(Solved): EXTERNAL THREADS External threads are illustrated much the same as internal threads on drawings. The ...

EXTERNAL THREADS External threads are illustrated much the same as internal threads on drawings. The simplified method is perhaps more commonly used than either the schematic or detailed methods. Unlike internal threads, external threads are usually specified on the longitudinal view rather than the circular view. The specifications follow the same sequence, however, which is the major thread diameter, threads per inch, form and series, class of fit, and LH when applicable. The only difference is that the letter A will follow the class of fit instead of the letter B. External threads are usually chamfered to their minor diameter to facilitate assembly. (Observe the examples of external threads shown below.) RH detailed LH detailed Schematlo Simplified THREAD FORMS Although the most common thread form used with fasteners is the Unified National, there are many other applications for threads. Threads may be used to transmit power, such as the Square or Acme thread used on a bench vice and the lead screw of a lathe. The Buttress thread will transmit power in one direction only. The Knuckle thread is commonly used with light bulbs. The Sharp-V thread is used where increased friction from its full thread face is useful, such as on brass pipe work. The Whitworth thread is the British version of the Unified National thread. The Worm thread is used to mesh with worm gears and transmit motion between two shafts at right angles to each other. Unified national Whitworth Sharp-V Square Acme Knuckle Buttress Worm NOTE: BREAK ALL SHARP CIRNERS \table[[(I)(1),2-PL DEC IN.(x,xx)

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,TTTLE,,,,,,DWG Na.],[,T,ED,STEP,S,AFT,,21A045]] INSTRUCTIONS: Refer to drawing 21A045 to answer the following questions. Is the material considered to be low-, medium-, or high-carbon steel? What stock length is specified (blank length)? What is the diameter of step A (blank diameter)? How many chamfers does the shaft contain? How many necks are to be machined into the shaft? What method of dimensioning was used on this drawing? (Chain or broken-chain?) How much tolerance accumulates on the length of step A? What is the tolerance on the neck width dimension? What is the tolerance on the diameters of the necks? What is the tolerance on the chamfer angle? What method of thread representation was used? What thread form is specified? What thread series is specified? What class of fit is specified? What does the letter A after each thread specification designate? Are the threads right-hand or left-hand? How many full threads does step B contain? (Disregard the chamfer.) How many full threads does step C contain? (Disregard the chamfer.) How many full threads does step D contain? (Disregard the chamfer.) How many full threads does step F contain? (Disregard the chamfer.)