Simple Laser Cutting Project Worth its Salt

I’ve finally gotten a break from making wedding ring boxes and have time to start working on other projects. I’m a bit late in posting seeing that it’s February, but I hope no one is salty over it. As such, I’ve decided to make a simple guide on how I typically go about my laser cutting projects these days, and the project is salt-related.

I’m using the free program Inkscape to design my project because I heard from people on forums it’s easy to use, has a large online community for support/plugins, is good for laser/vector work, and it’s common knowledge that everything you hear on the Internet is true.

I started by choosing an image that I wanted to engrave into the project. I used an image of the viral sensation #SaltBae. By the rules of the Internet, this is no longer hip since it’s about a month old now, but I’ve been busy so cut me some slack. Paste the image, right click on it, and click “Trace Bitmap.”

The Trace Bitmap tool allows you to convert a raster image to vectors (more info on raster vs vectors). The only setting that needs to be tweaked is the “Brightness Cutoff.” This value represents at what brightness is the threshold between what should be represented as filled vs blank space in the resulting vector. Checking “Live Preview” lets you gauge what is a good value.

After applying the Trace Bitmap command, it might look like nothing happened because the resulting vectors are aligned directly on top of the original bitmap. You need to move the resulting group of vectors off the original bitmap. Double clicking on the newly created group of vectors allows us to see the vector points and make modifications/cleanup/retrace if necessary.

To plan the dimensions of my box, I usually use the ultra-scientific method of holding my hand up to my nearest measuring device. In this case: the ruler of my Leatherman Wave multitool.

Prior to this I installed the Lasercut box extension into Inkscape. This extension is accessible through Extensions->Render->Lasercut Box. Simply plug in the parameters of my material thickness and desired box dimensions.

The resulting box pieces come grouped, so I Ctrl+U’ed it to ungroup. I then rearranged the pieces so that it was clear to me where the top/bottom of the box was. I’m making a box that is meant to open on one side, so I deleted one of the pieces.

To flatten out the tabs that were automatically generated for the top side of the box, I selected all the “side” pieces of the box and used the “Edit paths by nodes” tool (highlighted below). Then I made a box selection around all the segments I wanted to modify (highlighted in blue).

To make sure the nodes aligned when I modified them, I selected the”Snap cusp nodes” alignment option (highlighted below). Now when nodes are moved, they automatically snap to other nearby nodes.

I replaced the deleted lid with a plain rectangle that was slightly larger than the rest of the box. This gives space for grip and hinges. I drew out a square with random dimensions and selected it. I then entered the dimensions I actually wanted for the width and height for that square.

I wanted to make sure #SaltBae was centered on the lid, so similar to before, I enabled “Snap an item’s rotational center” before moving him over.

Added a few holes for where the hinges were gonna go and my work in Inkscape was pretty much done. Here’s where the lovely quirks of the K40 laser I’m using come into play. I have a love-hate relationship with this laser cutter, but I value my relationship with my wallet more, so I deal with it.

I found that the proprietary circa-early-2000’s Corel Laser software that was bundled with and mandated for my laser cutter setup read the .wmf format most reliably, so I exported the finished project in that format. Why didn’t we just design the entire project in Corel Laser in the first place? Because Napoleon Dynamite isn’t in theaters anymore and software has come a long way since then. I’m saving you some hassle here by recommending you just pick up Inkscape. It’s important to change the line width of everything imported into Corel Laser to “Hairline.” If you don’t, the laser will try to each line twice, once on either side of the line, resulting in overcooked, thicker cuts.

Time to engrave. Another quirk when using this laser is that no matter what you select, it will plan out the cut job relative to that selection only, not the entire page. What this means is if we just select #SaltBae, he will be engraved too far up and to the left. To resolve this, we create a small “anchor point” that we will include in all our engravings and cuts. This is nothing more than a tiny square that you put in the top left corner of your project that I probably should have just done in Inkscape but I forgot.

Selecting both the tiny “anchor point” and the image, hit engraving.

In the Engraving dialog, we can see #SaltBae positioned correctly, with empty padding to his top and left. The “anchor point” is there too, but hard to see. Had we not selected the anchor point, #SaltBae would be further left and up so his bounding box would’ve aligned with the top left origin instead. Important settings here are for the Pixel option to be 1. If set higher than 1, the laser would skip some pixels between cuts.

Time for the cutting. I selected everything including the “anchor point” I made earlier, and deselected #SaltBae by holding shift while clicking on his handsome curves in the object manager. Then I clicked on the cutting tool next to the engraving tool.

I find I get cleanest results using multiple passes at a lower power setting. For this material and my current setup, it’s gonna be 8 mm/s with 2 passes. There’s a “Repeat” field shown here, but it’s a trap because it requires you to hit “OK” to a dialog between each cut. Instead, we will select “Add Task,” bring up the cutting dialog once more, and then press “Starting.” This will allow the laser to perform the tasks without asking for permission to continue. A speed of 8 mm/s @ 12 mW does the trick for 5.2mm plywood on my machine.

On to assembly. After all the faces of the box were stained and glued together, I needed to add the hinges. This is where I realize it probably would have been easier if I just used thicker wood, but I wanted to burn through my thinner plywood stock. I improvised by using stiff wire fashioned into staples to affix the hinges to the wood. It looks as if I meant to do that from the start.

“The mark of a good maker is his ability to improvise.”
-Neon Penguin

Well I hope you enjoyed this quick tutorial! I have a few things cooking up in the lab, so stay tuned for the next project!

Like what you see? Please spread the word :)