Group 36 - Ryobi Contractor's Saw

Executive Summary

This section is much like an abstract and summarizes the entire report

Introduction

This section should include an introduction of the product and a brief description of group members (i.e. who was responsible for which sections or tasks)

Before Disassembly Section

This circular saw is primarily used for cutting wood. It runs on an AC current, and contains a 2.3 hp motor at 4600 rpm, turning electrical energy into mechanical energy. At the beginning of the project, it was new, so the group assumed that its initial operation was correct. The saw is operated by engaging a safety switch, and then a power switch. It was very loud, and even without the torque of the blade, kicked back when it was initially operated. This demonstrated the physical power of the motor. The group estimated that the saw would contain about 40 components, and predicted that those components would be made of plastic, steel, aluminum and copper.

Disassembly Procedure

• Document each step to disassemble the product
• How difficult was each disassembly step?
• What types of tools were required to perform this step?
• Include a picture of each disassembly step

After Disassembly

Component List

Part #	Component Name	Number of Parts of This Type	Material(s)	Manufacturing Process	Image
1	Motor Housing	1	Plastic, Brass, Galvanized Steel	Injection Molded, Die Cast and Machined, Stamped	PUT PICTURE HERE
2	Stator	1	Plastic, Copper, Magnetic Alloy	Injection Molded, Extruded, Stamped and Soldered	PUT PICTURE HERE
3	Trigger and Safety Switch	1	Plastic, Aluminum	Injection Molded, Extruded and Machined	PUT PICTURE HERE
4	Power Cord	1	Copper, Plastic	Both Extruded	PUT PICTURE HERE
5	Upper Guard	1	Aluminum, Brass	Die Cast and Machined, Machined	PUT PICTURE HERE
6	Reduction Gear	1	Steel	Extruded and Machined. Also dipped in an anti-corrosion coating.	PUT PICTURE HERE
7	Central Washer	2	Steel	Die Cast	PUT PICTURE HERE
8	Depth Adjustment Lever	1	Plastic	Injection Molded	PUT PICTURE HERE
9	Rubber Stopper	1	Rubber	Injection Molded and Vulcanized	PUT PICTURE HERE
10	Handle	2	Plastic	Injection Molded	PUT PICTURE HERE
11	Rotor	1	Steel, Copper, Plastic	Stamped, Extruded and Machined, Extruded, and Injection Molded	PUT PICTURE HERE
12	Vent Cover	1	Plastic	Injection Molded	PUT PICTURE HERE
13	Lower Guard	1	Aluminum	Die Cast	PUT PICTURE HERE
14	Carbon Brush	2	Plastic, Copper, Carbon, Brass	Injection Molded, Extruded, Machined, Stamped	PUT PICTURE HERE
15	Lower Guard Lift Lever	1	Plastic	Injection Molded	PUT PICTURE HERE
16	Long Screw	6	Steel	Extruded and Machined	PUT PICTURE HERE
17	Medium Screws	8	Steel	Extruded and Machined	PUT PICTURE HERE
18	Short Screws	4	Steel	Extruded and Machined	PUT PICTURE HERE
19	Central Bolt	1	Steel	Extruded and Machined	PUT PICTURE HERE
20	Long Spring	1	Steel	Extruded	PUT PICTURE HERE
21	O-Spring	1	Steel	Extruded	PUT PICTURE HERE
21	C-Clip	1	Steel	Stamped	PUT PICTURE HERE
22	Large Gauge Screw	1	Steel	Extruded and Machined	PUT PICTURE HERE
23	Wing Nut Bolt	1	Steel	Extruded and Machined	PUT PICTURE HERE
24	Wing Nut	1	Steel	Stamped	PUT PICTURE HERE
25	Wrench	1	Galvanized Steel	Stamped	PUT PICTURE HERE
26	Plain Washer	1	Aluminum	Stamped	PUT PICTURE HERE
27	Washer	1	Aluminum	Stamped	PUT PICTURE HERE

Design Changes

While the long, medium, and short screws all took the same size bit and had the same thread, the large screw took a different bit. This group suggests that the large screw be changed to accommodate the same size bit as the others.

Also, the carbon brushes are simply set into the saw and held in place by the vent. The group suggests that the brushes are fastened in place independently.

• Part number
• Part name
• Number of parts of this type
• Part material
• Part manufacturing process
• Image of the part
• CAD file for selected parts

Assembly

• Document each step to reassemble the product
• How difficult was each assembly step?
• What types of tools were required to perform this step?

After Assembly

Reassembly

Upon reassembling the saw, the group successfully tested it. It ran almost exactly as it had before, but once the switch was disengaged, the motor continued to spin from its momentum. The group surmised that the broken copper wiring in the carbon brushes must have had something to do with the braking of the motor. This problem could be quite dangerous if the lower guard malfunctioned.

Design Problems/ Changes

The group discovered that there was a lot of plastic used in the saw's construction. We felt that there was not enough metal at pivotal load-bearing locations on the saw. Instead, we found plastic at these locations. The high power of the drill and the brittle nature of the plastic could lead to a dangerous malfunction, were some of the plastic supports to break. We suggest that high-load areas be reinforced with some sort of steel.

We also noticed that there were no ball bearings on the bushings. Instead, the bushings were heavily lubricated with grease. If the lubricant was burned away by regular use, there could be a large amount of friction created, efficiently "burning out" the motor. We suggest that to increase the longevity of the saw, ball bearings are added to the bushings.

References

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