Will tool steel work for a disk?

[Dan-27]

So I'm thinking about whether to do another bot or not. If I do decide to make another I want it to be a decent machine that'll last more than the weekend.

I'm considering making a 'simple' spinner, clearly Mondeo flywheels don't make great disks so I was having a route around at uni. I've got 2 options, there's a 8mm Ti circle with a 260mm dia but I think 8mm's likely to bend, the other option is a cylinder of tool steel. It's 110 dia and 80mm wide so I could make something similar to Tornado's relatively small disk.

I've attached some rough inventor files to show what I'm thinking of. Two teeth, 40mm dia shaft (probably overkill) Smooth ali pulley attached on the other side of a 20mm bulkhead.

Will tool steel be strong enough or do spinning disks really need to made of Hardox or Ti? I made the teeth for PJ's Mondeo drum from tool steel and they survived but were a bit deformed at the tip.

[typhoon_driver]

Binkys disc is a single piece of tool steel

[Kenny]

Tool steel is a great material for disc/drum weapons, a few warnings tho when using it and how its hardened, for robotic combat i would recommend either a EN36, P20 or D2 ( D2 being the best and offcuts can be bought from ebay ) , each materials have their benefits EN36 is a cheaper option, P20 Readily available and used in most engineering companies so offcuts can easily be got, D2 is a expensive material but it is tougher and can hardened to a higher rockwell rating and this is why its used in a lot of press and cutting tools

Don't harden material yourself, get a company which deals in doing it everyday, they will have the equipment and the temperatures to reach rockwell ratings , If you can get parts case hardened a few thou thick this means original material is behind and will be alot stronger and won't fail during hits, don't harden to the maximum the material will allow, it will be very brittle and a very good chance it will also fail,

when making the teeth put a raduis at the edge it will last alot longer, doesn't after be a big raduis just not a sharp edge

[Eventorizon]

Binky's is D2 hardened to about 80 Rockwell / 800Brilnell. The teeth were pointed but they have naturally rounded to about 2.5mm rad curves after just a few hits. One snapped off to about a 4mm rad after hitting Cicatrix. (And launching it 2.5m in the air! :-) )

[Dan-27]

Thanks that's good to know, I'll machine a 4 - 5mm rad onto the teeth.

The block I found at uni is EN26, will that work or am I better off shelling out for a billet of something more suitable?

I've found a local flame hardening company called Multijet hardening, I'll see if they'll be willing to do a one off job for me. I'm going to have it running in bearings set into 20mm HDPE or Nylon bulkheads, will the hardening process effect the diameter of the shafts much?

http://www.multijet-hardening.com/

[Kenny]

EN26 will be good its a tough material so would be ideal for a disc, the hardening process may affect the dia a little but wont matter in robot terms as the tolerances are no where near what moulds require, ask them what rockwell hardness they can EN26 to, i would aim for 50-53 Rockwell any more it will be brittle

[Dan-27]

Great, thanks for your help Kenny.

[Eventorizon]

Thanks that's good to know, I'll machine a 4 - 5mm rad onto the teeth.

I would only add a 2mm. 5mm is actually quite large; similar to the rounded edge of a felt tip pen as it means its 1cm in diameter. It will self round after a while which is why you make the teeth as big as possible. I plan for the drum in C3 to a single 20mm bar sticking out. I will leave the edges square so they just round during combat.