Dial Caliper Radius Gauge

thingiverse

This is an adapter that fits on the end of a dial caliper with depth gauge. You can use this to precisely measure a radius, such as reverse engineering a corner filet. Different sizes may be needed but this particular one is 30mm wide. A smaller version will be needed to measure smaller objects. How to use: First, you fit the item onto the bottom of the caliper. Put the assembly onto a flat surface and run the depth gauge down until it sits on the flat surface. This will level it out with the points on the tool. These points make up an arc length. Zero out your caliper dial (works easier with a digital caliper) and press the depth gauge and adapter against a radius. Take note of how far the calipers depth gauge travels upward back into the caliper. This will give you the arc height. Go to the following URL and plug in the numbers to get the circle radius/diameter https://dev000.mmdeveloper.tech/publicApps/radiusFromArc.html --- Alternatively, the formula is as follows L = arc length, distance between the points touching the radius S = Sagitta, the height of the arc between the center of the points and the center of the radius 'corner' Radius = ((S ^ 2) + ((L / 2) ^ 2)) / (2 * S) I've been getting some mixed results on this so I wouldn't rely on it just yet.