Wooden Trackpad Rest

In an effort to keep my desk minimal while still giving it a personalized flair, I recently became obsessed with making a series of striking (and reasonably functional) accessories for my desk at work. The first was a simple desk organizer that holds my phone and a couple of pens (check out my build video here). Next on the list was a "trackpad rest" for the Apple trackpad that I use. And if you have concerns about how useful a trackpad rest really is...well...you've got a point. But you can't argue with how good it looks.

This may seem like a fairly straightforward CNC project, but there were plenty of lessons to learn along the way. I tried my best to capture those nuggets along the way and share those here in this instructable. Feel free to follow along on this build montage as well:

Walnut (or other hardwood that cuts well on a CNC router) - Dimensions: ~7"x7"

Polyurethane or similar treatment for the finished piece

Double-sided tape (for fixturing stock) - I use Shurtape

Sandpaper or a sanding sponge

Adhesive-backed foam

Tools:

Handsaw (or power tool equivalent)

CNC Router and assorted bits

The CAD for this design was fairly straightforward (I guess that's the benefit of a modern, minimal design) and took only a few minutes in Fusion 360. It essentially consists of an extrude, a cut, and a handful of filets. In fact, the hardest part of producing the design was collecting the measurements for the trackpad itself. The frame of the trackpad has a slight backwards 'lean' to it, meaning that if I were to simply measure from the front bottom edge to the back bottom edge, I would get an incorrect measurement for the actual, total footprint of the trackpad. This is not an issue for the side-to-side measurement, however.

Once the features of the design have been modeled, I'll take a minute to update the "Appearance" of my model to reflect the actual physical material (in this case, 3D Walnut) just to make sure that I like how it's coming together. I'll swap over to the render environment (I love how easy this is in Fusion), turn on live rendering, and then make the following adjustments to produce a reasonably life-like visual:

• Change focal length to 70mm
• Apply a focus point, reduce blur to 0.7ish
• Add a "table" surface and material (in the design environment)
• If I really want to go above and beyond, I'll add some contextual elements (in this case, a basic model of the trackpad itself)
• Add a custom environment and use it as the background
• Play with the lighting until I get something that I like

Side note about renderings: if I wanted to see if people were interested in ordering/purchasing one of these trackpad rests, I could very easily post this render on a website or social media, etc. to validate people's interest (before I even make the first one). If there's interest, then I can invest the time and effort in making the actual physical product.

After modeling and rendering, we're ready to get started on some CAM!

The CAM for this project consists of just a few basic tool paths, but order of operations is everything here:

1. Facing - This will clean off any excess material from the top of the stock. Because we don't need this top surface (we'll be removing it later), we don't have to be overly worried about surface finish on this one.

2. 2D Adaptive (External) - This adaptive tool path will remove excess material around the external profile of the model. I usually give myself an extra 0.1" of material around all external edges to give myself a little bit of "wiggle room" when placing my work coordinate system.

3. Parallel - I decided to perform this operation before clearing out the main pocket so as to avoid any splintering or tear-out on the relatively thin walls of the design. This, of course, adds a fair bit of complexity to the CAM work here because I have to use a dumbed-down model that has an uninterrupted surface. At the end of the day, though, I'd rather take a few extra minutes on the CAD/CAM side of things than end up scrapping a part and starting over! I still don't have a ball end mill, so my step over on this tool path is painfully small at around 0.007" for a 1/4" flat end mill.

4. 2D Adaptive (Internal) - This tool path removes the bulk of the material from the internal pocket where the trackpad will sit. It's typically good practice to leave material on the walls and floors when roughing, so that you can come back later with a finishing operation to get to final dimension (and the desired surface finish).

5. 2D Pocket (Internal) - Speaking of finishing operations, this pocket tool path will allow me to remove the leftover material on the bottom of the pocket. Any witness

6. Contours - These are basic cleanup paths that will ensure that all vertical walls have a smooth, clean surface finish and are cut to final dimension. For the external profile, we can use a ramping approach because the geometry is continuous. For the internal pocket walls, however, we'll have to use depth passes.

Check out the "Machining" step for pictures of the tool paths in action!

Preparing stock for the CNC is a bit of a chicken-before-the-egg issue. You need to know your stock in order to prepare your CAM setup, but you need to know your CAM setup in order to prep your stock. Typically I'll nail down the thickness of the material that I'll be working with before I start my CAM, but then I'll wait to cut any X-Y dimensions until all of the CAM is complete. There's not necessarily a right or wrong answer but that seems to work for me! I went with Walnut for this project because it has a beautiful grain and cuts great on the CNC.

As mentioned in the previous step, I'll typically give myself an additional 0.1" of stock on all sides in the XY plane. My stock is quite a bit thicker than I need in the Z direction, but the facing operation will take it down to final size.

The irony of it all is that I have a CNC machine but no power tools to cut my stock to size. So handsaw it is! It's actually a good reminder that you don't need (every) fancy tool to get the job done. Also, it's a pretty good workout.

When it comes to cutting a part like this on my router, I'm a big fan of employing the double-sided tape method. I use a brand called Shurtape (link available in the materials section in the Intro to the instructable) and it has worked perfectly for me. For a piece like this (~7"x7"), I'll usually apply two or three strips to the bottom of the piece, avoiding the edges (where the tool will be cutting) if possible.

A few tips that are absolutely essential for this work holding method:

• The bottom surface of your stock must be flat. There is absolutely no getting around this one (believe me, I've learned the hard way). If your stock "rocks" at all when placed on a flat surface, the tape will not have enough contact area in order to hold your piece down while cutting.
• Your spoil board must be flat (for all the same reasons as above).
• Your spoil board and stock must be clean of any and all sawdust/dirt/grime/residue.
• Your spoil board and stock must adhere well to the tape (this seems like a no-brainer but wanted to throw this out there just to be safe).
• Your part needs enough surface area to supply the required hold-down force. Notice that the final part must have the requisite surface area, not the initial stock. If you're removing all the material (and tape) that is supplying the hold-down force, it turns out this weird thing can happen where there's not any hold-down force left (strange, huh?).

All that being said, this particular project is a perfect example of when to use the double-sided tape method. The part is large enough to tape down securely but not so large that the "flatness" of the stock is an issue.

All that's left is to set the work coordinate and run our tool paths!

The cleanup for this part was fairly straightforward. A few minutes of hand sanding helped to knock off any burrs left from the machining and remove any major witness marks. Then, after cleaning any remaining dust off of the part, I applied a few layers of a polyurethane varnish. Nothing too fancy, but remember to do another quick round of hand sanding after your first layer of polyurethane. That first layer will cause the grain to rise and you'll want to smooth it out before applying another coat.

After I was done with the polyurethane, I used a few small pieces of an adhesive-backed foam and applied them to the bottom corners of the part. This will provide a better grip on my desk and will account for any unevenness in the bottom surface.

And that's all! The trackpad fit perfectly into the pocked I machined and looks absolutely fantastic. I couldn't be happier with how it turned out; it brings the perfect balance of striking yet minimal aesthetic to my desk. Hope you enjoyed following along and that you learned a thing about CAD, CAM, or CNC!