I went through 3 iterations when making this design. Throughout my design process, I had issues with link length, the slider joints, and how to position the coupler and follower.

Iteration 1

With my first iteration, I tried to incorporate an uncrossed mechanism into my jewelry box. I had initially thought that creating an uncrossed mechanism would not affect how well the box would open and that it would have been easier to manufacture.

Fig.1 PKMS Iteration 1 Model

I tried to make my design adjustable, by creating a row of holes on the lower part of the jewelry box, because I was not certain what position the linkages should be in for the box to open optimally.

Lastly, I focused on how I would create the pin in slot and slider joints. I originally thought that laser cutting a small wooden block to slide against the top of the jewelry box wall would be sufficient and cutting a small circular block would work well for the pin-in slot joint too.

I quickly realized that my design was not up to par with how I wanted my jewelry box to function. There was a lot of friction within the pin in slot and slider joints, making it difficult to open the box. Additionally, there was nothing securing the slider joint to the jewelry box. When I tried to open my jewelry box the slider joint would lift off its track. This instability added to the difficulty of opening the box.

Fig. 2 Iteration 1 Prototype Video

Iteration 2

After my failed first attempt, I went back to SolidWorks to try to fix my mistakes. I worked on improving the pin-in slot and slider joints and how to position the linkages. I still believed an uncrossed mechanism would work the best, but I thought that moving the linkages from the bottom of the box to the side of the box would improve how the lid opened.

Fig. 3 PKMS Iteration 2 Model

I still wanted to make my design adjustable, so I created a row of holes at the top of the box. This allowed me to play around with how I wanted to arrange my linkages. Additionally, since I moved my linkages up to the top of the box, I shortened them

To improve the slider joint, I created a more well-defined track for the slider to move in. To do this I added a track for the slider to move in on each short side pane of the box, and I had to redesign the lid to create an offset between the slider and coupler. Otherwise, they would have rubbed against each other. I also decided to do away with using a wooden slider and pin. Instead, I decided to use bolts and washers as my pin-in slot and slider.

Fig. 4 Improvements made in SolidWorks model

This design was not great. I still had a lot of issues with friction in the joints and how far I could open the box. One reason for too much friction in the pin-in slot joint was that the screw head was rubbing against the lid of the box as it slid along the track. I realized that I did not allow for enough tolerance between the bolts and the slot. Additionally, there was a lot of instability within the joints.

Fig. 5 Iteration 2 Prototype Vido

INSERT VIDEO AND NOTE THIS IS A PROTOTYPE AND THAT’S WHY THE SCREWS WERE NOT FASTENED WELL TO BOX

Iteration 3

Finally, I realized that I could create a better jewelry box if I used a crossed mechanism. For my final iteration, I focused on the friction and stability within the joints and how to make a crossed mechanism.

Fig. 6 PKMS Iteration 3 Model

To improve the friction within the pin-in slot joint, I made the slot wider and moved it farther down from the lid to make room for the screw head. I also made the slot for the slider joint wider. Lastly, I added washers to both sides of the linkage to improve the stability within the joints.

Fig. 7 Iteration 2 Sliding Link

Fig. 8 Iteration 3 Sliding Link

These adjustments were successful and allowed the lid to open smoothly. A video of my final design can be found on my "Final Prototype" page.

Fig. 9 Final Prototype