Hello all

I think it is time to start a design/build thread for my latest creation. I learnt a fair bit building my first wee robot, Gremlin, and I was quite amazed just how well it did in the two botfests it has entered so far! It had the benefit of being quite tanky and hard to get under (even without acetate thanks to the 3D printed brim, though acetate definitely improved it), but it lacked an active weapon, was rather slow and a pig to handle (due to one lagging gearmotor)! I will be doing some upgrades to Gremlin, as the ESC is capable of running much more powerful drive motors, so a high-speed Gremlin will be coming soon!

But for now, my latest robot, Kaneda. It will be a vertical spinner using a direct drive single tooth stainless steel drum (see thread). Motor will be running at 2S 4000Kv, so we have a theoretical no-load RPM of 29000, although I doubt it will reach this after accounting for friction and air resistance! The drum itself weighs 26g and theoretically has around 10J of KE, which actually seems kinda low. I definitely do not want to touch it at full tilt! another part of the argument to use a drum rather than a big wheel with bigger MOI, is the angle of attack when engaging an opponent. I want the engagement to be as close to 45 degrees as possible to ensure my robot stays sat on the ground while the other goes flying! This requires a compact design of spinner. the final point is also reliability. I want to keep hitting for a whole fight rather than self-bricking my robot and losing that way!!

But anyway here she is:

final render hi res.jpg
top view.png
front view.PNG
side view.png

Designed in fusion 360, to be finished in red and carbon fibre. Decals are a tribute to Kaneda's bike from Akira
On a side note I strongly recommend getting to grips with this software. It is reaaally powerful for design and modelling. I would say just get stuck in and design something and in a few weeks you will be flying. Tis free as well for hobbyists.

The overall chassis will be pretty similar to Gremlin, a 3D printed monocoque. Whilst 3D printed PLA is not exactly titanium, when printed as all one structure, the result is extremely rigid. I will augment this with some epoxy carbon fibre and we should be pretty nicely armoured at low mass!

Drive is just two N20s at 30:1. I will trial some sharper gear ratios on Gremlin before upgrading this one. Experience so far is that a slow bot is a driveable one! I picked a dasmikro as a speed controller, as it is waaay lighter than the Sabertooth 5A on Gremlin. Also used a 7A brushless ESC from Hobbyking for the weapon motor control. Same radio as Gremlin using an OrangeRX 6 4 channel receiver.

Battery compartment is compatible with either 260mAh or 180mAh 2s lipos, I shall see how power hungry/ heavy it ends up!

Anyhoo I have done a couple of bits on the build but will fill those in a different post, Up for work in 8 hrs!

TTFN

5C