BCM: The 3D Experiment: Week 3 ‘Starting to establish a relationship’

BCM: The 3D Experiment: Week 3 ‘Starting to establish a relationship’

Being the new owner of a 3D printer is a bit like being the new owner of a puppy. You’re excited by the prospect of years of interesting adventures together. You can’t wait to spend more time with this amazing, intriguing thing that has come into your life. Then you get home and find that it’s done something shameful behind the couch — again!

But with a 3D printer there are no doggy treats nor rolled-up newspapers, just a prolonged getting-to-know-you experience. The first two weeks of our experiment were pretty much taken up with just coming to grips with the hardware and various pieces of software, all of which are quite alien. The key lessons of Week Three, however, were centred more on the idiosyncrasies of manufacturing with hot plastic.

The two main types of printing filament are ABS (petroleum-based) and PLA (plant-based). ABS is more difficult to print with, mainly because it is prone to distortion as it cools, but it is more robust and long-lasting than PLA, and I prefer its matte finish. PLA causes fewer printing issues, is biodegradable and smells nicer during printing, but it has a tendency to warp when exposed to high heat (like inside a car on a hot day), is more brittle, and is less amenable to sanding and drilling.

The difference in the printing behaviour of these plastics became evident with this complex vase model. The blue one is ABS and started buckling about half way through the print, curving upwards and catching on the print head — basically destroying itself. The translucent PLA one also distorted but to a much lesser extent, so we still had to cancel the job about two thirds of the way through. We’ll be experimenting again with this vase, but it may be that the model itself (also shown here in modelling software form), is beyond the current capabilities of fused filament fabrication. No doubt future improvements in the materials and technology will overcome this issue.

It's not only the nature of the plastics that must be taken into account. Consideration also needs to be given to the way the object is constructed in the 3D modelling software. The two examples below were printed with the same plastic and the exact same print settings. While building the messy one on the left, the print head was 'stirring' the plastic around as it put down each layer. This could have been partly resolved by changing the speed at which the plastic was being extruded. But, instead, it was entirely resolved by going back into the modelling software and making those twisted pillars hollow.

Each new print job offers up new challenges, but this was our breakthrough week. After a rocky start to the relationship, with endless puzzlement and misunderstanding (and not a little swearing), we’re now beginning to find our groove. Like all good relationships, it takes time and patience and lots of coffee. I think we’ll be fine.

So what’s the point of all this experimenting we’ve been doing?  We’ll be looking at that next week.

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