Tag Archives: engraving

123: Semi-Precious Stone Engraving

The smoky quartz gives away its engraving with visible lines in the star.

A recent client sent me a few small precious gemstones to see how easily they could be engraved. I did some tests on them, with varying results, and sent them back her way. We went with a really simple five point star to test the engraving quality—with the smallest one just .07″ in diameter!

The tiniest piece, topaz, didn’t seem to show the same engraving pattern as the quartz.

Out of this initial batch, the topaz and quartz both engraved beautifully, but the opal’s engraving was basically invisible. This is probably due to a combination of factors. Opal is completely opaque, so no light can come through the material to highlight engraving. It’s a consistent color throughout, and it doesn’t burn, which means the untouched surface is only different from the engraved surface in texture. It’s very hard to capture in pictures.

This image was processed to try to show off that the opal was engraved. The star is there, I promise! Look closely!

My client received her gemstones back, and made some observations: in one piece, the horizontal lines that make up the engraving (because of how raster engraving works) were visible even at the laser’s highest engraving density setting. She also felt that the engraving wasn’t very deep and was wondering if a deeper engraving would affect the overall quality of the engraving.

Conveniently, I found out that Jennifer had done some tests on gemstone beads before, so we had some quartz of our own, as well as some garnet, to do tests. I became determined to solve these problems and answer these questions without requiring a new shipment of gemstones.

I was pretty shocked to see that the individual lines of the engraving were visible; this is something that happens on lower density settings (like 4, which is used to reduce engraving time but can leave ultra-fine gaps between the lines in certain materials). At the max density, this normally isn’t visible at all. I decided to try to engrave my pieces slightly out of focus, increasing the laser point’s diameter so that each pass overlaps somewhat.

My later engraving tests on beads of quartz and garnet were… less than successful.

As it turns out, though, none of my testing worked quite the way I’d hoped it would. Maybe the gemstone beads’ facets were impeding the engraving, or both of my solutions weren’t solutions at all, but all I got out of six different attempts were excessive chipping and almost unrecognizable engravings.

They’re supposed to be hearts! While I engraved the first batch with stars, I figured hearts would be a good shape for the quartz and garnet beads. I don’t think the shape mattered much in the end.

I engraved three pieces of quartz. From left to right, I gave them one engraving pass, then two, then three, at the same settings I used for the client’s quartz seen above. This time the chipping was so severe that you almost can’t even see the difference between the three tests, but upon close examination the heart that was engraved three times was actually a deeper engraving—completely moot with how poorly it turned out.

For the garnet, I was testing whether engraving out of focus would result in a smoother engraving, and it certainly doesn’t seem to be the case. Perhaps the offsets (focused, 0.5″ out, and 1″ out) were too severe a difference to see any value, but even the focused heart on the left was nowhere near as clean an engraving as on the client’s gemstones.

So I think the moral of these disappointing results is to always perform subsequent tests on the same exact material. I wasn’t able to give my client a good answer to her questions with these tests. Still, I’m fairly convinced now that chipping will prevent multiple passes from getting a deeper engraving without reducing the engraving quality, but the jury’s still out on whether adjusting the focus can have a positive effect. We’ll find out eventually!

67: Rubber Stamps

Sample stamps Jen lent me to compare to the laser-made versions.
Sample stamps Jen lent me to compare to the laser-made versions.

When we first purchased our laser, I poured over the instruction manual, reading every page regardless of how little of it I understood at the time. One of the many modes and features I read about but didn’t really grasp was Rubber Stamp Mode. The name was clear enough, but the description of the mode confirmed that I could process certain kinds of rubber with the laser to create rubber stamps. Years have passed since then, but this week, I finally picked up some appropriate rubber to give my own stamp making a shot!

Early prototypes were 1" tall, far larger than necessary.
Early prototypes were 1″ tall, far larger than necessary.

I decided on two designs, the logo for Pixelaser and the SMAAAASH!! icon from Earthbound. I prepared both in Illustrator and mirrored and inverted the designs so that the stamps would work as expected.  There’s actually a feature in Rubber Stamp Mode that will do this automatically, but it ridiculously considered the entire engraving table’s surface as an area to invert, and it was prepared to spend literally seven hours uselessly firing at it.  Maybe it’s a bug? In any case, doing those steps manually was brief. The laser software handled the rest, intelligently creating a beveled surface around the letters to prevent them from shifting when the rubber meets the paper. The end result reminds me a lot of the 3D mode I explored last year.

The stamps desperately needed to be cleaned after processing.
The stamps desperately needed to be cleaned after processing.

When I ordered the “low-odor rubber,” I also picked up two traditional stamp handles with space for 2″ by 1″ stamp rubbers. Because of this, when I first set out to design my stamps, I created them in the same aspect ratio. This was despite that both designs I wanted to use were less than a half inch tall when two inches wide. This caused issues where the blank area of the stamp would take on ink and then transfer it to the paper—you can see it in the examples below as a black frame around the stamped word. I solved this issue first by significantly lowering the speed of engraving (from 30% speed to 10% speed) and then by reducing the vertical size of the stamp.  It didn’t occur to me until then that I didn’t actually have to cover the entire surface that the stamp handle afforded me.

Final stamp designs before being applied to the handles.
Final stamp designs before being applied to the handles.

Despite some ink coverage issues partially owed to using an ink pad from some untold years ago, I’m thrilled with the result.  I hope Jennifer won’t mind me SMAAAASH!!ing things around the house now.

Plenty of stamp tests. The frames on some of the words are due to shallow engraving and too much white space.
Plenty of stamp tests. The frames on some of the words are due to shallow engraving and too much white space.