Make a Keychain With Fusion 360, a CNC Machine and Scrap Wood

So you built or bought that CNC machine and now your wife is asking, "What good is it?" What she really means is, "What good is it to me?" So you need to get a project going quickly like this keychain to show her just how good of investment you just made.

Start by downloading Fusion 360 There are a lot of CAD programs available but Fusion 360 has CAM built into it so you don't have to purchase and learn both a drawing program and a manufacturing program which will give you the code to run your CNC machine.

Wood scraps, paint, varnish, masking tape

CNC machine with 1/8th inch flat end mill and a vbit

Fusion 360

If you start with a planed board, skip this step. I always start by finding the dimensions of my wood before I start drawing because most of my projects are made from scraps. Photos here show how to prepare a block of wood from a slab of African Wild Olive which was cut with a chainsaw so nothing is straight. Most people would throw this into a fireplace. I don't have a planer so I use a facing end mill on my CNC machine for the final preparation of the surface I will cut on. I cut a notch in each end for a space for my clamps on the CNC machine.

Start a sketch in Fusion 360. Choose a plane to draw on. Choose "Elipse" from the sketch menu. Type in the dimensions for each direction. Add a hole for the keyring. Adjust the hole location with the "Dimension" menu item. Once you have drawn your 3" by 1.5" oval and made a hole for the keyring, close the sketch. After reviewing this I actually prefer 3" by 1.25."

The sketch doesn't look very interesting until you make it into a 3D object. Use the "Push Pull" command to make your sketch into a 3/8" thick object.

The beauty of a CNC machine is making multiple identical objects. Once you have your drawing, make a pattern to match the size of your wood. In this case I made 2 rows of 6. I moved the second row in order to fit them within the 3 inches of height that I can cut on my table saw as you will see later.

Make a new sketch for your text as you can modify this for each batch of keychains or make a new sketch each time. As long as the text is large enough I prefer the Georgia font, bold and if possible at least 1/2 inch high. If the text is too small the finer areas of the Georgia text are too shallow to sand and can easily get erased.

I like to use a 60 degree V bit (in Fusion select spot drill) for small text so it is deeper when sanding. Make a new setup for engraving the text. Fusion makes this real easy as you just select the bit and select the text to engrave and I never touch any of the other settings. By selecting "Simulate" you can see what your CNC machine will be doing including seeing how deep your engraving tool will be cutting.

Make another setup for boring and cutting out (contour) the keychains. I use a 1/8th inch flat end mill for both boring and cutting so you can post process (coming in next step) them as one setup so that you can continue from boring to cutting in one operation. Zero your Z axis as the length of the bit is likely different from your V bit. Don't change the X and Y axis. I've attached the Fusion 360 file for you. If you are using a different program you can download the .dxf version.

Select your machine from the list of machines after selecting the post process menu. For LinuxCNC which I am using I have to make some minor adjustments to add some height to the Z axis or it will drag across the project upon starting. The editor by default saves it as a text file which can't be seen by LinuxCNC and could cause you some confusion. When saving the file from the text editor remove the .txt extension and put quotes around the file name ending in .ngc.

Engrave and cut out and bore your keychains. Tape off the areas you don't want painted to save time sanding. Paint with spray paint making sure to get the paint into the letters. I wipe off extra paint to keep paint from clogging the sandpaper when sanding with a belt sander. If you use scraps like I do, slice off your keychains with a table saw while they are still taped from painting so that they hold together and don't fly around when cutting. Sand the face lightly on a belt sander to leave the paint only in the letters. Finish them with your favorite wood finish.

When you give your wife her personalized keychain she'll ask, "Honey do you need any more tools for our shop?" "My girl friends would really like these, and our kids, and their choirs...."