Braxton Kyle Bensel
G#: 801101065
Click this, this is cool!Return to my home page.
Return to my 2156 Portfolio.
Learn more about me!
Assignment 4A: Lead Screw Mechanism
In collaboration with Sheldon McCollum
The Spin Doktor
The Idea
The Spin Doktor is a workout machine designed to be small, easily manufacturable, and great for working out your upper arms. The Spin Doktor utilizes a lead screw to challenge users to spin the crank until the nut reaches the end of the shaft. Once this is done, the user has completed a rep and can let go of the mechanism. It will then return to it's starting state thanks to the springs.
The Evolution
Originally, the Spin Doktor was meant to have linear springs. However, these force of linear springs increases as the distance travelled increases, which could lead to a dangerous amount of force acting against the lead screw. Additionally, linear springs are large and take up a decent amount of room. This is why the Spin Doktor operates with Strip Springs. Strip Springs are rolled coils of metal, and can exist as Constant Force Springs. This means that the spring will extend but will exert a constant force no matter how much the string is extended. The advantage of this is that it is both smaller and has a better form factor and is also safer for use.
The Math
For the model, we operated with a Safety Factor of two.
The Model
Click on the model to download it!
Notes: The model doesn't feature the Strip Springs. This is because while I like to think I'm skilled at solid modeling, I don't have those skills yet to make a part that moves and updates as extensions occur, especially with a strip spring. The Strip Spring holders and the mounting hole for the strip spring are clearly visible on the model.
Lead Screw
Lead Screw Nut
Lead Screw Support
All other parts are manufactured aluminum.
The Self-Stopping Screw was selected because it has a feature that causes it to stop travelling once it reaches the end of the assembly. This guarantees users aren't injured when they reach the end of the screw and the mechanism suddenly jolts to a stop. Safety is our number one priority!
Notes: The model doesn't feature the Strip Springs. This is because while I like to think I'm skilled at solid modeling, I don't have those skills yet to make a part that moves and updates as extensions occur, especially with a strip spring. The Strip Spring holders and the mounting hole for the strip spring are clearly visible on the model.
Parts
SpringsLead Screw
Lead Screw Nut
Lead Screw Support
All other parts are manufactured aluminum.
The Self-Stopping Screw was selected because it has a feature that causes it to stop travelling once it reaches the end of the assembly. This guarantees users aren't injured when they reach the end of the screw and the mechanism suddenly jolts to a stop. Safety is our number one priority!
