A yo-yo may seem like a fun toy (and it is) but it’s also a perfectly concentrically machined part (or at least that’s what yo-yo makers aim for). This project puts your Bantam Tools Desktop PCB Milling Machine and your perseverance to the test in order to make the truest spinning yo-yo.
We’ll focus on two things: making a jig for holding round stock/material and making the yo-yo itself. There are many benefits to machining round stock as opposed to square stock. Particularly for round parts, round stock saves time cutting away material, wastes less materials, and costs less than square stock.
While machining round parts is generally better on a lathe (more concentric), the Bantam Tools Desktop PCB Milling Machineis still quite adept at it. The proof is in the yo-yo!
The OtherYo was modeled in Fusion 360 and toolpaths are generated from it as well. Download the attached Fusion 360 file to look at the model and see how the tool paths move. Feel free to make modifications of your own.
Although this is one of the easiest methods of making a modern yo-yo and all the steps have been laid out, this tutorial is aimed at people who are familiar with milling. If you're new to the Bantam Tools Desktop PCB Milling Machine, check out our Getting Started guide and Hello World project first.
Step 1: Tools, Materials, and Files
- Bantam Tool Desktop PCB Milling Machine
- Computer running Bantam Tools Desktop PCB Milling Machine Software
- Cold saw or bandsaw
- Ball end mill, 1/8"
- Flat end mill, 1/8" and 1/16"
- Chamfer bit, 1/8", 45°
- X-acto knife or other sharp knife
- Allen keys
- Fusion 360
- HDPE or similar plastic sheet, 3/8" thick, 4"x5"
- Hex nut, M4 x 0.7
- Socket-head screw, M4 x 20mm
- Socket-head screw, M5 x 18mm (5)
- Socket-head screw, #2-56 x 1"
- Washer, M4
- Washers, M5 (4)
- Double-sided tape We recommend Nitto Permacel Tape for its high-strength bond.
- Delrin rod, 2-1/4" diameter x 0.9" length (per yo-yo half) We recommend the 1-foot lengths since each is about $22 and ~6 complete yo-yos can be made from it.
- Bearing, 0.25" x 0.5" x 0.1875" “large” or “C” size bearing at your favorite yo-yo store
- Response pad, “slim” size (2) also from the yo-yo store
- Setscrew, M4 x 0.7 x 16mm
- Hex nut, M4 x 0.7 (2)
- Rubber O-ring with a thickness close to 1/16"
- Yo-yo string
All the files you need are attached here. Download the zip file.
Step 2: Cut the Stock to Size
We used our cold saw to cut the Delrin stock to about 0.9"-thick pucks. It leaves a smooth and flat surface that’s perfect for placing in our jig. A bandsaw could also work, but try to get one of the sides as flat as possible. The total thickness of the yo-yo is .0864” so this gives us of extra material to cut away. If your puck is too tall (anything above 1"), then it should be faced down. Cut two pucks per yo-yo.
If you used the HDPE from our store, the sheets should already be to size, but if not, cut the HDPE down to 4"x5" with a bandsaw. Then use a metal scraper or ruler to debur all the edges to make sure the parts sit flat instead of tilted on a bur.
Step 3: Drill Holes Through the Jig
Use the 1/8" flat end mill. With the bracket installed, put double-sided tape on the bottom edges of the HDPE sheet and line it up to the bed with the bracket. Extract all the files from OtherYo Mill Files.zip and load Jig Holes.mill. Notice that the z-thickness is set to 0 in Bantam Tools Desktop PCB Milling Machine. This is fine because our material dimensions are set in Fusion 360. Make sure to click "Align to Bracket" so that the origin is set to your bracket location. Run Jig Holes.mill to drill the mounting holes.
Step 4: Mount the Jig to the T-Slots
Remove the aluminum spoilboard by unscrewing its four screws. Keep the screws in a safe place.
Note: The spoilboard may need to be refaced the next time you use it to ensure high accuracy.
In the Bantam Tools Desktop PCB Milling Machine, remove the spoilboard by going to Setup Fixturing and clicking Remove.
Slide in the hex nuts to the top and bottom T-slots and align them to the holes on the jig as close as you can.
Tip: An Allen key works well for sliding in the nuts. Screw down the jig loosely so that it can still slide around with five M5 screws and washers.
Now let’s line up the jig’s left side. Load a 1/16" or larger flat end mill upside down into the collet, jog to the furthest left side of the mill (x=0), and lower it until it’s below the top of the jig. Slide the jig up against the tool and screw it down tight.
Step 5: Cut the Jig Pockets
Load and run Jig Pockets.mill with 1/8" and 1/16" flat end mills to cut out the jig features.
IMPORTANT: Since the spoilboard is removed, the cutting tool will have to reach ~0.25" further down the z-axis to touch off onto the top of the T-slots. Because we only have a limited z-travel distance, the tool has to stick out far enough to reach the T-slots without overreaching its z-travel limit. All tools should stick out at least 0.6" past the collet nut.
Step 6: Prep the Jig
Place in the M4 x 20mm socket-head screw with a washer and hex nut into the slot on the top right of the jig.
With the #2-56 socket-head screw, drive it into the hole on the left side of the jig until it reaches the bottom of the hole. It’s a tight fit, but it should form its own threads. Be careful not to strip out the hole.
Step 7: Cut Outer Side of the Yo-Yo
Let’s mill! Drop a puck into the right side of the jig (it may be tight) and make sure it's completely seated in the jig. Clamp it down by tightening the M4 screw and make sure the puck doesn't spin. It should be very secure, enough to move the Bantam Tools Desktop PCB Milling Machine around!
Load Outer Side.mill and go down the list of operations from top to bottom. The order of your tools is: 1/8" flat end mill, 1/16" flat end mill, chamfer (it's set as "Engraving Tool" in the Bantam Tools Desktop PCB Milling Machine Software), and lastly the 1/8" ball end mill. It takes about 45 minutes to mill out this side. The machine finish on the part is quite nice. Get cozy since you should never leave a running mill unattended.
Step 8: Cut the O-Ring Pieces
Now we’re going to cut little rubber pieces that hold the yo-yo's hex nuts in place. Cut open the O-ring perpendicular to its curve and then cut 1/8"-long pieces the same way. Cut three pieces for each half.
Next, insert the O-ring pieces into the hex nut pocket. They go into the far outer slots. Use something like the back of a knife to push them into place. When they're in, push the hex nut into the pocket. It might spring back a bit, but it will hold, and once the yo-yo is tightened, it will all stay in place.
We’re placing the nut into the half now so that after milling the inner side of the yo-yo, we can thread in the axle to pull the yo-yo off the jig.
Step 9: Cut the Inner Side of the Yo-Yo
Now that we have the outer side cut, mount it to the left side of the jig by pressing the pocket onto the boss (raised circular portion). Check that the part is seated flat on the jig and then secure it with the #2-56 socket-head screw. Tighten the screw until it holds down the part. The part should not be easily turned freely in the jig and takes considerable force to turn it.
Load Inner Side.mill and run the operations from top down again. You'll be using the 1/8" flat end mill, 1/16” flat end mill, chamfer, and then the 1/8" ball end mill.
IMPORTANT: For the last two operations, the #2-56 screw needs to be removed before cutting.
Take the yo-yo half off the jig by threading in the M4 x 16mm setscrew and pulling up.
Congrats, you now have one yo-yo half! Now go through the same steps to cut another.
Step 10: Assemble the Yo-Yo
First add a small amount of Loctite to the M4 x 16mm setscrew so that it covers the first two to three threads. Screw it onto a hex nut until the head of the setscrew is flush with the nut. Wipe off any excess and allow the Loctite to set.
Now remove the backing of the response pads and place them into the groove of each half.
Finally, place the bearing onto the yo-yo’s bearing post, screw the two halves together, and add a yo-yo string. Your OtherYo is complete!
If you have any questions, contact us at firstname.lastname@example.org. We're happy to help. And if you make your own OtherYo, we'd love to see it!