Forming Plexiglas

[Pearson]

I have found a powder coating guy that said he would let me try my plexiglass project in his oven. So that may be the best way for me to go. I am doing more than just bending the forward edge of the plexiglass. I am trying to put a bulge in the center of the entire piece, which will be about 35" square. The two side edges will have a curve to match the upper surface of the wing. The front and rear edges will have a very slight curve to match the piece of wood that goes horizontally across the top of the cross tubes of the fuselage. Then, aside from those curves along the edges, I want to blow a bulge across the entire middle area that extends upward between 2 & 3 inches. It sounds like some very interesting info in the book that was mentioned. I will have to investigate the various temperatures mentioned. Anything I can do that reduces the chance of ruining a piece of this plexiglass will be well worth the time and effort. Thanks for all the great ideas.

[Felixp51]

I formed the windshield for a Merlin GT over a round piece of wood.
I used a Heatgun ( One like to strip paint with ) to heat the plexiglas.
Just heat the area and slowly bend the plexiglas a little at a time.
Make sure not to overheat and don't try to bend it to the final shape
at once.
Worked great for me !

[David Bally]

My uncle, see ( Bally 1/3 B-17 G ) "blew" the nose for his project. We had done some trials with scrap plexi and found that it did not need to be very hot to be quite flexable, but it cools to quickly to work a big enough piece. As the plexi absorbs moisture, if it gets too hot small steam bubbles will appear. So he made a female mold with pin holes for a vacuum. The oven was coriggated sheet metal insulated on the exterior with fiberglass, with an oven element to povide the heat and a pyrex baking dish as a window. He clamped the plexi to the mold and placed it on the oven. When the plexi was heated till it was sagging he applied the vacuum and sucked it up into the mold. A couple of trials and errors-salad bowls he has a nice looking nose.

[Pearson]

Do you recall how thick the plexiglass used was? Did you take any temperature readings to tell how hot it was before the plexi started flexing?

[WLIU]

I will suggest that the manufacturer of the "plexi" will have that data online somewhere. I quickly googles "plexiglass properties" and came up with http://www.plexiglas.com/acrylicshee...ata/properties

If you know the specific manufacturer of the "plexi" that you are using, look up their web site for the exact data that you need. I will note that "plexiglass" is the common name for clear acrylic plastic. Search using that name also.

Best of luck,

Wes

[David Bally]

Was out of town over the weekend but stopped by Jack's last night. It was almost two years ago that he did the nose but he recalls the thickness was 3/ 32". He basically made a giant heat gun that blew the heated air on to the acrylic for more even heating. He used a laser thermometer and recalls the temp was about 275 although the readings where very inconsistant for some reason. He orignally heated the mold but found better results by not heating the mold. His grandson has set up a website http://www.theballybomber.com with pictures. This project has been the most educational he has ever done, the basis of EAA. Good Luck Dave

[Pearson]

David,

I checked out the website. Looks like an interesting project. I think I am going to build a jig with an air line hooked up to it, and heat the whole thing in a friends powder coating oven. I am trying to minimize the number of wasted sheets of plexiglas. I have already checked with the manufacturer and they say I need 300 to 325 degrees to blow it. I am only trying to put a nice gentle 2.5 to 3 inch bulge in a 3 foot square piece of glass. I too am out of town, so it will be awhile before I can do anything. Thanks for all the great ideas everyone.

[jollydowsen]

A fellow in Kitplanes, a few months ago, made bowed side windows for his plane in his wifes' oven. He built an extension to the oven box with simple materials and was pleased with the results. Probably had the temp info you require. Sounds similar to the suggestion above for Swift Skylights. Good luck! Link attached.

hey friend if you want o change your oven please visit : http://www.thertastore.com a lot of economy range is available.