Installing perspex (plastic) windows

[mtnbikepoacher]

Hey all,
I made the mistake of going the cheap route on buying plastic for my windows as acrylic was half the cost of Lexan.
When I went to drill into the window that took me an hour to shape and fit, it shattered (better now than on the track).
So I'm trying to figure out how to attach the windshield and avoid this happening again.
Is Lexan the same as Perspex? It's the popular plastic to use here in the states.
Is it able to be drilled better? Should I avoid using a drill at all and find another method of fitting it?

Thanks
Alan

[forum_admin]

Perspex and Lexan is the same, trade names for polycarbonate..

as for drilling, often a good item to blunt the tip on the bit a little and slight blunt the cutting edges... stops the bit snatching..

also a blob of washing up liquid helps for lubrication.

Si

[benwick3]

Perspex and Lexan is the same, trade names for polycarbonate..

Sorry Si but thats not quite true. Lexan is a polycarbonate as you say but is coated to prevent breakage. It is supposedly bullet proof and is used in riot shields. Also, unlike perspex it does not easily scratch. It is extremely bendable but don't try to bend using heat as perspex as the coating goes milky.

It is also considerably more expensive than perspex - a piece large enough to make a screen for my Clan was around £80 a couple of years ago if I remember correctly.

Al,

To prevent further problems with shattering I would go for Lexan, dispite the cost, but I would always use a laminated windscreen.

Pete Richards

[forum_admin]

Perspex and Lexan is the same, trade names for polycarbonate..

Sorry Si but thats not quite true. Lexan is a polycarbonate as you say but is coated to prevent breakage. It is supposedly bullet proof and is used in riot shields. Also, unlike perspex it does not easily scratch. It is extremely bendable but don't try to bend using heat as perspex as the coating goes milky.

Al,

To prevent further problems with shattering I would go for Lexan, dispite the cost, but I would always use a laminated windscreen.

Pete Richards

Cool you learn something everday!

I got some plastic windows from plastics4performance, thay have some sort of coating - I will look on the backsheet for a name.

Si

[sunstrip_steve]

Yeah polycarbonate rules, its dead strong......

[mtnbikepoacher]

Now that I have figured out how to drill it and what material is best, I need to know a good way to seal it.
My attempt to use clear silicone was a major mistake. The crap is everywhere.
I'm trying to avoid using the origial seals since they are rather heavy and more useful on road going cars.
I suppose for a start, I should get a second set of hands to install the windows...
Thanks
Al

[imull]

if its cracked, its likely that you have gotten a build up of heat due to friction of the drill bit.

some fairy liquid as suggested or go slower. I cut my plastic windows with a table saw so it is possiblr

[SuperSport]

Al,

Have you looked at your local DIY stores for the solution of the window fixings ?

Over here in the UK,, we use a perspex for secondary double glazing at home. This concept has been developed over the past few years and now we have a two part system that can best be described as a clamp channel.

I can direct send some email pics of the item in question if it would help.

By the way, I take it that this is for track work, which windows are you using perspex in and are there regulations as we have in the UK for their installation

Blond by design

[SuperSport]

It is also considerably more expensive than perspex - a piece large enough to make a screen for my Clan was around £80 a couple of years ago if I remember correctly.

Al,

To prevent further problems with shattering I would go for Lexan, dispite the cost, but I would always use a laminated windscreen.

Pete Richards[/quote]

Pete, what is the implications about replacing door and side glass with Lexan ? Are there any problems ?

BBD

[mtnbikepoacher]

Thanks for all the IMPut. (I know I spelled it wrong...)

After playing with diferent materials, I can to these findings.
Lexan is great. Easy to saw with a jig (saber) saw, and super flexy. I took a section that I cut of and could almost fold it without it even thinking of cracking. If I tried hard, I may have been able to put a crease in it, but it would be difficult.
The Lexan sheet cost about $65 US for a 36" x 48" section that was about 3/16" thick. It was a super pain to install with a windscreen gasket. It kept wantig to straighten out when trying to flex it into place. It passed the race test, and the 80 mph tow-behind-the-trailer test without it poping out.

Acrylic is brittle crap... I finally figured out how to cut it without it cracking the wrong way. Heat up a putty knife or gasket scraper red hot, then drag it along the line you want to cut on. Melts like a hot knife though butter... kinda smells like menthol oil When drilling the stuff, I found that heatinf the drill bit and drilling very slow with light pressure wirked well, but then I would crack the stuff when crewing a fastener though it... leave it for complete windows with no holes.
I only used the acrylic for the side rear windows. It was cheap, and didn't require any drilling as I used the window gaskets.
I still am thinking about the rear windows. They are really heavy. I may try and make a frame out of small aluminum and attach one of the plastics to it... Kinda retain the hatchback aspect... I found that crawling through the rollcage with 2 rigid mounted race seats requires a healthy diet and Yoga lessons, so getting at the rear area is a pain and needs a hatch!

Cheers,
Al

[Gin Man]

I have to make a rear screen for a G15 it has a slight roll on the outer edges [not top or bottom], I was proposing to form with heat with a hot air gun, I understand that one form of plastic sheet can be formed this way ? {Acrylic?/ polycarbonate? or what ever the common name is ] any suggestions??. I have a cracked glass screen as a pattern.

[Meltdown]

In the UK perspex and polycarbonate are two different things, both fairly easy to cut/drill with care but perspex will shatter and does scratch easily. Polycarbonate is reputed to be 250 times stronger than glass for the same thickness. UK motorsport regs stipulate that a laminated screen must be used up front but a minimum thickness of 4mm plastic can be used on the sides and rear.

Keep an off-cut to hand for testing any anti-mist/rain repellant product before applying it, my polycarb side windows would go cloudy if I were to use Rainex.

[ImpManiac]

^^ Wisdom.

Perspex is a trade name and the material name is poly(methyl methacrylate) (PMMA). Polycarbonate is an entirely different polymer with quite different characteristics.

IM