Jun 2013 16

3D Printer - part 2

Progress on my 3D printer continues.

I chopped out all the MDF pieces in about an hour — it helps having a complete set of plans and dimensions, and a good drop saw! I printed out some NEMA 17 stepper motor drilling templates and taped them to the wood. It's then a quick punch-drill operation and I have all the holes in the right place to mount a stepper motor.

I soon had a good pile of bits, ready to start assembly. I started with the base by gluing on the foot/stabilisers.

The X axis motor bracket and supports followed soon after. At the end of the day I was left with this collection of components and assemblies:

This weekend I tacked the printer bed. I recut the printer bed to give me a slightly larger working area and cut the linear rails to length. Working on a sheet of ex-scanner glass,  I mixed up some 5 minute epoxy and glued the first end into position.


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Jun 2013 10

A 3D printer - part 1

Now that one machine is working well, it's time to make another. While idly browsing the wide wide world of web recently, I came across the Printrbot Simple, which is a remarkably simple and compact 3D printer. Now I've wanted a 3d printer for some time, however they have always required a lot of components, many of them specialised and difficult to get a hold of.

The Printrbot Simple however uses laser cut wood for the bulk of it, and nothing too complex for the rest.

So after studying it for a while, I set about making one.

A 3d printer is a printer that extrudes melted plastic to build up solid objects, layer by layer. The quality is acceptable, although not nearly good enough for model making. However a 3d printer really shines through for fabricating components for other machines: brackets, mounts, supports, etc. Items that would require lots of tedious measuring, cutting, drilling, milling, sawing, glueing, and so forth can instead be quickly designed on the ...

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Jun 2013 10

MrCNC - part 4

Continued from part three...

At the end of the previous update I was busy waiting for a 5-8mm shaft coupling to arrive. However I realised that with a big of creativity, I could always steal one from elsewhere on the machine.

Using some heatshrink tubing, cable ties, superglue, and flexible tubing from an old inkjet printer, I bodged together this flexible coupling:

That left me with a spare aluminum shaft coupling, just what I needed to finish my new spindle.

The spindle I made out of MDF and consists of:

ER11 collet nut2 608zz ball bearings2 more 608zz ball bearingsA 8mm to 5mm shaft couplingA big DC motor with 5mm shaft, from an old cordless drill

It went together reasonably easily with a good helping of 5 minute epoxy glue.

The hardest bit was aligning the motor and the shaft. If it's not perfect, it rubs and the power transfer suffers.

Meanwhile, a pair of 2 flute, 4mm HSS end mills had arrived i...

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Jun 2013 3

MrCNC - part 3

Continued from part two ...

Now that the machine works, it is time to do something with it! My first carving was the LinuxCNC text which took a few attempts to get right, but once working seemed good. Second cut was something called "chips", which it turns out is a lovely wee penguin:

Detail is a bit rough around his foot, and the other flipper snapped off, however for a first go I was pretty impressed. The foam isn't amazing to machine, the beads tend to remain, but it's about all my machine can manage at the moment with it's poor-man's-spindle.

I spent quite a bit of time getting the homing configurations correct, as there are many different variables and they don't all make a whole lot of sense. When I finally got my head around HOME, HOME_OFFSET, MIN, MAX, etc it started making sense and I was able to get the results I was after.

For my second piece, Rachel had said "I...

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May 2013 26

MrCNC - part 2

Continued from part one...

With the Z axis mostly done, it was time to turn my attention to the Y axis. The Y axis moves across the work, and supports the Z axis.

I started by cutting the two end pieces out and match-drilling them. I now had a problem though; my linear rails were each 1m long, and not especially cheap, so in order to gain some vertical work-height, I had reduced the Y length and now had a gap to span between the outside faces of the machine and the ends of the Y axis rails. In other words, I had to make some spacers. I made these out of 18mm MDF which gave me some extra space for the shaft coupler and 8mm ball bearing at the other end.

As per the Z axis I added the linear bearings with my patent-pending mounting blocks, and another cast "bolt". Some careful measurements and adjustments with my square ensured that both sides of the Y axis were true and then it was ...

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