All work02 · Collins Aerospace · 2024
Rebuilding an essential engineering workflow in Excel so that users could search, calculate, and maintain it with familiar tools.
01 / Locate the axial gap
01 / Locate the axial gap
A shim is a thin spacer made to a controlled thickness. In a fluid-control assembly, it can take up axial clearance or set a component’s installed position. This simplified spring-loaded valve shows a gap behind a spring seat—the exact shim location depends on the valve design.
02 / Add the first shim
Available shims come in discrete thicknesses. A single shim may leave part of a gap unfilled, so the required adjustment can call for a combination. Here, a 0.10 mm shim starts to take up an illustrative 0.60 mm gap.
03 / Combine 0.10 + 0.20 + 0.30 mm
Adding 0.20 mm and 0.30 mm shims brings the example stack to 0.60 mm. Stacking allows finer adjustment than relying on a single available part. The remaining clearance, permitted stack count, and acceptance limits must still satisfy the assembly drawing.
04 / Controlled fit · consistent assembly
In a spring-loaded valve, changing a seat’s position can change installed spring length and preload, which can affect the force needed to open the valve. My Excel/VBA tool helped the Main Engine Fuel Control team search shim data and calculate distributions across different gaps. The valve shown here is a generic teaching example.
The challenge
The legacy shim tool had accumulated bugs, and knowledge of its inner workings had left with its original creators. New shims could no longer be added reliably. The Main Engine Fuel Control team needed a replacement that restored the workflow and could evolve with future users.
Find shims by part number or dimensions, keeping selection within a familiar Excel interface.
Calculate shim-distribution percentages from gap dimensions, then combine multiple gaps with their respective percentages into a shared distribution.
Add or delete shims in the database so the tool remains useful as the component set changes.
Outcome
I built the replacement entirely in Excel, combining VBA with worksheet functions. The new tool retained the legacy functionality and added capabilities, with a more flexible, intuitive interface aligned with the team’s other developing tools. Colleagues could update the tool and database over time.
The engineering lesson extended beyond the calculations: a useful internal tool also needs a clear interface and a practical maintenance path.
Project sources: end-of-co-op presentation, résumé, and LinkedIn projects. General valve principle: Parker VP170 service bulletin. The animated valve is a generic explanation; it does not reproduce Collins hardware or operating specifications.
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