Inter-locking joints in acrylic
If you are making a design in acrylic and would like to avoid using glue, we will show you here how to make inter-locking joints. Acrylic should be treated differently from wood when making joints, as the material is brittle and may splinter or shatter when exposed to pressure or is tightened.
Acrylic is especially fragile in inward bending corners. This applies to joints and in general. If you have the opportunity to round your corners slightly, it will help increase the strength. In the joints you can do as shown in the illustration below and make small circles in the corners. The larger the radius, the less fragile it will be.
To make the joints lock, remember to compensate for the material that the laser removes (for acrylic you should calculate about 0.15mm cutting width). In other words, the openings should be drawn slightly smaller than the width of the material that the joints will be inserted in. In 3mm material, they should be drawn as 2.7mm openings. As shown in our guide to inter-locking joints in wood, you can also make arcs as shown in the illustration below. If you make long joints, it can be a good idea to make multiple arcs for greater stability.
Below you can see two joints made in acrylic. The one on the left is made with arcs as shown above, and the one on the right is made without. The first one fits together and is stable, but can still be separated. The other falls apart and gives way when moved from side to side.
Example of design without the use of glue.
We have made a small example to show how you can make an acrylic design without using any glue. Below you can see a couple of mini stools in 3mm acrylic. Small rounded shapes or circles have been made in all corners, and arcs in all the joints in the same way as described above.
Below you can see how the parts are first drawn and afterwards, when they are cut.
Finally, you just have to assemble the parts.