Making a Clear Canopy
Pattern Home Page | Rudder | Max Points in Novice | Contests/Results | Rebuild Fiberglass Fuse | Building Techniques | Glasses | Fuel Facts | Links
This discussion came from the web site firstname.lastname@example.org (To subscribe to the list send an email message to: email@example.com and in the subject line of the message put: subscribe).
I'm intending to use Jellutong timber. This is a very tight grained timber (and easily carveable).
I have used custom wood, a fine particle board used in Kitchen and bathrooms. After sanding, the grain needs to be filled. I used an Automotive sanding primer, didn't even bother with a top coat. The plug is not directly heated so no special coatings are needed. I think the plastic I used was called P.E.T G, it worked really well, I had to buy a full 1.2x2.4 meter sheet of it, this will last about 10 years! It wasn't that expensive though. I bought it from a plastic specialist who said it was the stuff to use. Patrick Neal New Zealand.
I used wood that was easy to carve (anything that is easily carved will do). Simply use auto spray putty or primer to fill the grain and minor imperfections and sand smooth. The better you are at sanding the smoother it looks. We got 8 canopies done for the Flamingo and didn't pull of any spray putty. The day before Willie tried to form one without sealing the grain ie" barewood "and it looked awful( a grainy textured canopy-may be your into that effect, it looked ok except it was textured). I will check on the plastic we used. It was not PVC. A friend of Willies who does vacuum forming for a living knows what plastic to use for this purpose. I could also ask what the pros use to form on . The size of you canopy will be important as you need to select the right thickness of plastic. Obviously the deeper and bigger the canopy the thicker the material needed. Make the block a bit bigger than what you will be drawing to so that you will have the same thickness all around the edge when you finally trim the canopy off. Let me know what size canopy you are making. I have some leftover plastic and can give you a rough idea of the thickness if it is about the same size as the Flamingo canopy 35cm*10cm*10cm--used 0.6-0.75mm thick sheet. Will contact you with the info about what the plastic is called. I have a Typhoon canopy and the thickness of the unstretched sheet is similar. Regards Hanns Lim
The wood you are using (Jellutong timber), makes a great plug for making the tooling for a vacuum formed canopy. but not the best material for vacuum forming--If you are only after a couple - read up on drape forming---The best material currently available is PETG-- If you are after a quantity, send the plug to a professional vacuum forming operation -- Lanier , for example. Dick Hanson
There's a couple of ways you can do this. First, if you want to spend the money, there is a special casting epoxy you can get from CIBA-Geigy that's made for making plugs. It's a high temp type of epoxy, with metal filler in the mix to spread the heat evenly through out the plug. But, it is a bit expensive. And you have to by it by the case, which is a mix of hardener and resin. The case will run you over $100 US. The other way you can go, is to head down to your local arts and crafts store, and pick up a product called casting plaster, or casting stone. For a one off project, this may be the way to go. Or you can just carve a plug out of basswood, then use wood filler to get the surface grain filled, then cover with about 7 or 8 coats of clear dope, sanding with 600 grit between each coat. After the last coat is on, let it harden for a few days, then take some rubbing compound for the final polish. I use .040 PET-G for my canopies. You can order the small sheets from someplace like Acu-Vac, or any of the manufacturers of vacu forming machines. Otherwise, you have to order the plastic in 8 foot sheets. Hope this helps. Mark Wendt
You don't need to do any finishing on the plug it self, since it is not going to be heated at all. I usually make my plug from cherry wood and make it smaller by the thickness of the material used to draw the canopy. Draw your first canopy and leave it on the plug. This now becomes part of your plug and will give you the smoothest surface possible. Apply some wax to this. Now you can draw as many canopies as you need. You will get good, clear canopies. Hope this will work for you. Karl G. Mueller
Pattern Home Page | Fourth Control | Max Points in Novice | Contests/Results | Rebuild Fiberglass Fuse | Building Techniques | Fuel Facts | Links