Can anyone direct me to some proven and valid threads\posts for bending and forming single foam sheets of XPS?
I have tried laying up\forcing a 2.0# EPS parabolic and did not let it set up\cure long enough and experienced “springback.”
Ironically enough the nose was the only problem i.e; needed more lift as the tail maintained the proper rocker contour and turned out good. I have glued\laminated XPS sheets together then hotwired the rocker and outline profiles. After the constant battle with the “glue lines” while shaping and finishing I am back to bending the correct thickness sheet.
Does anyone have any developed techniques to share for stringerless single sheet forming to a rocker profile?
I have heard of using distributed weights along a preset rocker heights (fixtured) while either a.) using heat guns in the localiized areas needed for setting contour. b.) placing the fixtured foam in bags and setting in the sun for hours. c.) placing fixtured foam in an +110 degree enclosure (like a convection oven) for days to allow for thermal cycling to occur.
Which method works best for single sheet forming of XPS??
Heres a few pics of the board vacced down to a rocker table getting both the top and bottom skins epoxied on with a layer of glass between the foam and the skins.
Pampano, I loved how you and J’esus have developed rocker, set it and forget it . . . . . let the negative pressure and adhesive bonding do all the work on conforming the foam to the rocker. One point of clarification to take into account is that I have made the second outline, deck and bottom cuts to eliminate the resistance from the unused bulk out of the blank. Any other points on how I can get the blank\sheet to relax from resistance and “No Stressss” would be appreciated.
I’m not sure how you could get it to release and hold shape uniformly. I know everything will try to cold flow over time. I would think that heating an insulator like foam is an uneven process and might not come out uniform. Perhaps if you had an oven it could be done more evenly and help to outgas some. Rocker table in the attic or under a black tarp in the sun with some sand bags?
Stick a fork in it, as I think you just nailed it . . . . . with the combination of both elements!!
Take a formulation of parts as I referenced to in my original thread c.) fixtured blank within a pre-heated enclosure ** --While–** a.) applying direct heat guns onto fixtured blank. After shaping the parabolic I leave the board in the rack and add pre-load with weights to help maintain it’s shape. As you elluded to “everything springs-back after it cools off again . . . .”
Does this mean we need to over contour to compensate for the bend as it cools off to relax and to maintain the rocker profile?