What tool would a machinist use to indicate an angled surface and make it parallel to a surface plate?

A sine plate is specifically designed for the purpose of indicating and measuring angles with precision in machining operations. When a machinist needs to work with an angled surface and ensure it is parallel to a surface plate, a sine plate comes into play. The sine plate utilizes trigonometric principles to create precise angles and is typically used alongside sine bars or blocks, allowing machinists to set a workpiece at the desired angle while maintaining a parallel orientation to the reference surface.

In this setup, the workpiece can be clamped on the sine plate, making it easier to achieve accurate setups for machining operations. This precision is essential in industries like aerospace, automotive, and tooling, where tolerances can be very tight. The sine plate provides a reliable method for achieving and confirming the desired angles, which is vital in ensuring the accuracy and quality of machined parts.

While feeler gauges are used for measuring gap widths or clearances, levels assess horizontal or vertical alignments, and protractors measure angles, they do not offer the same capability for establishing a relationship between an angled surface and flat work surfaces as effectively as a sine plate does.