March 25, 1921 



HARDWOOD RECORD 



21 



Fig. No. 6 — Direct Connected Edeer, Black River Lumber Co., Willets, La. 

 (Formerly D. K. Jeffries & Co.) 



Meolianicil Drive Electrical Drive 



Mill No. 1 $10,.500 $2,567 . 



Mill No. 2 10,500 5,133 



Mill No. 3 16,800. * 5,302 



25 In Mill No. 2 the line shaft was driven by manila rope 

 from the engine, the rope costing much less than a belt, but the 

 rope sheaves and tension equipment more than for a belt drive, so 

 that total first cost did not differ gre.atly between belt and rope 

 drive. 



26 Sawmill and woodworking machines are almost always 

 driven at constant speed, in one direction, and (except band mills, 

 band resaws, and a few other cases) can be started at light load; 

 so the squirrel-cage induction motor is generally applicable. The 

 direct-current open motor is of course objectionable on account of 

 fire risk from sparking commutators. For driving band mills, 

 heavy band resaws, and in other places where Large starting 

 torque is necessary, the wound-rotor motor with starting resistance 

 is used. The current (60-cycle, 3-phase) is commonly generated 

 and used at either 480 or 600 volts, avoiding the use of trans- 

 formers except for lighting. As all the motors will be probably 

 set within 600 to 800 feet of the jiower plant, the saving in wiring 

 does not justify high generator voltage and transformers. 



27 Tables 1 and 2 give the comparative cost of sawmOls com- 

 plete, motor-driven and shaft-driven. Table 1 shows the com- 

 parison for a single band mill of simple design, and Table 2 the 

 comparison for a mill having two bands and one resaw. Owing to 

 the instability of current prices, these figures are subject to wider 

 variation than on a settled market, but they will illustrate the 

 desired point. The prices include sawmill and planing mill, and 

 for the large plant dry kilns are included. The boiler, engine and 

 fuel houses are built with a steel roof frame covered with galvan- 

 ized iron, or of brick with a steel roof framing and fireproof cover- 

 ing. The sawmill and planing-mill buildings are of timber con- 

 struction, although as they are the same for either kind of drive, 

 their cost does not affect the compai-ison. All machinery prices 

 include estimated cost of erection. 



TABLE 1 COST OF COMPLETE SAWMILL PLANT. SINGLE BAND MILL. 

 DAILY CAPACITY 30.000 PT 



Mechaiiical Drive 



Boilers, 450-hp $12,000 



Engine for sawmill, 200-hp. Corliss , , . 6.200 

 Engine for planing mill, 100-hp. slide 



valve 2.000 



Pumps, heater, piping and all power- 

 house accessories 3,200 



Boiler and fuel house. 50 ft. by 36 ft... 4.500 



Engine house, 50 ft. by 34 ft 4,250 



Sawmill and planing machinery, com- 

 plete 50,000 



Belting 4,400 



Electric-light plant, 25-kw 4,000 



Sawmill and planing-mill buildings... 12,000 



» 102,550 



Electrical Drive 



Boilers, 300-hp JS.OOO 



Steam turbo-generator, 300-kw. max., 



with condenser and exciter 20,700 



Pumps, heater, piping and all power- 

 house accessories 2,400 



Switchboard 1,750 



Boiler and fuel house, 50 ft. by 27 ft. . 3,400 



Engine house, 20 ft. by 34 ft 1,700 



Sawmill and planing machinery, com- 

 plete 43,600 



Belting ■. . . 2,600 



Electric-light plant, 257kw 4,000 



Sawmill and planing-mill buildings.. 12,000 



Motors and wiring 13,400 



$113,550 



Fig. No. 7— Motor Driven Trimmer, Black River Lumber Co. 



28 In Table 1 the estimated cost of the plant is about 11 per 

 cent higher when motor-driven. In Table 2, for a larger mill, the 

 first cost may be 8 per cent less for the motor-driven mUl than for 

 the other. Most lumber manufacturers and engineers in discussing 

 the subject have assumed that the motor-driven mill is more 

 expensive in first cost; but the table shows that it is quite possible 

 for the motor-driven mill to be cheaper in the sizes of mills most 

 often built. 



29 In operating expense the motor-driven sawmill makes a 

 saving in power-transmission loss, upkeep of shafting and belting, 

 use of oil, waste and supplies, depreciation, fire risk and insurance 



TABLE 2 COST OF COMPLETE SAWMILL PLANT; DOUBLE BAND AND 

 RESAW MILL, DAILY CAP.ACITY 120,000 FT. 



Mechanical Drive 



Boilers. rSOO-hp J40,300 



Engine for sawmill, 615-i.hp. Corliss. . .18,500 

 Steam turbo-generator for planers and 

 lighting, 750-kw. max. with con- 

 denser and exciter 36,000 



Pumps, heater, piping, etc 5,350 



Switchboard 2,100 



Boiler house, 52 ft. by 60 ft 7,800 



Fuel house, 30 ft. by 80 ft 6,000 



Engine house, 42 ft. by 60 ft 6.300 



Sawmill and planing machinery, com- 

 plete 236.000 



Belting 16.000 



Sawmill and planing-mill buildings. . . 54,600 



Dry kilns. 5 rooms 30,000 



8458,950 



Electrical Drive 



Boilers, 1500-hp J34,00O 



Steam turbo-generator, 1250-kw. max. 



with condenser and exciter 47,300 



Pumps, heater, piping, etc 4.O0O 



Switchboard 2,400 



Boiler house, 52 ft. by 45 ft 5.850 



Fuel house, 30 ft. by 04 ft 4,800 



Engine house 42 ft. by 40 ft 4,200 



Sawmill and planing machinery, com- 

 plete 205.000 



Belting 5,130 



Sawmill and planing-mill buildings. . 54.600 



Motors and wiring 22.800 



Dry kilns, 5 rooms 30,000 



8420,080 



premium. The greater flexibility of the machinery installation, 

 and the greater safety on the transmission floor, are self-evident. 

 There is a gain in production of lumber. In the rare cases where a 

 market exists for all surplus wood, every ton saved by more 

 economical power means increased revenue. 



30 Table 3 gives figures on the power consumption of a number 

 of sawmills, no planing machinery being included except in the 

 case of Mills Nos. 8, 9 and 10. 



(Continued in A^ril 10 Tissue) 

 TABLE 3 POWER CONSU.MPTION OF VARIOUS SAWMILLS. 



Power for entire ;jlunt, including planing null. 



