This is my first Instructable, but I have been modeling, 3D Printing, and CNC Milling for a few years. I am in middle school, but have always been interested in making things. I have always been a fidgety person and noticed fidget spinners and cubes at school, so I decided that I would try to make some. They turned out so well that I have been selling them to my friends.
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I used Fusion 360 for the modeling and tool path creation, then cut them on my Shapeoko 3. Getting the depth right took a few tries, but now I have things really dialed in. I can now cut 20 bodies out of a single 12 by 12 inch sheet of acrylic, but initially I was only able to get about 10.
As you can see, for the counter weights I used pennies because they look cool and are cheaper than bearings.
I like the acrylic material because it is strong, and has a shiny finish, and even though it takes about 5 hours to cut a full sheet, the finished product is really nice. The main drawback is they can chip when dropped on a hard surface.
Initially I 3D printed the bearing caps that prevent your fingers from touching and slowing down the bearing on my FlashForge Creator Pro, but the quality wasn't as good as I would like so I bought more acrylic and used the Shapeoko to cut them out which turned out much better.
Shapeoko 3 - Any CNC Mill will work
FlashForge Creator Pro - Discontinued use and now make the bearing caps on the CNC
Fusion 360 software for creating the models (You can just use the file I uploaded)
Nut driver to secure pennies (you could also use a small piece of wooden dowel the right size)
Acrylic 1/4 inch thick, 12 x 12 inches
608 ABEC-9 Skateboard bearings
Double sided tape (I use: https://www.amazon.com/gp/product/B01LT9K06Y/ref=o...)
Super glue (I use: https://www.amazon.com/Stuff-Thin-Instant-Glue-HS...)
Dish washer soap (to get the grease out of the bearings)
Degreaser (to get the grease out of the bearings)
Speed Cream oil (I use: https://www.amazon.com/Bones-Speed-Cream-Bearing-...)
New Pennies - Note: This use does not constitute defacing money and is legal because no changes are made to the pennies.
Step 1: Cutting the Bodies
I modeled the bodies of the spinners using fusion 360 with the idea that I wanted to make a ascetically good looking, sturdy; but not too bulky design. The triangular design let me puzzle the bodies together and let me maximize the amount of spinner bodies I could get out of a 1'x1' sheet of acrylic.
I tape the material down to the wasteboard using double sided tape I bought on Amazon. It works great for everything I have tried but gums up the bit a little, not enough to cause cutting problems though. Sometimes it gets rubbed on the outside of the cut and needs to be cleaned off with a towel or microfiber cloth though.
I used a fairly large .25" end-mill so it would be able to move greater amounts of material in the pockets in a shorter period of time. This was especially helpful due to the fact that acrylic is extremely tough to cut with a CNC mill (I have not cut aluminum yet but I expect this will experience will help). I had to whittle away at the material .015" depth at a time at 20 inches per minute because when I tried to go any deeper, the machine's Z-axis belt would skip and ruin the cut. Cutting over the material again shaves enough off the center hole and pockets so that the bearings and pennies don't fit snugly and need to be glued. The RPM on the router was set to 10,000.
A whole sheet of 20 takes about 5 hrs, but a singular body will only take a touch over 15 minutes.
I started the cut in the lower left hand corner of the material.
Full sheet of 20: spinner v5.f3d
Singular body: singular spinner body.f3d
Step 2: Open and Clean Bearings
I bought some cheap bearings from China that were packed with grease and caused the bearings to spin poorly, so I opened them and took a small screwdriver to remove most of the grease.
Then I soaked them in dish washer soap and water for about an hour (1 part soap to 3 parts water). The last step was to use a bike chain de-greaser to spray them fully clean.
After that they were put aside to dry for an hour or so, and then I applied 2 drops of speed cream so they have a light oil and improved spin time.
The top left bearing in the picture, is one that has not been opened yet for de-greasing, we took a pin and just popped it out and threw them away. When I put them back on they added friction and didn't allow the toy to spin as freely.
The top right bearing is a closed bearing and can't easily be opened and de-greased. I bought some of them but they didn't work well so you will probably want to avoid them as well.
The lower left and lower right bearings were ones that are of different types but both have been cleaned and de-greased. The left one has a plastic piece on the back side of it, and the right has is all metal and has exposed ball bearings on both sides.
Step 3: Bearing Covers/Button Caps
I had some left over material from the cut, so I decided that I would make some bearing caps that were a step up from the 3D printed ones I was originally using off of Thingiverse. They came off of the print bed warped, even with the heated bed, and wouldn't spin on the table. the new caps fit snugly into the bearing, have a good look to them, and are flat and smooth.
I have included the Fusion 360 file I made for the bearing caps here for you as well.
Step 4: Assembly and Finishing
My .25" bit leaves a little nub of plastic in the places where it finishes the pocket, because the 3 flutes that it has don't go all the way to the middle (yours may differ), but I was able to take it out with a small flat head screwdriver and some pressure.
You can fit 2 pennies in each pocket (six for each spinner) so I got a dollars worth of brand-new 2017 mint pennies from the bank. I also got some older ones to go under the brand new pennies. you'll want the older pennies to be within about ten years to keep proper weight and balance (the newer ones weigh about 2 grams while the older ones weigh about 3).
After you have your pennies ready, set the older ones in by hand, then use something with a flat head that you can hit with the mallet to push them the rest of the way down into the pocket. I used a nut driver and rubber mallet, but a piece of dowel would work good as well. A light tap will do, hitting it too hard could crack the plastic! After the old pennies are in on the bottom layer you should be able to push the new top pennies in by hand, I pointed the tip of the shield towards the middle to make it symmetric all around.
To make sure the pennies wont fall out when someone drops it, I slammed it (not too hard!!) on a piece of cardboard. If no pennies fall out after 2-3 tries the they are secure, but if a couple do fall out then you can put a drop of superglue on the bottom penny, be careful only to use a little drop. I have glued my finger to many spinners and sanding it off is a pain, and ruins the shiny finish.
If you want, you can sand the whole thing with a fine grit sand paper like 1500 or 1100 to give it a nice matte finish as long as you do it in random patterns.
After gluing, pop a clean bearing in an make sure it spins well, then put the caps on. Sometimes they need a little help since they are a snug fit for the bearings we purchased. If the bearing is too loose you can just take a small strip of scotch tape and put it around one side of the bearing and it should fit properly after that. I had some bearings that were not fully up to spec in my batch.
Step 5: Learnings
The black spinners are the 5th revision, originally I made a couple 3 bearing spinners and started with quarter inch plywood since we had some scraps laying around. Then I started with Acrylic sheets that we left over from building my workbench that houses the Shapoko CNC. The 3 bearing spinners were too big for my hands, so I started designing 4 bearing spinners and this is when I started to use pennies instead of bearings for counterweights because my skateboard no longer had any bearings left to use, and I needed more.
Cutting Acrylic was another challenge, as I mentioned before. Initially the travel speed and RPM of the router melted the acrylic and caused it to gum up the bit, but with some research I got the steps and found that the lowest 10k RPM speed works great. It also had problems with the Z axis stalling out and not going deep enough until I changed the depth to .015 of an inch. The toolpath is setup in the files that are attached have a good speed and depth per cut. It takes about 5 hours to cut a full one, but I have been through multiple sheets with no errors.
In my first runs I didn't get the depth right and had some problems with that, but having a flat bed, and getting the bit have a piece of paper pass under it got it dialed in just right. Now the cleanup on the edges is minimal.
Cleaning the bearings was another great step forward, as was using Acrylic for the bearing covers/button caps.
Step 6: Final Products
Here is one of the finished products, as you can see they look cool and work great. I am really happy with how they turned out, and so are all of my friends who have been buying them.