Christina Holman | Design Blog

Planetary Carrier Somehow I was able to use Creo to create all of the components of the gearbox in one day (not recommended). After destructing the B&D Li2000, opening up the gearbox (which took a bit of strength), and calculating the measurements of each component, I was finally able to re-create all of the parts. Ring Gear Then, with each individual design, attach the components to one another in assembly (left) so that the kinematics or the motion of the CAD-assembled gear train resembled that in the gearbox. Planet Gear Additionally, I was able to use the motion analysis feature in Creo to model the pitch diameters and gear ratios for the cylinders representing each gear. (We did not go into depth on how to actually create the teeth on the gear since it requires manufacturing details we did not have.) Sun Gear Below is a video demonstrating the mechanism analysis for a multi-stage epicyclic gear train like the one used in the B&D Li2000 Screwdri...

So ME359 has been great but it has been an exercise in stamina . For a 2-credit class, where weekly homework is 70% of your grade, this is a lot of time and energy -- but, still, exciting. Like I said before, I do really well when it comes to project-based learning and real-world applications. And this course's final project has really been wonderful for that. The final project is to reverse engineer the Black and Decker Li2000 Screwdriver and then use the computer-aided design (CAD) software Creo to re-create the gearbox. This is an interesting task since the B&D Li2000 uses a planetary gearbox, which consists of three types of a gears that all lie on the same horizontal axis. My task is to create the ring gear (the outermost gear), the three pinion gears that rotate around that inner radius of that ring, the sun ring around which the pinion gears rotate, and, then, the planetary gear connected to the central axis of the screwdriver. Ultimately, I need to create all of ...

For assignment #2, students were given the task of creating a well windlass from laser-cut Delrin sheets to lift a bottle (our "bucket") from the floor and 10 cm above the table top.  My partner Kat and I considered how to include a cranking mechanism, pulley systems, and a stable base for such weight. The requirements: 1) The mechanism could only use 500 sq. cm of Delrin and 50cm of rod. 2) Had to span a gap of 12 cm and be able to lift the top 10cm of the bottle above the tabletop. 3) Had to support a 1 liter bottle of water without wobbling or breaking. During our brainstorming session, we came up with 2 ideas: an obvious, traditional crank using the rod as a spindle and a cracking mechanism based on a pulley system. The latter seemed more suitable as 1) the rod is not durable enough to remain straight with the weight of the bottle and 2) Delrin has a low coefficient of friction, which is attractive for a pulley system. Given the restrictions of a 500 cm^2 sheet o...

3rd Design: With limited time and a failed second iteration , my partner and I hoped to resolve the dimensions issues and modify the design. A few things we noted: -- The lamp pole wasn't the best handle. We needed some sort of curve to aid grabbing the bottle opener. -- The arms were too weak and tiny but we liked the idea of a similar lift; maybe we needed a larger hook and another point of leverage. -- The base of the lamp (the bottom opening) appeared that it would work if it had been printed to scale. So we wouldn't mess with that portion of the design. We returned to SolidWorks and modified our design, by eliminating the bottom arm and forming a more exaggerated upper arm/hook. We added a little bump on the pole to make a better handle (similar to the curves on the first design -- the "Bottle" bottle opener). However, again, when we sent it to the laser printer, our drawing was scaled down about half or more. [ A note on SolidWorks: After remeasuring and...

2nd Design: We had a "meh" prototype in the first design , so my partner and I took new measurements and decided to shrink the height of the opening to half the size and add a dent in the opening for the flaps to grab on. Furthermore, as the engraving wasn't as visible as we had hoped, we wanted to challenge our aesthetics skills and create a more "Wellesley" design. We drew inspiration from the recognizable "Wellesley lamp." In Solidworks, we created a similar opening to the first design, decreased the height and added a rectangular dent below it for flaps to grab onto it. Additionally, we looked back on our brainstorming idea #1 of the slim bottle opener with the jaw-like opening. We decided to add that to our design as a second alternative if the trapezoidal opening gave trouble. We measured the bottle cap one more time to figure out how long the top arm should stretch across the bottle cap and how long/angled the bottom arm should be in or...

The first week of classes we were given an assignment to create a laser-cut bottle opener -- two in fact. Objective: To be able to laser-cut a 2D shape out of Delrin sheets and use it to open actual soda bottles. Brainstorming : How to Open and What it Should Look Like With past experiences with bottle openers, it seems that most try to use a level approach: there's pressure lifting one of the flaps while another point (or points) is applied on top of the cap to keep it in place. Most of my brainstorming ideas were inspired by my bottle opener back home -- it is quirky, compact and functional (look to left). A few ideas that we came up involved similarly closed openings but also jaw-like fixtures. My partner and I came close to 15 ideas in 5-10 minutes but we went through them all to select our top 3 favorites (in no particular order):  A slim bottle opener with a jaw-like fixture to be fit across and under the bottle cap A trapezoidal-shaped closed opening with a simple...