:MOVE mini buggy kit
As a prize for our winning Rube Goldberg Project14 entry, element14 gave use some cash to spend on new kit from their store. Megan picked a :MOVE mini buggy kit and I selected a Dremel drill to replace my aging minidrill. element14 also kindly provided a Microbit to give the buggy some brains.
The mini buggy is a great little kit, it runs on 2 large wheels on the outside that are controlled by continuous rotation servos. You code it’s motion using the standard microbit tools and there’s some good examples on the Kitronik site such as remote control. The final great feature which we’ve not tried out yet is the ability to attach a pen and hence turn it into a turtle bot.
We did have some challenges with the assembly. I misread the instructions and we did not add some of the bolts to the end step. However the biggest issue is with the wheels these screw onto some disk shaped servo “horns” using self tapping screws. The screws are small and the holes even smaller. This makes them exceedingly hard work to get through with a small screwdriver. The second significant issue with the wheels is that the screw tips protrude into the gap between the body and the side pannels. This would be fine except for the fact that the servo cables also pass this area and the screws can snag the cables wrapping them around the axles. So I think I’ll be using the other part of the prize i.e. the dremel to trim those off.
Posted in: Product Reviews
Metal sculpture in brass, mounted on an 1800s French Coin
I purchased two of these kits for use with my Code Clubs (www.codeclub.org.uk).
I found exactly the same issues as you – the screws protrude through the servo arm and snag on the cables, and the bolts are very fiddly.
I had hoped to get the children involved in building the robots but I have abandoned this as a result of the test build.
The microbit coding part is straightforward enough though and I’m looking forward to teaching with them next term
Thanks Rex, we resorted to tweezers to get the nuts in the right places. Will be trying the bot with a pen over the Christmas break, will let you know how we get on.
I find using tweezers on my nuts rather painful. I used a pair of side-cutters on the screws – is that advisable?
I think a Sharpie is the pen they had in mind for the drawing functions, by the way.
Self-tapping screws are typically hardened so although you can cut them with side cutters you might find that you end up with dints in the blades.
It sounds like your holes were glorious in the end? Were you successful in cutting off your protuberances? And maybe an extra pair of hands might help with the tweezing action? I’m going to have a look at the box now to make sure I’ve got the servo horns to plan my bodging approach to this.
Do you have ideas on some different options to improve the design here? We should give some feedback to the designer as it’s a nice concept and a very affordable, extensible product.
The problem with using servos is they are rather slow – so the movement of the robot is rather slow and ponderous.
I am always happy to receive real world feedback to improve a product.
I notice from the picture that you have the green panels on the outside. They have a smaller hole where the axle passes than the white panels, this intended to help keep the wires away from the ends of the screws. The White panels are intended to go in the outside. We also tuck the spare servo cable into the ‘boot’ area, making sure that the run from the connector past the wheel is reasonably tight.
During assembly the nuts can be held into the slots with a small piece of sellotape. Put it over the slot, drop in the nut and then put another piece over the other side. This means it can’t fall out, and should make assembly simpler.
A Sharpie, or similar marker is what we use for our drawing.
Thanks Dave, we’ll look at swapping the side panels.
There’s a MKII version of the :MOVE mini buggy out with improved traction:
https://www.youtube.com/watch?v=Jl1UhNH7a4I
https://www.kitronik.co.uk/5652-move-mini-mk2-buggy-kit-excl-microbit.html
I’d imagine the better grip improves the drawing accuracy.