We received a request to create a 3D model of a Triangle so we thought we would create one using Freecad and then write this liitle tutorial about how we did it. The file is also available so you can down load it. Please be aware that we have no idea what note it would make, especially given the various print settings and materials you could use to print it, but please experiment and let us know how you get one. Also if you have any recommendations as to how we could improve the model please comment below.

How to extrude along a path in Freecad

We are not going to go into too much detail with regards the size and dimensions of the model, in this instance we had a brief of approximately 10cm for each side using a rod of 12mm diameter.

The basic principal we are going to describe here is the notion of “sweeping“. Essentially this is extruding a 2 dimensional shape along a path. We are going to create the shape of the triangle, which will be used as the path and the extrude a circle of radius 6mm along that path.

Step 1. Create a path in Freecad To create both the path and the shape to extrude along the path you need to create them in Freecads “Sketcher” workbench. Simply got to the workbench dropdown list and select Sketcher and then create a new sketch using the icon, when asked select the XY plane.

Next you will need to create your triangle. This shape is easy, just three lines of equal length (to start with). Don’t forget to use the constraints for the shape. The bottom line is horizontal, the lines all have a length of 100mm, the two sides are at 60 degree angles and finally the lines ends are connected. From this original shape we added fillets to the corners to make them rounded and shortened two sides so that there was a gap. Lastly, we constrained the origin of one end to the coordinates 0, 0. Step 2. Create the shape to extrude Similarly we create the shape to extrude, or sweep, along the above path. This is somewhat easier as it is a circle. When we create a new sketch for our circle be sure to create it in the YZ, or a appropriate perpendicular plane. Constrain the circle to the radius that you require, here it is 6mm and then select the centre of the circle and constrain it, or lock it, to the position of 0, 0. Step 3. Sweeping in Freecad So after steps 1 & 2 we should have 2 sketches that both have an origin at 0, 0 but are on different planes. So all that we need to do no is Sweep or Extrude our circle along the triangular path. To do this we need to change the workbench to “Part” and from here we can access a number of different tools. the one we are interested in is the Sweep tool.



Select the sweep icon and we get the Sweep utility box open on the left of our Freecad window. To get the circle to extrude along the path we need to follow a sequence of events to get the tool to work.

a). Select the circle and use the right arrow button to move it to the right hand sweep box

b). Select the path to sweep and click the Sweep Path button

c). Select all the components of the path so that they are highlighted in green (right side in object view area) and click Done

d). check the Create Solid box

e). Click OK

Step 4. Export our new 3D model Now we have, essentially, a triangular shape rod of diameter 6mm. To 3D print our triangle what we should do is go to the Part > Create Simple Copy function from the top menu of the Part Workbench then select the new object and go to File > Export and export it as a .STL file. Step 5. 3D print your triangle So we have our .STL file from Freecad so now all we need to do is print it.

Currently we have not tested this and are currently in the process of printing it out. We believe that printing it flat on the print bed will offer the greatest strength to the triangle. The triangle, as the rod is round, will also need to be printed with supports. As a musical instrument we are not expecting much but it would be possible to print a whole range of sizes so that you can create a full range of notes. So get creative and let us know how you get on.