Lexan. Thermal expansion

[Bones]

Soon I will be cutting out the pretend Lexan I have been supplied which is called "Safeguard".

Looking at the protective covering it says to allow 5mm expansion for every metre. (Around 3/16" per 3 & a bit feet)

This sounds ridiculous and if I follow the instructions I will have a noticeable gap.

The temperature here will go from about 0 in winter to about 40 in summer and if Lexan is not subject to this type of expansion I might burn this current Polycarbonate I have and not waste my time.

Anybody have experience with Lexan growing and shrinking in size?

[RandyT]

You don't say what you are going to be doing with it.

They are referring to butt-seaming or placing the edges against immovable objects.  If you don't leave a little space, it will expand with the heat and start to buckle.

All common plastics do this to some extent.  Acrylic is just as bad, and whether you use IZOD, Lexan or any other Polycarbonate, you will see the same thing.

Heck, acrylic is so bad that if you screw it over something to protect it outdoors (like a sign) and don't give it 1/16" of slop around the screws, it WILL crack when the temperature changes.

Just the way it is.

RandyT

[Bones]

I was intending to use it on top of the CP.

Thanks for your help mate.

[Stingray]

The temperature here will go from about 0 in winter to about 40 in summer

What are you building an outdoor cab or something? The temperature indoors only fluctuates by a few degrees. I can't imagine it would be enough to cause any significant expansion/ contraction.

-S

[Veinman]

Where are people finding lexan sheets? They didn't have it at Lowe's. I haven't checked yet at Home Depot or Menard's.

I'm wondering if I'll have to buy it online. I want to use it to cover the top of the control panel when I build it.

[19rjs99]

I have never noticed any problems with my CP for Mame, but I had made a portable Golden Tee a while back. I took it to a party, in the trunk of the car, in the middle of summer. When I got there the Lexan was swollen over the trackball. There was a hump in the middle of the CP. After returning the unit to the house in the Air Conditioning it went away quickly.

Moral: Don't subject it to extreme temeratures. Also Make sure that the Lexan was in the correct temperature range before it is installed.

[NoOne=NBA=]

Lexan IS Poly-Carbonate.
It's just GE's tradename for it.

Likewise Plexiglass is acrylic.

I would just make sure that the bolt holes for attaching it are oversize, and you should be OK for all but extreme exposure.
That will allow it to expand between the bolt holes.
If you make the bolt holes exactly the right size, and cinch them down tight, the Lexan has nowhere to expand, and will buckle, as mentioned earlier.

[Stingray]

Where are people finding lexan sheets? They didn't have it at Lowe's. I haven't checked yet at Home Depot or Menard's.

Look up "Plastics" in the yellow pages. Chances are you'll find several places in your area that sell nothing but lexan/ plexiglass.

-S

[Bones]

The temperature here will go from about 0 in winter to about 40 in summer

What are you building an outdoor cab or something? The temperature indoors only fluctuates by a few degrees. I can't imagine it would be enough to cause any significant expansion/ contraction.

-S

The cab is going in my garage & I just leave the roller door up for my dog. The temperature between the two is not much. Your right though, 0 degrees is probably a 5 degree exaggeration.

In summer it can hit 40-43 degrees at least a handfull of days every year.

That's Oz for ya....

[sodapopinski]

It shouldent be a problem, like randy t said these spaces are recomended for objects placed tight together(ex. vinyl siding). You have one single piece of plexi. I wouldent expect it to be that effected. And, I live in edmonton(not the edmonton down under). are temp fluxes more than 40 degrees celcius. By the way, wife making you keep it in the garage?

[Bones]

By the way, wife making you keep it in the garage?

Not at all....

The garage is my choice.