Tag Archives: 52 Lasers

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!

121: Anodized Aluminum Moai

When Jen and I were first researching buying a laser, we didn’t plan on buying the one we ended up with. We were looking to get a small, semi-portable solution. But my brother Johnny found a family out in Terre Haute, Indiana, who had owned their laser for about a year and realized they weren’t really using it as much as they’d like and they wanted to sell it. Buying the used laser meant I inherited some of the previous owner’s mistakes—like a damaged lens and rulers that had art engraved on them—but I had plenty of time to cover up those mistakes with my own.

One of the benefits of buying used is that the previous owner didn’t need their material stock anymore either. Bundled with the machine were dozens of small samples of various laser-ready materials, including a piece or two of black anodized aluminum. I dug up one of those old pieces while cleaning out the office, and realized that I hadn’t spent much time engraving on the medium, so I decided to give it a try!

I’ll probably never find out who these two are, but I’m sure they had fun engraving this picture!

This piece of anodized aluminum had a remnant from the previous owner: an engraving test of their own that they didn’t keep. It also had one corner clipped off, so maybe the leftover engraving I have was a test run and they kept a more successful engraving. Either way, the laser is way too low-power to actually cut through this metal, so I’d be limited to engraving the surface. I don’t have the tools necessary to cut this into a better shape, so our two buddies will, for the time being, remain a part of this experiment.

Full color, desaturated, and then inverted so that it would engrave properly.

I settled on a picture of the large moai head Jennifer took some years ago. This picture converted into black and white really well, and as you have to with all materials that engrave from dark to lighter colors, I had to invert the picture so that the laser would fire on white, not on black.

My first engraving test was too powerful: I typically use 35% power to lightly engrave surfaces, but the laser overpowered the black, creating a blown out image. I settled on 20% power—recommended in the laser driver’s settings for this medium—and the contrast was much better. That’s what I get for ignoring Universal’s built in material settings!

Because it only took one pass to get an acceptable result, I decided to use this project to compare a few of the settings available in the driver. When engraving art that has shades of grey, the machine has to dither to convert those to art it can engrave. The machinist can choose to have the laser convert those shades to a patterned halftone, use an error diffusion method, or use a threshold to convert the art to black and white. You can also select from seven different Image Density steps; the lowest step is the quickest and skips the most space on the material between horizontal lines, and the highest takes much longer and leaves very little space between each pass. The difference between those settings is pretty remarkable, but I didn’t want to do seven passes for each, so I decided upon odd numbered settings.

In the end, I made a matrix of engraving settings: each row is a different Dithering option, and each column is a different Image Density. Twelve engraving passes later, here is the result.

The full grid of engravings. Most of the difference in detail is lost in these photographs.

As expected, the image density settings took different amounts of time to finish. Density 1 took only 47 seconds to complete. Density 3 took 2:08, while the default density setting of 5 took 4:10. The maximum density setting took a whopping 15:13. Since the engraving speed isn’t really affected by the dithering option, the results were almost identical down the columns.

Lower density engravings make the dither pattern more obvious.

It’s clear in person (and less so in this photography) that error diffusion is the best option to get a good clean photograph engraved onto this medium. I’d be willing to bet that will be true for most materials, as the halftone pattern (while great for low color artwork) just doesn’t blend a photograph’s natural shades well. This is even true in the lower image density settings.

While the dither pattern all but disappears at image density 7, the time spent is too costly.

I think the default image density setting, 5, was well chosen. It’s an excellent middle ground between the time spent and the resulting image. You can’t really get a sense that the image is comprised of multiple horizontal lines like you can in setting 3, but you’re also not spending 15 minutes on a 2″ by 2.25″ photo.

118: Crackers

Full disclosure, guys – I did not expect this week’s experiment to work.  I figured in the worst case, it would satisfy a curiosity, and I’d get to eat hand cut homemade crackers with dip.  Ryan, on the other hand, didn’t know why I was questioning it, and thought cutting cracker dough with a laser would be a low power, simple task.  The answer was somewhere in between.

Simple ingredients, simple recipe!
Food blogging, here I come!

I’ve never made crackers before, but I had everything on hand in my bare cupboard for this recipe from The Kitchn.  As suggested, I mixed up the dough, then split it in half before rolling it out.  I took advantage of the two batches to come up with two different designs (which Ryan graciously vectorized for me.  I admittedly started this project a bit late in the evening and need help.)

Rolling it as thin as possible – the dough is springy, so you can’t work it too fast. It needs to “rest”
I layered the dough on parchment paper, and on wood.

My goal for rolling out the rough was to keep it under 3mm, 1.5 ideally.  The thinner the dough, the crispier the cracker.  I rolled it out on parchment paper – food safe, and bad things wouldn’t happen to it in the laser, just a little singeing.  I then put it on some plywood for stability, and to prevent the laser from reflecting back after it hits the honeycomb bed, which might not be the cleanest.

Pro tip: I learned when rolling out the second batch of dough that it was actually easier to roll the dough between two pieces of parchment paper when it got thin.  It was easier to flip, it seemed to spring back less, and it stayed moister while I worked with it.  I did remove the top later of parchment when I put the dough in the laser.

Test cuts – third time is the charm!  Interesting thing about cutting the dough – it was a little “sparky.”  Naturally dough isn’t homogeneous, but instead a mixture of ingredients.  The laser reacts differently to this ingredients, which created tiny little light flares.

 

Less than 3mm thick, I’m thrilled!

So, I didn’t think the laser would cut the dough at all, Ryan was thinking it would be a breeze – maybe akin to paper.  It took a few tries to get though the dough, and the right answer was some there in between – we cut at 100% power, and a slow 8% speed.  I didn’t roll it perfectly evenly, so the dough was thicker in some parts, but it still all cut.  And my test measurements were all under 3mm thick!

Heart shaped vent holes – totally a pain in the butt.

The first design was this funky hexagon shape, with little 1mm hearts cut in for venting, so the crackers wouldn’t puff.  Officially, the design is too complicated.  The outer shape is fine, but the hearts took too long to cut, and didn’t come out easily.  I actually baked the hearts in place, and then Ryan popped them out after.  And the length of time tried out the dough quite a bit since we had to have the exhaust on.  with set up, test and cutting, it was in our windy laser for about 45 minutes.  The edges of the crackers were trying to curl up!

Triangles!  Classy appearance by my phone.

Second batch we went a little more simple – a nice rounded triangle with asterisks cut for venting.  They ended up delightfully mod looking, and in were in and out of the laser in under 15.

Light toasted!

Baking is pretty straight forward, but the crackers are easy to burn as you can see.  The first batch were a little extra crisp, but edible.  The second back felt under done while they were still hot, but after they cooled they were perfectly crispy.  So, watch them closely, and make sure you let them cool, unless you are going to a crispy-chewy combo.

Midnight snack.  Homemade crackers, but I totally bought the artichoke jalapeno parmesan dip, the leftovers of which had disappeared by morning.

Verdict – The recipe was tasty but be forewarned, the crackers themselves were not airy or flaky.  They were dense, and reminded me of pita chips actually.  I may have over kneaded them.  This is a fun example of too much tool for the job – a knife easily cuts the dough.  But this would be a fun recipe to perfect for fancy dinner parties, potlucks you want to impress at, or those times you want a crunchy snack and don’t want to leave the house.

117: PC Case Engraving

To ring in the new year, and celebrate the ten year anniversary of my previous build, I decided to build a new PC. Back in 2007, it was two years before we even started playing with lasers. This time around, I knew for sure I’d be laser engraving some piece or another. I’ve engraved a few macbooks and other portable devices, and I’ve even engraved a custom wood faceplate for a friend’s ATX midtower. So I’ve been pretty excited about the idea of engraving something on my own machine!

Over a few weeks in January I did the research, collected the parts, and then planned a small “build party” with some of my local PC enthusiast friends so we could put the machine together together. Hey, it only happens once a decade or so, that’s a pretty good excuse for a shindig, yeah?

From left to right, Brenn, Jen (<3), myself, Maul, Ray, and Mark. Also not pictured: Maul’s bro Joe! Thanks for the photography, Mark!

Together we had dinner, built the PC, played some couch games, and mulled over a few remaining questions. What should this new build be called? What part of the case will be laser engraved? What are we going to engrave on it? I was so wishy-washy on the name decision that I couldn’t even settle on it before the party was over. Furthermore, I wanted the engraving design to be related to the name, so I couldn’t really come to any decisions on that front, either. But we were able to figure out what part to engrave, and as it turned out, the answer was nothing.

Fractal Design’s Define C case is sexy, but made out of questionably engravable plastic.

The Fractal Design Define C is a sexy, sexy midtower ATX case. I love the shroud, I love the quiet, and I love the flat textured front. I like simple, unassuming case designs, and I wanted to continue down that road after my last build in an Antec P180B. But when we finally dug into the case, I learned a few laser-unfriendly things I could probably have sussed out from reviews online if I had been more thorough.

The front of the case is not an anodized aluminum plate, and it’s also not easily detached from the surrounding plastic chassis that covers the front exhaust system. It’s made out of the same plastic—it’s very pretty, with a subtle vertical brushed texture, but it’s still just the case plastic. Because the textured surface isn’t repeated anywhere on the inside (or indeed on any other external surface) I wasn’t going to be able to do an inconspicuous engraving test. So I wouldn’t be able to engrave the front plate, but what about the window?

On a quest for extreme sound dampening, my previous PC build didn’t have a window at all. But over the years I’ve kind of missed being able to peek in on my parts, so this time I bought a case with built-in acrylic window.

With a power shroud for modesty and excellent cable arrangement, who wouldn’t want to peek inside?

Unfortunately, there wasn’t going to be an easy way to test that material inconspicuously either, and with the  engraving quality difference between cast and extruded acrylics, I didn’t want to gamble.

When I looked closer at the acrylic window, I noticed there was a lip on the inside, one that would fit a secondary piece of acrylic just fine as long as the measurements were correct. So I did a couple of sizing tests with some old pieces of acrylic, got my measurements spot on, and settled on a solution: cut a separate piece of cast acrylic and snap it into the existing acrylic window. I wouldn’t technically be engraving the PC case after all, but the finished piece would still look as good. As a bonus, I’d be able to easily change out the acrylic in the future if I wanted to change the design.

Amusingly enough, it was mulling around design ideas that led me to my final decision on the name of the machine. I’ve always been a fan of the Metroid series, you can see it in some of my other projects. Most game servers I host have names based on “Maru Mari”, and you’ll be connecting to “Varia” if you try to stream content to my television. I had a feeling I’d end up going with the Metroid theme again, but it wasn’t until I thought about how much fun it would be to engrave the cold steel corridors of Tourian into acrylic that I really landed on it.

The full map is too big; I’d have to fit it in this cyan rectangle

Tourian is a big map. Well, it’s not big, but its hallways are long and the vertical shafts are all a daunting climb. I’d have to compress the map pretty significantly to make it fit the relatively tiny space I had for my acrylic window. To make matters worse, halfway through the design I realized I had laid out the template wrong and was designing for the measurements in landscape instead of portrait. But after cutting a few rooms in half (and completely excising the hallway before Mother Brain’s chamber) I was able to make it fit.

The final compressed map, corrected to a portrait aspect.

I added a few additional details (the opening text scroll and an excessively big title in the original typeface in the corner) and the design was finished. I cleaned up the acrylic, seated it in the window’s lip, and used a tiny bit of clear packing tape on the inside corners to make sure it wouldn’t somehow come loose.

A mockup of what the case might look like with the final design.

The panel looks great when it’s not connected to the computer, but as it turns out, I should look into buying some motherboard-powered LED strip lighting to brighten up this design. Most of the photography here is cleaned up to make the engraving visible, but it’s much more subtle than that when properly installed on the PC.

This door is all that’s left of a completely deleted room. Don’t tell the purists!

The end result may be disappointingly dim, but I still had a blast manipulating the Tourian map in a way that wouldn’t compromise the basic layout, and I will definitely be using what I’ve learned on this project to make some more “window inserts” for this case in the future. Once it’s lit up, the design itself should really shine, but for now it still makes for some pretty fun close up photography!

The engraving fights with the inner bits just a little more than I’d hoped.
I love that the escape shaft coincidentally has its own murky yellow and green lighting.
This example clearly shows how dim the engraving is compared to the LED-lit components inside.
A two character 8 segment LED readout hides in Tourian’s O.
One Metroid, permanently frozen.