Measuring with MASSO - Practical Use Case

Probing to File in a Real-World Application

In last month’s article, we explored the Probing to File feature—this month, we’re putting it to the test with a real-world example!

We had a desktop CNC machine that needed some custom-modified parts—specifically, additional brackets for testing jigs. To achieve precise modifications, we removed the existing part and mounted it onto a second CNC machine  equipped with a 3D probe. From there, we were able to check, measure, and probe the part for exact dimensions and heights.

Probing the Part

Once the part was secured in the machine, we followed these steps:

1. Setting the Work Origin – We probed the top of the part and the hole for the ball screw to establish our reference points.

2. Saving Probe Data – By enabling the Save Probe to File option, we captured the coordinates of the ball screw hole for later use.

3. Probing the Holes –

First, we probed each hole to determine its center point.
Next, we probed in each direction to measure hole diameters and  visually mark them in the drawing.
Finally, we probed the Z-axis to capture the depth of the counterbores.

After center-probing all the holes, we moved on to the part’s edges. We checked each straight edge at two points, allowing us to draw accurate reference lines in CAD.

Fine-Tuning the Probing Process

To ensure precise screw hole placement, we adjusted the Z height down by half the plate’s thickness (Z-6mm). This ensured that the probe touched the thickest part of the screws, providing two points to center the screw holes in the  drawing. Lastly, we probed the machine bed to determine the overall part thickness.

By probing all holes and edges at the same Z depth, we created a consistent reference plane—helpful for accurately aligning the probed data in CAD, even if the part wasn’t perfectly level.

Bringing the Data into Fusion 360

With the probing complete, it was time to bring the data into

1. Convert the File – The probe data was saved as a .txt file, which we renamed to .csv.

2. Import into Fusion 360 – Using Utilities → ADD-INS → Scripts and Add-Ins → ImportSplineCSV, we imported the CSV file as a spline.

3. Scaling & Sketching –

We scaled the drawing to match document units.
Created a new sketch and projected the key points (such as the  part’s edges) onto the sketch.
Added lines and constrained them using the coincident function.

4. Extruding & Adding Holes –

We extruded the shape down to the probed bed height using the extend to object option.
Projected the hole centers and checked the four probed points to confirm hole diameters.
Extruded the holes to match the probed Z depth of the hole shoulder.

For threaded holes on the side, we created a sketch on the part’s side and projected the probed screw hole points. Notably, the probed screw distance measured 4.399mm instead of the expected 4.9mm, indicating that the probe was slightly above the screw centerline. To correct this, we:

Sketched a line between the two screw hole centers.
Used the midpoint of this line to create a perpendicular reference line.
Centered the screw hole based on this midpoint—ensuring proper alignment despite minor probing variances.

Final Inspection

Reviewing the finished CAD model, we found that the part’s right angles were very close to 90°, suggesting excellent accuracy. Any small deviations could be due to the machine or the part itself. Additionally, parallelism on the X and Y  axes was excellent.

This technique proved particularly useful for measuring internal diameters—a task that traditional square-faced measuring tools struggle with on convex surfaces. It also helped us accurately capture tricky-to-measure chamfered  corners.

Takeaways

The Probing to File feature simplifies reverse engineering and precision measurement for CNC machining. Whether you’re modifying parts, recreating a design, or verifying dimensions, this technique ensures accuracy and efficiency in your workflow.

Stay tuned for next month’s Made with MASSO feature, where we’ll explore more innovative ways to enhance your CNC projects!

Measuring with MASSO - Practical Use Case