Undercarriage Assistant - Measuring
Using the three pinch rods in the Undercarriage Assistant, one can measure between 7″ and 24″.
Pinch rods can be used to measure distances between two points, such as from the bottom of one hole to another (e.g. for a stretcher in a Windsor chair).
The clear barrel of the pinch rod has a strip of pale masking tape attached. This can be marked with a fine felt tip pen (pencil does not mark the tape clearly).
Pull out the brass tips to the bottom of each hole and mark the tape at the position of the bottom of the sliding brass rod. Make sure to look at right angles to the rod, to prevent parallax errors.
The pinch rod can now be withdrawn. Reset it to the mark on the tape. This overall length is the distance between the bottoms of the holes. If you wish to maintain this distance, take the clip and attach it to the sliding rod where it emerges from the clear tube.
The length can then be transferred to a piece of wood directly, or the length can be measured with a ruler.