Project Overview
This project is a challenge in precision dimensioning and a showcase of CNC milling practices. A PVC gasket had to be machined to fit flush onto a metal block with complex hole geometry, with all dimensions captured in a single measurement session using analog calipers.
My Tasks:
Measured all critical dimensions of the metal block using analog calipers to within +/- 0.005 inches
Hand-sketched the part geometry with labeled dimensions before transferring to CAD
Modeled the gasket profile in SolidWorks and generated the CNC tool path using SolidWorks CAM
Operated the CNC mill and performed post-processing deburring on the finished part
Skills and Tools:
Caliper Measurements
Hand-Sketching Dimensions
SolidWorks Sketching
SolidWorks CAM/Tool Path Creation
CNC Milling
Post-Processing (Deburring)
Features and Specifications:
Final Dimensions: 2.752 x 2.498 in
Measurement Tolerance: +/- 0.005 in
Fit: Flush and precise seal across all mating surfaces
Machining: Single-pass CNC milling with no rework required
Contents
Sep 2024
Sep 2024
Boston University
Electromechanical Design
Problem and Task
This project is a challenge on precision dimensioning and a showcase of CNC milling practices.
My Task:
Measure a metal block with varying hole dimensions within +/- 0.005 inches.
Sketch the shape in Solidworks.
Program a CNC mill to cut out a gasket that would provide a tight seal.
Constraints
The measured dimensions had to be within +/- 0.005 inches of the actual dimensions.
The calipers had a tolerance of +/- 0.001 inches.
All of the caliper measurements had to be done in one sitting and cannot be redone after.
The final gasket had to fit flush onto the metal part.
Engineering Solutions
Mechanical
Analog calipers were used to measure all exterior dimensions, hole diameters, hole positions, and depths of the metal block in a single sitting. Each measurement was taken twice to verify consistency before being committed to the hand sketch. The part geometry was then recreated as a SolidWorks sketch, using the measured dimensions to define all constraints and hole positions. The gasket profile was extruded from a flat PVC stock sheet at a thickness matching the block surface.
Electrical
No electronics involved.
Software
SolidWorks CAM was used to generate the CNC tool path directly from the part model. Pocket milling operations were defined for each interior cutout, and a contour operation was used for the outer profile. The tool path was post-processed to G-code and verified visually before being loaded onto the mill.
Testing
Verified each caliper measurement against a second independent reading before recording to catch any misreads within the single-session constraint
Cross-checked the SolidWorks sketch dimensions against the hand sketch before generating the tool path to confirm no transcription errors
Performed a dry-run visual inspection of the simulated tool path in SolidWorks CAM to confirm all pockets and the outer contour cleared the part boundary correctly
Test-fit the machined gasket onto the metal block and inspected for flush contact across all mating surfaces and hole alignments
Results
The machined PVC gasket fit flush onto the metal block with all holes aligning correctly and no gaps along the mating surfaces, confirming the caliper measurements, CAD model, and tool path were all within tolerance.
Final Dimensions: 2.752 x 2.498 in ✓
Measurement Tolerance: +/- 0.005 in ✓
Fit: Flush and precise seal across all mating surfaces ✓
Machining: Single-pass CNC milling with no rework required ✓
Lessons Learned
Even with precise measurements, CNC Mill and caliper tolerances can make a difference in the results.
