Design Dilemma

[Eventorizon]

Re: Design Dilemma

Ian Lewis is the equivalent of a combat robot god with Razor and Warhead! Not forgetting Simon Scott and Vini Blood. I had considered shortening it and then powering just 2 with 4 motors but that i think is overkill. However I want it to be able to push (come to think of it, it seems like I want it to do everything but I know it cant!) so that I can keep robots against the disc.

I am studying at UWE in Bristol, that€™s where I make most of the parts and we also have a Laser cutter so that makes prototyping a relatively quick process.

And simply not telling them had crossed my mind but after they found my blow torch (for stone work) and my flat mates flare gun (No idea) they have come down like a ton of bricks€¦ shame really. And neither had I but the owner of the house is a mate and he knew I was into robots. He told his parents about it when he was telling them who would be in the house and they added a load of electronic stuff to the list of illicit items, along with a george foreman grill and funny putty

I will look into just 2 wheel drive, though I want it to look different to Inertia€¦ maybe a ramp at the back or something€¦?

I have just ordered a load of things from Ewan, 4 motors being the main thing as well as some connectors and wire so I would be interested to see his 4wd spinner
his 4wd spinner

[PJ-27]

Re: Design Dilemma

Lies! All lies I tells ya! We use Li-Po is Bitza 2 because it was the CHEAPEST battery we could find.

[psychostorm]

Re: Design Dilemma

If I can somewhat echo what has been said:
I'm inclined to say don't ditch the lifter on the grounds that most FW events in Britain are in fact non spinner. So the lifter is more valuable than the disc really.

So I'm with Gary on ditching the 4WD. Keep the nearest to the disc, scrap the other motors.

Make it smaller by removing the width of the motors & wedge the rear. It might spoil the looks but spinners will aim for those corners. Spinners can't hit what's underneath them.

Also design a replacement flipper that becomes an upward on the front as well. more useful for non spinner events.

[RogueTwoRobots]

Re: Design Dilemma

Wow, that's a pretty extensive list of things you're not allowed to have in the house! If I were you, I'd move

I would be interested to see his 4wd spinner

That was actually back in 2003/2004-ish I think? I believe he then sold it on once it was changed to 2WD (to a security company if my memory serves?!). Anyway, I have a couple of pics saved from back then:

[attachment=1:3lbd0xv1]vertigo (1).jpg[/attachment:3lbd0xv1]
[attachment=0:3lbd0xv1]vertigo (5).jpg[/attachment:3lbd0xv1]

[ewan]

Re: Design Dilemma

Interesting conversation here, and the CAD's look very nice

I'd personally go for an all-plastic chassis and armour, using rigid plastics like Nylon for the structural parts and lighter ones such as HDPE/Polypropylene for the cladding, this ought to save weight over aluminium. Also go for Li-Po's, they really aren't /that/ dangerous if used correctly and will provide the current you need for the weapon much more happily.

Here's what I built around 2005/6 which had been mentioned:







Contrary to some of the previous opinions I reckon 4WD isn't such a bad idea- The robot above could easily push any other in 4WD and though I opted to go to 2WD to save weight for extra armour/heavier disc I don't think I would have if I'd have been able to use Li-Po's - also this was when feathers were 12kg. It's absolutely up to you though, kudos to you for making something interesting and not a box!

P.S. ahh, seems Jamie found pictures faster than me!

[RogueTwoRobots]

Re: Design Dilemma

I stand corrected then Ewan. I thought your change to 2WD was gyro-based, but now that you've mentioned it was more a weight issue, I seem to remember reading about that. Having said that, it was 5+ years ago so I blame my deteriorating brain cells :wink:

[ewan]

Re: Design Dilemma

Know the feeling, I'm struggling to remember myself!
When I changed to an Astroflight on the weapon at an XFM event (before it blew up..) it gyro-danced to a ridiculous degree, but that was after I'd gone to 2WD I believe- so even having wheels pretty much in line with the disc isn't going to solve the problem entirely. The gyro effect will depend on many factors, having a smaller diameter disc and relatively wide wheelbase ought to help though.

[Eventorizon]

Re: Design Dilemma

I can see myself doing quite a bit of research in the near future.

The 4wd was intended to counter the gyro force and the beveled edges at the rear were to not let spinners get a good grip. The idea at the front was, if you want to hit me then you are going to have to let me his you, as the angled front edges guide you straight to the disc!

What would happen if s swapped out the Alu chassis for say Nylon, kept the 4wd, the disc and the shrimech, got Lipols or LiFe/A123's and then covered the exterior with 2mm Ti? (we have a sheet of it at uni going spare (Titanium going spare!))

[RogueTwoRobots]

Re: Design Dilemma

What would happen if s swapped out the Alu chassis for say Nylon, kept the 4wd, the disc and the shrimech, got Lipols or LiFe/A123's and then covered the exterior with 2mm Ti? (we have a sheet of it at uni going spare (Titanium going spare!))

Ali to Nylon will be a good alternative but don't go too thick or the weight saving won't be that great. 12mm minimum would probably be my recommendation (15-16mm if possible). That should be plenty strong enough for your needs, although you'd still probably have to cut the triangles out of the Nylon bulkheads too. Going to some form of lithium batteries and thinner ti armour will also help save weight, although 2mm ti isn't invincible against the more powerful spinners. I can't say for sure if that would save you enough weight to keep 4WD and the sri-mech, but if you can alter the material densities in your CAD file and search around for some rough weight values of lithium packs, that should give you some idea of what the weight will be.

[Gabe01]

Re: Design Dilemma

I still maintain the Bot is too wide reducing this will save loads of weight. I am aiming for a maximum width of 300mm

[Gabe01]

Re: Design Dilemma

Yours looks to be about 440-450 mm ish

[RogueTwoRobots]

Re: Design Dilemma

400-450mm width isn't too bad for a featherweight. A lot of them are close to that. Obviously the smaller the better, but the GR01s (and most standard drill motors) measure ~150mm from tip to tail, so to fit inside 300mm you need to have them butted right up back-to-back. This isn't too bad in theory, but stick a disc in between them and it's hard to keep the width minimal. With this sort of design however, more width makes the robot more stable/controllable.

[Gabe01]

Re: Design Dilemma

You are right indeed Sir, I love designing Robots, I forgotten how much fun it is and a lot easier with a feather. I do applaud the design of this one as it looks interesting. I will unveil mine in a build diary soon. I have to use yellow gas pipe in mine, so the design will be interesting.

[RogueTwoRobots]

Re: Design Dilemma

I have to use yellow gas pipe in mine, so the design will be interesting.

A featherweight version of T-Bone? Jonno would be chuffed! :P

[Gabe01]

Re: Design Dilemma

Sabretooths have always used yellow gas pipe and we went the same year as T-bone