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Forming a round domed crystal.!

Posted: Sat Nov 03, 2018 6:00 pm
by divine
To refine my crystal making techniques I chose to make a replacement for one of my A-11's. The advantages to the round shape are its symmetry and the ability to use the bezel to help form the domed shape. For these simple round crystals I use light bulbs that closely match the radius of the dome. For more complex shapes, if I'm lucky I have the old crystal to use for a mold. Otherwise the search for a surface to mold against can take more time than the actual production. In the future I will be experimenting with shaping the mold from epoxy or clay or another suitable material. The surface must be smooth as the concave inside of the crystal is difficult to shape and polish. The material I use is acrylic sheet used for picture framing. You can buy it in large sheets and in various thicknesses. I use small picture stands made of folded sheet and shaped to slip in a photo and set on a table. They are about 2mm thick and have enough material for 8-10 crystals for $.99. Holding the blank in a pair of forceps, I use a heat gun to bring it up to temp so its floppy but not melted. Then I place it on the bulb and press it down with the inverted bezel as shown.
Crystal Military 1.jpg
Crystal Military 1.jpg (240.87 KiB) Viewed 2220 times
When it cools you have a piece that looks like this. If it's not fully formed you can reheat it and mold it again.
Crystal Military 2.jpg
Crystal Military 2.jpg (275.29 KiB) Viewed 2220 times
All that remains is to cut the blank out and shape it to fit the bezel opening. The bezel in this case leaves a handy ridge that defines the edge of the crystal. I use various cutting burrs and sanding drums in my Dremel grinder for most of the work. Just work slowly as you approach the final shape. The edges can be worked down to taper the crystal profile or rounded and polished. Using a thicker stock will allow you to contour the top surface to match the original more closely.
Crystal Military 3.jpg
Crystal Military 3.jpg (258.72 KiB) Viewed 2220 times
For square or rectangular crystals you can't use the bezel to form the dome. I have used another piece of acrylic with a same shaped hole in it to press down on the edges of the heated blank. This works for relatively simple shapes that curve in both directions.

Things I'd like to try:
Holding the heated blank in a frame that would allow it to be pulled down over a raised mold.
Molding round crystals which change curvature at the edges or have vertical edges.
Molding shaped crystals that curve in only one direction and have vertical sides.

Re: Forming a round domed crystal.!

Posted: Sat Nov 03, 2018 6:59 pm
by JerseyMo
sounds good but were are the pictures?

Re: Forming a round domed crystal.!

Posted: Wed Nov 07, 2018 3:51 pm
by 441victor
The missing pictures are what happens when someone copies one of your old posts and pastes it as their own. ... 81&p=38172

Not a nice thing but maybe divine doesn't know any better or thinks us old men have lost our memories as well as our minds. Joel

Re: Forming a round domed crystal.!

Posted: Wed Nov 07, 2018 6:28 pm
by JerseyMo
no school like old school :lol: