A toolmakers microscope is a measuring device that can be used to measure up to 1/100th of an mm. It works on the principle of a screw gauge, but a few changes were added to it to make its operation more easier.
It needs application of optics too. A light focuses on the object and through lens we can see the shadow of the object, which resembles the object. More clear shadow would be enhance the accuracy of measurement
TMM (toolmakers microscope) has got a robust and strong base such that it can bear and withstand sudden loads. A column with a track is present to carry lens, along with illuminating source in certain TMM’s. Lens has two perpendicular straight lines marked that act as reference lines. Object to be measured is placed on glass table. Glass table is provided with 3 scales on it
Two scales are meant for measuring in X and Y directions and the movement of table the respective direction. The other scale is meant for measuring rotation as well as rotation of table.
Object to be measured is placed on glass table, illuminator is turned on. Let the object be a rectangle. It may look as shown if seen through lens
Using the micrometer heads get it to a definable point as shownNote down both micrometer readings
Now turning micrometer heads we can getpositions as shown above.After setting 2nd position note down micrometerreading meant for X movementAfter setting 3rd position note down micrometerreading meant for Y movement
Difference in micrometer reading of X movement gives us the length of the rectangle Similarly, the difference in micrometer reading of Y movement gives us the breadth of the rectangle
The large tool maker’s microscope is suitable for the following fields of applications; Length measurement in Cartesian and polar co- ordinates. Angle measurements of tools; threading tools punches and gauges, templates etc. Thread measurements i.e., profile major and minor diameters, height of lead, thread angle, profile position with respect to the thread axis and the shape of thread. (rounding, flattering, straightness of flanks) Comparison between centers and drawn patterns and drawing of projected profiles.