At Last one that makes sense to have the heat below the plastic rather than on top. At least this way you use all the heat as most built one forget heat rises. Great job
Yes ! can be used around bottom edge as the vacuum pulls the sheet into place there is a lot of wriggle room with this build about 20mm extra height at the bottom of plug so the PETG sheet pulls past the wanted edge, use small blocks away from and opposite corners that form a ridge. Use talcum powder as a release agent on the plug, the plug must be very smooth oil covered plugs create bubbles. I use balsa and hard foam plug, pull one canopy cut it out leave in place then pulled over the top.
you could built a pressure switch on the edge of the heater. When the frame with the sheet is on the heater it will start to heat up. When taken away the heater will stop.
I used PETG known by many product names such as VIPET by Mulford Industries. Ordered mine locally from a plastics forming supplier. Comes in sheets 2400mm x 1200mm .75mm thick for around $80. Several thicknesses are available, for my purposes .75mm is ok.
These are two oven elements from old cookers 240v AC direct wired to two 10amp light switches at side so one or both elements can be selected, a safety earth is incorporated and all enclosed - I used the wiring from the cookers. Wired in a 3 pin lead for wall socket. The tin frame is from the cooker back plate with pine board sides. Its not on long so not heating up much. Downside is heat focuses on the centre of sheet and edges are a bit cool, need to heat edges of sheet.
Yes the optical quality is affected but not a lot it depends on the form used, commercial methods use polished aluminium I believe. This method is ok for my needs in aeromodelling. Don't know - only used .75 mm thick PETG but I think it will handle thicker, difficulty is the centre gets hotter, and getting the edges warm enough, I use a heat gun at the edges, forming this way will show up every speck of dust or hair on the form or sheet.
Fascinating, and very informative, thanks. What's the maximum thickness of plastic you can form using this method? I want to make a protective cover for something, and would ideally want to use 3mm thick plastic.
brilliant piece of work!! my frames will be build before night what kind of vacuum pump were you using Also what thickness plexiglass were you using? and where do you get it in Australia?
Ozzie, Good job. I gather it was your first attempt. I made something similar before I researched it. I will vid mine when I have the system set up correctly. PETG is porous believe it or not so make a top for your heater box (or use an oven) I use a piece of ply covered in foil. PETG needs to sag at least a couple of cm's before moving it quickly to the plug. A heat gun set to 180C gives best results applied directly after you place the sheet. Point it into the corners you need extra attention on. If you can heat your plug to about 100C this also helps. don't turn on the vac until after you have placed your PETG. PETG will pick up any inconsistencies in the plug to 0.01mm so talc would not be a good release agent. I would use a car polish or fibreglass wax. There are hundreds of good videos on how to do all this.
you look like good ! make a video of your technique with the heat gun ! I use A4 sheet for cover file !! the result isnt bad but I have sometime some folds in corner
I watched your vid again and it occurred to me that you might be able to make a vacuum formed canopy over the original molding and then using it's smooth qualities make ANOTHER vacuum formed canopy over that and the optical qualities might improve further. Nice styling in your plane, by the way.
Just a suggestion about the heat distribution problem: try lining your heater box with alluminum foil to reflect the heat around the box equally rather than let the coils focus it upwards.
NICE VIDEO !! but how can i make a heater box like yours.. can you please tell me how to connect the wires, etc. to the heating elements.. Can you please tell me.. or a video of making a heater box would be nice to..
hi, i have also a vacuum just like yours, but my plastiek canopy is not so transparent as the original. there are here and there some tiny air bubbles in the plastic after vacuum draw. Do you have also that reslut? I think I should experement with other plastic ...
Hi! I'm impress with your set up!!! I'm interested to learn how you wired up the heating elements. And if you used the controls from and old stove.Hope to hear from you soon!
That was done very neatly. Nice home-built vacuum kit you have. DId the heat or other activities affect the optical qualities of the plastic sheet that you used? 2nd Question; How thick can you can with the plastic to get accurate forming? Thanks. Sydney.
Please, Please, Please, how would you like to make a windshield for a Dave Patrick Cub? They are not producing planes and this is something that no one is making. One guy did, Aerotech, but I called him today and he said that someone bought all his stuff. I know there are about 3 or 4 other guys looking for these windshields.
You are entirely too big to fit inside the glider. So I must assume you are going to put squirrels in the glider and let them fly around. I would recommend flying squirrels they have a lifetime of experience at gliding. They would make the perfect pilots for your glider.