This time I don’t have a finished model to show, but instead I decided to show a bit more about the building process of a new model. I wasn’t actually planning to make this model this year, but as the Dutch say: The blood crawls where it can’t flow. Every now and then a model gets stuck in my head and I just need to build it. And this model got stuck about a month ago…
In this case it is a redesign of a model that I designed and abandoned a couple of years ago. Here you can see one of the few photos I made of it, to get a sense of what the final model will look like:
It is a fully remote-controlled model with 20 functions, 7 in the carrier, 9 in the superstructure and 4 in the boom (driven from the carrier). It is a model that is close to, if not over, the edge of what is possible with LEGO.
In this post I will concentrate on the carrier. Compared to the original model I have made a couple of changes:
Most noticeable is the colour scheme, which is changed to a white-orange livery (since yellow is not as abundantly available as it used to be).
But inside a lot more has changed. I have swapped two M-motors to L-motors (which weren’t available at the time). I have redesigned the outriggers (and I will have to do that again since they are not working to my liking), the function-switcher (to use the modern 3L driving rings), I colour coded the functions (for ease of operation) and I made all kind of small changes to ease the building process (if there is enough interest I might make building instructions).
In this video you can see how the carrier looks and works now:
As you can see retracting the outriggers still requires some redesigning to make them go in more smoothly. Switching the steeringmodes is also not a foolproof system (and I don’t know if it ever will be). The mechanism relies on moving a central axle with gears between two positions two studs apart. There is a mechanism in place that ensures that it is only possible to switch between modes when the wheels are straight. However, this mechanism is located quite far to the front (between the 2nd and 3rd wheel pair). Because of the torsional (lack of) stiffness in the long axle the last wheel pair can be one teeth off during the switch. So after a few switches the alignment between the different wheel pairs can get lost.
Another issue are the two driven wheels. When in normal steeringmode the steering angle of these wheels are only determined by some elastic bands. So sometimes they start to wiggle about. When in crab steering mode only one steeringrack is engaged, whereas the other is moved through a linkage with quite some play. As a result these wheels also don’t steer very well when in crab steering mode.
So, still some work ahead of me… If I have found some solutions I will post them here again.