IDP 2026
Overview
IDP is a course at Seattle University that all Mechanical Engineers must take. A problem is defined, but we can approach it however we'd like. Even though we didn't win, we definitely got some style points. :-)
Top Skills Utilized
SOLIDWORKS
3D Printing
DFM
FEA
Problem to Solve
Our goal was to accurately shoot as many bean bags into a target as we could in a certain amount of time, basically a corn hole robot. The target had three holes, each with different amount of points scored.
The pre-defined variables were: distance from target, maximum volume, and weight. Additional points could be scored for reducing cost.
Brainstorming
We went through a couple iterations of designs before deciding on one to manufacture. Most of the design changes made were to promote strength and to design better for 3D printing.
R1
Lead screw through body for angle control, door striker plate for release mechanism, bungee cords for energy storage
PROS
Precise angle control
Angle control resists movement from firing
Release mechanism easy to latch and quick to release
CONS
Expensive
Non-elevated geometry makes it difficult to pull back easily
Too many parts
R2
Angle control with pre-defined slots, spring-loaded ratchet mechanism with physical trigger, bungee cords
PROS
Angle control much faster to operate
Less expensive without lead screw and metal latch
Progress capturing system when pulling back piston, less strain on operator
CONS
If 3D printed, trigger mechanism is too fragile
Angle control is redundant with piston stroke length for controlling power
Still difficult to pull back
R3
45° aluminium extrusion base, operator-controlled piston stroke length, PVC piston insert, bungee cords
PROS
PVC insert takes tension and compression instead of 3D printed parts
Aluminium base is rigid and gives stability when pulling back (also looks awesome)
Position of chamber easily modifiable by changing T-Slot position
CONS
Consistent power delivery dependent on operator skill
More expensive than R2
Assembly
We designed the robot to have a modular construction where parts could be easily replaced. This consisted of:
Piston
Chamber
PVC Insert
Piston Endcap
Aluminium Extrusions
Aluminium Frame Corner Supports (45° and 90°)
T-Slot Nuts
Challenges
While assembling and testing, we noticed some key issues that needed to be resolved.
First, we had a very basic profile for our piston that only slid on one side of the aluminium rail. There was too much play and as the force increased from the bungee, we would lose a lot of energy due to friction. We tested various profiles and found one that worked great.
Challenges
We also noticed that if there was a slight misalignment between the piston and chamber, the endcap would snag on the chamber walls and lose a lot of energy to friction. If we made the endcap smaller, the beanbag would get caught in the gap.
To fix this, we designed a collar for the PVC pipe to keep it concentric with the chamber opening. We later integrated this collar into the chamber.
Result
On competition day, it really was blood, sweat, and tears. Because the robot did make all team members bleed when our fingers snagged on the piston. But that's commitment!
The robot shot far with a satisfying clap when the piston and chamber met. Friction was greatly reduced by our changes. However, we press-fit and superglued the PVC insert into the piston, and at some point the insert started flying out of the piston.
So for next time, use epoxy! (Or find another solution haha)
I also coded our IDP team website in React. You can view it at idp.lucadenhez.com
Thank you for reading.
