52 



HARDWOOD RECORD 



April 10, 1921 



Power setting machine, for moving log forward after 

 every cut into position for the next cut. This 

 machine is mounted on the carriage. Two types 

 are used, one direct steam-driven, the other power- 

 driven. The latter is used exclusively for the 

 heaviest work, and motor may be mounted on car- 

 riage 5 to 10 hp. 



Live rolls, or power-driven rolls, for transporting 

 lumber after being sawed. These are connected 

 and driven together in trains of 6 to 20 or more, 

 according to the mill design; power required per 

 roll 0.4 to 0.6 hp. 



Band resaw, for further reduction of large pieces 

 dropped by the head band mill. It may be either 

 vertical or horizontal. The latter is used for resaw- 

 ing slabs as well as splitting thick stock from the 

 head band 7.5 to 200 hp. 



Transfer chain tables, for moving lumber sidewise 

 between machines. These are of such varying 

 length and width, according to the individual case, 

 that no power requirement can be specified. 



Gang mill, for sawing entire log into boards at one 

 passage through the machine. Two opposite slabs 

 are taken off the log by the head band saw, giving 

 the log two flat faces, after which it is fed to 

 the gang 50 to 400 hp. 



Edger, for ripping bark edges from the board and 

 squaring them 15to 250 hp. 



Slab slasher, for dividing waste stock into short 



lengths for lath, stovewood, or other by-products. . 20 to 75 hp. 



Trimmer, for cutting ends off boards and making 

 them of standard length 20 to 75 hp. 



Swing cut-off saw, for hand-trimming of large tim- 

 bers, etc 10 to 25 hp. 



Timber sizer, for surfacing two or four sides of tim- 

 bers at one operation 50 to 60 hp. 



Lath bolter, for preparing lath bolts from slabs or 



other waste wood 30 to 60 hp. 



Lath machine, for making lath from bolts 20 to 30 hp. 



Hog, a grinder with knives on a revolving disk, for 



chipping waste wood for fuel or other purposes ... 25 to 150 hp. 



Planers, of great variety in size and type. The 

 largest standard size requires about 75 hp. 



Exhaust fans, for transporting dust and shavings 



from planers to fuel-storage house 25 to 150 hp. 



Chain conveyors, for transporting waste wood and 

 sawdust, the length varying with the mill design 

 up to about 350 feet 5 to 30 hp. 



Pertinent Information 



Swamp Logging with Tractors 



(Oontinued from page 48) 



Six trips per day were made with three wagons to a trip, landing 

 about 65 cords per day direct from stump to car. 



After five months' continuous hard use under such extremely 

 abnormal conditions as above pictured, Mr. Eose reported to the 

 Holt Manufacturing Company that only one day had been lost since 

 the tractors were first placed on the job, and this was due to the 

 breakage of a minor part which was replaced at a cost of only $2. 



Illustrations shown in this article picture the Watab Company 

 operations during the winter. Sleighs have replaced the trailers and 

 by this means it is possible to haul approximately three times the 

 load that was handled during the summer. Notwithstanding this 

 advantage, it was the ability of the tractor to successfully work 

 against the adverse conditions which confronted it during the 

 summer which made it possible to keep the mill running. 



A Drying Schedule for Air-Seasoned Oak 



The following skeleton drying schedule Is recommended for the kiln- 

 drying of air-seasoned oak. It must be rememljered, however, that no mere 

 formula in itself will insure the perfect drying of wood. The Win operator 

 mast be trained to watch the condition of the lumber and to apply the 

 proper remedies If things start to go wrong. 



The schedule was prepared by the D. S. Forest Products Laboratory for 

 4/4 plain-sawed oak (highland variety), with a moisture content of 16 

 per cent. This moisture condition would ordinarily be reached in from 

 B to 12 months of air seasoninj!. 



After the stock is dry the temperature should be held at 145 degrees ana 

 the humidity raised to 80 per cent. This condition should be maintalnefl 

 for 10 houre in order to balance the moisture content, thus reducing the 

 tendency of the lumber to warp after machining. 



Sodium Fluoride as a Wood Preservative 



Tests made years ago Indicated that sodium fluoride might be Bucceas- 

 fuUy used as a wood preservative, because it had high toxicity, was not 

 injurious to metal, and was convenient to handle. Laboratory tests alone, 

 however, are never sufficient to establish the value of any material as a 

 wood preservative; actual service tests, even though they require years 

 to complete, are also needed. 



In order to obtain comparative durability records, the laboratory In 

 1914 placed sap-pine ties, treated with sodium fluoride, together with tics 

 treated with zinc chloride and creosote. In one of the mines of Tennessee 

 Coal, Iron & Railway Company at Birmingham, Ala. Similar serrice 

 tests were also started at this time on red oak ties placed In the tracks of 

 the Baltimore A Ohio Railway Company. 



After Ave years of service the mine ties which were treated with 

 sodium fluoride have been found In as good condition as those treated 

 with zinc chloride, both showing very little deterioration. The creosoted 

 mine ties apparently were in still better condition, while the untreated ones 

 were in various advanced stages of decay. The red oad railway ties treated 

 with sodium fluoride were practically all sound, as were those treated 

 with zinc chloride, whereas a large percentage of the untreated oak ties 

 had been removed. 



Both of these tests, as well as others started later, must continue for a 

 number of years yet before the relative value of the sodium-fluoride treat- 

 ment for ties and timbers is definitely known. 



Kiln-Drying Green Hardwoods 



Successful kiln-drying of hardwood lumber green from the saw necessi- 

 tates a very even control throughout the kiln at all times. This means 

 that variations in temperature of even a few degrees or variations In 

 relative humidity of 5-10 per cent are seldom permissible. Such uniformity 

 is possible only when the heating coil is properly drained, is relieved of 

 air, and is distributing heat uniformly along Its length. 



It is the contention of the Forest Products Laboratory, Madison, Wis., 

 that the return-bend heating coil system, by bringing about more uniform 

 distribution of heat in the kiln, enables the operator to obtain quicker and 

 better drying than Is possible with the header-coil system, as it is generally 

 installed. 



The return-bend heating coil gives a practically even heat distribution 

 under any steam pressure. The header-coll produces different temperatures 

 at either end of kiln, the extent of variation depending on the steam 

 pressure, length of coils, drainage, traps, etc. 



Refractory hardwoods require low temperatures, and the lower the tem- 

 peratures used the more evident will be the difference In the results 

 obtained with these two types of heating equipment. Under the same 

 careful operation, green hardwood lumber may be turned out from kilns 

 using the one type satisfactorily dried, and from kilns using the other 

 type checked and overdried at one end and molded and under-dried at the 

 other end. 



