How to build a feather weight?

[razerdave]

Chopping boards aren't axe proof or rammer proof either. They shatter. They're crap. HDPE, not LDPE. Remember that.

[RogueTwoRobots]

Of the three main plastics, Nylon and HDPE are currently the more popular ones. Polycarb was used a lot more in the past and still can be effective and useful but if buying new, it can be more costly than Nylon and HDPE.

Nylon is the stronger of the two materials, and the more expensive. It's good for making structural or load-bearing parts in your robot, such as bulkheads or mounts. I've tried various other plastics for these parts in the past (HDPE, Polypropylene, RG1000 etc) but always end up back at Nylon as it's the best for the job.

HDPE is better used as armour. It is quite soft in comparison to other plastics, which may sound bad but it actually makes it well suited to standing up to attacks from spinning weapons. When a blade hits, the plastic flexes which helps to dissipate some of the energy of the attack, and you're usually left with gouges in the material, but they can be easily cleaned up. Metal armour would bend and deform and you'd have to get a hammer out to re-shape it but because it flexes on impact, HDPE is more likely to retain its shape and if it does get deformed, heating it up with a heat gun is usually enough to allow you to correct it.

That said, HDPE doesn't have to be used solely for armour and you can make bulkheads, supports or mounts out of it too (one of my robots Onyx uses it for the central bulkheads). It's also worth mentioning that your armour is only as strong as its mounting. You could have the toughest armour in the world but if it's mounted poorly, it'll just fly off when a spinner hits it. In terms of thickness, a lot of people use upwards of 12-15mm thickness. That is fine, but personally I find it can make robots look bulky or cumbersome. I tend to use 8mm HDPE for my armour, and have never had a problem with it getting penetrated. You can also leave a gap between the armour and internal components so that if a blade or other weapon does get through the armour, the gap might be enough to stop it damaging any of your expensive parts.

[RogueTwoRobots]

And without wanting to bombard you with too much too quickly, it's also worth just mentioning when it comes to the overall design of your robot, make sure that it's relatively easy to get to all your internal components for you to work on them. Time in the pits to repair your robot can be limited and you don't want to waste a lot of that time having to dismantle half of your robot to get to a small component in a hard-to-reach place that's causing you trouble. Always design with ease of maintenance in mind; at the very least it makes competing at an event much less stressful

[daveimi]

+1 for don't use chopping board although they are only a quid in home bargains

[Flag Captured]

Ahh, I get you - I used some as a test platform for HardWired but I never tested them out in battle. Probably not the best of ideas then!

[Ellis]

Yeah, avoid chopping boards for full combat. Our first machine, Tormenta, was made almost entirely out of chopping boards of various thicknesses. After coming into contact with the later crowned 2012 Champs' weapon it... http://youtu.be/Wh7KsZiG9W0

[daveimi]

Yeah they're no good as armour, I've been using them as baseplates.

[Eventorizon]

And whatever you do don't use screws to hold the pieces together.

http://www.youtube.com/watch?v=FXey3Phs3eQ

NST did the same to Conker even though I had used HDPE as armour (Chopping boards are either PET or LDPE) The screws provided lots of weak points. And the forces were so great it just snapped the heads off.

And don't use Nylon 66 as a base. Use Nylon 6 else this happens...

Conker 1 GSL 2012 Aftermath.jpg

[daveimi]

It may be worth mentioning that there is a huge difference between throwing something together for “half combat” events, and seriously building something capable of surviving “full combat” events.

[Ellis]

It may be worth mentioning that there is a huge difference between throwing something together for “half combat” events, and seriously building something capable of surviving “full combat” events.

Very true. For live events, even the shattery-type chopping boards (there is a soft kind which should be fine, in fact potentially quite good) will last some time. It's only in high velocity impacts that they act like glass.

edit: oh, and, chopping boards are a complete horror to work with. They will melt and re-seal behind any powertool cutter. There is actually a bit of scrollsaw blade permanently stuck in one of Tormenta 1's bulkheads to this day, heh. HDPE is much nicer to work with, and though I haven't used it, I imagine nylon is too.