Mason's i \nn. patented in 1 H -, 4 . sho 

 master lead screw driven ai less than work speed so that 

 the master could be ol a co irsei and more durable pitch 

 than the work. U.S. patent 10383. 



imperfections of the operating leading screw , the springing 

 of the leading screw and ol the rod thai is being threaded, 

 .iiul othei unavoidable causes, all of which, although 

 apparent]) trivial and p '.- slight variations 



in the thread at different parts of the rod 01 blank, a\<- 

 hi sufficient moment to l»- seriousl) considered when a 

 si rew of absolute ,n 1 urai j is desired. 



It is interesting to note in figure I'* that Vander 

 Wo id's machine, to avoid the problems outlined in 

 In- patent, has returned to a starkly simple design. 

 We are not told, however, how he originated this 



master screw which is used to produce the ately 



threaded work pieces. Later generations, in the 

 search For ever-greatei accuracy, also returned to the 

 fundamental simplicity of a m ister screw as we shall 

 see when we eonsidei the refinements in mechanism 

 necessary to the extended development of the auto- 

 mobile and the airplane. 



As the power and speed of automobiles and airi rafl 

 increased, critical parts bee ime more highly stressed. 

 Gears and threaded parts were particularly trouble- 

 some details of the mechanism because ol the Stresses 

 concentrated in them. and. in the case ol gears, 

 because ol the internal and external stresses origi- 

 nating in minute deviations from the ideal of tooth 

 form and spacing. The problems were not entirely 



[ 1 1 1. -Vander VV01 rd's patent, seen here, o 



the combination of a master screw, toolslide and work in 

 id frame to be supported and driven l>\ outside 

 means ol no required precision 1 s patent 293930 

 dated I ebruai j 1HH4. 



l'APi k a7: si Ri-w-riiki ad (i mi\i; by mi: masii.r-scriav mi 1 1 k m > 



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