Bosch-Oscillating multitool
Bosch-Oscillating multitool
Evolved from its two-handed predecessor, this multitool has been optimized for one-handed usage, complete with a built-in dust collection system and outstanding handling.
Duration: 10 Weeks
Year: 2023
Execution: Group project
Challenge: Redesign a existing oscillating multitool into a one-handed multitool that focusses on so-called “plunge cuts.
Subchallenges:
- Create a balanced product.
- Remain a neutral arm position during usage.
- Ensure safety during use on a ladder.
- Incorporate easy and safe-to-use buttons.
- (Integrate dust extraction).
Research findings indicate that achieving optimal precision in work tasks hinges upon positioning the handle in close proximity to the device's center of gravity. Moreover, maintaining a neutral wrist position is deemed imperative for optimal performance during operation.
Research with the current product:
Bosch tasked us with redesigning their current oscillating multitool, originally designed for use with two hands, to be used with one hand. To understand the limitations that arise from using the current multitool with one hand, we conducted extensive testing with the existing tool.
Some of the crucial findings were:
- The hand needs to be close to the center of mass.
- The hand needs to be close to the oscillating component (gearbox).
- The current positioning of the motor causes oscillations in the vertical plane, resulting in reduced accuracy.
"Using the current tool with one hand results in low accuracy and often forces your wrist into an awkward angle relative to your forearm, leading to uncomfortable tension and vibrations."
Ideation to concept: After conducting the research, we briefly brainstormed ideas for this project due to time constraints. The main focus of this project lies further along in the process.
Concept 1:
For this concept, we redesigned the layout of the components by aligning the motor axis parallel to the tool axis. This adjustment changes the plane on which the tool vibrates and ultimately improves accuracy. The new motor positioning also allowed us to attach an additional fan on top of the motor for dust extraction. Furthermore, the main grip of this concept is positioned very close to its center of mass, which further enhances accuracy.
Concept 2:
This concept has a boomerang shape due to the positioning of the components. We arrived at this configuration through model making and discovered that it resulted in a well-balanced center of mass, especially in relation to the grip positioning. The grip and handling of this concept felt very comfortable and ergonomic.
Concept 3:
This concept is based on the new sander that Bosch recently released prior to working on this project. The grip provides a high level of control on both axes, and to further stabilize it, we slightly angled the back with the battery and added small wings to the body, allowing the user to use their forearm as an additional support.
Concept 1
Concept 2
Concept 3
Next step: In this step, we organized the exact configuration of the components and I designed the shape around them to align with the Bosch design guide. From this point on, the overall shape of the shell components was determined, allowing for detailing to be done in subsequent stages.
First steps on dust extraction:
However, dust extraction wasn't my primary focus; my initial task was to explore the idea of attaching a fan on top of the motor axis, and I was closely involved in detailing this function. To create a first proof of concept, we produced some 3D printed models, which revealed that generating sufficient airflow to effectively suck in dust would be challenging. However, we quickly identified some design problems during this process, that we still had to solve.
The final design:
Eventually, we developed a design that fits into the Bosch Blue line, incorporates integrated dust collection, features a redesigned gearbox that aligns the tool axis parallel to the motor axis, and includes fully detailed shell components ready for injection molding manufacturing.
The Bosch design:
For the design, we applied the Bosch design guide and also reused elements from current products, such as the dust collection bag used with the sander.
Optimized dust collection:
Airflow simulations proved that the shape used for the dust collection chamber wasn't optimal. Adding elements to narrow the chamber halfway and thus separating the fan chamber from the inlet improved the airflow significantly. This improvement was realized by adding a screw boss as the separating element.
Shell detailing:
After finalizing the aesthetics of this product earlier in the process, I mainly focused on the 3D CAD modeling. A significant part of this involved surface modeling and detailing of the shell components. To match the design quality with Bosch standards, we aimed to reuse many features used in current Bosch products.
A key focus of this project was manufacturability. Additionally, you can see a draft analysis of the two shell components, which are near perfect except for the dust outlet. We realized along the way that integrating it into the shell was a mistake, and we should’ve chosen to make it a seperate part.
Impact test:
We also conducted an impact test on the most fragile part of the shell, which is the dust outlet. This simulation showed that increasing the shell thickness from 3mm to 4mm for the outlet would withstand an impact of 1J, meeting one of the requirements. This finding provides another reason to consider making the outlet a separate part if Bosch decides to proceed with this design.
Ergonomic end result:
In the end, we succeeded in transitioning from a two-handed to a one-handed tool that is ergonomically usable.
Software used: