Surface measuring instruments NSQF LEVEL 4 Unit-3 Session 3

 

Surface measuring instruments

Source: IndiaMart

It is used as a measuring device to measure the accuracies in alignment, eccentricity of the parts/components. Dial indicators are also great for checking crankshaft run out, crank end play, shaft thrust, and gear backlash, flywheel face run out, flywheel housing concentricity, valve seat concentricity or piston deck clearance.

Dial gauge

Source:Mechanical Walkins
Source: Learn mechanical

"A dial gauge is like a fine watch. It consists of a graduated dial, pointer, plunger and a clamp. It measures the displacement of its plunger on a circular dial by means of a rotating pointer."

Source: Technology student

 It works on the rack and pinion principle. The stem/plunger has rack Teeth. A set of gears engage with the rack. The pointer is connected to a small pinion. The small pinion is independently hinged. i.e. it is not connected to the stem. 

Source: Dasqua Tools

The vertical movement of the stem is transmitted to the pointer through a set of gears. A spring gives a constant downward pressure to the stem. Thus any movement of the plunger causes a corresponding movement of the main pointer on a graduated dial. In addition to the main pointer the dial gauge has a secondary scale and a small pointer for indicating the number of revolutions made by the main pointer.

Zero setting of the main pointer of the dial gauge can be done by rotating the dial face until ‘0’ line coincides with the pointer. For use dial auge is attached to the magnetic mounting stand and the base of the stand is held on flat surface. The contact point of the Stem is brought into the contact with the part to be inspected.

The part is rotated or translated and deviations in readings are observed on the dial face by the movement of pointer.

Digital dial indicator/gauge:

Source: Rotagrip

 Its use is similar to the dial indicator/gauge and uses inductive measuring system and has LCD display. It has on/off function, zero setting at any position, hold function and plus-minus preset function. It is also used in conjunction with magnetic base stand. The reading is displayed on the dial.

Source: Universidad Magister

Telescopic Gauge: 

Source: Mindworks
Source: kincrome
There are a range of gauges that are used to measure a bore's size, by transferring the internal dimension to a remote measuring tool. They are a direct equivalent of inside calipers and require the user to develop the correct feel to obtain repeatable results. A telescoping gauge is a measuring tool with spring-loaded plungers used together with a micrometer to measure the inside of holes or bores.
Source: EngineHones.com

 Telescopic gauge is used to find out the internal diameter of pipe, cylinder bore and slots. This gauge has ratchet locking at top, handle, body and telescopic operated plungers. A telescoping gauge is an indirect measuring device, the head of which can be positioned inside holes or openings and then extended to touch the walls. Telescoping gauges are made insets to measure from small to very large bores.

Bore gauge :

                         

Source: Alliance Calibration

A dial or vernier bore gauge measures a bore directly. The gauge has three symmetrical anvils that protrude from the gauge body that are connected to the dial or micrometer mechanism. As the knob is rotated it moves the anvils in or out with respect to the measurements. The knob usually has a slipping mechanism to take the feel out of the device and increase reliability between measurements. The measurement given is the mean diameter of the three anvils, and is usually good to 0.001 mm.

Dial bore gauge: 

Source: IndianMart

A dial bore gauge is a special tool, which is used to accurately measure the inside diameter of a hole, cylinder or pipe and will also detect ovality and tapers in bores. Dial bore gauges are useful in checking for taper or out-of-round conditions in a cylinder bore as well as many other inside machinists measurements. In conjunction with a micrometer, a bore gauge will give the exact reading of a bore size. A typical bore gauge is comprised of a shaft with a dial indicator at the top and a measuring sled at the base. The measuring sled consists of three guides and an actuating plunger. Dial bore gauges give quick and accurate readings on the size, less than perfect roundness or wear.

Source: Penn Tool Co

Screw Pitch Gauges: 

Source:Amazon.in

"Screw pitch gauges are used to check the pitch of the thread immediately." It is very much in everyday tool used to pick out a required screw. The number of flat blades with different pitches is pivoted in a holder. The pitch value is marked on each blade. To know the pitch of any thread (nut, bolt etc.), by visual inspection the leaf is selected and placed on the profile of the thread. If the profile of screw pitch gauge leaf matches with the profile of the thread being inspected, the value of pitch is read from the leaf. If the profile does not match, another leaf is selected and process repeated till the profiles matches. It must be ensured that during matching air or light should not pass through the profiles.

Source:Trimantec


 Feeler Gauges: 

Source: Amazon.in

Feeler gauges are used for checking the clearance between mating surfaces. They are mainly used in adjusting the valve clearance and setting of spark plug gaps in automobiles. They are made from 0.03to 1.0mm thick of 100mm long leaves. The blades are pivoted in a holder. The value of thickness of the leaf is marked /engraved on it. To know or adjust the clearance/ gap, the leaf of the feeler gauge is selected and inserted in the gap, the leaf should not be loose or inserted with force. The leaf should go in the gap with slight drag/resistance. The value of the clearance/gap is read from the leaf of feeler gauge.

Source: TOUT EST LA 


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