SURFACE ENGRAVING USING A HAND DRILL
The tools that are used to engrave this way are rotating diamond, stone and rubber burs which are fitted in the Handpiece of an electric drill either by tightening a Chuck or by Twisting the Handpiece to open & close the Chuck Release. The engraving isn't very deep so the best way to engrave something is to only engrave the light areas in the image. All of the dark or black areas will remain clear.
INTAGLIO OR DEEP 3D ENGRAVING
Intaglio engraving is where the engraver cuts deep into the glass with a drill or copper wheel engraver to produce a 3D image effect. This is dependant on the thickness of the glass but the deeper you can go the better the effect will be although this takes a lot longer to engrave the results can be quite stunning.
This is where the engraver will build up an engraved picture by engraving tiny dots wth a diamond bur or tungsten point.
Sand carving is where an image or design is cut out of a mask which is then placed over the glass or sometimes it is cut out afterwards. The rest of the glass is then covered to protect it and the areas of the cut out are blasted with sand in a sandblasting unit before the mask is removed and he glass is then cleaned.
I use a combination of all four of these technques to create my enrgavings or use each technique alone depending on the result that I want to achieve
The use of a Handpiece is often called 'Flexible Drive Engraving' which refers to the type of drill typically used. The flexible drive hand drill has a flexible shaft running from a pendant motor has a high torque. I use both flexible drive and electric hand drills to engrave my work. I'm used to calling my hand drill a handpiece but that's a result of working in a dental laboratory for 32 years.