Re: [PSUBS-MAILIST] Acrylic Molds

[DJACKSON99@aol.com]

A+ for the oven description.  Thanks Doc.


In a message dated 1/8/2003 4:56:41 AM Eastern Standard Time, doc@bionicdolphin.com writes:

> Hi guys, just got in, I've been out exploring in the boonies around here.
> 
> I'll put together a drawing of the backwoods acrylic oven soon and post a link.
> 
> The basics of it are simple, picture a shoe box the size you need without the lid, line it with
> aluminum foil using double faced tape around the edges then stapled through the tape and foil.
> Now in the side cut an inspection hole about  1/4 of the way down and centered, 6" X 10" and
> cover it with 1/4" plate glass.
> At the bottom of the 2 ends cut several small breathing holes and a heater access door.
> Place your heater in the center of the box and build a metal rack that is about 3" higher than the
> top of your propane barbecue (without the legs) or propane heater, and place a sheet of 1/8" aluminum
> or sheet metal, (somewhat larger than your heat source) on the rack to evenly distribute the heat throughout the box.
> Around the top edge on the outside of the box attach a framework of 1x2 or or angle iron (bed frames work nicely)
> to clamp your former sheet and acrylic to. And finally, mount an oven thermometer on the wall across from
> your inspection window.
> 
> Now here is where the different techniques determine which way you need to go. For AquaNuts we really only
> have two choices ambient or 1atm. If it's non structural you can blow it, if it's structural it should be draped which
> will require a male mold, coffin like handles clamped along the sides of the acrylic and a few strong helpers.
> 
> To blow mold requires a box top of sturdy plywood with a air fitting centered and countersunk flush on the bottom
> side and fitted with a shut off valve and quick connector at the top side. Around the bottom border attach a gasket of
> weather stripping.
> Now with another sheet of plywood cut out the shape you want to make but make it a bit larger than the planned finished
> part. Paint the top side around the cut out with polyester resin or primer/ surfacer about 3-6" wide and sand smooth.
> Then polish with 2 or 3 coats of a good automotive car wax.
> 
> Your acrylic sheet will now be sandwiched between the former sheet and the top and secured firmly with either clamps
> or preferably bolts and wing nuts.
> 
> Now light up the ol barbecue and place your wood and acrylic sandwich on top of your box and secure it to the flange at
> the top of the box and you're cookin!
> 
> At around 175-300º F (depending on the thickness & particular properties of the acrylic used) the plastic begins to sag,
> this is where you begin to add a little air pressure (on large canopies you can draw your projected profile with a permanent
> marker on the back wall of the box as a reference), slowly increase the air pressure until the plastic is just slightly larger
> than spec and turn off the heat while maintaining your pressure and let slowly cool.
> 
> That's about it.
> 
> To make a simple bend you just need a strip heater available at most places that sell acrylic, solvents and tools.
> Or if you're really good and quick you can use a heat gun,,,,, I'm not!
> 
> I hope this helped, I'm off to dream about my next baking soda and vinegar powered Psub! Night all.
> 
> Doc
> 
> Reference;
> http://www.plaskolite.com/fabguide/pg11.pdf
> http://www.chemcastacrylic.com/technical/mx4b.htm
> www.tapplastics.com/plastics/ plasticsinfo/hi-acrylic.html
> www.sdplastics.com/acrylit1.html
> www.sunlight-tech.com/acrylic_tech_data.html
> www.manufacturing.net/esec/Article_85859.htm
> 
> 
> DJACKSON99@aol.com wrote:
> 
> > Doc
> >
> > I need to bend a 35 degree turn in a 1 inch thick sheet of Acrylic that is 4 feet by 4 feet. I found a couple of helpful web sites (below) but I'd really like to see a photo and description of your oven.
> >
> > http://www.chemcastacrylic.com/technical/techinfo.htm
> > http://www.bayplastics.co.uk/product%20guide/Altuglas-guidenavbar/prod-altuglass-tech(bending).htm
> >
> > Please keep it online.
> >
> > Thanks
> > Doug
> >
> > >Mark;
> > > I've done considerable research and testing on different ways to form
> > > acrylic in the barn, from gravity to blow molding to drape forming of
> > > up to 1 inch thick over a male fiberglass mold. For blow molding or
> > > gravity forming, you can coat your separation points (ring) with a
> > > layer of epoxy resin or gelcoat and a thin coat of car wax. You can
> > > build a 4'X8' forming oven out of plywood or chip 
> board, aluminum foil
> > > , a piece of 1/4" plate glass and a propane barbecue!
> > >
> > >Doc