I love CNC for creating custom items for friends and family. My sister is going and a big trip to South America this spring and I wanted to make her something for the trip, so I came up with a custom badge for her luggage. The shape is inspired from a movie she likes (can you guess which one?), but the process can be done with any shape you can draw up.
What do you need? Well, I used:
- CAD and CAM software: I used Solidworks and SprutCAM
- A CNC milling machine: I used a Tormach PCNC 770
- Tool holders and cutting tools: I used a 1/4" endmill, flycutter, and chamfer mill
- Misc: I used some super glue and a scrap piece of aluminum for fixturing and a vise for work holding.
Any equivalent items will get the job done.
Let's get started!
Step 1: CAD: Designing You Luggage Badge
The first step is to draw up exactly what you want. There are many options for CAD and this project could be created with any of them. I used Solidworks because I have access to it from my job and am used to using it, but almost any CAD program could make this part. Use what you are used to. I made a 3D model of the luggage badge, but this part could be done with a 2D program like Inkscape as well. I took a screenshot from a youtube clip and traced it out in Solidworks to make my 3d model.
Next, I extruded this shape, scaled it to size, and added a nice chamfer to the edges. This is a very friendly shape for CNC milling as there is only one sharp inside corner and the angle of it is fairly obtuse. Shallow angle, sharp inside corners are harder to mill out without changing the look of the part and requires smaller cutters, so keep that in mind when drawing your shape.
I like to draw a tool size reference circle to check for the largest cutting tool that I can use. This makes for a faster running program and a stiffer cutter that can leave a better finish. In this case a 1/4" endmill just fits through the narrowest section of the model.
Step 2: CAM: Adding the Toolpaths
Once you have the model done, you have to make the toolpaths and create the G-code program to run on your CNC machine. This is a complex shape that it would be impossible to write the G-code by hand. The program that does this is called a CAM program. Just like CAD there are a lot of CAM programs to choose from. I am using SprutCAM for my CAM. Again, this could be done with a less expensive 2D CAM program as well.
The first steps are setting up your material size and selecting your zero point. I am using a 2" x 2" x 1/4" piece of aluminum and selected the back left corner at the top of the part as my zero for my top side program. I select this zero point because it is the location of the fixed jaw on my vise and easy to zero in the x-axis and y-axis before I put in my material.
Next, you select the different tools and operations you want to do to create your part. For this part there are 3 different tools and operations. I face the part taking off 0.010" with a fly cutter. Next I cut out the outside shape with my 1/4" endmill leaving enough stock on the bottom of the material to clamp on to (I left 0.050"). The last operation is making the chamfer around the parts top edge.
You will have to pick the feeds, speeds, and depth of cut that is appropriate for your CNC mill. I had the luxury of making this on a Tormach with a 10,000 rpm spindle and over 100 inches per minute feed rate. If you struggle with this as I used to (I have no machinist training), use a feeds and speeds calculator. There are several out there and they provide a good starting point for your programs. I use G-wizard.
With all of your operations for the top side done, post the G-code for your mill.
Step 3: Milling the Top of Your Luggage Badge
Cut a piece of stock for your program and hold it in your vise. I am using 2"x1/4" aluminum flat bar that I cut to 2" long. Zero your coordinates where you said they were in your CAM program.
Load the G-code into your CNC mill. I like to run the program above the part before cutting in the material just to make sure there are no strange motion in the G-code I did not expect.
Cut out the top and sides your part!
Step 4: Milling the Bottom of the Luggage Badge
Now you have an excellent looking shape cut out, but there is still 0.050" of material on the bottom of your part that needs to come off. With a more simple shape you could just flip over the part, clamp it in your vise, and mill off the back. However, with the shape I drew, the points on the outside of the "M" shape would not provide a secure surface for clamping and would most likely deform if I tried it.
If I were making a lot of these I would make a set of soft jaws with the negative of the curves of the top and bottom of the "M" milled into it. For a project like this where I am only making one set it seems wasteful. What to do? Superglue to the rescue!
I took a piece of scrap aluminum and milled it flat except for a ridge across the top. Then I used superglue to glue my half machined part upside down on the block, while lining up the top two points of shape with the top ridge. I used Tormach's PathPilot conversational to make a fly cutter back and forth to take off the back of the part. I never know how much I can push a cutter when glued, so I take light cuts of around 0.015" per pass.
With the backing removed, we need to drill holes that we will tap and use for mounting. I did this again using the PathPilot conversational, but your could also do that in a CAM program or hand code it if you choose.
Once this is done, tap the holes and your badge is finished. A bottoming tap works the best for shallow holes like this, but they can be hard to start, so take your time and make sure the tap is straight. Release the part from the super glue by soaking in a covered container filled with acetone. I have tried using a torch to release the part, but I have had the superglue burn and it was difficult to remove the stain from the burnt glue.
Step 5: Mounting Your Luggage Badge
You can finish your luggage badge however you like. The tapped holes in the back make things easy for anodizing or your could buff it to a mirror finish. I chose to keep it simple and leave the as machined surface.
Remove your current luggage badge and use those holes and drill more holes as needed to hold your luggage badge down.
Use washers or make a backing plate to hold the badge down from the inside of your suitcase. I do not have good pictures for this step as my sister did it without my assistance and camera, but it should be straight forward.
I had originally thought of using a heat gun to soften the luggage case to inset the badge and make it less likely to snag on things, but since my sister and her luggage are over 2500 miles away, I kept it simple for her to mount. If anyone here tries this technique, please let me know how it goes.
I am curious on how this will hold up to the gentle caress of luggage handlers and their equipment. The beauty of CNC is that you can quickly make another one now that the programs are all written.