that with the Fillet tool (hotkey F). It sounds like a steak, but it’s not.

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Filleting is great for rounding hard edges or making transitions between two combined bodies. In this case, we’ll select the four edges of the ring…

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And we’ll play around with the radius until we achieve an effect we like. Your model will update as you plug in different numbers. You could make a teeny tiny radius, that would just barely round out the edges, or you could go with a bigger radius that would nearly turn the square ring into a round ring. You’ll also find that many numbers simply will not work with your model- if that’s the case, and the software can’t make the fillet you’ve requested, you’ll get an error message and a prompt to try a new value.

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Here’s what the ring looks like with a .5mm radius. Not too big, not too small- the Goldilocks ideal of 3D modeling.

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Now that my ring is looking just about the way I want it to, I’m going to double check the size. I’m trying to make this ring approximately a US size 4.5 – which converts to a 15.27mm diameter. I use the measure tool (Inspect>measure), select the inner circumference of the ring, and see that the diameter is 15.2. For this practice purpose: good enough, or as I optimistically put it above, “Perfect!” However, if I wanted to adjust it or make it another size, I can just go back and scale it until it’s the right measurement.

So now I’m ready to print. In order to do this, I’m going to convert my file to an .STL (Stereo Lithography). What you see in Fusion 360 is, basically, a bunch of math- the term for the surfaces that math creates is called, hilariously, NURBS, and less hilariously, non-uniform rational B-splines. Read about it on Wikipedia.

In order for the model to be utilized by 3D printing software, those surfaces have to be converted into a mesh of points and faces.

But don’t take my word for it:
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Select the body you want to print. I usually leave it at medium refinement- which, as I wrote above, is “usually good enough.” But what does that mean?

If we select “preview mesh,” we can see exactly how our NURBS are being broken down into triangles.  Here it is at medium refinement:

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And at low refinement:

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We’ve cut the number of triangles down by about half- this means that our file size will be drastically decreased, but we might also start to loose resolution. At piece this scale, it wouldn’t make a huge difference- but at larger sizes, you might start to see the facets of the triangulated piece.

Now, if we want to go the opposite direction, here’s the same model at high refinement:

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So. Many. Triangles. This is great for models that need a super high level of resolution and accuracy. In my experience, though, medium refinement is more than enough resolution for smaller jewelry items, and provides a good balance between great detail and manageable file sizes. That’s why it’s “usually good enough.”

If you’re going to 3D print this yourself on a Makerbot or other home printer, you’ll want to check the “Send to 3D Print Utility” box. This will send the file to Meshmixer, a free program that allows you to get your file ready for printing by adding support material, orienting it in the bed, slicing it up into layers, etc. It also has some fun editing features that we’ll get to another time, but here’s what you’ll see if you decided to export it to Meshmixer.

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Cura is another popular, free, and easy to use slicer software that, if you are doing printing on your own 3D printer, you can check out. This is what we use when we are doing 3D printing at home.

Ring Slicer Capture
Two little rings in Cura, all sliced up and nestled in their support material.

But since I recommend starting with a 3D printing service before buying your own printer, I’m going to show you how to upload and evaluate your models on Shapeways. It’s very easy. A site like Shapeways will do all the slicing/analysis/support material generation for you, which is a beautiful thing.

Disclaimer: As I’ve mentioned before, I use Shapeways, I sell work on Shapeways, but I am not, like, a paid spokesperson of Shapeways. I wish (Shapeways, call me). I use other services, too- but I will likely reference and use Shapeways for examples more than anything else, because they do a super job and their interface more transparent and easy to use than a lot of other similar sites. And they have good taste in homepage images:

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Screen Shot 2016-02-07 at 4.55.35 PMAny way, if you have your .stl ready to go, click on that upload button, above that stunning ring. You’ll select your model, click upload, and wait for it to be processed and uploaded onto the website. Once it’s uploaded, you’ll see these controls:

 

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You can scale your model with these tools, or update the version. With rings, you’ll always want to import it at the intended size- but decorative objects and stuff can absolutely be scaled up or down.

Below the model, you’ll see the results for the automatic checks for each material. These evaluate the wall-thickness of each model and do other initial checks for red-flags that would render a model unprintable. If you want to learn more about the specific requirements for different materials (and you should), I highly suggest taking some time to look through Shapeways’ material guide here.

Because each material has its own set of specifications, not all files will be printable in all materials. In fact, most of them won’t be, and that’s ok. It’s important that when you’re modeling, you think about what you want your finished piece to be made in, and design for those specifications. For example, looks like our ring is good to go in all the nylon options:

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Green check marks are a great sign. It means that, at a basic level, your piece has met all the requirements for the material and SHOULD be able to be printed successfully. Remember, though, that this isn’t a guarantee. Sometimes, even if a model has passed those checks, it won’t be able to be printed. It’s rare, but it happens – and if it does happen, it’s not the end of the world. The helpful people at Shapeways will refund you, and will generally give you some pointers on what you can do to resolve the issues.

Looks like my model passed all the checks for the precious and base metals, too:

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But ruh-roh. What’s this?

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Looks like we might have an issue with the stainless. Click on “View Issues” to take a closer look:

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If we click on Wall Thickness, we can see our problem areas. The outer ring of our “stone” is just a smidge too thin, because the wall thickness requirement for stainless is 1mm.

We have two choices- we can go back to our original model and modify our thickness… or… we can try to print it and see what happens. Sometimes, you can sneak these things by and they’ll work- but a lot of times, they won’t. It’s probably better to err on the side of caution, but it also doesn’t hurt to try. A “View Issues” warning doesn’t stop you from ordering a sample.

If you see this, on the other hand…

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Red Xs mean, “No, you can’t print this.” Add to Cart is grayed out, and they’re not even f***ing with a price. Let’s click on View Issues and see why:

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The Red X can occur for a lot of reasons, but usually, it will be the result of your piece not fitting in the bounding box. If we wanted to print this in porcelain, it would need to be bigger- 40x40x10mm is the minimum. At 18x22x7mm, our ring is not cutting muster. You’ll see too, that the ENTIRE ring is yellow- meaning we’ve missed the minimum wall thickness on the entire piece. It’s one thing if a few little edges fall a little outside the parameters, but another story if the entire thing is too thin. 0/10, would not print.

Kasia

Designer/HBIC

Designer, magpie, maximalist.

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