Tag Archives: glass

74: Rotary Fixture

Last weekend, I snuck a piece of hardware out of Eagle Engraving, Inc. while there was a lull in production. The hardware in question? A rotary fixture for our laser that allows us to engrave on cylindrical objects! I’d like to say they didn’t notice at all, but in reality they were totally cool with it and their resident laser ninja Monica even helped make sure that I had all the parts needed. Thanks again, Eagle!

The rotary fixture, slightly askew to account for the glassware's edge.
The rotary fixture, slightly askew to account for the glassware’s edge.

After installation and calibration, I first ran several tests on a piece of glassware that had sloping edges. Because the engraved surface of the material still has to remain parallel to the path of the laser carriage, I needed to use some shims to raise one side of the rotary fixture until the glassware’s surface lined up with the system.

Several engraving tests on one glass show off how images can be warped by bad diameter settings.
Several engraving tests on one glass show off how images can be warped by bad diameter settings.

The first several engravings helped me determine how important the diameter measurement of the glassware is.  Early on I was imprecise, which resulted in the round “Made in Aurora” logo used for the test appear as an oval.  3.0″ felt like a nice round number, but the glassware’s actual diameter at the center point where I wanted to engrave was actually 2.96″.  That kind of precision was required to prevent image distortion.

A close-up of the Planet Express glass.
A close-up of the Planet Express glass.

I used transfer paper to soften the engraving—several of my previous experiments with glassware showed that glass has a tendency to chip during engraving and create a harsher surface than necessary.  The transfer paper, while troublesome to remove, provided a filter that resulted in a smoother engraving, as visible in the difference between the Planet Express glass and the Shield glass.

A close-up of the Shield glass.
A close-up of the Shield glass.

The final piece we engraved was a red ceramic mug provided by Eagle for testing—it’s pictured in the featured image above, sporting a Hydra logo.  It was much easier to engrave thanks to a consistent diameter across the entire surface of the mug, unlike the glassware.

While Jennifer and I picked up a handful of cylindrical objects to engrave, we were only able to engrave cups and glassware due to an unforeseen lack of hardware: the rotary fixture includes one internal cone that holds the bottom surface of the cup and one external cone that fits inside the open top of said cup. You can use two internal cones to hold shapes that don’t have open tops (like the drum sticks I wanted to engrave!) but we didn’t have those handy.

Three round logos done right!
Three round logos done right!

While I’ve had to return the rotary fixture to Eagle since then, I do look forward to “stealing” it again in the future and, possibly, owning my own down the road.

 

 

34: Votive Holders

Here's a votive holder at the wedding reception itself!
Here’s a votive holder at the wedding reception itself!

I have a long and slightly bitter history trying to laser-engrave glass. The back of my old iPhone 4 wasn’t having it, and the fire flowers I tried to cultivate didn’t quite pass muster. Still, when a friend wants some glass engraved for her wedding, I’m certainly not going to turn her down!

A single lonely votive holder.
A single lonely votive holder.

Lara and Paul got married on August 23rd, and to celebrate the occasion, Lara wanted some personalized votive holders to give to guests as wedding favors. With a simple, clean design based off of her wedding invitations and website, my only concern was whether the glass she sourced would fight with me as much as my fire flower vase did. The votive holders she chose were also coated in a blue surface material, so I had some new concerns about whether the laser would properly burn away the blue.

A closeup of the engraving, featuring a right-facing flower!
A closeup of the engraving, featuring a right-facing flower!

As it turns out, I had little cause for worry. Not only did the glass etch beautifully with only a few test engravings to get the power settings right, it also cut clear through the blue, creating an excellent contrast even when viewed through the other side of the glass. One technique for engraving glass that I learned about after my previous attempts involved dithering the engraving slightly by marking locations to engrave with a dark gray rather than black proper. While this results in a slightly less detailed engraving, it reduces chipping, which was an issue I ran into a lot with the fire flower vase. In this case, though, I didn’t have to dither the engraving at all!

The cardboard template that allowed 20 votive holders to be processed in one pass.
The cardboard template that allowed 20 votive holders to be processed in one pass.

There was a gross amount of votive holders to engrave—literally 144—so I made sure to take what I learned about templates and I was able to process 20 at a time. This would make the project take far less time than processing a single glass at a time. It also allowed me to more easily implement one design element: a flower mid-piece that either faces left or right. In the design file for the template I whipped up, ten votive holders would feature right-facing flowers and ten would feature left-facing flowers. It’s a neat way of achieving balance that would have been nightmarish processing one holder at a time.

I come away from this week’s project definitely feeling better about working with glass, but I’ve surely got a lot left to learn, and a whole rotary engraving attachment still to acquire!

A nice stack. Don't light them in this configuration.
A nice stack. Don’t light them in this configuration.

19: Fire Flower Vase

My first attempt at etching glass was a hint of things to come.
My first attempt at etching glass was a hint of things to come.

“Well, that didn’t work,” ended my first foray into laser etching glass. I tried to create a design similar to the mesmerizing microscopic pattern found on the back of the Nexus 4 smartphone, this time on the glass back of a spare iPhone 4 that my nephew graciously donated for the cause. The resulting pattern was too big and the laser settings weren’t appropriate, making each vector line look more like a coincidentally straight shatter line rather than the light-reflecting divot I’d intended. I’ve shied away from etching glass since, and after this week’s project, I’ve realized I’ve still got a lot to learn!

Make sure to level the surface you want to etch!
Make sure to level the surface you want to etch!

While I’m doing general graphic design at Eagle Engraving in St. Charles, IL, my coworker and fellow laser ninja Monica is often etching all sorts of designs into glass. I’ve been envious lately of her knack for making designs spring forth from glass, and while I don’t yet have the rotary attachment necessary to etch round objects—like pilsner glasses—I did have a square vase conveniently made of mostly flat glass. Because the sides of the vase were tapered, I had to prop up the bottom side so that the surface was parallel to the laser plane. I ended up using a box of dialog boxes and a handy level to double-check my work.

The two designs chosen for etching were, perhaps, too many shades of gray.
The two designs chosen for etching are another sign of my Nintendo upbringing.
The lightest halftone didn't etch consistently. It almost looks like frost.
The lightest halftone didn’t etch consistently. It almost looks like frost.

The first etch was cut with the default raster etch density (5) and the grayscaled art above. I went with full power and full speed just to see how it would turn out, and the lightest halftone didn’t play well with mostly flat glass, only mostly etching. Apart from that, this turned out to be the single best contrast out of the set of four etches I made. The second etch, at maximum density, was overkill; the raster lines were so close together that wiping down the surface flaked away a lot of the glass, as shown below.

Etch glass at too high a density and much of it will chip and flake away.
Etch glass at too high an Image Density and much of it will chip and flake away.

 

The lower image density didn't help prevent chipping. Maybe the halftone was too dark.
The lower image density didn’t help prevent chipping. Maybe the halftone was too dark.

My third fire flower was etched at a lower image density. While this prevented chipping, some tinkering with the halftone patterns resulted in even more chipping in a much more widespread way. While the contrast was improved from etch two and nearly as good as etch one, the damaged areas really stand out. Who can guess where many of these tiny glass slivers are?

I had to cut at least one Super Mario World flower.  I settled on the default image density again after the tweaked results were poor, and while he’s still hard to see thanks to haphazardly adjusted gray levels, you can still see how much more personality he has. That just won’t do—he’ll only last another game or two, anyway.

Look at that smug bastard.
Look at that smug bastard.

I might have to table glass etching again for a while; I was unable to achieve satisfactory results on this particular piece. Still, I’ve since had a chat with laser ninja Monica, about her own tricks for getting better results on glass, so you can be sure you’ll be reading more about it here in the future!