Precision Profile Gauge for CAD

You've tried the rest, now try… this one!

There are many profile gauge designs out there that work brilliantly, but I found a few features missing for my specific use case: measuring profiles for import into CAD.  I wanted something precise, easy to lock down so I can take a photo, and easy to re-scale in the CAD software of choice.

This model has a number of features to optimize for CAD use:

• Built-in 100mm measurement to allow easy scaling
• Sharpened feelers to give precise points for measurement
• Tightening screw to lock down the curve once captured
• Closed frame designed to make it impossible to drop the feelers (I've found open-frame models to have a habit of coming apart at the worst moment).
• Optional rigid end-pieces to stop the feelers from complying around a curved object

To use it in a CAD program, follow these simple steps:

1. Measure your curve or profile as you would with any gauge, and lock the device by tightening the screw.
2. Take a photo of the gauge on a contrasting background (pro tip: take the picture from farther back using a zoom lens to get the most accurate dimensions)
3. Import the photo to your design program and use a spline tool to trace the points on the curve.
4. Draw a straight line along the 100mm reference and measure its length (remember - the photo will not come into the program appropriately scaled)
5. Select all parts of your drawing and scale them to 100/<<your measured length from step 4>>

For assembly, print ~90 feelers (aka probes), two rigid end pieces, and one of everything else.  Install the rigid end pieces first - they need to be inserted on their side and twisted into place before the frame gets full. Then, add the probes in groups of 5 or 10.

Enjoy!