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**typhoon_driver** · 10 January 2012, 21:37

Re: Design Dilemma

1400 rpm on the disc? That should be doubled at least to make anything effective (if I read that right).

Do the sums regarding the disc. I assume your design software will give you the rotational moment of inertia of the disc. With that work out the rotational kinetic energy. You should be aiming for something of the order of 800 joules or greater. For comparison, boner/old drumroll gets around the 800 joules mark, 360 I believe is approaching or around 4kJ and my old robot hornet 2 was around the 1.5 to 2KJ mark (depending on the variant). Videos of each can be found on Jamies youtube feed.

One thing I don't like about the design is the fact that the front panels are sloped inwards towards the disc \,/ (comma being the disc), I think they should either be flat or slope the other way. Problem with how it is setup just now is that you are shielding the disc from your opponents. Get a wide flat edge facing the disc and the disc may not be able to make contact and you won't be able to turn into an opponent (one of the best methods I found for making good contact with a vertical disc)

**Mouldy** · 10 January 2012, 22:15

Re: Design Dilemma

Plus the front looks like satans mutt (as seen on gadgetshow) which looks good... But is a nasty grab point for horizontals... Satans mutt is 4mm titanium on the front... And I've put a big slot in either side with 360

one on tv... The other at gadgetshow live doing a demo.

Another downfall in your design could be your self righter... With a mechanical disadvantage like that you'd need alot of force at the actuator... Check out my build diary for the lengths I had to go to, just to make 360s work.

All in all if I were you I'd go for 2wd run of a small lipo, make the robot invertable... Then make your disc around 3kg @ 3000 rpm of speed 900s and a seperate lipo at a higher voltage.

That setup should give you a reliable competitive first robot.... But the choice is totally upto you.

**Eventorizon** · 11 January 2012, 10:50

Re: Design Dilemma

The \I/ a the front was a concept I wanted to try. After years of watching Robotwars and then all the featherweight fights on Youtube It crossed my mind that unless you can protect your disc until it gets up to speed then it is close to useless in a fight. Take Tornado VS Hypnodisc. I was convinced that Hypnodisc was going to win but Tornado never let it get up to speed. The same held true for a couple of Supernovas final fights and S3 if I recall correctly. The \I/ also has the purpose of holding an opponent against the disc and it prevents them from turning away.

The dsign was also linked to a build someone had done in the states where they had put the disc in the middle of the robot's 4 wheels [1 in each corner] with ramps at either end. He has said this was to reduce the gyroscopic effect against turning and apparently it worked wonders, he just could not hit anyone with the disc... not so good.

And the Shrimech was a head ache but it should work. The actuator on its own will lift 750N then that drops to 160N with mechanical disadvantage but thats still more than the robot so... I don't know!

Though of course this is just a load of theory but I thought I could at least put it into practice

And I have been lucky enough to see the damage 360 did for myself! Robochallenge came to our local design event at Elvington and (I cant remember the guys name (feel Bad)) one of the team walked me through the build and the design features... was amazing! And they had Venom there to!

Extra...

I have just had a chat with the guy from Electronize and he reckons that the FX40HX will be fine for the job despite the stalling as it has inbuilt current and temperature cutoffs that self reset when it gets much for the ESC. He reckons I should be more worried about the motor now cooking itself when stalled... I guess the only way to find out is to try it!

**typhoon_driver** · 11 January 2012, 13:50

Re: Design Dilemma

You just gotta be a good driver to get a disc up to speed

Fair enough, it's your machine at the end of the day and you will learn more by doing than us telling you.

**Eventorizon** · 12 January 2012, 09:48

Re: Design Dilemma

So this is a complete rework...

4WD, Disc, runs on 2 wheels when inverted and can still attack. Nylon Base and vertical supports (Black) with 20mm sides and 10mm top HDPE (translucent).

I look to have enough weight left over for a second Speed 900 but I wont be able to run both off 1 40A Electronize so might switch to a solid relay...

Comments?

And I know its not as interesting but I think I will go simple for the first one, cutting the prototype armour for the other one was really difficult!

Attached Files

1104MK1 V4 01.jpg (166.6 KB, 274 views)

**typhoon_driver** · 12 January 2012, 10:26

Re: Design Dilemma

I would advise going for a soilid state relay anyway. Speed control on a disc sounds wonderful but in the few minutes of a battle, throttling it back is generally never on my mind.

New design is less fancy but looks more solid

Edit - just to add, I would see if you can run the disc lower to the ground so it's only a few mm off glancing it. I did this with boners drum and flippers couldn't get under me. Sure you may have a glancing blow with the floor but the robochallenge arena has a hardox floor so it's not an issue.

**Ellis** · 12 January 2012, 11:23

Re: Design Dilemma

Or you could add ramps/wedges to the front bits on both sides of the disk. Then the other robot rides up onto the ramp and you get a solid impact from below the other robot. With a heavy enough weapon you could get some serious flipping action going! Also the flat front edge would be other spinner food, in that sense angled front edges would be advantageous.

Like this from above:
|______________|Â¦|______________|
|__|_______|__|

Â¦ being the weapon.

(sorry, can't represent it much better on this keyboard)

**ewan** · 12 January 2012, 11:34

Re: Design Dilemma

I'd agree with the sloped backwards from vertical front, otherwise all looks good

**jonny** · 12 January 2012, 15:36

Re: Design Dilemma

Looks awesome

**typhoon_driver** · 12 January 2012, 15:45

Re: Design Dilemma

with a spinner you don't want to over complicate it and have other robots running over ramps or up slopes etc. As far as weapons go, spinning a piece of metal up to high speed is pretty agricultural engineering wise and you want the collision to be the same, as simple as possible.

**Eventorizon** · 12 January 2012, 17:45

Re: Design Dilemma

Yeah I can get the disc closer to the ground, 5mm off the ground should be enough. A ramp at the front would not be to difficult either and I can make it removable so I have a choice over it. What disc materials do people use, that model is currently set for carbon AISI 304 Steel (Its the most dense of the preset steels in solidworks)

**jonny** · 12 January 2012, 17:56

Re: Design Dilemma

omen's disc is hardox, not sure what grade though (can anyone enlighten?). to expand on my previous comment i like the looks of your design i'll be interested to see how well it works.

**Eventorizon** · 12 January 2012, 17:59

Re: Design Dilemma

Here it is, current weight is 12.5Kg thats with no wiring, relay for the speed 900's and the receiver, as well as all the nuts and bolts... I think this is now design 5 version 8 or something stupid...

Attached Files

1105MK1 V4 02.jpg (240.8 KB, 212 views)

**Laser** · 12 January 2012, 18:08

Re: Design Dilemma

Well its looking great,

as for disk materials people use Hardox 450, titanium and steel

**RogueTwoRobots** · 12 January 2012, 18:09

Re: Design Dilemma

Looks like a nice design modification. As Gary said, less fancy but much more robust and tried/tested. You've also negated the components, material and electronics for a srimech which is guaranteed to make your life easier as it's one less thing to go wrong.

For cost-to-strength, I think Hardox 450 is the first choice. It's hard by general standards, but as a spinning implement it's not the hardest material around. So if you put a nice sharp tooth/teeth on the disc, it'll have blunted after a few fights. But blunt teeth aren't bad. Boner's teeth have long lost any form of sharpness but can still rip things to shreds. Plus you can always reshape and resharpen your teeth before an event.
Harder materials tend to come from the realm of tool steels. P20, S7 and D2 are the few I've seen used or talked about in combat (although I have no experience of using them myself) but they also cost a lot more to buy and then have machined. If you've got the money though, may as well go for it.

Drumroll's current teeth are a material called Supralsim 690, where 690 relates to the hardness of the material. Compared to the 450 value of Hardox, it's a tougher material, but they've not yet been subjected to enough fight-time and impacts for me to tell how well they last.

P.S. If you're still struggling for weight at any point, the Nylon base is probably a little overkill. Can't remember what you said the thickness was, but I use 3mm aluminium and it seems to be more than capable.