Group 32 - Ryobi Palm Sander
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Revision as of 18:32, 9 December 2007
Contents |
Ryobi Corner Cat Finish Sander
Executive Summary
The purpose of our project was to analyze the function and design of a Ryobi Corner Cat Finish Sander. We started by analyzing the sander from the user's standpoint. After briefly sanding a piece of wood, we concluded that the product functioned well and the ergonomic design fit well into the palm of our hands.
We then disassembled the entire product and noted the quantity, material and shape of each component and its purpose as it pertains to the overall function of the sander. Looking at these pieces in detail allowed us to see how each piece was designed for a specific function. After deciding on the function of each piece, we were able to re-evaluate the shape and material in order to improve the pieces' function and/or to reduce cost. Ideas for improvements, including ways in which parts could be combined or eliminated, were also brainstormed. In the following report, you will see pictures of each of these parts and Auto CAD drawings of key components.
Following the disassembly, we attempted to reassemble the product. This process proved much more difficult than the disassembly. Yet, after fumbling some pieces around, the product had been returned to its original condition. We tested it again to make sure it worked, and it did. Towards the end of our report we included a description of how the product works now that we have dissected the entire sander. We decided on a list of the features that we liked and ones that we didn't like. We also suggested some changes in the design of the product that would either fix the things we didn't like or aid in the cost of manufacturing and assembly of the sander. Overall, we thought Ryobi did a good job designing the Corner Cat.
Introduction
The Ryobi Corner Cat Finish Sander is used for light, detailed sanding. It runs on 120V AC power at a speed of 12,000 orbits per minute. It features an ergonomic comfort grip, a dust bag, an iron-shaped pad design, and velcro for easy attaching/removing sandpaper and other pads. The small, compact design and uniquely shaped pad allows the Corner Cat to reach tight spaces that larger sanders may not be able to reach.
- Specifications
Motor: 120V, AC only, 1.2 Amp
Orbits Per Minute: 12,500 (no load speed)
Orbit Diameter: 1/16"
Pad Size: 3 3/4" x 5 1/2"
Cord Length: 10 ft.
Weight: 2.5 lbs.
- Greg Cummings: oral presentation
- Anthony Wasch: oral presentation
- Rick Hills: written presentation
- Jeff Ackerman: written presentation
- Jonathan Loebel: CAD drawings
(All members contributed to the assembly and disassembly process)
Power Point file: Presentation
Before Disassembly
- The purpose of the Ryobi Corner Cat was fairly obvious; it is used to sand and polish wood and other surfaces. Similar to other small power tools, we assumed the Corner Cat converted electrical AC power from an outelet into mechanical energy using a motor.
- After operating the product for a while, we concluded that it functioned well. The sander vibrated rapidly and sounded much like a vaccum. We assumed the vibration was due to a rotating weight much like the ones in cell phones or gaming controllers. The combination of the vacuum-like sound and the dustbag meant that there was also a suction component involved within the sander.
- We estimated that the sander contained 37 components all made of either plastic, rubber, aluminum, copper, canvas or velcro.
Disassembly Procedure
Disassembly time: about 30 minutes
| Step # | Process | Tool Used | Difficulty | Image |
|---|---|---|---|---|
| 1 | Removed top (3 screws) | Phillips Head Screwdriver / Hands | Easy |  |
| 2 | Unscrewed 2 inside screws | Phillips Head Screwdriver | Easy |  |
| 3 | Unscrewed casing (4 screws) | Phillips Head Screwdriver | Easy |  |
| 4 | Unscrewed 2 screws near the top | Phillips Head Screwdriver | Easy |  |
| 5 | Removed bottom plate (5 small screws) | Phillips Head Screwdriver / Hands | Easy |   |
| 6 | Removed fan housing (4 small screws) | Phillips Head Screwdriver / Hands | Easy |  |
| 7 | Unscrewed 3rd tier of bottom screws (2) | Phillips Head Screwdriver | Easy | |
| 8 | Removed half of the casing | Hands | Easy | Video of step 8 |
| 9 | Removed interior supports | Hands | Easy | |
| 10 | Removed motor from casing | Hands | Easy | Video of step 9 |
After Disassembly
Part Table
| Part # | Part Name | Quantity | Material | Function | Reason for Shape | Manufacturing Process | Image |
|---|---|---|---|---|---|---|---|
| 1 | Top Screws | 3 | Steel for durability | Fastening top | Threaded for fastening | Machined |  |
| 2 | Inside Top Screws | 4 | Steel | Threaded for fastening | Machined |  | |
| 3 | Side Panel Screws | 4 | Steel | Fastening sides together | Threaded for fastening | Machined |  |
| 4 | Bottom Screws | 5 | Steel | Fastening bottom | Threaded for fastening | Machined |  |
| 5 | Inside Bottom Screws | 4 | Steel | Threaded for fastening | Machined |  | |
| 6 | Third Tier Bottom Screws | 2 | Steel | Threaded for fastening | Machined |  | |
| 7 | Casing | 2 | ABS Plastic for light weight, low cost, ergonomics | Holds all components together, allows for air flow | To fit components, aesthetics, air flow for cooling and dust collector | Injection-Molded |  |
| 8 | Top | 1 | Rubber for grip, ergonomics, dampening vibration | Facilitates grip, reduces vibration transfered to user, allows for one-handed use | Curved and ribbed on sides for grip | Injection-Molded |  |
| 9 | Dust Collector (Bag) | 1 | Canvas and ABS Plastic for dust collection, durability | Collecting dust during sanding operation | Space for collecting dust | Injection-Molded (ABS Plastic) and Manufactured (Canvas) |   |
| 10 | Bottom Cover | 1 | ABS Plastic | Protecting Velcro pad while not in use and doubles as a sandpaper punch to maintain sandpaper shape | Fits iron-shaped Velcro pad and punches sandpaper for extended use | Injection-Molded |  |
| 11 | Velcro Pad | 1 | Velcro Sheet for easy fastening | Fastening included sandpaper/scrubbing pads for sanding/polishing using Velcro | Iron-shaped for flat sanding on wide back and fine sanding on tip and Velcro surface to easily affix sandpaper/scrubbing pads | Manufactured |  |
| 12 | Bottom Plate | 1 | ABS Plastic | Attaching Velcro pad, allow fan to suck dust through pad to dust collector, transmit mechanical vibration to Velcro pad and sandpaper | Holes to allow dust to travel through, fits form of case while allowing for vibration, fits iron-shaped Velcro pad, and has a slot for shaft to transmit vibration from the motor | Injection-Molded |   |
| 13 | Fan Housing | 1 | ABS Plastic | Funneling dust pumped up by fan to dust collector, separating components, and providing support for structure | Fits case to support it and has a large hole to allow dust to travel through | Injection-Molded |   |
| 14 | Plastic Supports | 2 | ABS Plastic | Fastening the Bottom Piece to the case during operation | Plastic supports fit tightly, strongly affixing the Bottom Plate to the case, and are good at absorbing vibration with their rib-like structure | Injection-Molded |   |
| 15 | (On/Off) Switch | 1 | ABS Plastic | Click the switch connected to the cord inside, which closes the circuit and sends AC power to the motor | Fits into side within finger reach for one-handed use | Injection-Molded |  |
| 16 | Cord | 1 | Copper and Plastic for conductivity, insulation | Transmits AC electric power to motor and when the switch is closed | Electric wires are insulated by plastic and the long length (10 ft) allows for use further from outlet | Manufactured |  |
| 17 | Stator | 1 | Cast Iron, Copper, Plastic | Coils supplied with AC current produce a rotating magnetic field causing the rotor to rotate | Surrounds the rotor to create a rotating magnetic field around it | Die-Cast |   |
| 18 | Rotor | 1 | Cast Iron, Steel, Copper, Plastic | The rotor is attached to a slightly offset and weighted output shaft that is given torque by the rotating magnetic field. This creates non-symmetrical motion which causes the bottom plate and Velcro pad to vibrate at high speeds; the fan at the bottom sucks dust through the holes in the Velcro pad, bottom plate, and fan housing to the dust bag and helps cool the motor by circulating air flow | Slightly offset and weighted on one side of the fan to produce asymmetrical rotation and create vibration; fan shape | Die-Cast |   |
Accessories
| Type | Quantity | Recommended Use | Image |
|---|---|---|---|
| Heavy-Duty Scrubbing Pad | 1 | Paint and rust removal |  |
| Light Scrubbing Pad | 1 | Light scrubbing and cleaning |  |
| Polishing Pad | 1 | Polishing |  |
| 60-Grit Sanding Sheet | 2 | Coarse sanding |  |
| 120-Grit Sanding Sheet | 3 | Light sanding |  |
| 240-Grit Sanding Sheet | 2 | Finish sanding |  |
CAD Drawings
CAD drawings were made in Solid Works
| View | Image | Native File |
|---|---|---|
| Rotor Iso | 
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| Rotor Iso 2 | 
|
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| Rotor Side | 
|
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| Rotor Top | 
|
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| Rotor Bottom | 
|
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| Rotor Exploded | 
|
Media:finalassembly.sldasm, Media:finalassembly2.sldasm |
| Rotor with Stator Iso | 
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Media:finalassemblyiso.sldasm |
| Rotor with Stator Iso 2 | 
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Media:finalassemblyiso2.sldasm |
| Rotor with Stator Side | 
|
Media:finalassemblyside.sldasm |
- How the Components Are Assembled
Assembly
| Step # | Process | Tool Used | Difficulty |
|---|---|---|---|
| 1 | Placed motor in one half of the casing | Hands | Hard (Correct alignment was critical) |
| 2 | Slid interior supports into one half of the casing | Hands | Easy |
| 3 | Inserted On/Off switch | Hands | Easy |
| 4 | Re-routed wires | Hands | Tricky |
| 5 | Slid second half of casing into place | Hands | Very Tricky |
| 6 | Screwed both halves of casing together | Philips Head Screwdriver | Easy |
| 7 | Placed and screwed in fan housing | Philips Head Screwdriver | Easy |
| 8 | Placed and screwed in bottom plate | Philips Head Screwdriver | Easy |
| 9 | Screwed top of casing together | Philips Head Screwdriver | Easy |
| 10 | Placed and screwed in grip | Philips Head Screwdriver | Easy |
After Assembly
How it Works
When the user toggles the switch, the electric circuit is closed and AC current flows through the power cord to the AC motor from a 120V AC outlet. The motor is composed of two components: the stator and the rotor. AC current travels through the twisted copper coils of the stator, creating a rotating magnetic field. The rotor inside the stator is given a torque due to its magnetic attraction to the rotating magnetic field. The main shaft is attached to the rotor. The main shaft is slightly offset and has a weighted fan on its end, so when it rotates due to the torque, it oscillates slightly. The no-load speed of the rotor is 12,000 orbits per minute (OPM), which is very fast. The orbit diameter is 1/16 in. The OPM of the rotor is a measure of how many oscillations per minute the rotor has. The higher the OPM, the faster the sanding pad moves slightly back and forth, creating more abrasive sanding action. While the rotor is spinning, the fan on the shaft rotates. The top of the rotating fan causes air to circulate through the case, cooling down the motor. The bottom of the rotating fan sucks dust through the holes below, funneling it to the dust collector. After assembly, our product runs the same as it did before.
Possible Analyses for Testing/Designing
Figure out what to do for this…
Reflection on Disassembly/Assembly
The assembly process was essentially the reverse of the disassembly process. It was slightly more complicated because it was difficult to align the stator properly in the case and fit all the wiring. The same tools were used (Phillips Head screwdriver and hands). We were able to reassemble the entire product and return it to its initial working state.
Overall Design
Pros
- Compact size
- Lightweight
- Inexpensive
- $30 at Home Depot
- Ergonomic rubber grip
- Sawdust collector
- Versatile
- Left/Right hand usability
- One-Handed usability
- Simplicity
- Only 18 components, 36 parts
- Multi-Use functionality due to Iron-shape of base
- Tip for precision, wide back for covering more surface (Video of sander in action: Sanding)
- Extra pads included
- See Accessories section
- Bottom cover sandpaper punch
- Extends life of sandpaper and make using new sheets easier
- Similarity of Parts with other Ryobi Products
- Easy, cheap replacement of parts and streamlined manufacturing for Ryobi products
Cons
- Variance of Screws
- Small Sawdust Bag
- Flimsy Wire Connection on Toggle Switch
- Difficult to align stator and wires in the casing
- Warning label on power cord in Spanish and French
Suggested Design Changes & Recommendations
- Use only one type of screw
- Although they were all Phillips Head screws, money could saved at the manufacturing level by using only one type of screw
- Combine the bottom plate and Velcro pad into one component
- This could further lower cost at the manufacturing level
- Include a larger sawdust bag
- Bag would have to be emptied often during extended use
- Strengthen the wire connection on toggle switch
- Improve the fit on the wire’s connector
- Provide better cues for aligning the stator and wires in the case
- Include a diagram in the manual or clearly mark the inside of the case
- Have warning labels on power cord in English
- Include variable speed functionality
- This would be a useful feature to have for advanced users to adjust the sander for certain applications, but would increase the cost and is a function probably best left for more expensive sanders to fulfill
- Make cordless
- This would be a useful feature to have for all users, but would significantly increase the cost and is a function probably best left for more expensive sanders to fulfill
Conclusion
Overall, the Ryobi Corner Cat Finish Sander is a well-designed product. It performs its function effectively, is easy to use, is easy to maintain, and is inexpensive.
- features are simple, easy to use, and do not hinder the function of the product
- size and features both fit its function
References
http://en.wikipedia.org/wiki/Electric_motor#Components
- How an AC electric motor works
http://home.howstuffworks.com/sander.htm
- Information on different types of sanders
http://www.ryobitools.com/products
- Specifications
- Price, further specifications
