Introduction: Laser Cut Double Sided Wooden Doorknob Hanger

About: I'm currently experimenting with hardware and woodworking projects at TechShop SF that help me to reduce anxiety.

The background: I want my roommates to know when I'm meditating, so that they know to give me some time to emerge from my room and to be more mindful with their own noise levels. At night, I also want them to know when I'm sleeping, as I tend to sleep earlier than most. My solution is this double-sided doorknob hanger!

In this instructable, I'll walk you through the process of preparing the file, cutting the hanger, and finishing it. If you don't have access to a laser cutter and would like a hanger like this yourself, you can get one at my Etsy shop.

You'll need these supplies:

Step 1: Step 1: Prepare the File

You can download the hanger template as an Adobe Illustrator file from Thingiverse. Here's what that file contains:

  • A "test" layer. That's the tiny shape I send to the laser cutter for testing the cutting and raster settings.
  • A "front" layer. That layer is the meditating side. It contains text and graphics with a black fill (which indicates etching to the TechShop laser cutter). It also contains the curved outline of the hanger with a .001 red stroke (which indicates cutting to the TechShop laser cutter), and it contains a rectangular outline around that with a tiny notch, also stroked red. When you send this layer to the laser cutter, you'll actually hide the outline layer, as that will only be cut on the back side.
  • A "back" layer. That layer is the sleeping side. It contains the same black graphics and red outlines. However, the red outlines are flipped - they were copied and reflected horizontally from the front layer.

You can modify the graphics as you'd like. If you change the outline of the hanger, like to accomodate a larger knob, make sure that you keep everything correctly aligned.

Step 2: Send the Front to the Laser Cutter

(Hopefully you have already sent the test layer to determine your optimal settings for your particular laser cutter).

First you will print the front side. Make sure you hide the other layers (test/back) and hide the "outline" layer inside the front layer. You should see only the rectangular outline and the inside graphics.

The reason for the rectangular outer layer is to make it easier to register once you're ready to cut the back side. The small notch on the side of that layer is to give you an additional registration point. (It's possible that you can register just as easily with only doing the curved outline, you are welcome to experiment with that method.)

When you position the image in the laser cutter software, take note of the exact X/Y position of the top left corner (which you can see in the image on the right hand side). That will you help you position the back image.

Step 3: Remove and Flip the Wood in the Laser Cutter

Now take that rectangular piece and flip it over.

Step 4: Send the Back Side to the Laser Cutter

Now you'll show only the back layer in Adobe Illustrator, and send every sublayer to the laser cutter.

We already cut that rectangular outline, so why are we sending it again? Because it will make it much easier to make sure we're lining up with the front side correctly. You can make sure the top left of the rectangle is the same X/Y as when you cut the front side, both by checking the coordinates match and by checking the laser is at the corner. You can also check the position of the notch on the left hand side, for a second point of registration.

How can we avoid cutting the rectangle twice, and sending a laser cutter through empty air? On the TechShop laser cutter, I simply pause the job when it's done with the curved outline. It always cuts the exterior lines last, so I know that the rectangle will always be the final path it tries to cut, and I can just end the job prematurely. I even added one additional inner rectangle before that outer one, so I have even more time to pause the job in time.

Another option is to use a different color for the rectangle, and change the manual controls in the laser cutter software to specify 0% power for that color. These techniques may not work for the laser cutter you're using, however, so talk with knowledgable folks if you're unsure.

What about weighting down the cut piece? The second time I cut this, I noticed how wobbly the rectangle was, since it wasn't weighted down. I decided to just cut the rectangle, with weights pushing in at the top and bottom. I can't cut multiple back pieces at once that way, but it does wobble a whole lot less, and I was still able to register it just fine.

Step 5: Pop Your Hanger Out

Congratulations! You've cut a double-sided hanger.

You may be feeling sad about the scorch marks around the hanger. You can avoid that by using blue tape in the previous steps, but I avoid that for waste-saving reasons. For me, the next step is always sanding.

Step 6: Sand the Hanger

Now use a flexible sanding sponge to sand off the scorch marks and brush away the dust after sanding. To avoid sand in your eyes, wear safety goggles or onion goggles (my favorite!).

Start your sanding with a coarser grit, like 80, and end with a finer grit, like 220.

Alternative technique: power up an electric toothbrush with an old brush, put a dab of exfoliating scrub on the brush, and scrub the soot marks away. Rinse it and hang it to dry. Then sand it as needed.

Step 7: (Optional) Finish the Hanger

A nice way to finish wood projects is with a Polycrylic Satin finish. It gives the wood a subtle sheen, plus it adds a layer of protection. Typically, you should apply at least 2 coats. Sand with the 220 sponge after the first coat, to sand away the grain that was raised from the first coat.