The polishing and plating of metals; a manual for the electroplater, giving modern methods of polishing, plating, buffing, oxydizing and lacquering metals, for the progressive workman . all over is again established after which itmust be thoroughly cleaned. This is the weakest point of mostof the rheostats now in use, and they fail here most rapidlywhen the contact surfaces are small in proportion to theamount of current they have to carry. Arcing will also becaused in this way if the springs which hold the lever downfirmly on the bars are allowed to get loose, or get set/ i. e.,lose their ela
The polishing and plating of metals; a manual for the electroplater, giving modern methods of polishing, plating, buffing, oxydizing and lacquering metals, for the progressive workman . all over is again established after which itmust be thoroughly cleaned. This is the weakest point of mostof the rheostats now in use, and they fail here most rapidlywhen the contact surfaces are small in proportion to theamount of current they have to carry. Arcing will also becaused in this way if the springs which hold the lever downfirmly on the bars are allowed to get loose, or get set/ i. e.,lose their elasticity. It is a good plan to measure a new rheostat and make atable of the volts and amperes it will carry when puttingit up. Then if you suspect trouble here you can get out yourtable, go to your voltmeter and test the rheostat, step by step,comparing it with the same steps in your table. Bad con-tacts and any consequent change in the carrying capacity of THE POLISHING AND PLATING OF METALS. I9I the rheostat will thus be shown at once. This table is alsoof great convenience to refer to when questions of currentdensity and variation of solutions come up, as they fre-quently Fig. 05. Rheostat^with twenty steps. Fig-. 65 shows a rheostat with twenty steps. It is similarin principle to Fig. 64, but differs from it in using roundwire of varying diameter which is curled up to save spaceand in having the switch lever pivoted in its center andmaking contact at both ends. It is made of varying capacityand varying number of steps, so as to cheapen the cost onspecial solutions. The rheostat shown in the illustration hasbeen measured and the following table of its carrying ca-pacity will be instructive to many platers as illustrating theratio of reduction in quantity of current, which does not fol-low the same proportions as the reduction in pressure. i9: THE POLISHING AND PLATING OF METALS. VOLTAGE AND AMPERE CAPACITY. VOLTAGE AT TANK WITH BAR ON. Volts. Amperes. ist segment of Rhe
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectelectro, bookyear1904
