General comments
Overall there has been substantial progress since the mockup review. This is a good thing and provides reason for satisfaction. However, in most cases, key aspects of the designs are working but the prototypes are closer to mockups than designed products, perhaps more so than in recent years. Imagine yourself in a store or other relevant environment and seeing your current prototype on display. Would it look out of place? Would it hold up in the use environment?

A very challenging part of the process remains. With an understanding of most of the functionality, it is now critical to design the devices as coherent, integrated, elegantly-resolved products, thinking carefully about overall form, human factors, efficient use of materials, ease of fabrication, cost and user safety. If you have questions about how your team might go about this, please feel free to ask for a design consultation, even before the Thanksgiving break.

Team-specific comments/suggestions that are intended to help each team with preparation for the final presentation are provided below. Please consider these comments before setting priorities before the holiday, and feel free to ask if there are questions. You will also receive comments from individual instructors over the remainder of this week. The average scores for each prototype are at the bottom of the page.

Your team will need to take a split approach in the next stages, working on the prototype and at the same time designing/preparing materials for the final presentation, where a large number of product development experts (100-150) from industry will review the projects.

To view a team's prototype and provide feedback, click on the links provided below.

Team-specific comments and suggestions
red, green, blue, yellow, orange, purple, silver

Red: Plastic bottle insulation fabrication
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The team has made a concerted effort to develop a material that can be made out of used plastic bottles, to understand its properties, and to think about its use. Because of the time needed to develop the material, the prototypes were very much like mockups.

Now is the time to move past bench-level tests and mockups for developing the material and focus on designing an appropriate manufacturing system and equipment, moving the process beyond craft work.

The list below is a summary of comments or questions that we hope will help the team improve the final product prototype.

• It is critical that there is a reliable sewing machine. It is important to tackle this issue head-on because, otherwise, a good effort could easily be undermined at the final presentation.
• The hardware design is at the level of mockups. When redesigning, try to match the different steps to have similar throughput, make the transitions between steps as simple as possible, and think carefully about the design of the machines as manufacturable equipment.
• The fixture for holding the bottle pieces in place works nicely. It could be reoriented so the edge of each successive bottle is pushed down by the previous one as they are sewn, reducing the chance of catching.
• The frame on the sewing machine is clearly a mockup. When redesigning, keep weight, efficient material use, and clothing catch points in mind.
• The hot wire bottle cutting mechanism seems slow. The bottles have a tendency to catch on the sides of the guides, and the curling caused by the hot wire make the bottle rings more difficult to process. It might be more promising to focus on one of the other bottle cutting concepts, such as the rotating bottle/cutting knife variations.
• It is a bit fiddley at times to feed the bottle rings into the roller. It would be nice if it was easier to see the input side from above. Curiously, several of the reviewers wanted to turn the roller counter clockwise and had to make a conscious effort to turn it in the right direction to feed the bottle segments forward.
• For the final presentation, it might be good to have a portable wall section detailing the plaster/insulation installation details.

Green: Oil filter draining
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It really seems like the team has a handle on the main functional issues. The technical risks seem to have been managed and are now understood. The challenge now is to transform the idea from a mockup that grew out of a series of experiments to a designed product.

Some suggestions and questions follow.

• The overall structure could be simpler, use material more efficiently, and take less space. Bent and welded tubular steel might be a good option. Does a cylindrical shape seem appropriate?
• The guards could be simplified. Many liked the clear sides. Does polycarbonate deteriorate with extended exposure to oil? In general, it is not very chemical resistant unless specially coated.
• Think about wire and hose routing so that as much as possible these items are not exposed to potential damage in a rough use environment.
• All details need to be designed carefully to withstand vibration and not come loose under repeated use. Eliminate unnecessary fasteners. Carefully think through the design of machine elements. Design for ease of assembly.
• The door may need to be taller to avoid binding.
• A larger diameter, finer pitch screw and higher output speed motor may improve the hole drilling performance. It might be nice to be able to see the drilling when standing in front of the machine.
• It seems that the motors may be over-powered. Careful sizing might reduce power requirements and component costs.
• Vibration isolators for feet would help with walking issues. It might be interesting to think of a wall mounted unit.
• The punctured oil filters are potential cut hazards. Is there a way to mitigate or avoid this?
• An angled or V bottom panel would allow oil to drain to a point. Is the drawer needed? Design the drawer to operate smoothly if it is to remain.
• The control panel is not really a designed layout. It will be simpler when the process is more automated, but think about the layout carefully and use robust switches that can withstand abuse.

Blue: Recycl-o-sort
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The component-level functionality is good. It is now critical to think about the overall product first and carefully develop an integrated system, designed from the top down—what should it be and how do the components subsystems need to be designed fit into it?

It would be great if this could be tested on the client's site, but there will need to be a big leap in overall design before it will be robust enough and safe enough to put in the field.

Some suggestions and questions follow.

• The overall device uses materials inefficiently. A welded structure may be more appropriate, but keep in mind that panels can be structural elements as well. Can it be made much simpler? Sharp edges should be avoided.
• The wait time seems huge. Will people really stand and wait that long?
• It seems very expensive to not address the panel orientation issue. Choosing a panel large enough to be sufficient at a ~30 degree inclination, potentially pointing due north, does not seem to be cost effective. Can the design address this (e.g., round design, square design allowing 4 orientations, multiple small panels in parallel and in different orientations)?
• It is a concern that the mechanisms are so easy to reach through the bottle insert hole. Can the door lock really be made fool proof?
• Is the mechanism environmentally robust? What will happen if beverages are poured into the device? Is the enclosure going to leak and expose the electronics to water?
• What goes on inside is interesting, but the windows are below sight lines. Will people stoop?
• Will the device need to be cleaned or removed for maintenance? Is this an easy process?
• It is difficult to envision recyclers taking the time to install new bags each time. Is there a way to avoid this? There was discussion of the bags being able to take up more than 1/4 of the space based on demand, but the bags used would not be able to do this.
• The mechanics/structure of the door and bottle removal devices need to be carefully detailed to withstand rough use.

Yellow: Smart shower
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The team has made good progress and the shower quality seemed quite reasonable. This was one of the prototypes at the review with more of a planned overall design. If the prototype is used as a basis for a redesign it should be possible to have a very nicely refined prototype for the final presentation.

Additional thoughts follow.

• The device is large, heavy, and the frame is difficult to make. Try using lighter materials (anodized aluminum or PVC for example) and make the geometry easier to fabricate. It should be straight and true (e.g., things that should be parallel should look parallel). Also, think about how the geometry might prevent the device from rocking on the wall.
• It may be more appropriate to use rapid prototyping to make your enclosures, and then finish and paint to emulate injection mould housings. This would make things lighter and also allow much finer detailing for the display icons. The display icons may be a bit small to see for those with reduced eyesight.
• It is really easy to trigger the low water flow when reaching for the maximum water flow button. Would it be good if the high flow button was much larger? More of a bump button?
• Currently the rack looks like safety hand hold bars. This confusion could lead to accidents.
• There probably should not be any exposed wires, just for customer perceptions. Could the connection point to the flow controller be both mechanical and electrical?
• In order to properly test and to avoid confusion about your design when you are showing it, it is very important to install a proper mixing valve/tap set on the tub. The overall shower display needs to be nicely finished for the final presentation. Think about how one might demonstrate without a shower curtain.
• The detailing for the cut reflectors could be cleaner. Feel free to ask for detailing suggestions.
• There was some concern that the sensor system was having problems with water droplets. Please test carefully and also evaluate an enclosed, steamy shower environment. If there are issues, would an emitter-receiver pair be more robust?
• The soap and middle shelf seemed a bit had to pull items from, perhaps because of the depth of the unit?
• The recharging issue has yet to be addressed. Is it possible to use an induced current charger, as is used for some electric toothbrushes?

Orange: Bean sorter
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The prototype seems to have a good chance of being used and the basics seem to be in place. Think carefully about how to redesign the system so that it is easy to use, and simple and easy to build correctly.

Additional suggestions and questions are listed below.

• The device is very large and uses a lot of material and floor space. Could it be designed to use less material, be a more efficient structure, and use less floor space? Even with a separate hopper system, could the two be more integrated so they go together in a more compact form?
• If this prototype is to be moved place to place for demonstrations, durable materials, such as steel, and a modular design for disassembly/reassembly with minimal tools and opportunity for error may be appropriate.
• There seems to be some debate about performance requirements. One approach might be to benchmark the new process to the traditional hand process in terms of both defect rate and production rate.
• The turning rate seems to be a sensitive parameter in determining efficacy. How does one know the right rate? Could it click like a metronome? Many found the required rate to be very slow. Maybe a pulley-based reduction stage? Perhaps it could be foot powered using very simple technology like that used in a spring pole lathe? Is there a need for a fine adjustment screw for the angle? Are baffles needed to regulate residence time?
• The chute design from the hopper seems quite fragile. It might make sense to design the output collection side to match the capacity of the input side bag, so both sides only need to be loaded/unloaded at the same time. Are the collection bags easy to remove and install?
• Think about sharp, unfinished edges.
• It would be nice to be able to see what is happening while using the device. Perhaps being able to stand to the side while using the device?
• The crank handle seems flexible and prone to damage.
• An instruction manual was identified as a key deliverable. Is this part of the scope for the final presentation?
  
  

Purple: Batteryless remote
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This is a design that has very good potential. Good work has been done, but things did not come fully together in time for the technical review. Thus, the project did not score as well as it could have, but it can still be an excellent project.

Think carefully about the product. What is the core proposition? A remote without batteries that is so pleasant to use that people will not want a remote with batteries? This should direct what to focus on. Having a convincing, well refined, functional, quiet, easy-to-use mechansim in an attractive, ergonomic package is important. It might be advisable to focus on one design rather than several parallel options. The team can use the information-to-date to pick the option.

Other suggestions are listed below.

• Rapid prototyping seems like an appropriate way to make your housings. A silicone over-moulding on a rapid prototyped housing is a nice idea and should really help to dampen sound transmission, but the solid silicone seemed to be a bit heavy. Please let the course instructor know if you are going to do more moulding so a proper degassing setup can be purchased.
• Think about pinch points with the open side levers. Can the form language of the lever match the rest of the remote?
• Finding a way to either make or purchase precise gears seems to be critical. Have all sources to purchase gears been exhausted? Are there other protoyping methods that might be appropriate (maybe wire edm)? Is it possible to avoid gears and use pulleys? This might be inherently more quiet. Or a hybrid system?

Silver: Shea butter maker
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The team has done a lot of work over the past few weeks and several positive developments have been made. After evaluating the prototype at the final presentation there are two primary concerns.

i) Function: Will the current design produce shea butter at a sufficient throughput, or does it plug up after fully filling the grinding plates? From the testing during the review, we worry that the latter may be the case. It does not seem like the screw can generate enough pressure to force the nuts through the plates. It is really important that the device demonstrably produces at the desired production rate. It might be advisable for a small task force to solely focus on the screw/die mechanics and design. The current design seems to be very similar to the previous D-lab prototype. It may be necessary to consider different ways to fabricate more sophisticated screws and barrels, perhaps casting.

The morning after the review we used a commercial meat grinder to create Shea nut paste in the Pappalardo lab. See the video (.mov, 1.9 Mb). Whole Shea nuts were fed into the extruder. The holes in the die were 1/8 inch in diameter. The resultant paste had a fairly smooth oily texture. The test illustrates the behavior of an extruder designed to generate pressure, as opposed to conveying material like a fixed pitch auger.

ii) Ergonomics and design details: Design the device to be easy to make and pleasant to use. If a clear attachment interface and functional volume is defined for the butter-making mechanism, this work can be done in parallel with the development of the butter making component, but still allow you to create an overall coherent design. Some suggestions are below.

• The basic geometry needs to be refined. If you have not done so already, it might help to look at recumbent bicycle designs, and the book Bicycling Science might also have useful information.
• When bending the frame, it is useful to print out a full scale pattern to check angles against during fabrication.
• It seems like a flywheel would really help in evening out the power stroke.
• The chain is under high tension. This may tend to stretch the chain. An adjustable, floating tensioner might help.
• Feeding through the legs did not seem very easy to do and was not a pleasant experience. Would a skirt cover the grate?
• The seat design might be simplified to have fewer parts. The short end grain in the angle brackets will tend to split over time.
• Can the entire frame be designed to use a simple repeated form vocabulary? This would help to make a pleasant artifact even though it is made from very humble materials.
• Think carefully about cleaning and safety. Can the cloth hopper be attached so that one cannot get hands into the auger from the side?

Average prototype scores

The scores provided below are based on prototype operation and the assessment viewpoints outlined in the technical review description. Different instructors focused on different viewpoints. The data are averaged from scores provided by 21 reviewers.