Test Bar / Lathe Aligning Mandrels

Description

• A test bar, typically made of hardened alloy steel, is inserted between the lathe’s headstock and tailstock centers. 
• The bar is designed to have a precise straightness and parallel surfaces, often within 0.0001″ or 0.0002″. 
• A dial indicator is used to measure the runout of the test bar as it is rotated by hand or the spindle. 
• The change in the dial indicator reading should be minimal, typically within 0.01mm in 100mm.