3 Ideas
Sketch Model Review
Mockup Model Review
Assembly Review
Tech Review
Final Presentation

Results of Technical Review

Team specific comments from David are written on this page, below the section of comments for all teams. Please be sure to read these comments. Comments from other reviewers, compiled for each team, are accessible through the "feedback" links below (certs required). Feedback will be coming in Friday, and no later than 5 PM Saturday.

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


beehive system


custom lipstick


lead climb belayer


pipe freeze prevention


aircraft baggage loader


lifting oven rack


modular surf board


scuba neutral buoyancy

General comments
Please read these comments thoroughly! 33 instructors and guests participated in the review.

All teams have shown good progress since the mockup review and a lot has been learned.

The technical review prototypes are good platforms for testing and provide a concrete reference point from which one can carefully design and detail a product. While some models were more refined than others, across all teams the prototypes are closer to engineering mockups than a designed product. Using what you have learned, now is the time to move from the mindset of exploring options to thinking through the design details of making a usable, real product. It's time to design and implement a looks-like, works-like prototype for the final presentation/product launch! This is where the jump to being a product, as opposed to the exploration of a concept or bench-level experiment takes place.

In preparing for the design review on Monday and working towards the final presentation, please refine and execute your device as a coherent, integrated, elegantly-resolved product, thinking carefully about efficient use of materials, ease of fabrication, cost and user safety, overall form, and human factors (amongst many other things).

One of the first things to do in preparing for Monday is to step back, look at, and discuss the prototype as a team. Regroup, and get the team on the same page about what the product is, your core value proposition, and implementation vision. Having been focused on different items/details in the push for the technical review, different team members may not be aware of how aspects of the product have changed. Or, based on what has been learned, how things should change. As a reflection of this, inconsistent descriptions and rationales about the products were provided by different members of the same team to review sub-groups. The review prototypes can be used to test and understand how to resolve challenges.

Please read the team-specific comments from me below (Prof Wallace). The written comments from other reviewers will be received no later than 5 PM Saturday. Also, carefully review your own notes from the review. Think about how your current prototype needs to change to be comparable in detail and execution to existing products that you can already buy. Looking at details in related, real products for inspiration can be very helpful at this point in the design process. We are aiming for comparable levels of detailing to what is seen in real products.

If your team has key functional aspects or system integration issues yet to be resolved, it is very important to tackle these problems soon in order to avoid surprises a few days before the final presentation. Core, integrated functionality should be solidly resolved this coming week so that there is time for implementing, planning, product testing, and preparation/practice for the final presentation.

All teams should aim to have the final prototypes completely ready and available for presentation practice by the Saturday before the final presentation. Your team will need to take a split approach during the final weeks, working on the prototype and at the same time designing/preparing materials for the final presentation.

My team-specific comments/suggestions that follow are intended to help each team in preparation for the next design revision/design review on Monday. Please consider these comments along the written feedback you will receive from other instructors as you make decisions,. Feel free to ask questions too.

Finally, please be sure to schedule a time to meet with me on Tuesday to discuss set design (if you have not done so already).

The average scores from reviewers for each prototype, with standard deviations, is at the bottom of this page.

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

Red: Beehive box lifting system
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The architecture progressed a lot from the assembly review. While there are a number of issues, I think that the bones for a good solution are there... It's now time to resolve and execute details.

For myself, I learned more from the "pre-review" on Tuesday than during the technical review. The sketch I sent after that review still encapsulates what I learned related to addressing lateral stiffness, stability, using standard boxes, allowing fine box positioning separate from lifting, simplifying shipping and assembly, and allowing potential for one device to service multiple hives. I was not able to get a sound impression for changes in direction/thinking post the Tuesday pre-review. Also, in the technical review, the proposition of "I'm a beekeeper and this is what the product does for me" did not come across as clearly as it might.

My impression is that further simplification while addressing issues with the current prototype is needed. The beehive itself is a really simple, wooden structure. For some beekeepers there is an aesthetic component to beekeeping. Can the design be resolved in a way that it belongs with the hive. For example, could wood be used for key structural elements rather than tubular steel or aluminum?

Some other thoughts:
• for the rod ends to help with lateral stiffness, they will need to be deeper/thicker than the ones used in the new test bed. For myself, in this application, flexures have relative stiffness benefits, and have fewer corrosion and fouling issues than rotational bearings for joints.
• try to design the travel stops to avoid putting the links in bending... The chain/cable stop is a nice approach, but ideally attachment points would be at or close to the pivots.
• when receiving feedback, a "yes and" approach first trying to think of ways to build off of comments can lead to new insights, even if the initial feedback does not really work or isn't plausible. A "no because" pattern tends to close down such opportunities.

Green: single person belayer
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The prototype was nicely executed and provides a good platform to work with and gain understanding for implementing the final product prototype. Given that the eddy current motion brake required motion to work, it's hard for me to visualize how it's so stiff at such a low speed. I wonder if there is friction somewhere that is providing most of the resistance? Are magnets actually clamping on the disc? The technical review prototype can now be looked at carefully and with some detective work more insight will be gained. Maybe friction is good... perhaps consider a centrifugal drum brake (sort of like a chain saw)?

Some other thoughts follow:
• it seems like the magnets used in the prototype would be very expensive
• the use model (part of a club facility, or individual user owned) seemed a bit unclear. The individual user case was less obvious for me. Regardless, it seems the products would likely be very different for the two cases. For individual user-owned, things like being small, light weight, safe near credit cards or phones, a carrying case, etc. become even more important.
• the attachment to the wall needs more resolution. Tying it off has potential for failure. Perhaps using screw links if it is often removed, or more permanent bolting to the wall if semi-permanent?
• will rope management and tangling be a concern?
• is the core proposition to lower the climber to the ground, or stop the climber and then allow them to resume? There was inconsistency on this point.
• the minimum 8 foot fall to engage the brake seems high.
• I think that it was a bit confusing that the test rig setup did not emulate a lead climbing situation. This may have caused some confusion about it's use/operation

Blue: aircraft baggage loading
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The design has come a long way since the assembly review. That's nice! Overall, the devie definitely helped compared to lifting. The general approach seems solid, so now it's about working the details to get it into a nicely usable product form. Also, it makes sense that it works for a 737, but it would be nice to convey the range of planes that it might be used in. In particular, when does the flat of the cargo hold become too narrow?

A few more specific thoughts:
• the lighter the better! In an ideal world it would be light enough just to pickup and carry around like an oversize briefcase.
• I wonder if ball transfers might have the potential to be a lighter solution than rollers, allow for slight lateral adjustment with going up the ramp, and reduce catching potential. I'm thinking of a sheet that is a grid of under-mounted ball transfers (under-mounted like this example. This is a strip rather than sheet implementation).
• the front stop that engages the bags could be rubbery to help prevent the unit's front from sliding laterally.
• it seems like single hand/single user action to reposition angle is important. Maybe a torsion spring on the hinge pivot could carry most of its weight during adjustment? Could the rod that engages the rack be extended like a handle and that's the lifting point for angle adjustment (happy to sketch the image in my head with you)?
• aluminum on aluminum mating surfaces tend to be sticky and gall.
• the back brake concept seems plausible, but there are a number of details in execution to think about. If you like, I'm happy to sit and sketch through some thoughts for this.

Yellow: modular surf board
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It's good that you are getting a handle on fiberglass layup techniques. Also, your overall plan for making a 3 part board and total of 4 modules is a good strategy.

• having looked at the process of modifying and patching existing boards, in combination with the level of precision needed in fabrication, it seems like making molds that integrate the necessary features and inserts for mating hard-points might be the way to a better executed prototype, and could be a time saver. We have the tools needed to fabricate such molds at the necessary scale. Happy to discuss further, as are your instructors. It would also be good to order some two-part urethane foams to do some experiments with. We can help with that.
• for the different module combinations you'll prototype, it would be nice to have explanations for their specific use cases.
• a lot of our review time was spent discussing the details of the interface between segments and cams, etc.. Happy to discuss this further, too. Details are important.
• it seems like there are two fundamentally different approaches to the joints. One is to design a pre-loaded joint where mating faces of segments carry the bending (and shear) load and the mechanical connection only provides pre-load to hold the mating faces in compression (this is the shoulder with alignment tongue and cam approach). Pluses include more compact board segments, less likely to get stuck in sand/salty conditions, and likely being light. Minus: need precision in the joint fabrication. Another approach is for the mechanical connection to bear the bending and shear loads, with little clamping force needed between segments (e.g., long rods on one side and tubes on the other). Pluses are requires less fabrication precision (elastic averaging helps to removes play). Minuses include the modules are more likely to stick together with salt or sand in the tubes, likely heavier, and individual modules become longer due to protruding rod.

Orange: custom lipstick
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The color mixing and replication process has a lot of potential. It is quite believable that this approach could allow less trained store staff do the job. Some pigments have different "strengths" in mixing, so you will likely need a few sizes of plugs rather than just one plug size. Please get implements that are stiff enough to mechanically mix the plugs. It's nice that the customer can see the color mix being accurately replicated. Perhaps the containers of "production size" plugs could be in a nice visual display?

The mixer and melting phase of the system has potential for nice visual qualities and letting the customer see the process of their color mix coming together. For the physical unit, detailing of sub-systems and integration into a coherent product, designing housings with as-manufactured design intent, and mounting electronics needs to be addressed. I'm happy to sketch with you on this a bit to think about directions. Also, if you have not done it, making a mood board to have insight while designing would be really helpful. (e.g., here's some free work from pinterest!).

The final stage of the process (casting the stick and installing the case) is the part of the experience that seems to need the most conceptual resolution. At the moment it is quite complicated and seems to have the most remaining conceptual challenges.
• one option might be for the stick to go away. It was pointed out that some lipsticks come in a "pallet form" and brush-like tools are used to apply it. In this form factor, the container for mixing could be the case that the wax also cools in and the customer takes away (eliminating the whole molding robot).
• For a stick form factor, it seems like the automated insertion of the case does not really save time since the employee needs to place the case into the robot anyhow. Would it be possible to have the user just push the case down, and this provides the force to first separate the mold, and the open mold sides could also serve as guides for sliding the case onto the stick? Probably clearer to do a quick sketch with you to clarify.

Purple: pipe freezing prevention
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From the technical review you have a proof of concept. That is good.

Now one really needs to think about how to make it into a product. You'll probably not build the system completely from off-the-self plumbing components. The pump system and electronics, remote controlled valve and electronics all need careful detailing and resolution. It is likely that a custom designed, integrated valve/actuator may be needed. A few times the phrase in "future versions of the product..." came up in the review. That future is now!

It seems like the scope of the product should include a system profile and installation guides for different situations. In which situations is it applicable? In which is it not? Could temperature, wind conditions, and a bit of information about the type of construction and date of construction be used to less conservatively estimate when pipe freezing is likely? If there were documented profiles for regions/house types/freezing issues this might help people understand if they want to buy the product.

I may have missed this discussion, but my impression is that this is a plumber-installed system. To work properly, it seems that all end-of-loops for areas that might freeze (i.e., near exterior walls) should have the device. Further, since parallel loops may have different flow resistance, there might be balancing required between branches. Seems like the system and plumbing knowledge required might preclude most homeowners from installation. Think that a good installation guide is important.

How does a user know if the system is working properly (i.e., the circulation is correct/calibrated)?

It would be nice to have a structured storyboard for the overall UI to think through different aspects of the system.

To help with freezing in the test rig, it would be good to make a better thermal conduction circuit between the pipe and the blast freezer. Just let me know and I can sketch with you. For both consumers, and also those interested in understanding your product, it would be really helpful to find ways to clearly demark existing plumbing or test setup equipment from the actual product.

Silver: oven shelf lift
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The current prototype seems like a workable proof of concept/path. That's great. That said, it is executed at in a mockup form. Now it's time to design and detail it knowing what the system is.

• please think through what level/quality of oven this is most likely to be on. We can buy such an oven, even if it is a more expensive model.
• the button location is tricky. Hard to anticipate all the cases. Maybe there could be a wireless button that the user can put in a location that works best for them? I still think the momentary nature (stop in any location) is important for safety.
• if you can drive both mechanisms off the same motor that is a cost saving. Also, can't change the spacing between the wall and the back of the stove.
• there are also pulleys that prevent the wire from coming off the spool. Also, need to have compliance in the cable loop. Could be done with a tensioner.
• damping in the joints would prevent swinging, which is undesirable. Might need to look into the lateral stiffness more too
• current version is a bit fast!
• I wonder if the attachment of the top of the mechanism could utilize the standard features for mounting shelves.
• I wonder if the actuated shelf should also have the ability to slide out normally and be removed. It seemed like if the bottom linkages had the features of a typical shelf retainer this would be doable.
• look to ferrules on cables rather than clamps? Also, perhaps cable material that has lower thermal expansion?

Pink: scuba neutral buoyancy
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You did a lot of tests and many/most failed, but the exciting thing is that it seems a lot was learned. The in-water test at the pool was really informative. It's design time!

Here's what I learned from the review...
• device tucks onto the back of the diver, ideally along both sides of the tank (to frame so tank can be removed separately) but without protruding beyond the tank's profile.
• flow resistance in and out of the device is important to managing feedback loop. Can't be too slow.
• the expansion tank design that came to my mind is quickly sketched below. May or may not be appropriate but is pretty much the same concept as the pool demo but with a barrier so works in any orientation.
• if you are working on soft goods, if you like we can arrange for a consultation with a product designer with a lot of experience in this area. Also a very friendly person! Please let me know.


Average reviewer score
The average reviewer score is on a scale of 0-10, where 10 is highest. The score is based on prototype operation and the assessment viewpoints outlined in the technical review description. The data are averaged from rankings provided by 33 reviewers.