Theoretical Background

# tells the reader something about the principle/s theory involved in the project

 Project Description

# physical description

# how does it work?

 The motorised sharpener consists of a cutting blade, a push button, a motor, two shafts, two bearings, a set of compound spur gear trains and various dimensions of perspex that make up the casing.

This sharpener is DC operated with a three volt supply from batteries. The activated motor transmits a certain power to drive a compound gear train. The driving gears in turn drive the cutting blade of the sharpener to sharpen the pencil.

 Process Description

# before creating the FINAL DESIGN, what stages did we cover?

 After designing the motorised pencil sharpener, analysis of the product was required before the assembly and manufacturing phase.

The information regarding the design of the motorised pencil sharpener was arrived at by drawings, an exploded three-dimensional view of the product and a prototype of the product.Following this, the design was analysed for manual handling and manual insertion using the Boothroyd Dewhurst method

There were two problems encountered during the design stage: getting an appropriate and attractive shape and conforming to the given specifications.

This problem was solved through brain-storming sessions, consultation with lecturers and knowledge gained during the course of study at the Polytechnic.

Finally a design that was both attractive and within the specifications was created.

 Assembly and Testing

# how is the product put together?

# how did we test the product?

The assembly procedures of the motorised pencil sharpener are as follows:

1. The motor together with its holder and pinion were screwed to the base using two self tapping screws.

2. The driven gear was fitted tightly into the shaft. The residue plate was then slid into position.

3. The sharpener holder was fitted tightly to the shaft and the sharpener was fastened to its holder with two capped screws.

4. The whole assembly was aligned in such a way that it was directly below the hole in the top plate.

5. The battery bracket was tightened to its holder and this together with the sharpener was fastened to the side plate with self tapping screws.

6. The four side plates were glued together after the assembly of all the internal components.

7. The contact switch was then screwed to the top plate using self tapping screws.

8. Finally the top plate and the contact switch were glued on to the top of the four side plates.

Once the assembly was completed the motorised sharpener was tested using a HB pencil.

 Discussion

# what was achieved?

# what were its shortcomings?

# what was learned?

The motorised pencil sharpener was constructed. However because of some manufacturing/assembly problems and time constraints, the sharpener did not cut the pencil properly.

One of the main causes for this could be the lack of proper alignment of the components.

The other possibility could be inadequate torque transmitted.

However, these problems could be overcome by taking the time for proper alignment and calculating appropriate transmission ratios.