NEW I N S T R U M E N T FOR T E S T I N G THE L O C A T I O N OF HOLES

F. M. A r ' e

Translated from Izmeriternaya Tekhnika, No. 4, p. 20, April, 1968

The effect of any play between the measuring pin and the hole of the tested component should be eliminated when the mutual position of two surfaces, one or both of which may be holes, is being checked. Instruments most commonly used at present for this purpose have one stationary pin and another pin mounted on a slider, which operates an indicator. These instruments have essential constructional defects, since they require the taking of indicator readings with the pins pressing first against the nearest surfaces of the two holes and then against the furthest surfaces, and calculation of the arithmetic mean of the two readings.

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The simple constructional modification suggested in this article provides measurement data without computations or unnecessary manipulations. For this purpose the moving pin is provided with a compensating lever.

The figure shows a contact instrument for measuring the distance between two holes in the casing of details. Truncated pin 1 is fixed in one of the holes of the measured detail by means of spring-loaded lever 2. Measuring pin 3 mounted in the slider is provided with compensating lever 4 fixed to axle 5. Pin 3 is pressed during measurements by spring 6 to the further side of the hole, whereas the measuring end of lever 4 is pressed by spring 7 to the nearer side of the hole.

The instrument is set for a zero reading on the indicator by means of a reference gauge. A clearance a be- tween the probe and the hole wiU cause the pin to be displaced by distance a until it touches the lower side of the hole. The play between the pin and the upper part of the hole will then amount to 2a. The measuring end of the lever will be displaced by the same amount of 2a and the contact point of the lever with the indicating device will be displaced by a, since it is located in the middle of a second order lever arm.

Thus, the indicator will read the actual deviation in the distance between the two holes irrespective of the clearance between the probe and the hole.

S T E P - B Y - S T E P MEASURING METHOD FOR UNIVERSAL

MEASURING M I C R O S C O P E S

G. I. K u z n e t s o v

Translated from Izmeritel'naya Tekhnika, No. 4, pp. 20-21, April, 1963

We have developed and brought into use a simple device for raising the measuring range of any measuring (uni- versal or instrument) microscope. Articles with complicated outlines over 200 mm long can be measured by this means.

Distances are measured in steps, parts, or sections, which are then added to obtain the total length of the tested detail.

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The device consists of a four-sided rule 1 (see Figure), 300-400 mm long, whose faces deviate from parallelism and flatness by not more than 0.001 ram.

Cursors 2, which are mounted on the rule and provided with a sliding fit, serve simultaneously for fixing the articles and a base for

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The rule with its cursors is mounted on stands 3 which are fixed to the microscope stage.

Having measured a segment of the article from its technological base up to the cursor, the latter is displaced together with the article along the guides of the rule towards the left and the next segment of the article is measured between the first and the following cursors, etc. The required length is obtained by adding the measured segments.

Articles with a length exceeding 400 mm are measured by means of three cursors, so that the last cursor is re- moved from the left-hand side and fixed again at the right-hand end, with the article being moved simultaneously from left to right.

M E A S U R E M E N T OF P R O D U C T S BY MEANS OF N A - 1 LEVELLING I N S T R U M E N T S

P. Z. T u s h i n

Translated from Izmeritel 'naya Tekhnika, No. 4, pp. 21-22, April, 1963

It is possible to measure the thickness of walls in a large article, for instance, a boiler, container, or pipe, by means of two levelling instruments NA-1 (Fig. 1). Levelling instrument NA-1, which is placed in front of the measured object, is provided with a moving pLane-parallel plate for the purpose of sighting its reticule on the object's contour and with a thimble calibrated in 0.05 mm for reading the position of the object with respect to the telescope barrel axis. In order to measure the thickness of its walls the article is pLaced on a plate, or lifted into a horizontal position by jacks if i~t is too large.

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In order to determine the difference in location by the height h of one levelling instrument's sighting axis above the other, it is necessary first to set the two instruments simultaneously (Fig. 2) and independently of the measured article by a rule calibrated in millimeters.

The readings are taken in the following sequence:" the cross-hairs of the levelling instrument telescope 1, or to be more precise its bisecting plane, are sighted by means of the pLane-parallel plate to a millimeter division of the rule. The integral number of millimeters is then read off the rule and fractions of the millimeter from the thimble with a scale factor of 0.05 ram. Levell/ng instrument 2 is set in a similar manner. The difference in readings of in-

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