Gold Team!
Technical Review!
Presentation Video
Safety Sander
A disc sander that automatically stops rotation when human contact is detected via capacitive sensing.
Product Contract
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Reviewer Feedback
Chuck Xia
Feedback
During the demo, there was some issue with the capacitive sensing, a critical module. Beside adding the two wires systems on the sanding disk, how about adding a conductive plate that the user have to stand on? Would that reduce noise? There are a lot that still needs to do within the internal part of the sander, breaking mechanism, the decoupling design, not including the design of the housing and the sander table. Calculations are great start, unexpected things always comes up when you build it. 34ms sounds great, can the product meet that value or the spec? The loud noise at the beginning is disconcerting. During the review, I would have like to see everyone given the opportunities to answer questions. Be aware of your team members and respect their input.
April Anlage
Feedback
You've made great progress since mock-ups but it looks like you've still got a ways to go - a number of re-designs seem imminent. It's good that you've identified the mechanisms (either off the shelf parts or new designs) and seem to know which direction to head but it's best to de-risk those (i.e. build and rigorously test) as soon as possible, in case you again run into unexpected findings. This is a good time to prioritize and decide what's most critical and what can wait until the next iteration. I'd also encourage you to start thinking in detail about the housing. Can it help keep your axle level and safe from jostling? How does it communicate that your product is a "next-level" sander and not your average, everyday sander? You've identified your product's (goal) improvement in stopping the disc as compared to human reaction time, which is a great measure. Given your anticipated changes in mechanisms and hard-to-predict factors like friction, do you still think this amount of reduction is realistic? Do you have other ways to demonstrate the lack of damage to the audience - will the disc stop spinning fast enough to show little to no damage on the hot dog?
Juergen Schoenstein
Feedback
I was impressed by some of the progress that you have made since the mock-up review, but mostly confused by some choices that seemed to have created more complexity and essentially undercut the main value proposition of sensing the risk of touching the moving sander disk. I know that you know this, but I need to say it nonetheless: Make sure to keep your primary focus on resolving this sensing issue, as it is critical - without it, everything else is merely and afterthought. It seemed like your mock-up solution was simpler and thus more reliable, so maybe returning to that approach is a safer way to proceed. But a technical solution alone doers not resolve the question of translating this into a product: I was not sure that I got a sense of WHO your target audience is. Sometimes it sounded as if you were thinking of persons who have little experience with sanders, and therefore are at a high risk of injuring themselves - but the size and potential cost seemed to make this a tool for professional users with high demands on using this tool. But the risk scenarios may be very different between these user groups. What IS the risk scenario that you are trying to mitigate? What are the limits, what residual risk will you have to explain/justify? How detrimental will occasional false positives be? If the processing of resetting it, an occasional hobby user might be fine doing that several times in a workflow, but if you are aiming for someone who is a high-volume user, they might be less tolerant for such frequent workflow interruptions. That's why identifying a target user and getting to know their needs and concern is crtitcal even in the design phase (not only in marketing considerations).
Sam Ihns
Feedback
Speaking with members of the team it seems clear that the challenge of detecting touch is a top priority. Doing so with your current set up will be very difficult, and you have much to do both in the actuation of your mechanism and also your final product embodiment so solving this problem as soon as possible will be really valuable. A slight change to your user experience may allow you a much easier time detecting touch - consider if you had some mechanism by which the user calibrates the capacitive sensor every time they approach the sander. They could press a button to start calibration, then touch the (unmoving) wheel with their bare hand and then touch it with the work piece. This may give you much better thresholds for sensing, and since presumably the user is concerned with safety (seeing as they purchased this product) this extra ten seconds may not be a huge deal. Switching gears for a second - benchmarking your safety. Time taken for the sander to stop, which appears to be your current benchmark for your trigger mechanism, is easy to understand for a non-technical user, but when I heard it my immediate thought was "how many rotations of the sanding wheel is that?" The rotation (not the time) is what will cause injuries and this is certain to be brought up in your Q and A if not addressed in the presentation. The sander could take a full half second to stop and still be safer than a 25 ms stop time provided it goes through less rotations to come to a complete stop. You may also be able to use this to your advantage, as even if your sander does not meet your time requirements you may be able to tune it to meet a nice rotation requirement. You've come a long way and should be proud of your work so far, excited to see it on stage in two weeks!
Juhan Sonin
Feedback
Feedback in a PDF: https://www.dropbox.com/s/98mae6eorpl3iov/MIT2009_Gold_TechReview_Feedback_Sonin_Fall2022.pdf?dl=0
Atissa Banuazizi
Feedback
Hi Gold Team: I’ll echo the comments that have already been made about the need to focus on the sensing module. I think that the fact that capacitive sensing wasn’t fully operational led you a bit astray on the presentation side of things. Sensing was deemphasized in your demo video to such an extent that it wasn’t necessarily obvious how all the different subsystems fit together, and the video explanation therefore felt somewhat disjointed. (It was easier to follow during the in-person demo!) Even for a show-don’t-tell milestone like the tech review, you want to intro your demo with a clear statement of the overall goal of the product, and logically progress through each of its functions, motivating them with references to specific user needs. Additionally, clear transitions between each subsection will really help in your final presentation, when you are explaining the technical details of your design. You had some great visual aids, both mounted and drawn, which were used very effectively; just be careful of pointing to something inside the frame when there’s no way for your audience to see in there.
Josh Wiesman
Feedback
Start to separate the product into sub-systems allowing sub-teams to tackle the technical challenges that remain - make sure the entire team is being utilized. Also, it may be a good idea to prioritize certain design elements over others, ie, improving time to stop may not be as critical for this stage as performance of the capacitive sensor, which was effectively not working due to noise and or other issues. Start to think about the final presentation - because you are demonstrating a hard stop this could go by very fast without the audience realizing what happened. You will need to spend some time setting the stage. Additionally, explaining how the different elements work together will be key. Really take your time to break out the exploded view and highlight what each element does (and why). One thing not addressed, but could come up in questioning - can you have a variable speed disc sander or is this only good for one speed? You may want to highlight that as a feature or prepare your answer. I would think a bit more about cleaning and maintenance - saw dust is very different from gravel / dirt (coefficient of friction and moisture retention). While the brake itself may be ok, the other parts may not function as intended with build up of dust over time. Highlighting how to clean the product is not a bad thing or weakness in design.
Ellen Roche
Feedback
Hi gold team, I tried to summarize some of the staff discussions and my take on things here. I hope this format is helpful and saves you some time. We are here for you for whatever you need in the next 13 days :) ● Go back to mock-up sensing and triggering ● Distribute tasks - don’t have small subteams working independently ● Divide into sub systems , entire team should be utilized ● Is this good for only one speed? Discuss in presentation ● Focus on function, don’t worry about form so much (that can be solved) ● We want it to work first and foremost and then a rendering or a casing can work for final product vision ● Think about how you will demo this - maybe integrating a slow mo video? One quick demo might be missed on stage Go gold!