Polyproplyene

[glen]

just had a quick glance at some other threads and couldnt find anything much about polyproplyene, so ill just ask here.

im looking to change my bot cobra over to a different material for its lid, as its been using 10mm lexan and i had a massive split occur straight down the lid when a spinner hit the side (didnt even touch the lexan itself).

i was thinking polypro would do the trick as ive heard it is good for robot use, but i need a bit of info that has been hard to come by on google (probably because of my half-assed searching ) -
* what is the density of polypro approximately? im hoping that its around the same as lexan
* ive read that polypro can be bent back and forth repeatedly and not fatigue, is this true?
* is polypro clear to radio signals?
* is polypro harder than lexan?
AND * is there any little quirks to working with the stuff, eg does it crack, does it deform easily..

oh yes and finally how does the stuff stand up to axe bot attacks

any help greatly appreciated.

Its easy to work with, yes it does bend back and forth without fatige, but im not sure as to what extent. it doesnt crack as its a relativly soft material and stands up to axes quite well, but spinners may tear through altho this doesnt cause a problem as it heals itself. Its more rubbery than lexan and alot of robots including rampage 2 use it all over.

[sam_t]

Ill will try to answer your point from my personal experence with polypro.

The density is typicaly slightly lower than polycarb so that should not be a problem.

To a limited extent, it is softer to polycarb making it less likley to crack and simpler to bend.

As far as I know it has no adverse effects on radio over polycarb

no

Personaly I have found it difficult to cut with a jigsaw as it tends to build up swarf on the blade but its very easy to work with wood tools.

Sam

[blazerbotics]

We have switched from polycarb to polypro on the feathers, mainly due to the fact we get it cheap! The main reason weve switched is due it no cracking.

You can also heat it so that you are able to bend it, also you can actually weld it by melting it together! Were currently looking at making some bits for the top of Merlin, to put on top of the Ti to give abit more protection from axes.

If you look on the RS website i think it gives most of the data on there.

Weve had no probs cutting it with a jigsaw, what weve found was best was to use the most course blade you have (we use one for rough cutting wood) and set your pendulum motion to full (if your jigsaw has pendulum motion), and goes through like butter!

[glen]

thanks for the replies, thats all really helpful information.

this plate is sunken into the body so im not worried about spinners slashing it, although grants comment about it healing itself is interesting, does it melt back together or something?

Its somewhat like cutting board material (and if youve tried to cut that with a very fine blade, youll notice the plastic around the eroded area of plastic, will try to re-form into its origanal shape, perhaps sealing up some of the eroded area) how this is much use in fighting robots I dont know but the impact-resistance of polypro is probably the reason to get it.

[grant_ploughbot]

well we did some tests on 10mm polypro with tantrum. it went straight through the stuff, with about a 1 gash, but when we went to look at the damage it did, where the hell had it gone?
it can be cut into but returns to its origional position unlike metals, and so damage is hard to find, possibly winning a fight if it comes down to damage.

[knightrous]

If you have a spinner with chisel teeth, it will most likely tear a chunk out instead of slicing through the poly. Saw blades make minimal work of poly and I reckon chisel shaped tooth on a moderately powered spinner will do the same.

[maddox]

High Density Polyethylene has about the same properties. The wheels from TAN did prove the self healing abitly at Debenham After a flip one of the wheels looked as bend as a banana, the next day it was as good as new.
Of course, if it is ripped appart it wont reglue itself.