Section VI. FABRICATION OF EPOXY GAGE SECTION 



To make epoxy wave staff sections, a suitable mold is required. The 

 mold is fabricated by using a room-temperature curing silicone rubber. In 

 order to conserve the silicone rubber, a close fitting aluminum container 

 is fabricated as shown on Figure 41. A gage section pattern is also re- 

 quired as shown on Figure 41, for either the relay-operated wave gage, or 

 the other two types. The finish on the epoxy gage section will be that 

 of the gage pattern; care should be taken to ensure a smooth surface. 



RTV-630 is available in gallon cans; the kits contain the silicone 

 rubber in one container and the curing catalyst in another. The silicone 

 rubber is used as the mold vehicle due to its releasing properties in 

 removing the epoxy section when hardened. Place the gage pattern in the 

 trough as shown in Figure 41, fill the space between the pattern and the 

 trough with the RTV-630 and allow to cure as specified by the manufacturer. 

 Use the amount of catalyst recommended by the manufacturer. Failure to 

 do so will shorten the pot life and cause uneven cure of the mold. Avoid 

 trapping air in the RTV-630 while stirring and pouring as bubbles cause 

 holes in the completed mold. The trough should be filled to the brim. 

 If excess is above the trough and gage pattern when curing is complete, 

 it can be trimmed with a long sharp knife. When the mold is cured, remove 

 the gage pattern and thinly coat the inside of the mold with vaseline. 

 Recoat mold with vaseline between gage section moldings. 



Assembly components for the desired gage section on a jig outside the 

 mold and check them electrically. After checkout insert the components 

 in the mold as a unit and be sure that the metal gage sensing points are 

 in the bottom of the mold. Align the gage cable with the mold so that it 

 will be in the correct position when the section is completed. 



After the components have been placed in the mold, fill it with one- 

 half the epoxy resin required for the gage section. Allow the section 

 to cure 4 hours and fill the rest of the mold with epoxy resin. About 7 

 pounds are required for one gage section. The resin is furnished in two 

 parts and must be mixed in equal parts by weight just prior to using. Do 

 not allow moisture in the resin during pouring and curing a.s it will cause 

 the epoxy to turn white. Even a good healthy sneeze over the mold will 

 turn the gage section white. 



When the epoxy has cured (overnight) remove the section from the mold, 

 clean it thoroughly and recheck it electrically. Be sure the sensing tips 

 are not coated with epoxy. 



The epoxy sections become brittle in cold weather and care should be 

 exercised when handling to prevent breakage. 



The epoxy sections should be stored in a slotted wood board to keep 

 them from warping. If a section becomes warped, it may be straightened 

 by heating, placing in a straight position, and allowing to cool. 



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