RepRap Prusa i3

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My first exposure to 3d printing was working in the architecture departure at Auckland Uni. I was also working for an engineering consultants at the time and had designed a pretty complex bits for a façade tension system. There were two of these things and they had a fair few parts. From memory each came in at around $NZ 10k each.

I discovered the Architecture Department had this new fangled machine that used cellulose-based/ starch powder and water as a binder to prototype 3d objects. This methodology, powder-bed 3D printing,uses inkjet-based technology to built the model in layers. The digital 3d model is sliced, and the inkjet head ‘prints’ each 2d slice sequentially using alternating between the binder and the powder. From memory the powder was dropped liberally onto the glue, a bit like when you put glitter on the glue on Christmas cards as a kid. When the print was finished the powder that had fallen on binder was ‘the object’ and loose powder was brushed away and reused.

Anyway, a scale model of the spring box, to make sure it all went together and worked, would have been great.

Unfortunately, the project’s complexity/intricacy was beyond the capabilities of the printer. The parts were intricate and thin-walled even at 1:1 so as soon as you tried to make them out of starch as a quarter scale you were printing expensive rice paper. The scale model never materialise but the spring boxes did get built and worked, c/o the guys at Culham Engineering. The other upshot was that I was introduced to 3D printing technologies.

3d printing went away for a bit in my mind, until the MakerBot arrived on the scene. I remember reading a review for one online, perhaps a third gen one, and thinking, “Hum, that is cool, things seem to have moved on”. This machine printed out solid ‘useable’ plastic objects, not fragile powder prototype models. But it was expensive (3 grand $US) and I was a student at the time. I started Googling into the technology and came across the RepRap project…you could build your own 3d printer!

A render of ‘2015 RepRap Prusa i3’ from Instructables. I built mine in 2013, but 2015 looks moreorless identical except some cosmetic changes.

These printers used the same fused deposition modelling (or fused filament fabrication if you want to avoid legal implications) as the MakerBot; you feed it a cheap-as-chips plastic as a filament and it heats it and extrudes it through a small nozzle (mine is 0.5mm) to form the object in ~0.3mm layers.

So I built myself the RepRap 3rd generation machine, the ‘Prusa i3’.

My RepRap. Looks suspect right? Not like a clock, or a bomb-clock though.

The framing on my RepRap is from 6mm MDF which I got laser cut at the university (an d for some reason painted green). The rest of the hardware is mainly threaded rods and printed parts from another RepRap owner – I love the idea of my printer having (perhaps?) a lineage back to one of the first machines. It does not look like it is something you can use to create a physical manifestation of something you put together in AutoDesk Inventor does it? It never ceases to amaze me that you hit print and the bed heating LED flicks on. Then a few minutes later when the bed and extruder have heated up, the machine’s five stepper motors start singing and this object starts to appear that has never appeared before. What looks like a hair-brained load of bits and bobs strung together really is a marvel of social technology. Watching it work is quite hypnotic, like watching ants labour.

The RepRap project has been a bit of an eye opening for me, and the progress of the project is interesting reading. Conceived by Dr Adrian Bowyer of the University of Bath, and then developed by a core group of enthusiasts, this entirely open source project is now being developed in mass parallelisation by a worldwide community. It is free to anyone anywhere. Now Jo Smo (me), can hack together a 3d printer relatively cheaply using parts you find in the in the hardware store and can get two-a-penny off eBay. The eventual aim of the RepRap project is to make a machine that can replicate itself in its entirety (including the electronics)

A large RepRap – if I want to build one as big as a house, or a mini one, I can. Same electronics and innards. Fix a MIG welder in and you are printing in steel.

Reading through what I have written one might be mistaken for thinking a 6 year old could put together a RepRap. A word to the faint-hearted: Building the thing was quite an undertaking. There is no assembly or instruction manual. It’s not like a lego set where all the bits are there. There are different variations of the same printer and all its components. Everyone has an opinion on what works and what does not. You can buy a kit of parts (which would make things far easier), you can also now buy the printer pre-assembled. I did it the hard way and sourced everything independently. This was quite frustrating, particularly in New Zealand where all the hardware stores stock the same thing – invariably not quite what you are after – and you take a shipping hit on anything you buy from eBay. Nevertheless doing the build unaided opened my eyes to a world of micro-controllers and I understand my machine and the technology to the last resistor, belt and screw.





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