Moulding and cutting perspex

[Tim Falce]

I need to make a convex headlamp cover and a side screen out of perspex, has anyone had any experience of cutting and moulding perspex? help and advice welcomed.
Thanks

[StephenRae]

Presumeably you will be using polycarbonate..the problem with it is that it absorbes water. When heated enough to 'drape' it over a former you end up with air bubbles.
If you keep a piece of say 300mm sqare 3mm thick at about 80-100'c for about a week then heat both sides between two electric fires until it is floppy, lay it over a lens screwed to a piece of wood and 'help' it into shape with a piece of wood with a hole bigger than the headlamp rim...prepare to be frustrated!
The side panels can be 'bent' using much less heat avoiding the bubble problem.

[Adam43]

We replaced all the windows (expect the front screen) in our car. Although we were very lucky and it needed little shaping.

Isn't there a minimum thickness? I think it is 4mm. Obviously that isn't a problem with the headlamp. And if my blue-book was nearby I'd check.

Cutting it is fairly easy. Just make sure it is secured well so that it doesn't vibrate (and crack). A jigsaw is fine as long as you use the correct blade and speed.

[Tim Falce]

Thanks Stephen, it doesn't sound that easy. What is Polycarbonate, is it different to perspex?
Ths side screen is more or less flat so that shouldn't be too difficult to do, I may see if I can get a headlamp cover ready made.

[Carlos]

Polycarbonate is a lot stronger (fracture strength) than perspex so is much more durable for windows and easier to work with(used for riot sheilds). If you can find off the shelf parts, it is deffinately worth it. To many problems and head aches doing it yourself. If you cant find the parts off the shelf try a Polycarbonate windows supplier and ask them to make them for you (make sure its a fixed) price)

[Adam43]

I was quoted £160+VAT to make our windows. However DIY allowed us to do it for £60 (including buying a new Jigsaw!).

We did a good job, but I guess pro windows would be better.

When in use, polycarbonate has the advantages that Carlos says, but is a little more difficult to keep a good finish on. Not a major issue, but it doesn't buff up like glass! I think it is a also a little lighter.

[StephenRae]

Falcemob...Lexan is one trade name for polycarbonate...if there are any companies near you who make guards for church windows they usually have lots of odd shaped offcuts.

[zefarelly]

I was quoted 180 for poly carb, I took the glass to a local glasier and got them made for £60. the only trouble is it scratches, even when wiping it with a soft rag !!! it also cracks quite easily, but if you catch it with a small drill bit in time its ok !

[Tim Falce]

Originally posted by zefarelly
I was quoted 180 for poly carb, I took the glass to a local glasier and got them made for £60. the only trouble is it scratches, even when wiping it with a soft rag !!! it also cracks quite easily, but if you catch it with a small drill bit in time its ok !

Scratching isnt realy a problem as bits of perspex don't seem to last that long on my car

[thebear]

Originally posted by falcemob
Scratching isnt realy a problem as bits of perspex don't seem to last that long on my car

Most side windows in commercial busses are made of polycarbonate (PC). It is of a grade that has been treated to be `mar resistant' and works extermely well.