Ball Polishers





In the paintball industry thousands of rounds can be fired in a week, and sometimes in a day. Some of these rounds go unbroken and are left to degrade and become unusable. A process for reclaiming the paintballs would allow an opportunity for increased profits at paintball facilities. With this need identified, a design team has been formed. The design team, which is composed of five Senior mechanical engineering students, has designed and fabricated a prototype to satisfy the identified need.14_11_recycleprocess

Recycling process that the prototype achieves.



The design for the Paintball Recycler uses a three step process. The first process applies baking soda, the cleaning agent, to begin the primary function of cleaning the paintball. To accomplish the application of the cleaning agent, two concentric cylinders were constructed to tumble and coat the paintballs evenly with baking soda. The inner cylinder has perforated walls of a sufficient size to allow the cleaning agent to pass through, however it does not allow paintballs to fall through or become trapped. The outer cylinder contains the baking soda and has walls to bring the agent from the bottom of the cylinder to the top, which then drops and is applied to the paintballs again. The holes allow the desiccant to pass between the two tumblers, enabling it to be reused which reduces the amount of desiccant used per batch. Two screw conveyor systems were used: One to transition the dirty paintballs from the holding container to the tumbler and another to slowly refill baking soda to the outer cylinder. Using a screw conveyor system allows mechanical control of the amount of product being input by controlling the angular velocity of the screw. A pulley system was designed to allow one motor at 10rpm to control both conveyor screws in order to reduce cost. The tumbler is attached to the hopper system using a turntable rotating plate and is powered by another motor of 75 rpm and a flat belt.


Designed Hopper and Tumbler Assembly

Once the cleaning agent has been applied evenly to the paintballs, gravity forces the balls into one channel of precisely spaced counter rotating brushes. Spacing between the brushes simultaneously causes broken pieces and particles to be pulled off the paintball, while removing the cleaning agent from the paintballs. This step of the process completes the function of cleaning the paintballs, while at the same time beginning the first step of the sorting function. The brush system is also powered using a 75 rpm motor with a sprocket and chain system. Once the paintballs are cleaned and particles are sorted from the paintballs, the paintballs pass to the primary sorting function which is completed with the use of a flat plate that has spacing so to allow first the undersized paintballs to be sorted out and then the correctly sized paintballs. The remaining paintballs are then sorted into the oversized bin at the very end of the sorting channel.

14_11_BrushesandSorting.pngDesigned Brush and Sorter Assembly




Prototype Fully Assembled

Hopper Assembly

The hoppers were assembled by cutting out pieces of sheet metal appropriately sized by the design drawings. The individual pieces were then welded together to form the hoppers. Once the hoppers shape was constructed, a hole of 2-inch diameter was cut in the desiccant hopper and a hole of 4-inch diameter was cut in the ball hopper so the conveyor screws could be installed.

Tumbler System Assembly

Assembly of the inner tumbler was completed by taking a piece of sheet metal and milling out the holes for the desiccant to fall through. The metal was then be rolled into a cylinder shape and welded. A circular piece was then welded to the bottom to complete the inner cylinder. Four evenly spaced fins were the welded to the outside of the inner cylinder. A lip was then welded to the outside of the inner cylinder with two holes cut into it on opposite sides to allow paintballs to escape. The outer cylinder of the tumbler also began as a piece of sheet metal rolled into a larger cylinder shape than the inner cylinder and welded together. Four slots were welded to the inside of this tube to allow the fins to be inserted and held in place. The tumbler was attached to the hopper system with the use of a Lazy Susan. A chute made of sheet metal was then fixed below the exit of the tumbler and lead to the entrance of the brush system.


Construction of the Outer Tumbler

Brush System Assembly

The brush system frame holding the four brushes in place was made out of sheet metal. One side of the brush frame was fixed to the chute coming from the tumbler exit. The brushes were coupled with a sprocket chain drive which was connected to a motor to provide brush rotation.

Sorter System Assembly

The sorter system was assembled by cutting out pieces of sheet metal sized by the design drawings. Since the bottom plate of the sorter has to be precise so to sort paintballs correctly was sent to a machine shop to be laser cut. Once all pieces were cut out and the bottom plate was cut by the machine shop the system was assembled by welding the pieces together.


Cutting out Sheet Metal for Prototype Assembly


Built Prototype in action.


The prototype underwent two different tests to determine if met the engineering specifications of:

-90% of the output balls are clean

-90% of the output balls were of the correct size

-2,000 paintballs processed per hour

-Sound level of no greater than 55dB

-Low maintenance

-100 hours of operation before replacement parts were required


The testing process included testing 100 paintballs at a time and a separate test of 2000 paintballs at a time.  Although most of the engineering specifications was met, the prototype was deficient in 100 hours of operation before replacement parts were required due to one of the conveyor screws fracturing after 10 hours of operation.

14_11_Specs chart

Listing of how the prototype measured up with the engineering specs.



Julian Ballatore-South

Julian is a Senior Mechanical Engineering student from Northern Nevada who will be graduating in May 2014. Julian has much experience in Solidwork drawings, and simulations.

Michael Cannon

Michael Cannon is a Mechanical Engineering student who will be graduating in May 2014.  Michael has engineering experience as a quality control technician with QES of Reno.

Amanda Jones

Amanda Jones was born and raised in Las Vegas, NV. She will be graduating in May of 2014 with a degree in Mechanical Engineering. Previous engineering experience includes working as an intern at Southwest Gas and Paiute Pipeline.

Logan Kiff

Logan is a Senior Mechanical Engineering student from rural Northern California who will be graduating in May 2014. Logan’s extensive internship experiences have made him an expert in applying engineering to business world experiences.

John Mack

John is a Senior Mechanical Engineering student from Reno, Nevada. John has extensive internship experience with drafting and product design and has worked on several projects utilizing sheet metal, motors, and various fastener techniques.