II. Design Process - SK

Assembly Design

My first step in the design process was to figure out which lengths I wanted to make the links. I started by making a model of the 5-bar mechanism on the Planar Mechanism Kinematic Simulator (PMKS). Then, I adjusted the critical points so I could get my desired range of operation. I wanted to get a range where the input could only rotate between 120-180 degrees, so I could assemble a circuit where I could control the motion of the input.

Below is the model of the mechanism on PMKS:

Figure 1. Model of 5-bar slotted slider mechanism on PMKS.

I then adjusted the lengths of the links so that the input link is 6 inches. Below is a picture of a kinematic model of my mechanism:

Figure 2. Kinematic model of 5-bar slotted slider mechanism with desired lengths.

Material Brainstorming

After finalizing my design, I decided what materials to make my mechanism. I completed my project at home, so I wanted to make my mechanism using items I could find around the house and at a hardware store. I found that building the links and housing out of wood would be a very accessible material option. I used simple plywood for the links because they are lightweight and could be easily rotated by a servo motor. I used standard SPF (spruce-pine-fir) 2x4 wood planks for the housing of my assembly because it is widely available and very sturdy.

For the joints, I found that standard nuts, bolts, and washers were able to make functioning joints. Adding some lubricant between the washers reduced the friction between the joints. To prevent the links from hitting each other, I planned to separate the links with nuts.

I oriented my link assembly horizontally so the motor can adequately rotate the links.