Wednesday, 22 February 2012

Visual Illusion - balls rolling uphill

 In response to a challenge on the Thingiverse Blog I offer this attempt to design a part which will give the visual illusion of balls rolling uphill.

When viewed from the correct angle, this piece should give the illusion that all 4 ramps slope up to the middle platform. Viewing from any other angle gives the game away!  ( I haven't printed one yet, but I couldn't resist the challenge!)

Find it on the Thingiverse:

Monday, 20 February 2012

Do you want some inspiration for your 3D Printer project?

Check out this link: "The Man Who Prints Houses"

and the movie trailer here:

From the "About" page:

3D-printing is a method that physically realises digital designs layer by layer using a fluid substance that can be hardened by lasers or other binding agents. To date, it’s been used for small-scale manufacturing and as architectural maquettes. Enrico, however, has far grander plans.
Having built his printer – the world’s largest – from scratch, there’s no shortage of work offers for this highly-skilled and imaginative engineer. Throughout the course of the film, we see Enrico embark on an array of innovative projects: constructing the tallest printed sculpture in existence, working with Foster + Partners and the European Space Agency on a programme to colonise the moon, solidifying a sand dune in the desert, and printing the closest thing to an actual house: a small Italian dwelling known as a trullo.

I sure hope this movie makes it onto one of my local TV stations soon!

Thursday, 16 February 2012

Lights ... Cameras ... Action!

One thing I’ve been meaning to do for some time is to rig up some sort of illumination for my printbed. The room where I do my printing is reasonably bright, but the X-Carriage and Extruder casts quite a shadow over the printing area, and it can be quite hard to see what is going on, especially if I am printing with filament which is similar in colour to the printbed (formerly blue painter’s tape, now red / orange for my Kapton-on-PCB heated printbed).

I’ve been thinking of hooking up a LED under the X-axis carriage; this could either be powered in parallel with the heating element (meaning it would switch on and off with the hot-end heater), or preferably, would have its own wires back to the power supply so it is always on. I hadn’t got around to working out what specification of LED(s) I should install, when I came across a cheap USB LED-Magnifier in a “Specials” bin at the local supermarket – only $4 for a really bright lamp with 18 LEDs in a ring, and a nice flexible “gooseneck” for positioning (and you can find similar items on the internet):

[Image copied from   – I forgot to take a picture before I hacked the lamp!]
This should cast a lot more light than a single LED, can be positioned to put the light wherever I need it (handy for cleaning out a jammed extruder!), and also has the advantage of not adding any mass to the moving X-carriage. I figured it should be pretty easy to hook it up to my RepRap power supply.

First, I cut off the USB plug (which was surprisingly difficult – the spiral wire which creates the “backbone” of the gooseneck is very tough!) and exposed the two wires – black for ground and red for 5 volts. Then, a bit of testing with my multimeter and adjustable DC power supply showed that the LED lamp draws about 180 mA @ 5 volts (and gives a really bright, uniform light in the process!) – OK for a PC USB port, but probably a bit too much load for 5 volt line on the Arduino.

The Arduino Mega is only rated at 40 mA per pin , so I was concerned that connecting the light to the 5 volt rail could overload the Arduino, and I sure didn’t want to find out the hard way! However, my ATX power supply is rated at 500 W, so has plenty of capacity to power a little LED lamp on top of the existing load of the RepRap printer and heatbed.
I could have attached the lamp to the 5 volt binding posts on my ATX power supply , but this would have meant running an extra pair of wires from the power supply to the lamp – simple enough to do, but not very “elegant”. A tidier solution was to hard-wire the LED lamp to the incoming 12 volt supply, so the light would be “always on” whenever the RepRap is powered up. (The lamp has its own on / off switch, so I can turn it off if I want to.)

Of course, the lamp is designed to run at 5 volts, so I needed to step the voltage and current down to avoid blowing the lamp. A bit of basic maths suggests the effective load of the lamp at rated voltage is about 30 ohms, and that I would therefore need to add about 40 ohms in series to maintain a current of about 180 mA @ 12 V. I rummaged through my “box of bits”, and found a 100 ohm resistor, and the maths suggests the lamp should draw about 95 mA when run in series with the 100 ohm resistor @ 12 volts.

(I hope this maths makes sense – I’m a structural engineer, not an electrical engineer!)
Anyway, I hooked it up in series, ramped up the voltage to 12 volts, and turned it on – success! None of the magic blue smoke escaped, and the lamp lights up nicely (but not quite as bright as before – as expected). I guess my maths can’t be too far wrong after all!

So I soldered the resistor to the ground lead, wrapped the leads in heat-shrink and taped them to the gooseneck, and then fixed the gooseneck to the frame with cable ties, so that I can point the light where I need it. Finally, I wired the leads to the incoming 12 volt supply on my RAMPS:

So ... how does it work?

In a word – great! The following video shows how much easier it is to see what is going on while printing.

Wednesday, 15 February 2012

It ain't Reprap, but it just HAS to be shared!

People are always accusing me of having geeky hobbies (RepRap, Arduino, etc), but this guy has me totally beat!

You may have seen the news items doing the rounds lately:

“Canadian Joe Murray excavates his basement with R/C earthmovers in just nine years”
(Check out the scale here - this is just a model under his house!)

There are some brilliant videos here:

or better still - check out his YouTube Channel:

I am just awe-struck - and SOOOO jealous!!!

Monday, 6 February 2012

Doesn’t everybody love free stuff?!

Thanks to a posting on the RepRap forums,116843 , I was alerted to a limited-time offer to get some really top-class 3D modelling software for free.

Specifically, for a “limited period” (no, I’m not sure how long!), DAZ is making the Pro versions of DAZ  Studio 4 , Bryce 7 and Hexagon 2.5 available as free downloads, which can be fully registered. 

I’m not sure what the rationale behind this is, but I suspect DAZ is shifting their business model from selling software to selling content, and they need millions of users out there to sell their content to. (I expect to get lots of e-mail offers to buy and download model files, but I can live with that!)

In my previous tinkering with 3D software, I have come across Daz Studio (very similar in functionality to Autodesk 3DS Max etc), and Bryce (fantastic for creating "virtual landscapes"), but this is the first time I've seen the Pro versions offered for free. I’m not sure how relevant these packages are to RepRap (maybe you could print landscapes for your model railway layout?), but they're pretty interesting packages for anyone who likes playing with 3D software. (E.g. you could use DAZ Studio to create photo-real renderings of your digital creations before you print them.)

I haven't seen Hexagon before, but it looks like it might be a good tool for making "organic" models (such as "character figurines", animals, replicas of Henry Moore sculptures, etc). Most traditional CAD packages (like OpenSCAD, Inventor, Alibre, etc) are good at making mechanical components from geometric primitives (cubes, cylinders, etc), but are rather harder to use for "free-form" modelling (like sculpting with “digital clay”).

I suggest any one who is interested should download and register them all now (while the offer is still available) and give them a try. What have you got to lose (apart from possibly getting a heap of marketing material from Daz in your Inbox)?