--- title: "Alignment tests on a lathe" subject: "Metrology" chapter: 13 key: "semester_3/metrology:machine-tool-geometric-tests" source: https://www.bctengineer.com/q/semester_3/metrology/machine-tool-geometric-tests site: BCT Engineering --- # Alignment tests on a lathe Metrology · Chapter 13: Machine Tool Metrology - Asked in: year not given, 6 marks - Video: [alignment test on lathe machine | Alignment Tests on Machines | Dial gauge |Metal cutting](https://www.youtube.com/watch?v=ILlX5vPK3bI) — Modi Mechanical Engineering Tutorials - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_3/metrology/machine-tool-geometric-tests - Whole chapter: https://www.bctengineer.com/md/semester_3/metrology/chapter-13 ## Question What are geometrical (alignment) tests of machine tools? Describe the tests for level of installation and the spindle tests on a centre lathe. ## Short answer Geometrical tests check machine accuracy without cutting. Level is checked using a precision spirit level (0.02 mm/m) placed on the bed longitudinally and transversely at various carriage positions, adjusting until level within 0.02 mm/m. Spindle tests: true running of nose and taper bore with dial indicator, axial slip via end-face indicator, and parallelism of axis to bed using a test mandrel and traversing indicator. ## Answer **Alignment (geometrical) tests** check the accuracy of the machine tool itself, without cutting: that the slideways are straight, the spindle runs true and the moving parts are parallel or square to each other. The results are compared with the permissible values given in standards (for example the ISO 230 series). The quality of the workpieces depends on the accuracy of the machine. #### Test for level of installation The machine is installed on a firm foundation. A precision spirit level (0.02 mm/m) is placed on the bed, at the headstock end and then at the tailstock end, along the bed and then across it, with the carriage at various positions. The readings are noted and the levelling screws or wedges are adjusted until the bed is level in both directions to within 0.02 mm per 1000 mm. This ensures that the bed is not twisted or sagging under its own weight and that the other tests are valid. #### Spindle tests 1. **True running (runout) of the spindle nose:** a dial indicator is held on the carriage with its stylus on the nose of the spindle (or on the locating cone), and the spindle is rotated by hand; the movement of the pointer is the runout (typical permissible value about 0.01 mm). 2. **Runout of the spindle taper (axis):** a test mandrel is fitted in the taper bore, and dial indicator readings are taken near the nose and at 300 mm from it. The readings give the eccentricity and the alignment of the axis (permissible 0.01 mm near the nose and 0.02 mm at 300 mm). 3. **Axial slip (end float) of the spindle:** a dial gauge touches the centre of the spindle end face (or a steel ball in the centre hole) while the spindle is rotated and pushed along its axis; the pointer movement is the axial slip (about 0.01 mm). 4. **Parallelism of the spindle axis with the bed:** the dial indicator is traversed with the carriage along the test mandrel in the vertical and horizontal planes. The readings should be within 0.02 mm over 300 mm, and in the vertical plane the free end of the mandrel may only be higher, not lower. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What do geometrical (alignment) tests of a machine tool check? A. The accuracy of the machine itself without cutting, e.g. straightness, true running, parallelism B. The accuracy of finished workpieces after machining C. The power consumption of the spindle D. The surface finish of cutting tools Answer: A. They check that slideways are straight, spindles run true and parts are parallel or square, compared with standards. (Key point: Purpose) 2. How is the level of installation tested on a lathe? A. A dial gauge runs along a test mandrel B. A precision spirit level is placed on the bed along and across at several positions and levelling adjusted until level within about 0.02 mm per m C. A mandrel is fitted in the spindle taper D. The spindle is rotated with a ball in the centre hole Answer: B. This ensures the bed is not twisted or sagging, making the other tests valid. (Key point: Level test) 3. How is run-out of the spindle taper (axis) tested? A. A dial gauge touches the spindle end face B. A spirit level is placed on the mandrel C. A test mandrel is fitted in the taper and a dial indicator is read near the nose and at 300 mm from it D. The indicator touches the spindle nose while at rest Answer: C. Readings at two positions show eccentricity and alignment of the axis (about 0.01 mm near nose, 0.02 mm at 300 mm). (Key point: Taper runout) 4. How is axial slip (end float) of the spindle tested? A. A dial gauge on the carriage touches the outer diameter B. A spirit level reads the bed C. The mandrel is moved in vertical and horizontal planes D. A dial gauge touches the centre of the spindle end face (or a ball) while rotating and pushing along the axis Answer: D. The pointer movement along the axis gives the axial slip, about 0.01 mm permissible. (Key point: Axial slip) ## Related in Metrology - [Straightness of a bed using a spirit level](https://www.bctengineer.com/question.md?key=semester_3%2Fmetrology%3Astraightness-by-spirit-level-numerical) — Metrology, chapter 13 - [Spirit level sensitivity and tilt](https://www.bctengineer.com/question.md?key=semester_3%2Fmetrology%3Aspirit-level-sensitivity) — Metrology, chapter 5 ## Related in other subjects - [Classification and main parts of centre lathe](https://www.bctengineer.com/question.md?key=semester_2%2Fworkshop_technology%3Alathe-classification-main-parts) — Workshop Technology, chapter 6 - [Work holding and tool mounting on lathe](https://www.bctengineer.com/question.md?key=semester_2%2Fworkshop_technology%3Alathe-work-tool-holding) — Workshop Technology, chapter 6 - [Thread cutting on lathe and change gears](https://www.bctengineer.com/question.md?key=semester_2%2Fworkshop_technology%3Alathe-thread-cutting-change-gears) — Workshop Technology, chapter 6 - [Lathe operations, taper turning and turning calculations](https://www.bctengineer.com/question.md?key=semester_4%2Fmanufacturing_and_production_processes%3Alathe-operations-taper-turning-numerical) — Manufacturing and Production Processes, chapter 7