Almost two years ago I made a series of rings out of bowling balls. Since then, I've had bowling balls taking up space in my garage. This Bowling Ball Bowl was a lot more work than anticipated. From trying to figure out how to cut it in half to the extremely dirty task of hollowing it out, this was one of my more interesting and challenging projects yet. If you love bowling or a new challenge with bowl making, the Bowling Ball Bowl is your next project!
Step 1: Tools and Materials
Step 2: Cut Bowling Ball in Half
I tried various methods for cutting the bowling ball in half. I started thinking about how to use the bandsaw, but shortly came to the realization that mine doesn't have enough clearance. If your bandsaw has a large capacity, make a dedicated sled for it that will hold both halves of the bowling ball securely as you cut through it. I then tried a traditional hand saw but the pushing motion wasn't working. Ultimately the best saw I found was a sharp japanese pull saw. It took about 45 minutes to get through, but it was the best option for me.
Once I was close to the middle, I dropped the bowling ball on the cement floor of the garage and it broke in half.
Step 3: Bowling Ball Holder - Top
I needed a way to hold the bowling ball securely while hollowing out the middle. I used scrap circles of plywood left over from my disc sander project, but any shape of plywood will work for this. Cut out a circle just larger than the inner diameter of the bowling ball shell.
Step 4: Bowling Ball Holder - Bottom
Using a circle cutter (Jigsaw would work too) cut a smaller hole in the bottom of the holder to keep the bowling ball secure.
Step 5: Bowling Ball Holder - Assembly
Drill four holes in the holder and assemble using carriage bolts with the bowling ball in place.
Step 6: Hollow Out Bowling Ball
Clamp the bowling ball holder to your work bench. Use a carbide cup wheel in an angle grinder to hollow out the bowling ball.
This is an extremely dirty and dusty process! You must use a respirator and goggles. I'm not sure what exactly the inside of bowling balls are made of, but breathing in that much dust and getting it in your eyes is less than desireable. As well, your shop/garage will be covered in white dust for the next month. I am still cleaning up this dust three weeks after this step.
Step 7: Smooth Inside of Bowling Ball
Using a random orbital sander with 80 grit paper, sand the inside of the bowling ball. I found this process easier once removed from the bowling ball holder. Sand until all the tool marks from the cup wheel are removed.
Step 8: Flatten Lip of Bowl
Using a large piece of sandpaper or disc sander, flatten the lip of the bowl.
Step 9: Round Lip of Bowl
Using a 1/8 inch radius router bit, round over the outside edge of the bowl.
Step 10: Finish Outside and Inside of Bowl
It was just a coincident that I purchased a new lathe when I needed it! This made this step much easier. If you already have a lathe, some of the previous steps may be easier for you than they were for me. Hot glue the bowl onto a waste block centered as much as possible. I sanded all logos off the outside of the bowl. You can leave these logos if you like.
The grits of sandpaper I used in my sander were:
I then used all the grits of Micro-Mesh lubricated by water to polish the bowl.
Step 11: Flatten the Bottom
Using a shop built Doughnut Chuck, flatten and finish the bottom using the same process as the rest of the bowl. Be sure to carve the bottom slightly concave to give a rim around the bottom for the bowl to sit flat on. I added the foam to the doughnut chuck instructable because using it without the foam cause a small indentation in this bowl.
Step 12: Enjoy Your Bowl
After the bowl is finished on the bottom, remove it from the chuck and admire your handiwork! This was a great project that was mostly fun. If you make your own bowling ball bowl, please share your pictures!