Aug 2013 6

3d Printer - part 7

Progress continues on my 3d printer...

Power Supply

Meters for my power supply arrived a few weeks back, but I only just got around to installing them. I had to drill out a 38mm hole for the mechanism to fit inside of, but I only have 45mm+ hole saws and 32mm spade bits, which made things a bit complicated. If only I had a CNC machine, this would be a piece of cake! For some reason that did not occur to me and instead I used a 32mm spade bit followed by a few minutes on the Dremel with a sanding disk. Did the job pretty well, even if it did cover the garage in MDF dust.

A couple of hastily drilled mounting M3 holes and a whole lot of epoxy leaves this:

I wired the voltmeter in parallel, and the ammeter in series with the output. Nice and simple, works a treat. Completed power supply was reassembled and tested on an RCD protected output, just in case. All tests passed and the meters were even wired up correctly.


Testing showed that t...

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Jul 2013 17

3d Printer - part 6

Progress continues slowly on my 3d printer. While waiting for the increasingly erratic Chinese postal system, I set about getting the extruder and hot-end working.

The hot-end is responsible for turning the plastic filament into a model, by melting it and squeezing it out of a tiny hole. The filament looks a bit like white spaghetti, or like the cutting cord used in line-trimmers in the garden.

The extruder grabs the filament and pushes it down a tube to the hot-end. The hot-end has a large block of metal with a heater and temperature sensor built into it; these work in concert to keep the metal block at a constant temperature, about 180°C for melting the PLA plastic that I have.

So I sent about making sure it was all going to work. First test was to ensure that the temperature sensor worked correctly. The hot-end I'd purchased had a thermistor built into it, which is a type of resister that changes its value as its temperature rises and falls. I did some tests ...

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Jul 2013 7

3d Printer - part 5

Continued from part 4.

My linear bearings finally arrived, just under a month in transit. I wasted no time at all in putting them to use. First I added some supports to mount them by; these are just my usual 1mm thick sheet of styrene, epoxied to the bearing with a couple of supports on each side.

Y axis limit switches were then added:

And then the Y axis was joined to the Z axis. I used some MDF spaces to ensure the Y axis was level with the rest of the machine and glued the whole lot in place.

I then clamped it with whatever heavy objects I could find. It may be a mess, but it worked!

While that was setting up, I started building the electronics. I used a similar approach to my CNC machine, using female mating sockets and some self adhesive copper strip to form bus bars. The various components then get soldered up into sub-assemblies that plug into the female headers.<...

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Jun 2013 23

3D Printer - part 4

Progress continues on my 3d printer. This week I have been continuing to work on the Z axis. With the rails and bearings ready I needed needed to make something to connect the threaded rod to carriage. I decided to use my tried-and-tested method of casting a white-metal block directly around the threaded rod.

To do that, I fixed up my previous mold and found some white metal. I melted it on the stove (thanks for the tip sis!) and poured it into my mold, tapping it a few times to get rid of any bubbles. Then I pushed a block of wood down on the top and waited for it to cool. I destroyed the mold to remove my item, but never mind. I don't anticipate needing to make any more for a while. I gave it a quick clean with a file and used my drill on grunty-mode to remove the threaded rod. I gave it a zap with CRC and drove the rod through a few dozen times to clean out the thread. Here is the finished block:

I threaded it on to the rod and wondered how I was ...

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Jun 2013 20

3D Printer - part 3

Just a quick update: my stepper motors have arrived!

Of course now I realise that there was quite a bit I could've done without the stepper motors :)

I've wired up limit switches for both the X and Z axes:

And I've made bearing blocks for the Z axis, seen here with the motor on the wrong side. I have also made up the brackets and support for the Z axis.

A quick test fit of the various bits to see how it all fits together:

Now I need a 5-to-8mm shaft coupling (although as I've learnt I am capable of making them myself) for the Z axis leadscrew, and a 2 sets of linear bearings for Y axis. I ordered the bearings nearly a month ago, but they must be taking the scenic route to get here as they still haven't arrived. In the meantime there is plenty I can do, e.g. wiring the whole thing up.

Still, exciting progress :-)

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