I would use whichever heat treatment business that can do the job fast. Building a bot always take longer than you expect so saving time is important.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

you can definitely drill hardox it is just a long slow and painful process
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Lasertech does use a 2.5D lasermachine, able to cut tapered holes (or untapered)

But I have to admit, the 8mm holes ain't perfect whatsoever. If more accuracy is needed, you could see those as a pilot hole.
And drilling on Hardox 550, that's no task for HSS or HSS-Co. And if you use TiN coated drills, the coating will be removed after 1 hole. Full hardmetal or a regrinded tap (maybe)

I use solid carbide straight flute drills - they go through hardened steel like butter.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Thx Nick.

Before I never thought I would meet any time problem building until I actually started getting parts and stuff.

Question: Aside from 65mn, is there any other types of steel that could do similar things?(when hardened can be a substitute for hardox, but maybe not as good) I figured that I'm most likely going to have countersunks on my future builds so hardox itself can be a bit hard to work on given the tools I have available.

That's quite a complex question. We use Hardox / Bisalloy because its cheaper than the alternatives and has near to ideal properties for bots, plus there is no extra expense for heat treating. In the US, they still use S7 steel for weapons, although their builders are moving towards wear steel for the same reasons as we have.

Wear steel is designed to be both hard and tough, while other steel can be made much harder, they will also have less toughness and shock resistance. S7 is a speciality steel that can be heat treated to higher hardness than wear steel but still has reasonable toughness - in fact 'impact resistance' is its key selling feature and its used for industrial punching and cutting operations.

With wear steels, you are stuck with the pre-set hardness and toughness, while with S7 or that 65MN you can adjust the properties in the heat treating process. If the parts are treated at lower temperatures, annealed for different times and cooled at different rates, then you can have parts that are a bit softer but much tougher. That can make a huge difference as long as the heat treatment place knows what they are doing. I found that for my S7 parts, reducing the hardness From Rc 50 to Rc 45 made a huge difference between shattering and just chipping a bit.

I worry that your 65MN spring steel will be too brittle at the hardness needed to stay sharp against other steel. There should be a Chinese steel equivalent to S7; you want an impact resistant steel meant for heavy duty punching or die forming operations.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Thanks, that's a whole lot of info.

Hmm... I searched for some extra data of 65mn and found out that it's possible to heat treat 65mn to be similar to hardox (somewhat balanced hardness and toughness), but under that heat treat 65mn would be inferior to hardox in every way... I have yet to find something else to beat the wear plates in terms of armor.

I think it would be better to use hardox next time and try my luck with the countersunks... Countersunks are pretty nice but not compulsory after all.

I guess I will solely rely on my luck with the current 65mn parts, the only good news is I don't have any events other than the Nationals before I can get new parts again.

Ah... you just reminded me of another steel I have heard of recently. S136 was said to be a bit tougher but a little softer than S7 in general. However it's said to be quite expensive and I think it might be crossing into the territory of the higher grade hardox steels, in which case the S136 would be beaten in terms of price. An interesting material nonetheless.

Just arrived in Sydney today...

Did a simple mockup of the chassis, it seems mostly fine, only needs some filing.

Had a dream on the airplane... what about Whiplash's weapon on Overhaul2's body?

I guess a picture helps...

Looking good!
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Awesome
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Thanks guys, I will keep updating the building process in the coming month or so...

Several problems I met:

1. I forgot to buy the shaft for the spinner... It should be a 20mm steel shaft that's about 230mm long, where can I get it in Sydney? (There's probably not enough time for me to wait for Ebay delivery, not that I can't even find shafts on Ebay.)

2. The holes in the timing pulleys seem to be too tight for the M8 bolts to fit... How can I enlarge the holes?

These guys do precision ground linear shaft:

http://www.linearbearings.com.au


Glen or I can probably dig you up some 20mm shaft but possibly not quite 230mm long.
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The Engine Whisperer - fixer of things

You will have to drill out the timing pulley holes - 8.5mm is a good clearance for M8 screws.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Look on monday but think the stack we have is 200 long,

Small parts carry some ground shaft also - https://www.smallparts.com.au/store/item/0r02000275hcst13/shaftinggroundprecisionhighcarbonsteel/
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