Stainless Steel for a non -combat robot?

I'm an A-level electronics student, and I'm making a highly ambitious coursework project - A robot. Officiallly it is designed as a search and rescue robot, but the chassis and drivetrain etc are all pretty similar to a combat robot.

The chassis baseplate is 6mm aluminium (50cm square), and the power is two 750W motors (36v).

The front of the robot was originally made of 0.8mm aluminium, but I now realise that this was a bad idea - it is very dented and beaten up after hitting bits and pieces. It does have a steel bar behind it, but it gets dented around this. The aluminium I used was very low grade, and very soft.

I think I should upgrade to stainless steel for the front, to make it more springy and resistant to damage. Remember that this isn't a combat robot - I just don't want it denting if I drive it into something slowly. The robot weighs around 70kg at the moment.

I think I will go for 0.9mm stainless steel (probably from here - however, before buying it I would like your experience and opinion. The two questions are:
- Will I be able to bend it? I rolled the aluminium around some metal tube to get the shape, then screwed it to the (polycarbonate) sides of the chassis.
- Will it be strong enough? I want the strongest stuff that I can easily bend into shape.

I have no idea where 0.9mm steel is on the scale from tin-foil to un-bendable. The curve is about 7.5cm radius.

Any other questions about the robot, feel free to ask!

Many thanks

Andrew

Edit - photos a bit big! Here are the links:
http://img80.imageshack.us/img80/4831/dsc03374a.jpg
http://img137.imageshack.us/img137/2167/dsc03270d.jpg

First of all mate slap yourself a flipper on that and come and battle.

Second... the ali you used will be very weak indeed at .8 thickness. Stainless will be much stronger. I wouldnt say you wont dent it still tho...with 70kg behind it you will get some dents with .9 stainless. i am sure you can bend thicker grade. Maybee try 1.5 thick and you will have even more strength.

Looks good by the way.

Shane

Does your school have a sheet metal bender? If so go for some 2mm steel and you'll be fine. If by hand then yeah around the 1.5mm mark (although I have bent 2mm titanium by hand :))

As shane said, go for thicker than 0.9mm. Are you able to stick a box section bumper on the front? Rather than thickening up the material, I would look at modifying the design. Bolt a piece of 20mm x 20mm with a 2mm wall thickness mild steel box section and it will be fine.

My school does have a sheet metal bender - 30cm wide. I need 50cm wide.

The front already has some box section (I think steel) behind it (hence the bolts), although it is more like 1mm wall thickness. I'll see if I can beef it up when I replace the front.

Many thanks

Andrew

Why not see if you can pick up a fairly thick pice of steel pipe and cut it in half? Alternatively if you want a nice cheap way of doing it you could always use some MDPE water or gas pipe and cut it in half - find your nearest road works, go speak to the bloke in the hole and there ya go!!

You can then put an ali skin on it and it would be fine.

Andy
PS: The stick a flipper in it and stick it in the arena! :proud:

Look at the LED's, It must be something to do with Team Shock :rofl: :rofl:

hey looks good, any videos of it driving?

if your metal folder isn't big enough get your sheet on a work bench then clamp some box section using a set of G clamps to each side the bench and lift up to bend then use a flat hammer to make it abit tighter

Metal bar for the front seems pretty cheap. I'll get some of that. I think I might go with the .9 steel due to cost constraints, and also as I don't mind a few dents.

Andrew

edit - just a thought; how would I attach that bar to the steel? Rivets? Tapped holes and bolts? I can do anything apart from welding.

yeh either option might be an idea to drill the holes before bending and tap them as it will be hard after bending plus with the force the drill will push down with it might un bend the sheet:)

looks great btw

Didn't notice the pics at the bottom of your first post until now. Looking at the design I think your best option would be to use some PVC piping as used by the guys that dig up our streets (someone mentioned it earlier). It comes in various sizes and its the kind of thing you can find just lying around the streets *thinks back to a uni project requiring some* :roll:

It would fit nicely into the design and would happily take the dents. It won't be nice and shiny but then again you can always throw your original piece of ali over the top.

Pvc piping would do. But polypropylene gas piping is a lot lot tougher.

hey mate is that under 13.6kg or 100kg because if it is i think if you were to fight with it i would suggest trying to put
protection on the tracks as they look really exposed



and if you do, do what shanes says, slap on a flipper and join em (i will when i get enough money which im thinking of
taking a paper round which should get me about £20 a week for parts of the featherweight my family want to build
which is essentially cassius jnr from rexe's robot challenge which will be painted which i hope is dark green) :P

It would be the heavyweight class - under 100kg.

I'm adding more pulleys to the tracks to increase tension and increase the ability to climb over stuff. I've turned them on a lathe, and now I just need the axles to arrive so I can fit them. I'll then add 2mm aluminium armour over the tracks. Hang on - for a search and rescue robot, armour isn't the right word...

I've put in an order for some 1.2mm steel - I'll keep you updated with my progress.

Andrew

Update:

I bought the steel sheet, and bent it into shape. It looks great - under the protective plastic is really great (undented) brushed steel. I'll attach some photos ASAP. It makes a great ringing sound if you hit it, rather than the aluminium's thud.

I bought a 20x20x2mm square section steel bar to mount along the front (on the inside), but I then found the chains are in the way. This means that the reinforcing bar will have to be mounted on the outside - this is not a problem, as it will increase the protection for the steel sheet, and transfer more of the energy into the polycarbonate sides.

However, this robot has to look good (obviously :proud: ). The new brushed stainless steel looks fantastic, and I don't want to spoil it by adding the black and tarnished steel bar onto the front. The 2cm bar looks a bit out of place, so I am planning to use a 1cm square (solid) stainless steel bar. This will look better, more appropriate, and will give enough protection. I'm only trying to stop dents caused by pushing objects (eg bins) at slow speeds - this isn't a fighting robot!

My DT teacher says he thinks the steel sheet is strong enough on its own, but I think a 1cm solid bar wouldn't hurt.

Any thoughts?

Andrew

for this purpose 2mm will stand up to the abuse