Polypropylene armour?

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joey_picus
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Polypropylene armour?

Post by joey_picus »

Quick intro first, I'm a long time lurker but first time poster on these boards at least...started off with fanfic, got some parts with which to construct a featherweight, and then Dave Weston sold me on ants too (as well as selling me some bits) with some RRC videos so I now have to spend twice as much money on robots. :P

Anyway, onto my question...although the recieved advice is to use 1mm or similar polycarb as armour I've been considering polypropylene (among other things) because it's apparently less prone to cracking under stress and slightly lighter, but because the forums are a bit sparse on this I thought I'd ask for more info, so...is it more suitable as ant armour than polycarb?
Also where could I get hold of it in suitable thicknesses? (...for that matter, what would be a suitable thickness? I'm torn between thick to take damage and thin to bend and absorb impacts...)
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Simon Windisch
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Post by Simon Windisch »

I've never used polypropylene so I can't help. I know that acrylic is rubbish though!

Good luck with it anyway.

Simon
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Post by Remote-Controlled Dave »

Polystyrene is also rubbish. lol.

I don't think you really need to worry about the "right" armour in antweights like you do in other weight catagories, its more about the way they are constructed. In my time, I've fought spinners with a cardboard robot and a aluminium robot and had the cardboard one suffer far less damage.
So I wouldn't worry too much about something thats a bit less likely to crack, if polycarb has been used for ages by other roboteers and stood up fine. Just go for what is cheapest.
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Post by peterwaller »

I would stick to polycarb as it is used in all classes of robot as well as for the arenas plus riot sheilds and bulletproff windows. 1mm thick is the most commonly used on ants for armour although some have used upto 12mm in small quantities but weight will normally limit you to 1mm.
You can get small sheets from model shops or larger quantities fro places like RS Components
http://uk.rs-online.com/web/search/sear ... 4654&Nty=1
or Technobots
http://www.technobots.co.uk/acatalog/On ... t_103.html
With 1mm polycarb you can just bend it with a pair of pliers without the need to heat and to cut just score along the line and then snap off.
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Team Orr
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Post by Team Orr »

yeah go for polycarb, i used 2mm on my ant and put it up against some ace spinners, not even a scratch!

btw... are you on the F.R.A?
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BeligerAnt
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Post by BeligerAnt »

Welcome to the forum Joey!

I don't know of anyone using polypropylene in ants, but it is pretty tough stuff.
I did find a 3mm sheet on eBay:
http://cgi.ebay.co.uk/3MM-WHITE-POLYPRO ... 240%3A1318

But I think 3mm will be a bit too thick for antweight armour. 1 or 2mm is about the thickest you can go for all-over armour before you run out of weight.

Just found Direct Plastics Online http://www.directplasticsonline.co.uk - they sell Polypropylene and HDPE in 1, 1.5, 2mm thickness and not too expensive. They don't do polycarbonate though :(

HTH
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Simon Windisch
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Post by Simon Windisch »

Just for the record, Polycarbonate's density is roughly 1.2 and polypropylene's is roughly 0.92 which makes polypropylene roughly 23% lighter.

Also, I use Direct Plastics for RG100 for my feather and it's great stuff.

Simon
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Post by Andrew_Hibberd »

I looked into polypropylene a while ago, i came to the conclusion that 1mm proberly would be a little weak for armor. However it is 23% lighter, so you could use 1.5mm thick for armor and be a little heavier than 1mm polycarb

I had been planning to replace my 4mm polycarb supports with polypropylene as it would save quite a large ammount of weight. What I didn't do much research on is how well it would hold a m2 tap.
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joey_picus
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Post by joey_picus »

Thanks for all the advice and welcoming people...yep, Jack, we've crossed paths before on the FRA boards I think.

Looking at directplasticsonline polypro seems a lot cheaper than I expected (?7 for a 1m squared 1.5mm sheet!) so I may well be giving it a go, no reasons not to use it really.

Does anyone have experience with forming the stuff? I've read a couple guides on shaping and welding it but didn't know if they'd work at this scale as well. Also I was looking into vacuum forming but according to Josh that's not compatible with materials that are actually any use :P
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Post by leo-rcc »

Well polycarb you can vacuum form so that is not really true. However with vacuforming you reduce the thickness of your material since you stretch it out.

Polypro is nice material. I use hdpe on Angelus and have had Katjuscha trash it around a couple of times and that holds well. Apart from the wheels coming of. :-?
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