Ultrasonic drilling combined with hard abrasive powder can efficiently bore through any brittle stone or crystal regardless of the material’s toughness or hardness.
Any size hole or shape can be created in stone given the size of ultrasonic machine, energy supply, knowledge of metallurgy, and fabrication.
The ultra-fast aggregate removal created by ultrasonic drilling creates precision holes and machine marks.
Ultrasonics can create round and oval shape holes to the more complex shapes such as squares, triangles, and stars.
Soldering many tubes to a single horn allows for multi drilling in one continuous motion.
The range of materials easily drilled include shell, mica, gypsum, limestone, obsidian, sandstone, nephrite jade, slate, silicon, volcanic tuff, granite, basalt, chalcedony, crystal quartz, kyanite, topaz, beryl, and corundum.
Materials slower to drill include amber, gallium, and any soft amorphous material.
Star shaped drill holes are smooth and uniform inside. The shape of the metal drill tube dictates the shape of the hole.
A star drill hole having an internal twist where the lobes or points uniformly rotate within the stone is the direct result of a twist made in the metal drill tube during fabrication.
A twist in a metal drill tube is caused by forcing a work-hardened round metal tube through a drawplate’s shaped hole.
The pressure and stress induced on the tube when entering the drawplate causes the tube to turn or twist when exiting.
Annealing or heating the tube before stressful shaping through a drawplate will stop the turning action and keep the tube straight and non-twisty.
The end of the metal tube slowly disintegrates as the tube drills through the stone.
As the star portion of the metal tube disintegrates from drilling, the tube slowly transitions its shape into the round portion of the tube leaving a drill hole that is part round and part star hole.
Ultrasonically created drill holes and drill cores have a slight taper.
The entrance hole in ultrasonic drilling is wider and becomes smaller as the tube pushes forward within the stone because there is less room for the tube to oscillate side to side.
The brass tube is not directly scraping the rock, the hard silicon carbide (hardness 9.25) is the cause of aggregate removal as the oscillating tube grinds forward.
The vibrating metal tube scrapes the abrasive powder in water (slurry). The water enables the hard abrasive to stay between the rock and tube at all times.
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