Fantastic advice. Answers a question I've had for a long time. Have you done any casting resin curing this way? I'm looking for a way to cure water-clear casting resins at low temperatures. The typical process (if you talk to the "deal toy" guys) is 6 atmospheres of pressure in an oven, with about 2 hours of 375 degrees (F) along with some gentle ramp up / down time. They seem to de-gas using pressure, not vacuum. Supposedly some dental molding processes use a UV process instead of heat. I'm trying to come up with a process that I can do myself that will not require excessive equipment or hazard. Any thoughts are appreciated. Alden Danny Miller wrote: > Lemme tell you EXACTLY what to do. > > Go down to Hobby Lobby and they've got these clear hard plastic > containers with a hinged, rubber gasketed lid. The hinge is made of > bent chromed wire and forms a wire bail latch (snaps down, like a lager > bottle). They're fairly thick and I believe acrylic. > > Drill a hole in the bottom of the container. Get a big rubber stopper- > bigger than the hole, it's not going to stick in there like a stopper- > drill a hole all the way through that, jam a barbed hose coupler in the > rubber, and connect your hose to it. Remove the wire latch/hinge and > discard. > > Set the lid on the table with its gasket. Put your target item on it. > Set the container over it as a "bell jar", it's upside down so the hole > in the bottom of the container is at the top. Put the rubber stopper > with the vac hose sticking out of it over the hole and it will seal > itself tight. In fact you don't want the stopper to be permanently > attached to the jar or you'll need to find some other way to break the > vac to open it because that lid ain't separating from the container. > This way, you just grab that rubber and peel it sideways to pull it off. > > I vacuum urethanes, silicones, etc that I'm making like this to de-gas > them. You really need a clear chamber for that because if you pull vac > too fast they expand wildly and overflow a container even 5x bigger than > the resin in it. > > Just what are you trying to do, anyways? > > Danny > > Rich wrote: > >> Thank you for the reply, Marcel. I need a glass or steel bell Jar with a >> vacuum pump But your approach is certainly creative. >> >> ----- Original Message ----- >> From: "Marcel Duchamp" >> To: "Microcontroller discussion list - Public." >> Sent: Friday, November 21, 2008 12:23 AM >> Subject: Re: [OT] Bell Jar >> >> >> >> >>> Rich wrote: >>> >>> >>>> I am looking for a very low cost bell jar and vacuum pump. Does anyone on >>>> the list have one that they would like to sell? I don't expect to pump >>>> down to ten to the minus 6 torr. But I want to get down to the lowest >>>> possible pressure (below 100 u) >>>> >>>> >>> Depending on what you need it for, you may find a pressure cooker works >>> for you. I used one for several years and you can probably find them in >>> second hand stores. New ones are probably in the range of $20 to $40 or >>> so. >>> >>> For mine, I used a canning pressure cooker that is something like 12 >>> quarts in size. A little vaseline on the edge and a rubber gasket >>> between that and a slab of 1" plexiglas for a lid will seal the deal. >>> >>> A hole was drilled and tapped and a plastic hose barb fitting for the >>> vacuum hose was inserted with teflon tape. Not quite as nice as a real >>> bell jar but it worked perfectly for de-airing two part RTV rubber for >>> mold making. >>> -- >>> http://www.piclist.com PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >>> >>> >> >> > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist