Tag Archives: Technic

More remote control

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In my quest to build a reasonable remote controlled car in LEGO Technic, I tried rebuilding the 2015 off road set 42037. There is space to fit an L-Motor and a servo in the chassis (at the expense of the pistons mechanism for the engine). The battery box fits in the back of the roll-cage, and the IR receiver sits in the driver’s seat.

From a space perspective, this seemed a promising start. The motor shaft has an 8-tooth gear which drives another 8-tooth gear on the differential shaft. I tried various options for holding the drive shaft firmly in place so the gears wouldn’t cog.

This option is sturdy enough that the motor shaft remains in place. In the car, I used 2L and 3L technic liftarms. A stronger connection can be made using 2L (shown in blue) and 3L  (shown in grey) thin lift-arms which have cross-holes for a blue pin-axle.

In the above picture, the dark grey 8-tooth gear is on the motor shaft. (with the yellow half-bush). The light-grey 8-tooth gear is on the tan crown gear that meshes with the differential.

Unfortunately, after a few minutes of play, the L-motor is powerful enough to cause damage to an 8-tooth gear: the teeth are forces sideways (in an anti-clockwise direction in the photo below).

Unfortunately there isn’t space to move the L-motor up vertically without seriously changing the structure of the car. Back to the workbench.

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.