Ball Bearing and Blade Apparatus

One of the main problems with the current design of the blender is the amount of glue used to connect the blade and bottle cap to the pitcher.  Glue is currently being used in three different areas on the bottleneck; the rubber washer is glued to the top of the bottle cap, the bottle cap is glued to the bottleneck, and the base of the neck is glued to the bottom of the pitcher. Relying on glue is not ideal for a few reasons, glue is not necessarily reliable for the long-term, it is not the best idea to have such toxic glue come in contact with food that will be ingested, and glue around the ball bearing could potentially lead to accidentally gluing the bearing and preventing rotation. 

The rubber washer is glued to the top of the cap in the current design because it kept coming lose when placed inside the cap.  The problem with having the washer positioned on the inside of the cap was that there was not enough surface area for the glue to adhere to.  A different design and position of rubber seal could both eliminate the need for glue and yield a more effective seal.  The purpose of the rubber seal is to prevent the contents of the blender from leaking through the cap into the ball bearing, and out the bottom of the pitcher.  A good seal will also minimize friction between the rubber cover and the rod, allowing the rod to rotate freely in conjunction with the transmission wheel. 

Ideas for developing a new design for the rubber seal began with trying to completely cover the bearing, leaving only a small slit for the rubber rod to peek through.  Initially, just working with the bearing and cap it seemed as though securing the rubber to the bearing would require a tie of some sort.  Zip Ties presented themselves as a very good and durable solution, however, due to their locking mechanism, the top of the ball bearing is no longer round, and does not fit into the bottleneck. 

Zip Tie disrupts circular shape

Possible alternatives for Zip Ties are materials like rubber bands and string, however, because the rubber seal is quite rigid and difficult to work with, it is unnecessarily challenging to obtain a properly placed rubber seal.  The next option explored was to simply wedge the rubber between the outer edge of the ball bearing and the inside of the bottle cap.  Hammering the bearing into the cap is secure enough to ensure that the bearing remains in place. 

Rubber Seal

Rubber seal jammed into the bottleneck

Bottom angle of the rubber seal in the cap

With the ball bearing firmly placed in the bottleneck, the next step was looking at how the bottle cap could attach to the neck without glue.  Going back to look at the blender model that guided us during the semester, it was discovered that the bottle cap was not secured with anything, in could be unscrewed freely. Thinking about the potential benefits of not having the cap firmly glued to the neck, this design made more sense than worrying about developing a glue-less method because a semi-removable cover makes maintaining and cleaning the blender much easier.  The only potential draw back is that the seal may not be entirely water-tight; however, the liquid meets the cap at an angle where gravity is working to keep the liquid from dripping through the cap.  Thus, because the ball bearing and rubber seal were positioned in a way that made it possible to simply screw on the cap, eliminating glue from the cap was very simple. 

Full glue-less apparatus

The last place excess glue was used in the pitcher was the connection between the blade and ball bearing apparatus and the base of the pitcher.  Initially, we constructed the entire structure before inserting it into the pitcher from the top.  The widest part of the neck was on the inside of the pitcher, and because it is easiest to apply glue to the widest part, the majority of glue was on the inside of the pitcher with only a thin support layer on the outside.  It is not entirely practical to assume we can completely eliminate glue from this location on the pitcher, but we can minimize the amount that comes in contact with the blended matter.  Finding a better way to attach the blade apparatus to the pitcher can be looked at in conjunction with finding a better way to secure the pitcher to the axle connected to the rear wheel.