Re: [PSUBS-MAILIST] Acrylic Molds

[DJACKSON99@aol.com]

Dan

I think you are addressing by problem on bending 1" Acrylic.  The manufactures actually have formulas for temperature and heating area and method based on the thickness of the sheet. ChemCast is the best I have seen. (www.chemcastacrylic.com/technical/mx4.htm)  I was planning on building an narrow oven that has two pieces: one on top of the sheet and the other under it, and long enough to extend over the edge and be joined together.  Likely a plywood box like Doc describes but with an electric element and thermostat so I can better control the long heat up and cool down cycle required for the 1" Acrylic.  Maybe I can use a metal rod and a battery charger for the heater, and I can rig a thermostat to my PC and have it turn the AC to the charger off and on as needed. A small fan with the motor outside the oven and metal blades inside might keep the temperature even too.  It would make a great dehydrator when I'm done! Jerky anyone?  

Other Ideas?  

End View    _______
Oven Top    |     |
Sheet ==========================
Oven Bottom |_____|

Side View  ____________________________
           |                           |
           |  ======================   |
           |___________________________|


Thanks for you input.
Doug Jackson
             

In a message dated 1/8/2003 7:28:30 PM Eastern Standard Time, JMachine@adelphia.net writes:

> Doc,
> 
> I made a bend like that one time, but the plexi wasn't that thick.   Mine
> was only quarter inch.
> 
> I did the bend by laying the Plexiglas flat down with the bend line hanging
> off the end of the work bench.  I ran a horizontal steel rod a few inches
> under the sheet and hooked the ends of the rod to a welder on really low
> amperage.  The rod got hot and heated the Plexiglas directly above it in a
> straight line.  It got pliable above the hot rod. Be sure to keep the height
> of the rod even and don't work in a draft.  It has to heat evenly to bend
> evenly.  With your thick stuff you may want to make shields on each side of
> the heat rod so you don't heat two wide of an area if you want a tight
> radius bend.
> 
> Hope this helps,  Dan H.
> 
> 
> ----- Original Message -----
> From: <DJACKSON99@aol.com>
> To: <personal_submersibles@psubs.org>
> Sent: Tuesday, January 07, 2003 11:11 PM
> Subject: Re: [PSUBS-MAILIST] Acrylic Molds
> 
> 
> > 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-altug
> lass-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
> >
> >