Student Case Study: Reverse Engineering + Additive Manufacturing with HP MJF: Ski Boot Buckle
- jonathang22
- May 14
- 3 min read
Updated: May 28
By Yan: Selkirk College Student of the Digital Fabrication a Design program.
The Problem: A Broken Ski Boot Buckle
The part I am working on is from my instructor Shawn, which he received from a repairing business
during his visit to KORE summit in Kimberly. It’s a part for footwear according to him, for
description purposes in this report, I named it the Ski Boot Buckle.
The buckle is an injected plastic part, with an overall
dimension of 35´22mm, average thickness of 1.25mm. Without having the radius on
edges measured, I observed larger radius added, making the part thinner. It also looks
thinner at the junction of edges, where the failure happened, as shown in photo above,
I put a staple to open it wider to easily illustrate it.
Failure of this tiny part will result the whole boot to be completely useless, as the
user can hardly get it to buy separately.
Options for solutions are:
# | Options | Pros | Cons |
1 | Replace with the same part from used boot. | • same dimension • same material | • with tear and wear • same weakness |
2 | Replace with a similar part available | • may work, saving the boot from completely wasted | • compatible, but not perfectly match |
3 | Replace with a 3D printed part | • Reverse engineerable • Same dimension • Optimized structure. • Optimized material. • Saving the whole boot. • Repeatably printable digital file. • More improvement if the printed part fails. | — |
Options for 3D printing materials available:
# | Material | Property |
1 | PLA | • Brittle and prone to cracking or snapping under load • Poor impact resistance • Low flexibility |
2 | PETG | • High impact resistance • Moderate flexibility |
3 | PA-12 | • Very high impact resistance • High flexibility |
Options for printing methods available:
# | Material | Method | Advantages |
1 | PLA | FDM | • Have layer lines, prone to delamination. • Strength depending on layer orientation. • Less durable, may fail under extended use. |
2 | PETG | FDM | — |
3 | PA-12 | MJF | • No support structure, powder supports parts. • High durability and fatigue resistance. |
With all options compared, the superior solution is to replace the broken buckle with one that is using HP MJF 3D printed, the final parts are shown as:
When I received the final printout, I compared it with the original part again by bending it, the original part is brittle and cracked like PS (polystyrene), while the print out has smooth finish requires no further post-processing, it has properties of impact and fatigue resistance that is right for the buckle.
The biggest challenge for me was to align the scanned model in VXelements, to create planes and cross sections, and subsequently to transfer the cross sections to fusion as sketches. It was a successful assignment, though the final model surfaces are not parallel, give me an angle of 0.033 deg, as shown in photo:
What I would do to improve is to get more skillful with the scanning process, mesh
editing and surfacing in VXelements.
Steps in achieving this part shown as:
