ORIGINAL: Larry S
Well,
I gave it a try and only ended up ruining one large sheet of plastic. I use PETG, 020''. I had enough to try three times. First one I had it in the oven where it was drooping down some, then put it over the plug with the vacuum on. I ended up with a piece that had folded in a couple of place in the front of the canopy and wasn't quite formed all the way. Next sheet I tried, I let it droop to much and it got on the tin foil in the bottom of the oven. Third and last sheet I raised the frame with the sheet higher, let it droop more then tried that. When I went to put it on the plug, it again folded is several places. Seems it will fold nice over the top of the canopy but won't around the front of it. Any ideas??? I ordered more plastic, I won't give up to easly.
Larry
Many times, the front of the canopy needs to be elevated relative to the rear of the canopy so that the 'folds' (webbing) don't occur. This occurs because the PETG isn't being stretched locally. Imagine wrapping a sheet of paper over your knee. In the oven the PETG should sag then retract a 'smidge' indicating it is ready for the forming process. Another thing that is helpful is to 'deepen' your plug with something like balsa. Glue your mold to it then 'fair' the extra material as if it were an extension of your plug. That reduces webbing. I have a small vacum former (10x14) but am going to build a bigger one because I am building bigger airplanes, now. I speak from experience and not anecdotally!
I fixed the spelling from the 'fair' to then 'fair'...