I decided to design and make the box that would hold the engagement ring that I would later use to propose to my (now) fiance. I was inspired by an aperture design I saw about three years prior on imgur by user walyu who created a large box with a keyhole that opened the aperture. Unlike the large box that walyu made that also served as a jewelry box, I wanted my box to be handheld. So, I designed a simple box in Solidworks (SW) that used a mechanical iris aperture that I could easily machine using the lathe, endmill, and drill press I had access to at work.
Materials:
- 12″ long, 2-1/2″ diameter 6061 aluminum rod (link)
- 12″x12″, .006″ thick brass sheet (link)
- 24x 3/32″ OD x 5/16″ length steel dowel pins (link)
- 3x 4-40 x 3/32″ 18-8 SS set screws – McMaster P/N: 92311A102 (link)
- Black felt for interior (link) (you can get 1x unit from Michaels for ~$2)
- 3M spray adhesive (link)
- Loctite super glue (link)
Tools:
- Lathe
- Bridgeport
- Drill Press (optional – could use Bridgeport)
- 3D Printer (optional – could use other method for holding ring and positioning leaflet pins)
Drawings:
- RING BOX BASE
- RING BOX COVER
- RING BOX WHEEL
- Leaf – coming soon
The first step was creating the leaflets of the aperture from .006″ thick brass sheet. A pattern was printed from the CAD model and the leaflets cut using scissors. A spray adhesive was used to attach the pattern to the brass sheet and then MEK (methyl ether ketone) was used to remove the adhesive after the parts were cut.
I considered soldering the pins to the leaflets using a propane torch, but the test I ran resulted in a lot of solder pooled around the pin. It held, and I could have spent time perfecting the method to make it look nice but I decided to go the easy route and just use Loctite adhesive to hold the pins to the brass.
Getting the pins properly positioned required a fixture. Using SW, a fixture was designed and printed out on my 3D printer. This allowed for holding the leaflets in position while a drop of loctite was placed at the base of the the pin for bonding the two together.
To test the function of the iris aperture, portions of the body were 3D printed and assembled with the brass leaflets.
The test setup worked perfectly, albeit with a small hole at the center where the iris does not fully close. I think that going a little thinner on the brass material may make it possible to fully close, but I would not go too much thinner otherwise it may be difficult to work with.
With that tested, the real box could be started. Using the lathe and 2-1/2″ diameter aluminum rod, the “ring” that is rotated to open and close the aperture was turned down to proper diameter and the center hole was cut out. A knurl was also added to the outside to make it easy to grip. Next, the holes that would be drilled out for positioning the leaflet pins were marked using a pattern and drilled out with a drill press.
The base was next, starting out on the lathe to get the proper outer geometry and boring out the center cavity. An end mill was used to cut the slots for the pins of the leaflets to slide.
The last part was the outer shell that captured the ring and leaflets. This part was turned down and bored out on the lathe. The end mill was used to cut the slots on either side for finger access to rotate the ring. After drilling and tapping 3x 4-40 holes, spaced 120 degrees apart, for the set screws to hold the assembly together all of the parts were complete.
Before assembly, I sanded and polished all of the visible surfaces of the parts when to give the box a mirror-like finish.
Next, a black felt-like material (from a jewelry stand) was cut to line the inside of the box cavity. A dome with a slot through it for holding the ring was 3D printed and was also covered in black felt.
The final product:
A few weeks later, on the morning of Thanksgiving 2015, I proposed in front of the large tree in the backyard.
I would also be happy to share my designs with anyone that wants to make a similar box. Or, if you want me to help you with designing your own box send me an email.
