Sagitta Rule: Difference between revisions
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== Calculating == | == Calculating == | ||
The following spreadsheet is provided to calculate the ''sagitta'' value for different radius curves for 10 foot and 20 foot rail lengths. | |||
* [http://ibls.org/files/2020/CharlesField_TrackPanelJig/Length_of_Curved_Rail_20201115.xlsx Sagitta calculator spreadsheet (XLSX)] | |||
== Construction == | == Construction == | ||
Revision as of 14:32, 2 December 2020
- In geometry, the sagitta of a circular arc is the distance from the center of the arc to the center of its base. It is used extensively in architecture when calculating the arc necessary to span a certain height and distance.
In Live Steam a Sagitta Rule is used to directly measure the radius of a curved section of track.
Calculating
The following spreadsheet is provided to calculate the sagitta value for different radius curves for 10 foot and 20 foot rail lengths.
Construction
It is easy to construct a Sagitta Rule. Obtain a large paint stir stick (for 5 gallon buckets of paint) from a big box store or where paint is sold. Print the following paper rule. Cut out and tape or glue to the end of the paint stir stick.
