A "marriage of true minds" — Shakespeare's Sonnet 116
Laser cutters vs 3D printers? Subtractive manufacturing vs additive? Sharks vs Jets? Capulets vs Montagues? These two technologies, both alike in dignity, can become besties.
Not only that, but merging techniques and materials challenges students with opportunities to think and plan in sophisticated ways. Students have to anticipate, measure, allow for tolerances, and think in terms of an integrated system rather than an isolated one. Sounds like productive ground to me!
This laser-cut box has 3D printed inserts.
"Wisely and slow. They stumble that run fast." — Friar Lawrence, Romeo and Juliet
I’ll outline the steps I take when making these kinds of projects, but there will be variations based on your app preferences, materials, etc.
Step 1. Design and print
Making the insert design is the first step, but you need to know the thickness of the material to be laser cut first. The wood I typically use for laser cutting is 3mm thick, so I know I’ll want the walls of my 3D printed design to be 3mm. I’ll add an outer ring that’s just 1mm thick to serve as a flange.
But hark! The added 1mm ring will effectively make my main design’s walls just 2mm. That means we need to add 1mm to the main walls for 4mm. I coded my example in Codeblocks, but the 3D editor is equally up to the task. Either way, create a design with a 1 mm thick outer perimeter, then thin walls that are the same height as your laser cutting material, +1mm.
Here, the orange wall of the main design is 4mm. When combined with the 1mm yellow ring, the design will seat perfectly in 3mm wood.
"But soft, what light through yonder window breaks?" --Romeo, Romeo and Juliet
Here's a link to the Codeblocks project for this circular window insert.
Step 2. Make the box
After you have printed the inserts, you can use calipers to take measurements of the actual item, and then you can plan the hole sizes you’ll need to cut. In this sample project, the main circular design’s walls had a 60mm diameter, and the rectangle was 29x78mm.
That meant my box needed to be at least 70mm high and at least 88mm long in order to accommodate the cutouts. The actual box was bigger than that.
My next step was to go to MakerCase. This is one of a number of web apps that allow you to specify a box’s dimensions, easily add finger joints of the correct size for your material, then export the design as a SVG for laser cutting. Be sure to specify the correct thickness of the material you’re using, and also be sure to disable “Panel Labels” when you're exporting the SVG.
An app like Makercase lets you customize and visualize a box, then export as a SVG.
Before sending along to the laser cutter though, we'll need to make holes for our 3D printed inserts. Export the box design as a SVG from Makercase or wherever, then import that SVG to Tinkercad or a vector graphics program for editing such as Gravit Designer or Inkscape. In Tinkercad, it will look something like the yellow portions in the image below. The height doesn't matter because we'll export this as a SVG, and it will only export whatever is in contact with the workplane.
Add holes to accommodate the 3D prints. I have had good luck using holes that are the same size as the 3D prints. With a little encouragement, they will pop into the opening, and no glue is needed. Friction is your friend here!
What's tricky is that the box design, in yellow, is one object, so you can't align the holes as you would normally. One workaround is to use boxes (in red here) as measuring sticks. In the image below, I have centered the rectangular hole by using the four red boxes to measure the distance from the edges of that portion of the box wall. I'll delete the red boxes before exporting as SVG for laser cutting.
The red boxes here are actually just measuring sticks helping me center the rectangular hole.
Here's another approach I often use. I'll import the box SVG (yellow) into Tinkercad, duplicate the box design (blue), then group all but one of the (blue) box sides with a hole, as in the image below. Rinse and repeat with the different box sides. The result is individual box sides that can be aligned with holes using the align tool.
When I group the blue box design with the hole, I'll be left with one side of the box that I can work on independently.
Next, export your design as a SVG. It says "For Lasercutting," but, pro tip, it's brilliant for paper cutters like Cricut and Silhouette as well. 2D fabrication!
Click export, then select SVG for scalable vector graphic, a format your laser cutter will find yummy.
Here, I have the entire box ready for cutting. The larger rectangle on the right will be the lid, and the smaller one will be glued on to serve as a lid guide inside.
Step 3. Put it all together
"What must be shall be." --Juliet, Romeo and Juliet
All that's left is assembly. When getting ready to glue up the project, be sure to think about which faces of the wood you want to be on the outside. For the inserts, I typically put the flanges on the inside, but some may like the look of having them on the outside faces.
The pieces on the lower left and right will be glued together to form a lid. The smaller piece acts as a guide inside that prevents it from slipping off.
|Put a dab of wood glue on all of the finger joints. Wipe up excess with a damp cloth.|
|Using bar clamps helps ensure a strong connection as the project dries.|
If you want to include laser cut writing in your project, be sure to use a laser-friendly font to prevent parts of letters from falling out (like the middle of a "D" for example). In the Shape Generators panel, find "Script" and choose Majorsnafu, Techniqu, or Stencil, turn the word into a hole, and position on a side of the box.
Take it further
That's it! I hope your project turns out better than the star-crossed lovers' one did for them. Please share what you make @morrill_rob. Find the complete list of Rob's Tinkercad Classroom articles here.