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Cutting laminated windscreens
Jeffers_S13 - 15/1/08 at 01:36 PM

I need to trim about 1/2" off each side of a laminated windscreen and then re-radius the top and bottom corners.

Has anyone done this successfully ?

Can I simply score both sides then cut through the film with a sharp knife ?

How can I radius the corners ? I know you can get glass grinders for making lampshades etc but Im going to need something a little more substantial.


jabs - 15/1/08 at 02:12 PM

Have you tried a glaziers. My local one cuts laminated glass and has all the gear for polishing the edges


billynomates - 15/1/08 at 02:18 PM

Seen it done on 'Overhaulin', they score the glass and then poured lighter fluid on it, which they then set alight to melt the laminate. They had to do it a few times to trim the window to just the right shape.
Sounds simple enough, but I'm sure there's quite an art to it.
Local glass suppliers may be a safer bet.


BenB - 15/1/08 at 02:48 PM

http://www.secondchancegarage.com/public/149.cfm

might help................


Mr Whippy - 15/1/08 at 03:54 PM

interesting but having watched twice a guy making new screens first for my Falcon and then later for my buggy both times it took three attempts to cut the glass, I don't think he made a penny in the end.


tks - 15/1/08 at 03:59 PM

all i now is that it depends on the layers the screen has.

also its best to be a plane window.

i know that with waterjet cutting its a easy job.

and for manual glass-plastic-glass is the best bet.

Tks

p.d. a Fiat Panda has a plane front window


minitici - 15/1/08 at 05:42 PM

quote:
a Fiat Panda has a plane front window


I presume that was the original Panda?

If so would an sva inspector notice that the 'E' markings were for a slightly different size screen if it was cut down?

I ask - since I have an early, un-registered kit car which requires a flat screen, this always seemed like a stumbling block with the sva. (car has a windscreen aperture therefore can't just not fit a screen for sva).


BenB - 15/1/08 at 06:19 PM

Doesn't the E-marking just relate to the type of glass used IE its not shape / size specific. So if the glass is E-marked and you've cut it down it shouldn't matter. Anyway, I doubt the SVA man will measure the screen and go away and see how big that particular windscreen should be....


Jeffers_S13 - 16/1/08 at 12:42 PM

Thanks for the link, I notice that is on a single plane screen.

This is a curved screen, I need 1/2" takign off each side to get it to fit the screen aperture.

I spoke to a glazier and he said it would need to be ground, and 1/2" isnt really feasible as it would take hours and hours of work because the wheels arent very coarse and they will clog with the plastic film.

He thinks cutting isnt an option on curved screens due to the changes in tension as you go around the curve. Im keen to have a go though ! just out of interest to see what happens.

Im thinking that cutting/scoring on each side is still an option though as it will be a straight cut and then the corners could be ground to curves again.

Im looking for someone thats attempted it either successfully or not

Thanks

James


iank - 16/1/08 at 02:37 PM

When they were building minisprints (mini's with a couple of inches taken out of the pillars and waist) the success rate for fitting the cut down the screens was around 75%.

Here's the website of the guy who had the job.
http://www.statim.co.uk/Minisprint.htm

[Edited on 16/1/08 by iank]


Delinquent - 16/1/08 at 04:54 PM

Couple of things to note -

1. you'll have a FAR greater success rate using a brand new screen than on an old one - I'm told it's because the glass gets brittle with age.

2. Don't expect a very high success rate if you're doing it yourself

The score both side & lighter fluid seems to work well, but you need to get the scores accurate, don't let them stray off course.


Jeffers_S13 - 18/1/08 at 01:50 PM

Thanks for the replies and the link to the minisprint, interesting stuff. Ive ordered a few bits and bobs from ebay and have a couple of methods to try, I'll let you all know how I get on.


Jeffers_S13 - 31/1/08 at 10:50 AM

As promised, here are some results !

I bought a few different tools from the usual online outlet that has everything All of them were only a few quid each so I thought they'd be worth a try. Couple of days later I had a door mat covered in A5 jiffy bags.

Diamond grit ceramic tile cutter

Diamonator glass cutter, scorer

Diamond grit grinding wheel for glass and stone grinding, I thought this would be useful for finishing the edges.

And a nail file...no actually its a diamond grit sharpener of the cheapest nastiest variety !


I wasnt holding out much hope for the disc cutter and thought Id have better success with the glass scribe and the lighter fluid method.

I got a knackered screen to practice on. Scoring curved glass at the exact same place on both sides is DIFFICULT ! It seemd to work ~OK if patience was used, I scored both sides and used some big pliers to crack the glass, it cracked along the seam of the score quite well but in a couple of places some of the cracks extended into the area I didnt want cracks, these would only get worse once on the car I think so I gave in at this point and didnt even attempt to put solvent or lighter fluid in to melt the plastic.

I then tried the disc cutter. Quite surprisingly this thing cuts through the glass and laminate like butter, totally awesome speed. I was expecting it to be a really slow process. But at cost of leaving a very nasty chipped edge on the underside :



Similar to using a jigsaw on plywood without scoring the cutline with a Stanley knife first. So, perhaps you could score a line with the scribe thing and then use this I thought.

I then lopped off a corner of the scrap screen with the disc cutter so I could try the file and grinding wheel.

The file does a pretty good job and removing the uber sharp edges...BUT the grinding wheel is something else, its truly awesome. I tried to 'tickle' the edge but it just eats into the glass much like the disc cutter. Its amazing.

I instantly marked up the actual screen I wanted to cut :



I found that working from the outer edge and gently pushing the wheel up to the line worked great :


Hardly any effort is needed, it just munches the glass. I did this in about ~30 seconds (?)



The picture doesnt show just how neat the edge is, no cracks just a smooth~ish edge, very accurate and VERY quick. The tiny strip of plastic looking stuff is just some window glue/seal that was still on the screen I was modding. The grinding wheel turns the glass and plastic laminate to powder, I wore breathing mask and goggles. I did the whole screen in about 30 mins. Which was about 3/4" strip on both sides with rounded corners.

The wheel was starting to get blunt by the end but they're only a few quid each, two would have been ideal but I was impatient. I finished the edges to an even better, more smooth finish with the hand file thing.

Job done.

I hope someone else finds this useful.

James


Delinquent - 31/1/08 at 11:54 AM

cracking effort mate, well done!

I'd be interested in hearing how that holds up once in the car, if any cracks start spidering out once it's in use.


Jeffers_S13 - 31/1/08 at 01:19 PM

Yes, me too !

It'll be a couple of months before it gets bonded in but I will try and remember to post how it goes once the car has had some use

James


mad4x4 - 30/4/08 at 06:49 PM

quote:
Originally posted by tks
all i now is that it depends on the layers the screen has.

also its best to be a plane window.

i know that with waterjet cutting its a easy job.

and for manual glass-plastic-glass is the best bet.

Tks

p.d. a Fiat Panda has a plane front window


A Landrover Defender has a flat window cost about £45 New and are Laminated......


ghetto_eddie - 1/5/08 at 08:32 AM

quote:
Originally posted by Jeffers_S13
Yes, me too !

It'll be a couple of months before it gets bonded in but I will try and remember to post how it goes once the car has had some use

James


James, Seen as though this post has been resurected..

How was the screen when fitted to the car? Did you have any problems?

Edd


Delinquent - 1/5/08 at 09:24 AM

quote:
Originally posted by ghetto_eddie
quote:
Originally posted by Jeffers_S13
Yes, me too !

It'll be a couple of months before it gets bonded in but I will try and remember to post how it goes once the car has had some use

James


James, Seen as though this post has been resurected..

How was the screen when fitted to the car? Did you have any problems?

Edd


Glad it's been resurrected, could really do with tapering down the screen I'm planning on using from about 30mm at the top


Jeffers_S13 - 20/11/08 at 05:16 PM

Its still not in ! we are back on with the car again now though hopefully in time for next season. We ended up buying a makeshift car for the this year so our new one got neglected. I WILL reply when its done !


ashg - 2/10/13 at 05:39 PM

if you want a perfect edge do the same but run water over it at the same time. its messy but the results are even better. we have done this a few times with great success on my mates american trucks when they had their roofs chopped. also we tend to use an air powered die grinder with a smaller diamond blade.