Thursday, March 31, 2016

3D printing: it's coming, and it will revolutionise this hobby

Don't believe me? See Peter Wingfield's site here: In particular see the series of software images he used to develop the body for the so-called Ferrari Breadvan, here: (Thanks to the folks at Profil 24, who have this link on their web page).

So what's a 3D printer? It's a device for spraying little droplets onto a surface, under the control of a computer program that tells it where exactly to put each droplet. This is the same way your inkjet printer sprays little ink droplets onto a piece of paper, except the 3D printer sprays little droplets of melted polymer, and allows them to build up, layer upon layer, into a 3D object instead of a printed 2D sheet.

A decade or so ago I visited the laboratories of the mechanical engineering department in a major Canadian university. They had an early, home-made 3D printer that cost somewhere in the vicinity of $250,000 to build, and that was with lots of cheap graduate student labour. Given the costs, they were predicting rapid prototyping would be the first uses of the technology, so a company could verify things like fit and ease of assembly prior to committing to a production line using conventional injection molding or other methods. As a souvenir, they gave me a small, functioning adjustable wrench which is really quite clever: there is no way they could have made the three components separately and assembled them, because it is impossible to insert the little geared roller into the body; they had to have been deposited at the same time.

At that time, the polymer filament, which is fed into the printer off a spool that looks like a Weed Wacker thread, was the big issue. It has to melt at relatively low temperatures but solidify quickly once deposited, and this limits the properties of the finished product. It is also fairly granular due to the size of the droplets, as you can see in the image above. So it might be dimensionally stable but might not have the visual, mechanical or thermal properties necessary to replace a finished plastic product. Hence the limitation to prototyping, not production.

Fast forward to 2016 and Staples offers a home hobby system by MakerBot for about $2000, click here, that will make objects that fit inside a 4" cube. (MicroMark used to offer a cheaper hobbyist-type system but now I can't find it on their website -- maybe the customer complaints were too much.) The resolution of the MakerBot system is 0.2 mm, about 0.008", so still a bit coarse; you can see the pattern of the traversing print head in the pictures of Wingfield's 250 GTO Breadvan if you zoom in. The resolution will be at least partly due to droplet size, but also probably to the resolution of the stepper motors used to shift the print carriage from one track to the next -- pay more and get better resolution even if the droplet size is the same. Recall how happy we all were when the 8-pin dot matrix printer was replaced by the 9-pin system...

Software is a separate purchase or you can use the free software that comes with it; there is also an industry-standard file system just like JPG or PDF standards, so you can download stuff off the Internet. Finally there are home systems that you can use to scan and digitise an existing object, say for instance a Hewland gearbox which no one seems to make in 1/24 or 1/25 scale; Staples offers a MakerBot scanner/digitiser for about $1100. The real challenge would appear to me to be in making something as thin and flexible as a model car body -- transaxles would likely be a lot easier. I haven't seen Wingfield's models in the solid plastic but I am guessing that he has made significant progress in that area, probably by first deciding where to start depositing drops.

This will likely require all kinds of fiddling, both with the type of polymer used and the computer program. In fact it reminds me of early home printers, which were expensive, finicky and produced low-quality results. Compare that to today's ink-jet printers which are cheap, plug 'n' play, and produce publication-grade images.

I'm excited. It's the next step towards the transporter beam in Star Trek: first we stopped buying books because we could download and print them on a dot-matrix printers; then we stopped buying CDs because we could download and burn them in a CDR writer; now I'll be able to download and print toys for my granddaughter, not to mention kits of every possible obscure car you might care to imagine. Who knows what we'll digitise and ship next, byte by byte, over an expanding digital network...

If I were Jimmy Flintstone, I'd be digitising stuff like crazy and offering the digital models for sale online: $15 for the digital file to make a Cadalicious body to go with your Revell '59 Caddy kit, $20 (plus shipping) if you want a hard copy printed and shipped to your door. First one in will build the reputation and the customer base. And maybe he can fix the quality of some of his bodies while he's at it ...

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