Printer skeleton

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Printer skeleton

To be perfectly honest, at the time I actually had it in mind to go with a pure wolfstrap solution, however rather than waiting on some order for optoswitches I figured I’d go down to the thrift store and get some myself. Having stepper motors and structure come with the printers, it rapidly became clear that scavenging would outline the shape of things to come.

Shown here is the moving structure that came with the first printer. Unlike most parts I see online, the gears are solid metal and are of a much smaller diameter, thereby allowing smaller step size and in turn greater precision. The belts are ready made for these gears and are clearly capable of handling linear motion, which itself has driven the recent trend towards gt2 belts in the reprap community.

Optoswitches

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This model had 3 optoswitches, in total, however, this was not the only one I would have to take apart, and as I soon discovered the number can vary widely. The second printer I dissected contained only one. I should note I’m not the first one to try scavenging for optoswitches, nor did I come up with the idea independently.

A small, hapless printer

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A small, hapless printer

A printer was purchased at the salvation army for around $7. I made sure this one had a stepper motor to it – most modern printers work off cheaper servo motors. Nevertheless, there are still a few relatively recent printers I saw using steppers.

Oftentimes it seems the servos in printers today are little more than cheap DC motors with encoders strapped on. The encoders themselves appear just to be optoswitches reading patterns off flimy transparent film. The transparent film rotates around with the motor shaft and periodically spaced dark patches cover up the optoswitch, thus registering a “step”. This makes me think a similar process could be adapted to produce more affordable printers – dc motors would be cheaper and easier to find than steppers, and you could completely bypass the need for costly stepper drivers. Still, this would be more a firmware project than anything, since existing firmware to my knowledge rides on the assumption there is one pin to encode a step and another for direction. You would also loose the automatic breaking stepper motors have when not activated. This might have to require an entirely separate project unto itself…

What’s he building in there?

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What's he building in there?

It’s 201X and you find yourself stuck in the middle of a new dark age. life is nasty, brutish and short. With a little know how and a lot of scrap, though, you’ve managed to work your way up to having a reliable source of power from sustainable solutions. An aging computer was luckly saved from scrap, which provides you with adequate computational power for whatever software you’ll have over the next few decades, if not centuries. As you settle into this new dark age, you start to wonder, what next?

Why, a 3d printer, of course.

It’s not as far fetched as you would imagine, you say to your bemused post apocalyptic friends. Old style printers have all the stepper motors, gears, belts, pulleys, and optoswitches you’ll ever need! Heating elements can be found in any number of household items – toasters, hair driers, soldering irons, etc. Plastic can be recycled. Biodegradable plastics might even be manufactured if you’re clever enough. Projects like wolfstrap have existed for some time which describe how to make the structure from wood. We’ll have to assume for the project here that you have stepper drivers and a microcontroller, true, but hey, if you’re setting out to build a 3d printer, chances are you already have some parts laying around from before the apocalypse.

Alright, now back to reality. It’s January of 2013 and I find myself with some time on my hands and a modest carpenter’s workshop. Interested in 3d printer but wary of costs, I start working up what I foresee to be a grand technology tree with the aim to homebrew as much as I possibly could. I build off a simple thought experiment – if this were the collapse of civilization, what technology will be remembered? What technology would be lost? Would older generations be able to perpetuate the technology they remember before memory fades and tools are broken? Could we simplify, making it easier to produce what we see as high technology from cottage industry alone? Could we rework technology, making it sustainable for the civilizations after us? Would there even be hope for such a civilization?

3D printing lends itself nicely to this thought experiment. It’s a relatively new technology, just recently made accessible to the general public, and with it you could make any number of other useful machines to improve quality of life. You’d think if something like this were able to survive then society would have things pretty well sorted out. Physically, though, these things are little more complex than an ordinary paper printer. Seriously, it’s just one more axis to consider. As such, these things are easily self replicated and are quickly making their way into homebrew operations. The computer that runs a printer stands to be the most difficult to source after the collapse of civilization. If printing becomes sufficiently advanced, though, even these devices may not be out of reach, albeit perhaps only of sufficient power to drive the printer in turn.

So with that, I begin. The printer starts based off plans for the wolfstrap, shown here. I’ll give away the ending and tell you the printer works, but what happens between then and now will have to come in the next installment…