How do you make windows?

[gdcd74]

Hi guys, just wanting to know the different methods people use to make clear "glass" for the castings. I dont have a vacuum pump and dont want to go spending that sort of money.
Any suggestions for how and what products to use?

[DavidJohnson]

Further back in this section of The Workbench there is a thread on clear plastic windows.

[gdcd74]

Sept 23, 2008 2:13:54 GMT 1 DavidJohnson said:

Further back in this section of The Workbench there is a thread on clear plastic windows.

had a look and couldnt find, what is it called and what page?
Cheers

[DavidJohnson]

You are in the correct place with this message. Look for "Forming Clear Plastic Windows" on page 3.

[only87]

Casting clear windows should be no problem without a vacuum, but you need a lot of experience in casting and the right mix of materials. And there is the problem, the materials. It's not easy to find a real satisfying clear resin.

You don't necessarily need a vacuum for vac-formed glazing either, a vacuum is only needed for complicated parts. For simple car glazings you basically need a hairdryer, a "male die part" (a solid male mold), and clear blister plastic in the right strenght.
Heat the blister with the with the hairdryer until it gets soft and pull it over the mold. Let the blister cool down for a few seconds and it will keep its new shape.
You will have to figure out the right strenght of the blister material though. If it's too thick, you won't get enough heat to soften it, if it's too fragile the heat will just eat it up. So it has to be somewhere in between. Also note that there is heat-resistant blister material, this is totally unusable.
For the male mold I use some sort of PlayDo clay that will harden if you put it in the oven. It's called FIMO, don't know if you have something similar down under.
To hold the blister while heating it I use two back parts of a small passepartout frame. I cut a small hole (2 x 5 cm, depends on the size of the male mold) in both back panels and clip them together with the frame clips. The blister foil comes between the two panels. I heat the part of the foil that is visible through the small hole while pulling the whole passepartout frame over the male mold.

There are more sophisticated ways of "vac"-forming, but this one is easy for beginners.

You will need a real vacuum if you want to make parts that have a step in it or if you want to include detail like wipers into the glazing.
The basic process is the same as above but the vacuum will suck the air out between the foil and the male mold. That way the foil will smoothly adjust to any shape the male mold dictates.
But for that you will need an apparature that will build up an airproof vacuum underneath the foil. And that is where it gets costy, unless you find one of these children playsets that were produced in the 60's to the 80's. They show up on eBay worldwide from time to time, the usually cost around 30 to 50 USD plus shipping as comlete sets.

[gdcd74]

Sept 23, 2008 3:53:24 GMT 1 only87 said:

To hold the blister while heating it I use two back parts of a small passepartout frame. I cut a small hole (2 x 5 cm, depends on the size of the male mold) in both back panels and clip them together with the frame clips. The blister foil comes between the two panels. I heat the part of the foil that is visible through the small hole while pulling the whole passepartout frame over the male mold.

Didnt really get this bit? What is a "passepartout" frame?

[only87]

A passepartout is the kind of frame you put the pictures of your beloved in to put them on the desk of your office or on the piano at home. You know them.
They are called passepartout, which literally means "one size fits all" because they usually have a darker background so the photo doesn't have to fit the exact size of the frame and it still looks good.
The cheapest ones don't even have a frame, just glass on the front and some sort of corky material back, I think it's linoleum. The glass is held on by metal clippings that can be easily removed to change the picture in the frame. These are the ones I was referring to.
If you have two of them and throw the glass away, you can clip the two linoleum parts together.
You can of course use a different method, this is just how I do it.
I use them because they are cheap (you can usually find them at 2,99 Dollar a piece in shopping malls) and because the clips make the changing of the blister foil very easy if you want to make more than one piece of the same glazing.

[bjorn]

A very, very good description of making "glass" Peter! Thank you so very much.

Björn

[gdcd74]

Thanks for that. Now the mission is to find the transparent film.
I worked out overhead projector film - doesnt work - duh - its heat resistant so when used on an overhead projector it doesnt melt.
I will let you know how i go.
Cheers

[cfesmire]

Thanks for that info Peter. I've been thinking about making a vacuum table ever since I found one of those old perforated air hockey game tables at a yard sale for a dollar. Ah, the days before electronic video games.