Updated: Apr 28, 2018
This is a simple project to get started with using Fusion 360 and 3D printing something useful. I use these supports for all sorts of finishing: spray paint, oiling cutting boards, lacquer and polyurethane - anytime you've got to finish all sides and keep the workpiece off the table.
There are a lot of designs for these paint pyramids out there, but I opted for designing my own for a few reasons. Mostly, a lot of the designs out there have a square base, like the actual pyramids in Egypt. These are a little more stable, but have to be oriented with the square base downward or they end up different heights. My design has an equilateral triangle as the base, and is shaped as a true tetrahedron. All the edges are the same length and the there is no 'bottom' so using them to support your work is easier.
I use these supports for all sorts of finishing: spray paint, oiling cutting boards, lacquer and polyurethane
Building the model in Fusion 360 is very simple, just a few steps to complete. The only critical dimension is the taper angle during extrusion, in Step 4. Everything else is up to you, and is easily scaled to make a bigger or smaller support.
Here’s how to do it:
Create a new component
Sketch an equilateral triangle, I used 25mm
Extrude the shape with a taper angle of -19.47 degrees
Chamfer all edges by 1mm
Save your file and export to Cura
Begin by right clicking and creating a new component. Then start a sketch on the XY plane. Using the line tool, draw a triangle. Size and shape doesn't matter now, we'll clean that up. Using the 'Equal' constraint, set all three lines equal. This creates an equilateral triangle without using numerical constraints on the angles. Finally, right click on one of the lines and add a dimension. I used 25mm, or about 1 inch. This will set the overall size of your paint pyramid. Click 'Stop Sketch' to exit.
Now, we'll turn that 2D sketch into a 3D model. Click on 'Extrude' and select the triangle shaped sketch. Looking at the 'Edit Feature' dialog box we have a few options. Distance will change how long the extrusion is. For this model, as long as you enter a value greater than 25mm, you'll get a perfect tetrahedron. The critical dimension is the Taper Angle. The value we need to make a tetrahedron is the inverse cosign of (-1/3) or
acos((-1) / 3) = 109.471221 degrees. Enter -19.47 into the taper angle.
Finally, clean up the edges. I find adding a small chamfer or fillet on the outside corners makes for a better 3D print. Without the chamfer the printer pauses at the corners and over-extrudes a small bulge on the outside faces of the corner. Click 'Modify' and add a 1mm chamfer to all six edges.
My design has an equilateral triangle as the base, and is shaped as a true tetrahedron.
That's it, save your model and export it to Cura or whatever slicing software you prefer. I printed these in PLA, with a layer height of 0.13mm, a shell thickness of 1.2mm and 0% infill. The benefit of this design is that it is self supporting, so you don't need any infill to produce a high quality and strong print.
I've posted the STL files for download Here.