Variable Width 3D Printing The Hard Way

The problem: you want to produce varying line thicknesses when 3D printing. The solution, if you are the Liqtra company, appears to be to put seven print heads together and enable one for thin lines, all of them for thick lines, and something in between for everything else. The technical details are scant, but from the video below and some pictures, you can get a general idea.

There are some obvious benefits and drawbacks. You’d expect that for the right kind of part, this would be fast since you are essentially laying down seven tracks at once. The downside is your track width varies in pretty course steps, assuming you have to use the maximum width of each nozzle to prevent gaps. New slicing software is a must, too.

The demos and pictures show multiple filament colors because it photographs well, but you’d assume in practice that you would use seven spools of the same material. The good thing is that you could print with a single nozzle where that’s important. We assume all the nozzles are the same size, and that will control the practical layer height, but that’s a small price to pay.

The company claims a much faster print, but as we mentioned, this will depend on the specific printed part. They also claim inter-layer strength increases as well, although we found that surprising. This is probably overkill for home users, but we imagine this would be an interesting technology for people trying to run production quantities through a printer.

We don’t remember seeing this approach with a homebrew printer, although having multiple extruders into one or multiple nozzles isn’t unusual anymore. It seems like you could experiment with this kind of technology pretty readily. Of course, there’s more than one way to speed up production.

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Multiextrusion 3D Printing And OpenSCAD

In a recent posting called Liar’s 3D Printing, I showed you how you can print with multiple filament colors even if your printer only has one extruder and hot end. It isn’t easy, though, and a lot of models you’ll find on sites like Thingiverse are way too complicated to give good results. An object with 800 layers, each with two colors is going to take a lot of filament changes and only the most patient among us will tolerate that.

What that means is you are likely to want to make your own models. The question is, how? The answer is, of course, lots of different ways. I’m going to cover how I did the two models I showed last time using OpenSCAD (seen below). The software is actually really well suited for this hack, making it easy for me to create a framework of several models to represent the different colors.

About OpenSCAD

I’m not going to say much about OpenSCAD. It is less a CAD package and more a programming language that lets you create shapes. We’ve covered it before although it changes from time to time so you might be better off reading the official manual.

The general idea, though, is you use modules to create primitives. You can rotate them and translate them (that is, move them). You can also join them (union) and take the difference of them (difference). That last is especially important. For example, look at the callsign plate above. Forget the text for now. See the two holes? Here’s the OpenSCAD that creates that shape:

 difference() {
 // cut holes
 translate([4,basel/2,0]) cylinder(r=2,h=basez+2);
 translate([basew-4,basel/2,0]) cylinder(r=2,h= basez+2);

The cube “call” creates the base. The cylinders are the holes and the difference “call” is what makes them holes instead of solid cylinders (the first thing is the solid and everything after is taken away). One key point: instead of numbers, the whole thing uses (mostly) variables. That means if you change the size of something, everything will adjust accordingly if you wrote the script well. Let’s look at applying these techniques for multiple colors.

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