Thermoforming A Curved Acrylic Hatch

[SV Siren]

I would leave the paper on until it needs to come off. Let us know how the cold farming goes. In a previous lifetime I was a plastics engineer that worked at a Thermoforming company. I used to thermoform everything from 10 mm to 60 mm plastics Of all sorts.

[er9]

Originally Posted by Jim Holland

Many thanks ER and Siren for your advice, very helpful. I do have time (I've put a temporary plywood "hatch" on the boat) so am going to try cold bending. Does it matter if the backing paper paper stays on the acrylic during cold bending? Ideally I'd like to keep it on to reduce the chances of getting sealant smeared all over the acrylic during installation. Although I imagine it would need to be removed for bending with heat, so maybe remove also for cold bending? Thanks again.

It would be ok to leave it on unless its going to be in direct sun. If its in a sunny spot, put a thin piece of constuction paper or cardboard over it to keep the sun from baking the paper on.

[Jim Holland]

Thanks, I'll leave the paper on, and report back on how it goes in a couple of months or so. Thank you both for sharing your knowledge and expertise.

[Sailorman Ed]

It would be ok to leave it on unless its going to be in direct sun. If its in a sunny spot, put a thin piece of constuction paper or cardboard over it to keep the sun from baking the paper on.

Not only sun but heat and time can back the paper on. Once baked on, it is not coming off! (I also was/am a plastics engineer in a previous life but only up to 25 mm thick - 100 lb sheet)

[One design]

I'm in the process of fully rehabbing a smaller sailboat.
1 item I'm having trouble with is the board for the sliding hatch.
The plastic panel is ½" thick x. 28 ½" long x 31½" wide.
With a crown of 1" from dead center sloping to side.
I looking for help on doing it cold or heated.

I have access to a commercial oven (deck oven) I can't however use it for the 48 hrs I see for dry time. If that'd be required?

[Pauls]

Forming acrylic is a common process and will work very well when done correctly. As an extreme, and common, example, bubble canopies for aircraft are formed from acrylic by clamping it around the edges, heating it, and then blowing in compressed air under the acrylic, which pushes it up into a bubble. That's why they're called "bubble canopies".

The important thing to do is to heat the acrylic very evenly and to NOT OVERHEAT IT. Overheating will cause bubbles inside the acrylic.

Make a form with the radius you desire for the acrylic. It does not need much strength, but should have a good surface finish. Place your acrylic (a bit oversize) on the form, and heat it in an oven. A regular household oven is fine, if it is big enough. The acrylic will drape and conform to your form. Take it out, trim to final size, and install with your VHB.

I don't recall the temperature to use, it will be available on the web.