Tag Archives: Power Functions

BB8 in Lego – second and third bash

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The biggest problem with making a Lego version of the Star Wars BB8 droid is the round shell: there is no spherical LEGO part that is large enough to contain a motor, a battery box and the infra-red receiver. Purists, please look away now, for I have committed a sin: the shell is not a LEGO piece, but is a two-plastic sphere. basically, a giant Christmas bauble.

Here is my second attempt at BB8. The weight distribution is too high, and the mechanism flips over quite a bit. So back to the drawing board…

… and here is version 3: the wheels are further apart, and the centre of gravity is lower. I also added four “boat weights” to improve stability.

in the meantime, a fellow Brit is also working on a Lego BB8. His version has a ball made of Lego Technic parts. See https://ideas.lego.com/projects/126131/updates and http://www.brickshelf.com/cgi-bin/gallery.cgi?m=mbellis

It is possible to use a genuine LEGO sphere – as seen in this video – but there isn’t enough space inside for the Lego power functions components.

Someone else has worked out how to do the head with magnets – http://lego.gizmodo.com/someone-figured-out-how-to-build-a-tiny-rolling-bb-8-us-1761492071. That was my plan for the head too, but I can no longer prove it, and I haven’t got that far. However, their version only rolls forwards.

Development continues …

 

Remote controlled Bulldozer using SBrick

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The quest continues to find a LEGO set that can be easily converted to remote control. In a moment of tidying up, I re-discovered this bulldozer (Dozer set 7685) in the corner of my study. A prime candidate to try adding motors and an SBrick.

This bulldozer set is not supplied with motors, and has no instructiors for adding them. But there is lots of space internally. I rebuilt it a few times, added two M-motors, a few gears, a battery box and the SBrick. Staying true to the original model was quite a challenge. The tracks are now half a stud further out than in the original model, and the plough-arms at the sides only just miss the tracks.

The remote control equipment in the Power Functions range uses infra-red, and therefore isn’t technically “radio” control. It offers limited control – basically forwards and backwards at full speed. The SBrick permits finer motor speed control, uses Bluetooth instead of infra-red, and is controlled from a smartphone. Up to four motors can be controlled at once, though only two are used for this model.

More details of the drive mechanism, the build, the SBrick interface and the challenges in building this model will follow in future posts. Please let me know what you are interested in (in the comments below) and I’ll do my best to answer.

BB8 in Lego – first attempt

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Ever since the first trailer appeared for Star Wars Episode VII, the world fell in love with BB8. I could just buy a non-Lego version, but I would like to see if it is possible to create a working BB8 in LEGO Technic. There is only one way to do this – trial and error. Rupert Cross, I dedicate this post to you.

WARNING – LEGO purists beware that this blog-post contains non-LEGO parts. If that sort of thing offends you, look away now. Also I offer an apology to Technic guru Sariel: please do not show this video to your hamster.

First attempt – 2nd January 2016.

The first mechanism I tried has a pair of wheels at the bottom which can rotate and drive. The tan-coloured gears make the wheels drive. The grey gears (crown and pinion) are used to rotate the driving plate – making it possible to steer the driving wheels in any direction.

The two motors are attached to the “Power Functions” remote control and battery, and these are mounted as shown.

Turning the thing over, we have a mechanism that can steer and drive independently. Watch the video to see it in action. Remember, this is the underneath – so those wheels should be on the ground.

The structure is then housed inside a hamster-ball. LEGO don’t make a sphere big enough for this project, so I had to improvise. FULL DISCLOSURE: No animals were hurt in the making of this project.

BB8-3

Immediately I can see a problem. The battery is so heavy that it skews the whole thing over to one side. So far in fact that the wheel is barely in contact with the inside of the ball. Let’s see it in action.

At the beginning of the video, at the bottom of the ball, you can see the wheel steering. Then it tries to drive … and the whole structure unbalances. With insufficient traction, the hamster ball is just able to wobble.

Rupert, this is how one becomes an expert builder: trial and error. Don’t be scared to make lots of mistakes. As you can see, this one was a bit of a disaster. But we learned some valuable lessons:

  • The LEGO Power Functions battery box is heavy,
  • The mechanism must be well balanced,
  • The co-axial drive mechanism works – and might be useful for something else.

Back to the drawing board I’m afraid. I have some more ideas … so watch this space. In the meantime, I found a guy in Hungary (in Hungarian – or auto-translated into English) who came up with a mechanism last April. I don’t know if he ever completed his version. If that’s you, please add your comments below.