Fixed windscreen - anyone used PETG for a replacement

[Rafiki]

My her forward Westerly Corsair has a fixed windscreen made up of 3 parts in an aluminium frame, the top part of which forms the channel for the sprayhood. The central section is heavily crazed and needs to be replaced. It is slightly curved; width just over 100cm, the middle of which is just over 5cms further forward than the end. It is 8mm thick.

I think originally it was Acrylic ( Perspex). I am told by a fellow Corsair owner who has done the same replacement that 8mm Acrylic will bend cold into this shape, but the resultant stresses can cause the screen to later shatter ( this happened in his case)

I am thinking of using PETG which is available UV stabilised as it appears less brittle and bends more easily without the internal stress issue, but it is difficult to interpret some of the technical data.

So my question is has anyone here used PETG for such an application, and did it work satisfactorily, ie not split or shatter later and not suffer UV degradation too quickly.

Andrew

 

[VicS]

My her forward Westerly Corsair has a fixed windscreen made up of 3 parts in an aluminium frame, the top part of which forms the channel for the sprayhood. The central section is heavily crazed and needs to be replaced. It is slightly curved; width just over 100cm, the middle of which is just over 5cms further forward than the end. It is 8mm thick.

I think originally it was Acrylic ( Perspex). I am told by a fellow Corsair owner who has done the same replacement that 8mm Acrylic will bend cold into this shape, but the resultant stresses can cause the screen to later shatter ( this happened in his case)

I am thinking of using PETG which is available UV stabilised as it appears less brittle and bends more easily without the internal stress issue, but it is difficult to interpret some of the technical data.

So my question is has anyone here used PETG for such an application, and did it work satisfactorily, ie not split or shatter later and not suffer UV degradation too quickly.

Andrew

PETG looks good on paper ( or screen ) but no experience of using it

An alternative is to get a new perspex window cut to size by someone who can use the old one as a pattern to "drape mould" it to shape. I had to do that for two of the cabin windows on my boat.

 

[Rafiki]

Vic,
I have got a quote from one company to mould using the old one as a template, but they said if the material was 8mm thick the new one would be 8mm larger all round. Another company I spoke to said that using the old curved screen as a template wouldn't work as once you placed the hot sheet of new material on the old acrylic the old one would deform - but it doesn't sound as if you had that problem, but maybe yours weren't curved.

 

[pvb]

I suppose you've already asked Trafalgar about it?

 

[VicS]

Vic,
I have got a quote from one company to mould using the old one as a template, but they said if the material was 8mm thick the new one would be 8mm larger all round. Another company I spoke to said that using the old curved screen as a template wouldn't work as once you placed the hot sheet of new material on the old acrylic the old one would deform - but it doesn't sound as if you had that problem, but maybe yours weren't curved.

They are very curved which is why they had to be preformed. They are only 5mm though.

I dont understand why a plastic fabricator could not make an exact duplicate given the old one as a pattern.

Try these people if you want to pursue the idea of pre-forming Perspex

http://www.projectplastics.co.uk/drape-forming.html in Colchester
or
http://www.sunlightplastics.co.uk/about-us/ in Waterlooville
maybe also
http://www.aldaplastics.co.uk/about-us/ in Eastleigh

 

[Rafiki]

Vic, I have tried Project Plastics and if I decide not to go down the PETG DIY route that's who I will go to.
The problem with drape forming on top of the old item you are copying is that you get something slightly bigger - think of using a tennis ball and repeat and repeat etc and you end up with the shape of a football!

Regards

 

[VicS]

Vic, I have tried Project Plastics and if I decide not to go down the PETG DIY route that's who I will go to.
The problem with drape forming on top of the old item you are copying is that you get something slightly bigger - think of using a tennis ball and repeat and repeat etc and you end up with the shape of a football!

Regards

If my replacement windows had been larger than the originals they would not have fitted, but they did!. They were made using the originals as patterns so not the umpteenth generation copy. I can see how that could be a problem. Your window has such a small amount of curvature I'm surprised there is a problem

They were made by a firm in Colchester but I dont know if they are now Project Plastics or Precision Plastic Fabrication who are also in the Colchester area .

 

[Aja]

PETG will scratch very easily. If you are going to get it formed, which is inherently an expensive business, I would go with acrylic every time. Talk to Ian Thomson at QD Plastics http://www.qdplastics.co.uk? He does a lot of this sort of stuff and will point you in the right direction.
Donald

 

[alahol2]

These people seem able to do it... https://www.youtube.com/watch?v=0TOW92869cg