Group Assignment on Mechanical design & machine design

Group members

KiCa

Week 12 - Mechanical design & machine design (Group Work)

This week’s task was to design a machine that includes mechanism, actuation, automation, and application.

Our idea was to create a movement system for a handheld massage device, eliminating the need to manually hold it in uncomfortable positions. We used a commercial KiCA A3D handheld massage device as the main actuator.

KiCa

MSCW analysis of the project

Must have:

  • Movement of the massage device in X and Y directions

Should have:

  • Buttons to control the movement

  • As much open space below the device as possible to allow for massaging access

Could have:

  • Mechanical mechanism to pull the device upward in the Z direction

  • Additional weights for a deeper massage (Jani’s idea)

Won't have:

  • Motorized movement in the Z direction (not enough time, only a group of two)

Design process

With the Easter vacation approaching, we focused on quick progress.

Task Division:

  • Lauri: Mechanical design, construction, 3D printing, laser cutting
  • Shahmeer: Stepper motors, software control, construction, 3D printing, laser cutting

Step motor development

  • Identified the correct pins for Arduino connection using a guides: "Stepper Motors and Arduino - The Ultimate Guide" https://howtomechatronics.com/tutorials/arduino/stepper-motors-and-arduino-the-ultimate-guide/
  • Used a CNC shield:

shield

  • Uploaded test code to drive the motors and experimented with settings to reduce noise and create smoother acceleration.
  • Adjusted the maximum current using a screwdriver: some values reduced noise, while others caused stalling or excess noise.

shield_screw

Massage Device Holder

The massage device fit nicely into the first version of the massage device holder.

holder_v1

Initial movement test were possible with this. The goal was to restrict the movement of the massager in all directions except the vertical direction, so it could freely move up and down on the massagee.

holder_v1

A new version was designed with longer vertical guide holes to reduce wobble in lower positions. Also a button was added through the holder to press the device's on/off switch.

holder_v1

When trying to move the device into the new holder, it got stuck in the old piece. The sharp edge of the device caught on the hole edge, we had to sand it and apply some force to release it.

stuck

Mechanical design

We started by trying to modify last year's group's project https://fabacademy.org/2024/labs/oulu/machine_projects/Team1/ for our needs, but it fell apart when we modified it, so we decided to build from scratch.

First, we built the largest cube-shaped enclosure possible using the aluminum extrusion profiles we had on hand. Since additional profiles were not readily available for quick delivery, we had to work with what was available.

cube

We designed and laser-cut components to attach wheel systems that glide along the aluminum extrusion profiles. However, the initial design had some slack in the wheel placement, which caused wobbling. To improve stability, we adjusted the design by moving the wheels 0.8 mm closer together for a smoother ride.

wheels2

We used string as the belt. Since we only had one pulley part in the lab, we quickly designed and 3D printed another.

pulley

We hung the massage device holder at the lowest position so it didn't need to be manually inserted in the vertical rods to get a massage.

hung

Summary

The project progressed well with functioning mechanical and electrical systems.

The iterative design approach helped us quickly identify and solve mechanical issues.

Working at the Fab Lab was very convenient as improved parts could be quickly manufactured.

The fab lab was very busy many days leading to some delays.

lso many tools such as small torx heads were not quickly available / found.

The Prusa 3D printer handled the large parts well. All parts printed successfully on the first try.