MET 102 Module 5 review-questions_solved

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  • 1. Module-5 Gage BlocksReview Questions Solved1. Describe a telescoping gauge and explain how it is used.  Telescoping gauges, or snap gauges, are non-graduated precision measurement tools  To measure : I. Inside diameters and the II. Distances between parallel surfaces  Telescoping gauge consists of a cross arm mounted on the end of a handle.  A spring mechanism in the cross arm allows the cross arm to be lengthened or shortened within a particular range,  The cross arm can be locked in position by tightening the nut on the end of the handle.2. List the principal pats of telescope gauges.  Cross arm  Handle  Spring mechanism  Tightening nut3. What are the advantages of using three-point gauge?  It can be readily centralized and aligned for accurate measurement of the true bore diameter.  Extensions permit measurement of deep bores or holes and a micrometer- type scale4. Illustrate several applications for which precise balls or rollers may be used.  Linear and angular measurements  V-groove
  • 2. 5. Explain how to use precision balls and rollers to determine an angle of a vee- groove. Use of precision balls and rollers to determine angle of a vee-groove. 1. Set workpiece in position and place a roller of known size in groove and determine height “A” as shown in Figure 4(a) 2. Select a slip gauge of suitable thickness that when placed against the vertical face of the groove will Figure 4(a) allow the roller to make contact dose to the top of the angular face and determine height “B”. Note measurement in Fig. 4(b). Figure 4(b)
  • 3. 3. Calculate angle of groove Subtract height measurement “A” from “B”. This gives the length of XY as illustrated Figure 4(b) in Fig. 4(c). Length of YZ is equal to the thickness of slip gauge used. Calculate angle θ from tan θ = XYYZ Figure 4(c)6. What is a feeler gauge?  Thickness, or feeler gauges are precision measurement tools.  Composed of a number of blades, each machined to an exact thickness.  Used alone or in combination to measure gaps and narrow spaces between surfaces.7. Give an application for using feeler gauge.Feeler gauge used to establish the spark gap between the distributor points of anautomobile.
  • 4. 8. Why heavier blades of feeler gauge should be used in the outside positions in combination?Heavier blades should of course be used in the outside positions in combination inorder to protect the set and ensure accurate measurement.9. List the necessary precautions in connecting with using feeler gauges. I. The leaves of feeler gauges become rather readily burred, bent, or warped, or constant use shaves off a few ten-thousandths of thickness. The leaves of a thickness gauge should be checked regularly and damaged blades replaced. II. The retaining screw should exert only light pressure on the blades. III. Apply a thin film of oil to the blades to prevent rust. IV. Use the minimum number of blades to make a certain thickness.10. How to evaluate sheet metal thickness. Sheet metal thicknesses and wire diameters are specified either by gauge numbers or by their actual thickness in inches or millimeters.11. Describe sheet metal and wire gauge. Sheet metal and wire gauges have slots that correspond to the different gauge sizes (Fig. 6). On one side of the gauge is stamped the gauge number; on the other side is stamped the decimal equivalent of the gauge number.12. Name the main advantages of using gauges over using micrometers or vernier measuring tools. - Simple design - Easy to handle and measurement - Variety of sizes and scales13. How gauge blocks are stabilized and why is this necessary?Gauge blocks stabilized through alternate subjections of extreme heat and cold untilthe crystalline structure of the metal is without strain.
  • 5. 14. State five general uses for gauge blocks.1. To check the dimensional accuracy of fixed gages to determine the extent of wear, growth, or shrinkage.2. To calibrate adjustable gages, such as micrometers and vernier calipers, imparting accuracy to these instruments.3. To set comparators, dial indicators and height gages to exact dimensions.4. To set sine bars and sine plates when extreme accuracy is required in angular setups.5. For precision layout with the use of attachments.6. To make machine tool setups.7. To measure and inspect the accuracy of finished parts in inspection rooms.15. For what purpose are wear blocks used? The wear which occurs during use will be on the two wear block only, rather than on many blocks and the useful life and accuracy of the set will be prolonged.16. How should wear blocks always be assembled into a buildup? Wear blocks should be used at each end of a combination.17. State the difference between a master set and a working set of gauge blocks. The Class AA set, commonly called a laboratory or master set, is accurate to (± 0.000002 in) and (± 0.000 05 mm). These gage blocks are used in temperature controlled laboratories as references to compare or check the accuracy of working gages. The working set is accurate to (+ 0.000 008 in) and (+ 0.000 2.5 mm and - 0.000 15 mm). These blocks are used in the shop for machine tool setups, layout work, and measurement.18. What precautions are necessary when handling gauge blocks in order that the effect of heat on the block is minimal? I. Handle gage block only when they must be removed. II. Hold them by hand for as little time as possible.
  • 6. III. Hold them between the tips of the fingers so that the area of contact is small. IV. Have the wok and gage blocks at the same temperature If a temperature- controlled room is not available, both the work and gage blocks may be placed in kerosene until both are at the same temperature. V. Where extreme accuracy is necessary, use insulating gloves and tweezers to prevent temperature change during handling.19. List five precautions necessary for the proper care of gauge blocks. I. Gage blocks should always be protected from dust and dirt by being kept in a closed case when not in use. II. Gages should not be handled unnecessarily since they absorb the heat of the hand. Should this occur, the gage blocks must be permitted to return to room temperature before use? III. Fingering of lapped surfaces should be avoided to prevent tarnishing and rusting. IV. Care should be taken that gage blocks are not dropped or their lapped surfaces scratched. V. Immediately after use, each block should be cleaned, oiled, and replaced in the storage case. VI. Before gage blocks are wrung together, their faces must be free of oil and dust. VII. Gage blocks should never be left wrung together for any length of time. The slight moisture between the blocks can cause rusting which will permanently damage the block.20. Calculate the gauge blocks required for the following buildups. (Use the check column for accuracy). a. 3.1743 in b. 6.2937 in c. 7.8923 in d. 32.079 mm e. 74.213 mm f. 89.694 mm