Pucky Prototyping & Build

[Piggeh]

After watching Robot Wars and seeing the power of some of the new bots I really liked the concept of the full body spinner (like Mr Speed Squared) and have decided my next robot should be a spinner. Not only that but I want to try something that I don't believe anyone has done yet(probably because they're sensible) and build a spinner with a custom brushless motor which is hollow which houses the rest of the bot. The entire build centers around this. I could use friction drive, I could cut gearing into the blade but these are proven ideas that already have been validated. I want to see if I can pull it off and if its even remotely viable enough to create a competitive weapon.
The prototype will not fit into a weight class. I want to focus on developing the motor first, before applying it to a competition bot. I fully expect to make 10 motors before getting something that runs well enough to be remotely competitive.

Weapon.png

This is my first CAD mock up of the weapon assembly. The green part is the stator, which I intend to 3D print for the prototype testing, If I can find a way of doing it without spending a bucket load of cash I will create the final version using electrical steel laminations like a commercially produced stator. There is then a 0.5mm air gap between the end of the stator and beginning of the rotor. The rotor is the cutting disk which I will have cut from steel and install the magnets to it. This CAD doesn't show it but I intend to make this thicker by about 5 - 10 mm on each face and support it laterally by creating two roller bearings which will allow the disc to spin but not move.

This will allow me to test the real world power behind the weapon and allow me to tinker with different setups for magnets, coils and coil gauges. Once I find one that works I will work on creating Puck(Named so as it reminds me of a hockey puck) . This will probably end up being a featherweight bot by my current estimations. The CAD design I've done here was intended to be a beetle, however after as much trimming as I could bear it was 2.5kg. Hence the prototype first, competition later as I want this to be built right and not explode because I made that support too thin on my first attempt at what could be a very powerful weapon if it works as well as I hope.

Pucky.pngPucky2.png
The model on the right does fit a battery and ESCS, with ample room for wiring. I haven't modeled a place for the removable link, my current idea is a flap on the top to access it but i'd love constructive criticism on this.

And that is my crazy plan. A hell of a project for my 3rd bot, but I'm determined to give it a good go.
I'm in my final year of college so am quite busy, so expect updates to be few and far between, but I will start once i'm back at college and have access to the CNC and 3D printing equipment.

Edit: While writing this post I found someone who had the same sort of idea on Robowars101. Glad to hear this may not be such a crazy idea. The post can be found by Sketchy http://robotwars101.org/forum/viewto...t=novel#p56970

[katch]

Looks like a completely nuts idea, my first thought would be the tolerance for a motor . The slightest de-formation of that outer ring and it will just stop working. You might want to seperate it from direct impact.

[Piggeh]

This is an issue I thought about for a while. My current idea is to build a hybrid of this and how many already build friction drive spinners using bearings around the circumference of the disc. However I'd probably lean towards roller bearings as they should handle impacts better. I understand the chassis itself would take a large shock in collisions so its going to need to be extremely strong. If anyone has any other ideas i'd love to hear them.

[Omnibot9]

What RPM could it reach? Would it be more than is permitted for a full body spinner in other words. I imagine the motor uses electromagnets on both sides?

[Piggeh]

It would depend entirely on how the motor is wound. I'm not entirely sure what KV rating to aim for, I'm thinking around 500Kv at the moment running on a 3S so giving a theoretical maximum of 5550 RPM without load. In terms of regulations I should be okay as long as the spinner can fully stop in 60 seconds. The spinning element will run above 500RPM, but will be less than 500mm in diameter and the spinning element will be less than 20% of the total weight. In a featherweight this would mean less than 2.72kg if I've done this correctly. The motor uses electromagnet coils on the stator while the rotor using permanent magnets.

[Tim The Plumber]

If you mount the housing for the spinnig blade/motor/bearings onto the chassis with an allowance for some sort of suspension between that and the chassis it might help a lot as this will allow the blade to impact the other bot them have it's bounce around without being so close to the anvil of it's own bot.

If any of that makes any sense...

Inflated rubber tyres or something....

[Piggeh]

Hi Tim, hadn't thought of shock mounting the weapon itself. I'm working on how to do this now. Will update when I have something reasonable.