What is the difference between perspex, polycarb, etc. etc.?
I am after something to replace the engine cover on the Twini Rear Engine.
It is a flat cover, and I was going to use something clear to save me removing the cover when people want to have a look.
Needs some rigidity, and ideally some sound insulation.
The local Bunnings has some sheets that are about 4mm, but they are a bit small.
Any Ideas?

Perspex is a brand name of Poly Carbonate sheeting.

Cheers,

Dicko.

I think acrylic sheeting is recommended over poly carbonate these days because it does not go cloudy and get stress cracks throughout.

i think that Lexan is one brand of polly carbonate ,,, & perspex is clear plastic

i`m pretty sure that if you hit perspex it will crack,,, & polly carbonate won`t (as easilly)

2 different materials i believe

edit--> oh & i`d go with polly carbonate cover

_________________
No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

You're right, Perspex is in fact poly(methyl 2-methylpropenoate) commonly referred to as "Acrylic"

You would've better off using Poycarbonate fr ts extra strength and durability.

Cheers,

Dicko.

I would get onto someon like DOTMAR and see if they have any offcuts that might do the job,

http://www.dotmar.com.au/engineered-pla ... ducts.html

im sure they will have something that will fit the bill

Key characteristics/differences, Acrylic compared to Polycarbonate (Lexan):

More likely to chip, less impact resistance then Polycarbonate. (still 10-24 times more resistant than glass)
Less likely to scratch.
More of a consumer (household) level and is easier to find at hardware stores.
Does NOT yellow after time.
Better clarity and can be restored to optical clarity.
Key characteristics/differences, Polycarbonate (Lexan) compared to Acrylic:

Impact/chip resistance is much higher with Polycarbonate. (about 30 times more resistant than glass)
More likely to scratch.
Substantially more expensive. (roughly 2 to 3 times)
Used for more industry applications
Bulletproof when thick enough.
More bendable.
More formable.
Yellows over time due to ultraviolet rays
Easier to work with (cut, less likely to break)
Poorer clarity, diffuses light, can lighten (could be positive).

I use a company called acrylix, based off of grange road, I forget the actual name of the street they're on.

* acrylic is a thermo form in my experience. It can be heated and vacuum formed. It cuts nicer on a laser cutter too. Issue is it may melt and deform from engine heat.

http://pslc.ws/macrog/pc.htm

So is sheet polycarbonate. However it doesn't cut as nicely and burns/chars more easily (laser)

I would get an aluminium sheet and punch some cool louvres in it, like the old twin engined works cars. Only because I don't trust the heat.

If your really keen though I'm sure acrylix could point you in the right direction for a clear thermoset sheet.

Had a poke around, seems people use acrylic or pc for engine covers without issues.

Acrylic is stiff and cracks easier, is harder. However pc is more 'plastic', this is why it stops bullets more effectively than acrylic, it grabs them and deforms rather than cracking. If you we're ever worried about bits flying off the rear ending I would get pc.

Acrylic is way cheaper though.

David,

Speak to the guys at Menzel Plastics
http://www.menzelplastics.com.au/
What they don't know isn't worth knowing!


Also try Acrilix Plastics.
http://www.acrilixplastics.com.au/


WG

Thanks for all the info.
I will give Menzel's a call.

We use both Arcylix & Menzels but check your price as one will definitley be cheaper than the other.

We use Lexan in jail's as it is super tough (10mm sheets) and a few other more common applications.

_________________
Justin

I got some Lexan Margard rear screens made up by City Plastics in East St Brompton. One for the rear one piece f/g door on the Mini Van, and the other for the f/g rear hatch on the SD1. They previously had perspex fitted to them, but this started to craze, scratch , discolour all too easily within a relatively short time.

_________________
Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)

Like they said, Perspex is a brand name of acrylic which can be laser cut, but prone to shattering on impact. Polycarbonate (polycarb, lexan) is a shatterproof material similar in look to acrylic. Make sure you get uv stabilised polycarb for outdoor use and it shouldn't yellow or haze.

Just to throw my 2cents into the ring,

Acrylic, can be folded but you need a heating bar and takes a lot of heat
can crack if you have to cut or drill holes, be very carefull drilling holes
cannot cut in guilotine
Polycarb, can be folded in a sheet metal folder, just need to adjust the folder for thick material

Have you thought about glass? a sheet of laminated glass is not that dear and will outlast
any plastic, just need a strong frame to hold it so it wont twist

15 years working with plastics, mostly PVC, speaking of which you could get clear PVC although heat would be a problem, tends to go soft above 60°C