Foam Cutter Part II: Cutting a turbine

The foam cutter has the ability to cut at angles such that a lofted part is created. Please take a look at my previous posting on how I created the foam cutter: https://adamblumhagen.net///foam-cutter/

The turbine blade is a great example of the foam cutter’s ability to cut at angles. Here is a 3D model of a turbine blade. Notice that the profile on the front is slightly larger than the back’s profile and the blades twist at a 45 degree angle from front to back.

I export the turbine as a .STL file and import it into a 3D printing slicer software to break it up into layers and get the coordinates for my foam cutter. In this example, I am using Slic3r to obtain the GCODE using sprial vase mode since I only need the perimeters. Here is a picture of the resultant GCODE. One side of the foam cutter will travel along the coordinates on the top layer and the other side will travel along the coordinates of the bottom layer. All layers in between will be discarded.

I can import the GCODE into a spreadsheet program like excel, and remove the unneeded parts.

Here is what the meat of the GCODE looks like. I only need the X and Y coordinates I remove the “X” and “Y” and convert the formatting of the columns to number instead of text. In Slic3r, I added output “layer_num” after every layer. Since I only need the first and last layer, I added a layer counter in the column farthest to the right to help me choose the first and last layer.

Here is a plot of the first layer using the X and Y coordinates. There are 546 sets of coordinates in the first layer and 518 sets of coordinates in the last layer. The location that each drawing starts at is highlighted. Notice that both sides start at very different locations. Since both sides need to cut in a synchronized fashion, I need to find a similar location on one drawing and shift all of the coordinates so they are drawn at the same time (see the next figure for more explanation of what I mean by synchronization). Also note the number coordinates was different, so either some of the 546 coordinates need to be deleted or some of the 518 sets of coordinates need to be duplicated.

Making the coordinates in one drawing synchronized with the other drawing means that when the foam cutter on one side is at a certain coordinate, the other side of the foam cutter is also at a specific coordinate so the wire will follow the contour of the turbine. You can imagine, if the wire was the red line below, the wire would need to be at synchronized coordinates to maintain the shape of the turbine as it cuts. The red, orange, green, purple, pink, and yellow dots show some approximate synchronization points that I eyeballed. This manual process is very time intensive since I have to move rows using copy/paste commands until there are the same number of coordinates on both sides and all are synchronized.