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[Old Codger]

I have decided to get into 3D printing and intend to do the basic 3D model in Anim8or. Now, is anyone here already doing 3D printing? I think I understand the basic steps: create the 3D model - save/export it in a format the next software understands (.obj most likely) - send the result to a "slicer" to turn the 3D model into a series of layers - send the output of the slicer to the printer for printing.

Now I got a great deal on a used 3D printer ($89 vs $250) with a print area roughly 8 inches on a side (210mm X 210mm X 205mm) that uses PLA plastic line as print stock. What I would LIKE to be able to do is break a model into components smaller than 8 inches with an eye towards assembling the pieces into models LARGER THAN 8 inches. From what I have been able to gather, turning a single 3D object into multiple pieces requires some sort of CAD software. If so, can anyone here suggest a good - hopefully free - CAD suite to do the conversion? I figure somebody here has already gone where I am going and so can point me in the correct direction.

 Here goes. {crossing fingers}

[davdud101]

I'll tell ya - I have a small desktop CNC which is the closest I personally own to a 3d printer. I have had some parts that I modeled ion Anim8or 3d printed by a guy and they came out great. I've been trying to get into 3d carving with my CNC (even downloaded Fusion 360) but I haven't even opened the program yet. I'm going to buy a 3d printer soon, probably within the next year or so and perhaps we can learn together.

That said, I'm *thinking* Fusion 360 or SketchUp **miiiight** have tools for that in them. Not sure about generating gcode directly in the programs as I haven't tried.
Also Anim8or isn't the most dead-nuts precise tool out there so just be aware of that. I like it for rough dimensions and it can definitely work for less intricate stuff, but for things like boolean operations and extremely precise operations it's a bit tough to get clean results that would be useful on something like a 3d printer or CNC router.

[2020 Hindsight]

I've done 3D printing using Anim8or. The way to do it is to export to a .stl file. To do this, in Object view, select Object->Export ...
This opens the "Pick a File:" dialogue. At the bottome of this dialogue  there is a drop down selection "Save as type" for the file type. Select "STL (Binary)(*.stl)", (or "STL (ASCII)(*.stl)" should also work , but the files will be bigger - theoretically you can tweak these in a text editor, but I've never felt the need to do this.)

Once you have your STL file you can import them into a slicer of your choice - you can pretty much use any slicer for any printer as printers all take gcode files. However if you want to do something printer specific like two colour printing, you are best sticking to the slicer the printer maker recommends. My go to slicer is Raise3D IdeaMaker.

You can also create gcode for CNC machines from the STL files - but that gcode has instructions for a cutter - so passing 3D printer gcode to a CNC machine is a bad idea. For starters there won't be a code to spin the cutter. (Obviously you need to use the appropriate software to convert your .stl file to a CNC cutting path.)

[2020 Hindsight]

If you are lucky you may be close to a FabLab. They are almost guaranteed to have 3D printers available (at my local FabLab they charge for usage time). And if you are lucky they will also have a CNC machine. My local FabLab has two: a small one (Roland MDX40), and one big enough to make large furnature (ShopBot).

Here is a map of FabLab locations:
https://www.fablabs.io/labs/map

There will be people there who can give you help and advice too.

[2020 Hindsight]

I've used - or at least played with Fusion 360. My biggest problem with it is the free licence for people with revenue of less than £10,000 per year (or however it is worded). They have now reduced functionality twice for the free version while I've had it installed. Personally I think any company using it need their heads examined, because they are putting their entire business at the mercy of a license that can be changed at any time. And they keep changing the interface, so the workflow that worked yesterday won't necessarily work today.

I keep meaning to look at FreeCad. But I've seen a video saying that it has a fundamental design flaw in it, and you are better off using a development branch that addresses this problem. I suggest you listen to the video, and read some of the comments:

&ab_channel=MakerTales

Under the video there is a link to the RealThunders Branch: https://bit.ly/3iBzQly I've not looked at it, but I think that it is probably the version to learn with.

I noted to myself that this FreeCAD course looked like it may be worth watching:

&ab_channel=FreeCADAcademy

[2020 Hindsight]

...
Also Anim8or isn't the most dead-nuts precise tool out there so just be aware of that. I like it for rough dimensions and it can definitely work for less intricate stuff, but for things like boolean operations and extremely precise operations it's a bit tough to get clean results that would be useful on something like a 3d printer or CNC router.

The other week I wanted to print a simple roller. I created the .stl with Anim8or using the boolean operations script. My first attempt failed, because I tried to subtract one cylinder from a wider one, but made the "mistake" of having them both the same length. When I made the small diameter cylinder poke out both ends of the large diameter cylinder it worked. (Although the choice of how to divide the ends up into triangles was a bit eccentric.)

[ENSONIQ5]

A simple roller solid can be created in Anim8or without booleans by lathing a rectangle.  The object is limited to 32 facets around the circumference but this can be improved with smoothing and the topology of the ends is tidy.

[2020 Hindsight]

A simple roller solid can be created in Anim8or without booleans by lathing a rectangle.  The object is limited to 32 facets around the circumference but this can be improved with smoothing and the topology of the ends is tidy.

Would smoothing have a toasted cheese effect on the precision of the corners? The end caps the binary operation produced fit perfectly (once I made the inner cylinder longer) - the surface just isn't divided like I would have done it by hand - but I shouldn't care about that.

[Old Codger]

A simple roller solid can be created in Anim8or without booleans by lathing a rectangle.  The object is limited to 32 facets around the circumference but this can be improved with smoothing and the topology of the ends is tidy.

If I were going to create something round with a round hole in the middle lathing would seem to be the way to go to me. I use lathing so much these days I have my own name for it. I call it "spinning" the shape.

But wouldn't smoothing screw up the end caps?

Have to try that out and see what happens.

[Old Codger]

A simple roller solid can be created in Anim8or without booleans by lathing a rectangle.  The object is limited to 32 facets around the circumference but this can be improved with smoothing and the topology of the ends is tidy.

While the topology of the ends does stay tidy, my experiments would tend to indicate that you don't actually get more than 32 segments in your circle.

Here's what I did:
1. Generated a square spline offset from zero and lathed it in y for 32 segments.
2. Then I smoothed it with a tension of 1. (By inspection I determined that tension much than 1 starts messing with the topology of the ends) This produced something with what looked like 64 sections around but it also double to geometry across the radius and across the outside.
3. Then I smoothed a 2nd time again with tension of 1.

At first glance it looked like I had a wheel with 128 segments. But then I looked closer. What I discovered was that my original 32 facets radially were preserved but were merely broken up into (now) 4 segments each. I've attached a couple of graphics to illustrate. The first one is a render zoomed in to show a quarter of the circumference. The 2nd is a screen cap of the same model in the same amount of zoom but in wire frame mode. You can see the original 8 segments (per quarter turn) as were there after lathing. Look at it and tell me what you think. Did I mess up?

[2020 Hindsight]

Thanks Old Coger.
I've just had a try on build 1.01.1402 and got the same result.

Is there a reason for limiting lathe to 32 segments? I suppose it makes rendering faster, but isn't so useful for 3D printing.

Anyway I feel we are digressing from the point I was trying to make about using the boolean operations scripts:

You wanted to break down a large print in to smaller prints to fit on your printer's build plate. The boolean operations seem like they should be usable for that purpose. But davdud101 seemed to be indicating that boolean operations introduce inaccuracies. I wondered if he was talking about where a plane on both shapes the boolean operation take are coincident (I mean same position in space and parallel - like the opening to the hole through the roller when both cylinders were the same length)? Or is there another problem?

How are you intending to assemble the parts? Glue? Or nut and bolt? Or some other way?

[Old Codger]

2020 Hindsight asked, "How are you intending to assemble the parts? Glue? Or nut and bolt? Or some other way?"

If I had my "druthers" I druther engineer the pieces to snap together but I can see using glue. I'm thinking about making my granddaughter a Minnie Mouse toy or something like that. I was also thinking about taking some of the things I've made in Anim8or and turning them into real objects. If I used different color material for the different parts I can see how I could make the detail using paint or even printed custom decal material. I really don't know what I'm going to do considering I have never done 3D printing and that is a whole other ball of wax from crafting machines in Anim8or. I am anticipating a good bit of teething problems. I know just setting up my regular dot matrix printer/scanner took a while when I had to replace the older one. I have spent too much time with microcomputers since 1983 to expect the setup on the 3D printer to go smoothly. But I'm old and retired and what else do I have to do?

Oh and if you look at Steven's answer to my question about lathing you'll see that 32 segments is a limitation built into the software itself. I accept his answer that it had to do with computing resources. I'm just going to be interested to see how my normally fairly simple shapes come out as physical objects. 

[2020 Hindsight]

It is satisfying watching your objects being printed. I'm sure you will have fun!

Tweaking is required to get good prints. A lot of people try to print objects using the fastest settings, but the best way to get a good looking print is to print slowly (or at least not too quickly). You often see echos of corners in printed objects because they have been flinging the print head around too fast.

The biggest problem I have with printing, is printing large objects. The wider an object is, the more it contracts as it cools, and tries to peel itself off the build plate. But I tend to keep to small components anyway. The printers at the FabLab have transparent enclosures to keep the ambient temperature up. They seem to have success printing large objects.

One guy at the FabLab printed a violin he downloaded from ThingiVerse for his daughter. So it is possible to print large objects

It might have been this one:
https://www.thingiverse.com/thing:1533229
or possibly this one:
https://www.thingiverse.com/thing:2752036

I've seen youtubers get good finishes on prints by painting them with primer, and then sanding with wet and dry to get rid of print layer ridges.

[ENSONIQ5]

Smoothing with a tension of 1 just places edges and points between existing edges and points without actually smoothing anything, whereas a tension of 0 would give 64 smooth facets.  Your point about the end caps is valid but this can be addressed with 'edge reinforcing' prior to smoothing.  There are a few ways to do this but the goal is to double- or triple-up any edges you want to keep sharp before smoothing.  The roller below was lathed from a rectangle with 32 facets (first image - note the tripled edges around the inner and outer rim) before being subdivided (second image).

[ENSONIQ5]

There is also another way to create a 'roller' object with 100 facets by creating 2 concentric 100-sided N-gons (or create one and duplicate/resize it), selecting them both and selecting Build > Join splines, then extrude with start and end caps both ticked in the extrude dialog.  100 sides is the max for the N-gon and the end cap triangulation means smoothing probably isn't an option, but it's something to consider.