Introduction: Press Fit Wooden World Tree Lantern in Walnut
For my earth day weekend I wanted to do a project on the laser cutter. I decided create a wooden lantern out of walnut that would accept a snap clip pendant cord available at most hardware stores. I also experimented with colored paper & veneer.
Step 1: Create Your Vector Files
Use a vector graphics or drafting program to create your vectors. I do a lot of vector work in CorelDRAW, but you can use Adobe Illustrator, or an open source platform like Inkscape. Digital fabrication tools that use a print driver, like most laser cutters, don't allow you to offset for your kerf (the extra material that is burned away by the width of the laser beam), so you'll need to take that into account in your design.
Step 2: Prototype Your Design
I like to run prototypes of a new design in cardboard or inexpensive plywood to validate my joints are working in the way that I expect, & to make sure that my vectors aren't resulting in burn out or other problems you can run into with delicate designs. I decided to run this prototype this model in 1/4" plywood before I tried the solid walnut.
I ran more than one iteration to get the press fit joints sized for the fit needed.
Step 3: Create a Fixture
I frequently create a simple fixture using cardboard when I want to elevate a workpiece above the honeycomb in the laser bed. I can place my material precisely, & the elevation prevents flash back marring of the wood from the flare when the laser intersects with the aluminum honeycomb. It also makes is easy to confirm that the pieces have "dropped" & that I've got a clean cut all the way through my material.
I tape a piece of cardboard down to the rulers in the laser bed, & run a cut on just the outer geometry for my parts. I'll lift out the cardboard lantern parts to create a gap under my workpiece.
Step 4: Test Your Cut Speed & Power
Use a scrap piece of the same material you're going to be working with to validate your speed & power settings for the cut. I ran a number of tests to find the best cut quality at the fastest speed possible. Some material cuts more cleanly using a lower power setting & slower cut speeds.
Step 5: Mask & Secure Your Material
When I'm working with wood, I like to mask off the top surface of my material. The mask will protect the surface from soot & resin vapors produced during the cut process. I also like to secure the piece to my fixture using masking tape. This will help prevent the material from accidentally shifting during the cutting process. This is especially important if I find I need to make multiple passes to get a clean cut.
Step 6: Cut the Internal Geometry in a Separate Pass
I always run all of the internal vectors first. The fixture makes it easy to confirm if the internal designs have completed successfully. The scrap pieces should drop into the well I've created with my fixture. If they haven't dropped, I can run an additional pass. The reason to delay the external geometry is to avoid any shifting of the parts until I've successfully cut the internal vectors. You can see in the photo that my internal cuts didn't drop on the first pass (likely because my test cuts didn't have masking tape...rookie mistake:-)
Step 7: Cut the External Geometry
Cut the other geometry for your piece. The photo highlights why I do this independent of the internal cuts. After a side is cut free, it can shift or tilt. If this happens before all of the internal pieces have fallen, I won't be able to run an accurate second pass on the internal design.
Step 8: Remove Your Parts & Pull Off the Masking
Remove the parts from the bed of the laser & peel off the masking. You may need to use a small sharp implement like a dental pick to weed out small pieces of the mask. Be careful to avoid marring the finish on your parts.
Step 9: Experiment With Light Diffusers
I'm going to experiment with some handmade colored paper & some sheets of wood veneer.
Step 10: Assemble the Lantern
Play with your diffusers & determine which result you like best.