By: Mike Zarate
Project Discription
This is a Reverse Engineering project I did for an IED class in High school, of a mechanical pencil called the Pentel P205, where i took the product apart. I seperated all the parts determined the function of each part, mesured them, and remade them in CAD.
Product Description
This Mechanical Ratchet pencil is made by an office supply line called Pentel. This Mechanical Pencil has a 4mm sleve for for technical drawings. The grip at the bottom of the pencil offers you a great control with absolute presision. This drafting pencil has a hidden eraser with a lead plunger that distributes the lead in small incriments when it is pushed down. This happens because the spring contracts and it in turn pushes the clamps out of the clamp holder and opens the clamps up this makes a small incriment of lead come out of the pencil.
The Actual Mechanical Pencil
The Pentel P205 Dissasembled
The Assembled Mechanical Pencil
Part 1: Base
Description: The main part of the Mechanical pencil that holds everything in place.
Overall Dimensions: 4.445 x .356
Material: Polypropylene
Density: 1.200 g/cm^3
Mass: 0.006 lbmass
Volume: 0.141 in^3
Surface Area: 8.352 in^2
Part 2: Lead Holder
Description: This part hold the lead for reserve and is attatched to the clamp colar and holds the erasor.
Overall Dimensions: 3.909'' x .249''
Material: Polypropylene
Density: 1.200 g/cm^3
Mass: 0.003 lbmass
Volume: 0.054 in^3
Surface Area: 4.998 in^2
Part 3: Clamp Colar
Description: Held in place by the lead holder used as a spacer for the pencil and guides the lead into the clamps.
Overall Dimensions: .776'' x .076''
Material: Brass
Density: 8.470 g/cm^3
Mass: 0.001 lbmass
Volume: 0.003 in^3
Surface Area: 0.278 in^2
Part 4: Erasor
Description: The erasor holds in the lead fo the pencil and is used for misteaks made when drawing.
Overall Dimensions: .563'' x .171''
Material: Rubber
Density: 0.930 g/cm^3
Mass: 0.000 lbmass
Volume: 0.011 in^3
Surface Area: 0.312 in^2
Part 5: Erasor Holder
Description: This part goes into the lead holder and holds the erasor in place/
Overall Dimensions: .399'' x .199''
Material: Aluminium
Density: 2.710 g/cm^3
Mass: 0.001 lbmass
Volume: 0.011 in^3
Surface Area: 0.312 in^2
Part 6: Spring
Description: The spring makes the pencil work and gives it the ability to pop back out after you plunge more lead out.
Overall Dimensions: .706'' x .160''
Material: Tin
Density: 2.710 g/cm^3
Mass: 0.000 lbmass
Volume: 0.002 in^3
Surface Area: 0.485 in^2
Part 7: Top
Description: Covers Erasor
Overall Dimensions: .809'' x .250''
Material: Aluminium
Density: 2.710 g/cm^3
Mass: 0.000 lbmass
Volume: 0.005 in^3
Surface Area: 1.324 in^2
Part 8: Clamp Holder
Description: This part keeps the clamps from letting to much lead out.
Overall Dimensions: .580'' x .154''
Material: Brass
Density: 8.470 g/cm^3
Mass: 0.002 lbmass
Volume: 0.007 in^3
Surface Area: 0.444 in^2
Part 9: Clamps
Description: These are used in the clamp holder and letting the right incriment of lead out
Overall Dimensions: .395'' x .076''
Material: Brass
Density: 8.470 g/cm^3
Mass: 0.000 lbmass
Volume: 0.001 in^3
Surface Area: 0.138 in^2
Part 10: Tip
Description: This part directs the lead to one spot and prevents the lead from breaking
Overall Dimensions: .799'' x .221''
Material: Polished Aluminium
Density: 2.710 g/cm^3
Mass: 0.001 lbmass
Volume: 0.015 in^3
Surface Area: 0.703 in^2
Product Innovation
The Innovation that i have made on the Pentel P205 Base is i added better finger grips. It is now equiped with oval finger grips the new grip on the Pentel p205 conforms to your fingers perfectly and allows for hours of drawing or writing, and has a sleek look and a great addition to the pencil.
