* ALL MATERIALS ALUMINUM UNLESS INDICATED 



'/ 4 HOLE^ 



KNURLED 



3 / 8 P.P. 5 / 6 I D. 



M /, 6 x 14 THD. 



■ BULB NUT '/ 2 OO. 

 3 / 8 x 16 THD. 

 (BRASS) 



mm 

 \) 



SPRING 3 / 



HN3UL 



\FIBER BATTERY 

 INSULATOR: 2 x2^2 



^WIRE 



ATCR 



LIGHT INDICATOR AND BATTERY CASE 

 FOR MECHANICAL THUMB 



Figure 2.— Scale drawing of "mechanical thumb" attachment to Magness -Taylor pressure tester. 



and the pressure applied with the tester in the other hand. However, more 

 uniform results are obtained when the tester is clamped to a bench or table. 

 Another method is to hold the product rigidly against a stationary surface 

 with application of the "mechanical thumb" perpendicular to the product sur- 

 face, as shown in figure 1. Pressure should be applied steadily and slowly. 



4 



<r U. S. GOVERNMENT PRINTING OFFICE : 1963 O - 687196 



