Below is a  simple train demo which uses the LEGO Mindstorms NXT to control 2 9volt trains.  I actually really enjoyed creating this, all I need to do now is actually make some trains!

Click here to view the video on YouTube.

This has been programmed in RobotC and uses 2 light sensors and 2 touch sensors to detect and stop the train.  NXT motor port A powers the main track loop.  NXT motor port B and C power the part of the track that comes off the points as they are isolated.  So if NXT motor port A & B are on, train 1 will move. If NXT motor port A & C are on, train 2 moves.

Please let me know if you would like further information.

Click here to view the video on YouTube.

Hello all and sorry for the lack of updates! The first part of the year I have been focusing on getting fit and heathy, I am nearly at my goal and so I have jumped back on to the LEGO projects.

I have already displayed at a few local shows this year however the next big one for me is AFOLCON.  I will be taking George and a few new creations including Wheeler and a small walker.  I also hope to show off the Rotacaster platform.

Sadly my giant T1 robot won’t be ready for AFOLCON however I do hope to take it to the Great Western LEGO Show in October.

Please watch this space as there should be quite a few updates coming soon!

Building Big (warning its 7.5mb)

The video below shows the platform easily moving over 12.5kg of weight using 4 XL power function motors. The wheels are a little on the heavy side compared to a normal Lego wheel however they are massively stronger and can hold over 100kg per wheel.  They are 6 studs wide.

Click here to view the video on YouTube.

If you are interested in these wheels, please contact Rotacaster.com.au

Click here to view the video on YouTube.

Mindsensors RCX Multiplexer

I was utterly impressed with the Mindsensors.com RCX Multiplexer and using Xanders driver suite (check BotBench) how fast I was up and running.  I wish there was a way to run the RCX Multiplexer off the NXT power supply but thats a small thing compared to how useful it is.  I wish I had 3 more of them so that I could control 16 RCX motors!

Android NXT Remote Control

So to try and work out how to control the NXT via Android, I stumbled across the NXT Remote Control project which is free to download.  This uses Lego’s Direct Commands to control the 3 motor ports on the NXT.  This means it bypasses your own code and you have no control over it.  However, what I managed to do is reduce it down to a very simple program that sends messages to the NXT which you can deal with in your own program.  In RobotC, it sends messages that are compatible with the MessageParam command and so you can send a message ID and 2 params to the NXT and deal with them in RobotC anyway you want to.

Code will be available soon once I have tidied it up

Here is the result.

Click here to view the video on YouTube.

I have to be honest and admit that I loved building using studless Lego.  It does involve building in a different type of way, you could say in a more structured / planned way.  However until I have enough of it to build giant robots, I will be sticking with studded Lego which I have tons of!

I still need to spend some more time with the NXT motors as they still feel very alien to use due to their random fitment and shape but I am sure I will master them soon.

Merry Christmas everyone and have a great New Years!

I have great plans for these wheels but first I thought I would put them through a simple weight test. Now according to the website the wheels can take up to 35KG per wheel however I don’t think the plastic Lego axels can!

I spent around 15 minutes building a rather simple platform to test out the wheels on. 2 of the wheels were directly connected to 2 PF XL motors (1 per wheel). The main point of this test was  to see is how much weight a simple layout could move and more importantly turn.

Once I get a rough idea of the basics then I can scale it up for my bigger models using more gearing, more motors or even more wheels.  As stated in my previous post, moving heavy weight is my biggest issue when building my robots.

Click here to view the video on YouTube.

In my opinion, 2 non geared xl motors moving and turning 12.5 kg of weight is pretty impressive!  Maybe I should use them to move my son around the house:)

For more information on these wheels, please visit Rotacaster.

The main issue I always face is how do you make a huge model move! Now George and Bob both struggled on non slip carpets, however most surfaces were not a problem for them. As I plan to make my next project a lot bigger than the last 2, I instantly hit issues. Both George and Bob were quite thin models with a main long beam. George had a height of 5ft 7in. They both probably weigh between 20 and 25KG each.  So imagine building something 6-8ft tall, with a main body 2 times fatter than George and a horizontal arm beam of around a meter long with a model of a mini gun on each end. Once built, if this things weighs less than 40KG I would be impressed!

For this next project I have given a lot of thought to the weight / moving issue. I have researched a few different options and the first one I hope to prototype is using Rotacaster omni-direction wheels to take the pressure off the tracks.  These wheels can basically move in any direction and support up to 25kg per wheel!

Currently the omni-direction wheels only come in 48mm size which is a little small to use as the main platform, however if I keep with the normal track design but place these wheels behind the track to support the main body, which is the heavy part of the model, then the resistance on the tracks will be less and should then have an easier job moving the robot.

Lately I have also been investigating Lego compatible metal axles. Trying to transfer the power from several XL motors to the robots tracks is actually quite hard work because the motors are strong enough to twist plastic axles and snap cogs.  They can also bend quite a bit when used as axles for the wheels / sprockets as they are supporting quite bit of weight. Metal axles would cut down on issues but could damage the plastic. I do hope to get hold of a few to test out and review. If anyone else is interested in metal axles and cogs that are compatible with Lego, then check out the Bricklink store Brick Machine Shop.

Another big issue for building large models is the cost of parts! Most Lego technic sets have maybe 10-15 large Technic beams in it. They might have 1, 2 or even 4 motors. When you start planning to build a large technic model, you’re looking at 10+ motors and thousands of beams! Also as everything is further apart, you need to invest in quite a few extension cables for the motors and they aren’t cheap. Lately I have even run out of Technic pins!! The last couple of models I have built used the Lego Starwars Hailfire Droid with wheels from set 4481 as a main bearing. These wheels only exist in this set (pretty rare) and cost over £20 per wheel to buy from Bricklink.

A few ways I have gone about keeping costs down is by parting out my sets and using them. A few years ago, I didn’t build but only collected sets. It was when I had to build something for a show that I did then switch over to building instead of collecting. I have now decided after many years to start integrating my sets into the stuff I use to build. Any rare sets I keep separate. I also asked on the Lego forums (e.g Brickish) for parts that people might have spare. A few people have been very generous to the cause! Generally I don’t need brick and non Technic parts and so I can use these parts to swap for bits I need.