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HARDWOOD RECORD 



March 10, 1921 



Conditions of the Problem 



10 In deciding whether to 

 drive a sawmill by lineshaft or 

 motors, the first consideration is 

 the probable life of the plant. Un- 

 like most manufacturing plants, 

 the sawmill must nearly always 

 be built close to the supply of raw 

 material; for it is not coninier- 

 cially possible to transport saw- 

 logs far from where they grow, 

 except in the ease of valuable 

 timber like mahogany and other 

 tropical hardwoods. When the 



He has been ignorant and dis- 

 trustful of electrical machinery, 

 and has feared that he could not 

 get capable help to handle it. But 

 these drawbacks are fast disap- 

 pearing with the increase and 

 success of electrically driven 

 plants, and there is now no more 

 difficulty in keeping capable help 

 to operate an electric plant than 

 a shaft-driven plant. 



14 A unique condition of saw- 

 mill operation is that fuel costs 

 nothing. The waste wood from 

 the mill contains 8,500 to 9,150 



supply of accessible timber is Fig. 2-interior of Sawmill Showing Motor-Driven SUb Slasher and Trimmer B.t.u. per lb. when dry, the larger 



sawed, the plant must be aban- 

 doned or moved with a very small salvage value. Sawmills whicli 

 have a timber supply in sight to saw for twenty years or more 

 form a small percentage of the total number. The first cost niusi 

 therefore be kept down to a figure which can be wiped out from 

 the profits in a few years — fifteen, ten, or even eight years— with 

 out making too great an annual charge. 



11 The size of the sawmill plant is important. It is found that 

 for very small mills the first cost of the electric power plant 

 and motors is greater than for a steam plant and belted drive. For 

 medium-size sawmills the first cost does not differ greatly when 

 everything is considered; and for large plants the first cost may be 

 less for a motor-driven than for a shaft-driven mill. 



12 Accessory or by-product equipment will affect the choit-e 

 between the two kinds of power transmission. As previously ex- 

 plained, the planing mill is considered as a part of the complete 

 installation; but beyond this every intelligent lumberman is con- 

 stantly trying to make the waste wood from his sawmill into useful 

 products. As an example, a large mill recently built for the manu 

 facture of yellow-pine lumber makes from waste wood (a) kiln 

 sticks for spacing lumber in the dry-kiln stacks, (b) lath, (c) rosin- 

 barrel staves, (d) shingles, (e) box boards and cleats, (f) short 

 stove wood, (g) molding strips and (h) ground chips for fuel. More- 

 over sawmills are built today for producing small wood specialties 

 primarily from the log, the output of lumber in the form of boards 

 or other building material being small and incidental. One large 

 plant has been built recently for making oval wood di.shes, butter 

 boats and clothes pins; another makes all possible stock into agri- 

 cultural-tool handles, barrel hoops, door knobs, teapot buttons, and 

 a great variety of small woodturnery, while a third has given 

 serious consideration to the question of putting in machinery for 

 making candy sticks — those used in the manufacture of lollypops. 

 A small savraiill followed by such a remanufacturing plant is 

 usually motor-driven, while the sawmill alone might not justify 

 the investment; for the small specialty machines can lie driven 

 electrically with convenience and economy. 



13 The lumber manufacturer is generally not an engineer. 



values coming from highly resin- 

 ous wood, although as it falls from the saw it contains from 40 per 

 cent to 50 per cent of moisture, or even more. Cienerally the mill 

 produces more waste wood than can be used for fuel or otherwise, 

 and tills surplus must be sent out in a long conveyor trough and 

 liurried in a pit or in a closed iron "burner." Decreased fuel con- 

 sumption by saving power-transmission losses is therefore of no 

 interest to the lumberman. The argument has even been made 

 that decreased fuel consumption under the boilers is poor economy, 

 because the saved wood must be conveyed a longer distance to the 

 "burner" than to the boiler room, thus using more engine power. 

 But this conclusion is incorrect for the following reason: The pri- 

 mary fuel of the power plant is the sawdust made by the mill, which 

 is in ideal form for handling by automatic conveyors. This is gen- 

 erally mixed with dry dust and chips from tlic planing mill, which 

 reduce the percentage of water in the fuel. There is seldom enough 

 of this by-product ready-ground wood to run the boiler plant, how- 

 ever, and it must be supplemented by more wood especially ground 

 from waste pieces by a "hog," at a large expenditure of power. 

 Therefore any increase of fuel economy reduces the surplus of hog 

 (•lii]>s required, and saves many times the power consumed by trans- 

 ]iorting the waste pieces to the "burner." But the fact remains 

 that as the sawmill possesses an ample supply of almost ideal fuel 

 which costs nothing, the choice of power plant and transmission 

 must rest on other con.siderations, except in the rare cases when 

 all waste wood can be marketed. 



15 It is clear that the large sawmill cannot afford to buy electric 

 power as a general thing. With free fuel the installation of a power 

 plant is almost always justified, the only exception being when the 

 waste wood can be marketed at a price higher than its value as 

 fuel. 



16 In sawmills, as in other industries, motors give the advan- 

 tage of unit driving, and the whole mill is not dependent on one 

 line shaft or main belt. But it is to be noted that in the sawmill 

 proper this advantage is not so great as in most other manufactur- 

 ing plants. In a machine shop or other factory where ono machine 



[Continued on page 28) 



Fig. 4 — Interior of Sawmill Showing Two Direct-Connected Motor-Driven Fig. 3 — Lath Mill Showing Direct-Connected Motor Driving Lath Bolter and 



Edgers Lath Machine 



