Design help please

[Matthew]

Hi,
I am designing a new robot and would like your thoughts on my design. I have designed a robot before but it was too fragile and wasn't thought about enough in the designing phase. To eliminate theses problems I have used a simple CAD (sketch up) and is the reason I am posting this thread.

I am designing a full body spinner as they seem very exciting and capable of lots of damage. I am planning for it to have an aluminium chassis as it is easier to machine than Hardox (especially for a noob). For the outer body I am planning to use a saucepan or something of similar shape.

Red=Chassis
Green=moving parts
Blue=Armour

Stage 1=Drive motors and base chassis
Stage 1.png
Stage 2=Upper chassis and weapon drive motor
Stage 2.jpg
Stage 3=Armour and weaponry
Stage 3.png

Apologies for the small images,
Kind regards,
Matt,

[Omnibot9]

What do you need help with? Have you considered using the robot itself as the spinner i.e. spinning on the spot? This can also be quite effective with the right motors and there are a lot of advantages (fewer parts, two motors causing movement, no weapon speed restrictions).

[Omnibot9]

What do you need help with? Have you considered using the robot itself as the spinner i.e. spinning on the spot? This can also be quite effective with the right motors and there are a lot of advantages (fewer parts, two motors causing movement, no weapon speed restrictions).

Actually there might be speed restrictions for the type of spinner I suggested but I am not 100% certain on that.

[Matthew]

Thanks for the reply,
My first robot used the same idea as you mentioned but it didn't really get up to speed and I believe this design could be superior if it works as planned.
As for your first question I would like the community's opinion on the design as I don't want to finish it to realise a design fault which I have missed. I frequently had these errors in my previous build which careful planning could have of eradicated.

[Piggeh]

I'm also working on a spinner . I personally would add more bearings than the four you have as when you collide with something (whether it be another bot or the arena itself) your the spinner will put a huge amount of stress on the bearings, possibly shattering them. A good example of this was Mr Speed Squared where the disc shattered the bearings after a few impacts. You might be able to solve this by using many more bearings around the circumference. Remember to leave space for all your electronics inside though! Batteries, speed controllers, receiver and all the wiring between it all is very easy to forget when in CAD. Looking good sofar!

[Omnibot9]

Speaking of spinners. What do you guys think of this idea? I am hoping more experienced engineers might give me some pointers.
http://www.fightingrobots.co.uk/thre...g-top-robotics

[daveimi]

Read the build threads n get to some events. Start basic n work up to fancy stuff, it's quite a steep learning curve to begin with without having exotic weaponry to worry about :-)

[Matthew]

Thanks for responses,
Pigggeh: I hope there will be plenty of wiring room as I expect the motors will require the chassis to be quite large (using cordless drills). I agree about the bearing point you raised. Should I place bearings on the top as well to protect against downward strikes like that of an axe?
Omnibot: I can't really comment due to lack of experience but CAD seems a good start.
Daveimi: I aim to complete stage 1 before attempting anything exotic. This will allow me to adapt, if its too complicated, into something like a bulldozer.
Thanks,

[Piggeh]

I would definitely add bearings on the top, not just for the threat of axes but when the disc collides with something force isn't just applied laterally. For example if the disc/blade hits an angled side of another robot the disc could be deflected downwards/upwards slightly even if you tear straight through the armour. In extreme cases this could bend your disc leading to it crashing into your chassis. In my opinion I'd rather let a bearing take the grunt and explode with the possibility this will jam your blade, than having the blade warp with the possibility of it crashing into and damaging your chassis. Even with bearings you can still have the blade warp however. It's mainly down to personal preference and learning from experience.

I assume from your CAD that you intend to mount the "saucepan" (That would be really cool to see) directly the weapon motor. This is probably a bad idea as when you collide with something alot of force is going to be transferred directly to your weapon shaft, possibly shearing the rotor spindle. If you look at spinners especially in the heavyweight class(You can see how Carbide does this in Episode 6 of robot wars, You can also see PP3D's build log on the forum which uses a large titanium spindle for the disc with the ETEK motor mounted behind it. I assume chain driven) they do not drive the weapon directly from the motor. You could move your motor off center and either chain or belt drive it to a central shaft which your outer weapon is connected to.