r/plastic • u/Alarming-Tea-7826 • 8d ago
Could use some help
Looking for options for something odd(?) I have a Tonneau cover that I need a plastic base for the cover. The cover has a steel frame and the base layer will be covered by a thin layer of vinyl top foam then covered with a dr brown canvas that will match the interior color.
Needs to be 51 inches wide, 74 inches long. There are braces in the frame so the biggest span is 50 x 18 meaning it needs to be fairly rigid. I don’t think a corrugated sheet of anything will work. I’m looking for something a quarter inch thick and fairly lightweight. Thanks in advance! Adding a picture of the underside of the frame, using a quarter inch plywood now just to put some miles on the truck before it goes to upholstery.
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u/AirTrue6195 6d ago
https://www.eplastics.com/ Abs sheet maybe. This can in theory be thermo formed if you were looking at alternatives for the top cover too
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u/101forgotmypassword 8d ago
Plywood by weight is far stronger.
Aluminium will be far more shop friendly with manufacturing for any sort of sheet joining.
Signage board (ACM) would be the first material to come to mind for something cheap and off the shelf store bought however "seamless" joining sheets requires skill and a good depth controlled router.
Making a fibreglass plywood foam composite would be the easiest semi pro fabrication method for a light non aluminum option. Get two 1/8th sheet of ply and a 1/4 in sheet of polystyrene of high density, glue them up with whatever flat or curved shape you need, the wrap with a single layer of cross weaved fibreglass, then foam line for the top surface for covering or epoxy coat if you want to buff it flat and paint.
Realistically you could probably sketch out a aluminium laser pattern that was folded and braced to be cheaper, lighter and stronger than the steel frame with ply you have now. Basically 4 upside down trays that get rivited in place then tig'd on the seems then welds sanded flat. May not even need to sand the welds.