General Description of Lumber Milling - (Long)

Discussion in 'Logging, Mining and Industrial Railroads' started by lassenlogger, May 14, 2004.

  1. lassenlogger

    lassenlogger Member

    Thanks to those that worked so hard to get "The Gauge" back online!

    I thought this general description of the lumber milling process would help modelers better understand the sawmilling practice, thus, making it much easier to model a realistic lumber mill operation on a model railroad. I think that very accomplished modeler “Shamus” had pictures of his sawmill online; he seemed to have captured the basics.

    The following is from the introduction of Ralph Clement Bryant's 1922 text book titled "Lumber: Its Manufacture And Distribution."

    “The manufacturing procedure is similar in all regions without regard to species, although there may be variations in the process of re-manufacturing hardwoods and softwoods. Small mills lack many of the labor-saving devices and high-speed machines found in large mills yet the general methods of manufacture vary only with the difference in equipment. Machinery for the re-manufacture of rough lumber is seldom found in small plants, therefore this operation must be performed in a factory not owned by the sawmill operator.”

    “The following description of manufacture refers chiefly to plants of medium or large size which are equipped to place finished products on the market. The logs are delivered at the sawmill by water, rail, wagon, motor truck, or some other form of wheeled transport and are stored either on land or in water until required for sawing purposes. They are rolled upon the log decks of small mills by hand power and are brought to the decks of large mills by some form of power-driven device, and when necessary are cut into shorter log lengths before they are thrown upon the deck.”

    “Logs are taken singly from the deck, placed on the power-driven carriage and cut by means of the head-saw into the products desired. During the process of reducing the log to the sawed products, the log is turned, as often as required, to secure both the sizes desired and the highest quality of material. The first cut on a log removes a slab which passes from the head-saw along a line of live rollers to the slashers, where it is cut into lengths suitable for lath stock, or for firewood. This material is then conveyed through the lath mill where lath stock is picked from the conveyor. Firewood for local consumption may be removed at some other point, the residue then being conveyed to a refuse burner, where it is burned, or to a refuse grinder or “hog,” where it is converted into chips and then carried to the fuel storage house for use as fuel in the power house.”

    “Small logs, which usually are “sawed alive,” yield but two slabs, while larger logs which are “sawed around” yield four slabs. The thickness of slabs depends upon the sawing practice at the mill.”

    “Boards and dimension, as they are cut from the log, pass from the head-saw along the line of live rollers to a point in front of the edger, where they are shunted at right angles upon a storage table, from which they are taken by the edgerman, and run through the edger. During this process waney boards are made square-edged and wide boards ripped into narrower widths. The boards and dimension as they leave the edger are shunted at right angles upon a storage table in front of the trimmer, while the waney-edged strips either are shunted upon conveyor chains leading to the slasher, or those of suitable width and length may be sent through the trimmer, then seasoned in a dry klin, and later worked into narrow molding stock.”

    “The boards and dimension are taken from the storage table in front of the trimmer and placed on the trimmer table up which they are carried by chains and trimmed to the desired length. Defective pieces are cut into shorter ones in order to secure the highest grade practicable without an undue waste of material. The trimmings from boards drop into a chute and are conveyed by chains either to the burner or to the refuse grinder. Short, clear pieces may be removed from the conveyor and reworked in to ‘shorts.’”

    “As the boards leave the trimmer they drop upon the grading and assorting table, where they are roughly graded and then assorted, often by species, grades, thicknesses, and lengths. The lumber is then taken either to the yard for air-seasoning or to the dry kilns for artificial seasoning. Common grades of softwood lumber often are air-dried, while the higher grades, as a rule, are kiln-dried to prevent sap stain.”

    “The lumber which is to be air-seasoned is carried to the yard and stored in front of the piling space, and later stacked in the pile by laborers using some hand or power method. When required for shipment, the lumber is removed from the pile, loaded on some conveyance and taken to the car, if it is to be shipped in the rough, or to the planning mill if it is to be surfaced or worked into some pattern or patterns. At the planning mill it is re-manufactured and as it leaves the machine, defects are cut from the ends, and the “off-grades” are placed in storage sheds or re-stacked in the yard until there is an opportunity to ship them on an order calling for such stock. The accepted product from the machine is then loaded on a freight car for shipment.”

    “Stock that is to be kiln-dried is taken from the assorting table to the kiln-stacking point, where it is loaded on trucks, either by hand or mechanical means, and then run into the drying chambers. When the drying process is completed the stock is removed, graded, and assorted and taken to a storage shed until required. It is then shipped in the rough, or worked to patterns in the planning mill where defects also are cut from the ends of the boards, and the lumber grades and placed in cars for shipment.”

    “Certain classes of material, such as flooring strips, may be taken directly from the kiln to the planning mill and worked to pattern. This practice is not a common one, because pieces that are worked in a bone-dry condition are much more subject to machine defects, such as torn grain, than are those which have been stored in a shed for a short time, during which period the lumber absorbs some moisture which renders it less brittle, and fewer degrades are produced. Some mills, which work their stock direct from the dry kilns wet the truck loads of lumber by means of a hose, or submerge them in a tank of water for a moment which makes the lumber easier to work.”

    “Timbers are handled in a different manner from boards and dimension, since they are shipped in a green condition. From the head-saw they pass down the line of live rollers to a “butting” or cut-off saw, where they are cut to proper length. They then pass on rollers to the timber sizer, if they are to be worked to exact sizes, and surfaced on one or more sides, and later moved to timber docks or ramps, where they are stored until a car load has been accumulated. They are then loaded on flat or gondola cars for shipment.”

    “Timbers are cut on orders, that is, they are not carried in stock in standard sizes, hence they are manufactured only as they are to be shipped. Boards and dimension may or may not be cut to order, depending on the class of trade for which a given mill manufactures. Mills which sell to the general retail trade carry relatively large quantities of so-called “stock” sizes which are cut previous to their sale, as there is sufficient demand by the building trades for certain sizes to assure the mill a market for the product. Cargo or other mills cutting for a diversified class of buyers -“order mills,” – cut stock chiefly to fill orders, since there is such a great variation in the market requirements as to size that it is unwise to carry heavy stocks on hand.”

    “A large percent of the softwood lumber output of the larger mills of the country is either surfaced or worked to pattern at a planning mill operated in connection with the sawmill plant. The reason for this is that many products are more salable in some finished form than in the rough and there is a marked saving in freight on the waste material which is removed during the process of re-manufacture. Even though the product is of the lower or lowest grades and is to be used for some purpose which does not require surfaced material, the pieces usually are worked to standard size in order to reduce the weight.”

    “Yard stock, in some sections, was formerly surfaced green before it was air-dried in the yard, because it was believed that the product seasoned more rapidly. This method also enabled the shipper to load out his seasoned stock directly from the pile. Woods like eastern hemlock were degraded less when worked green because the knots did not tear out in dressing to the extent they did after the boards had become shipping dry. This practice also prevailed to some extent in the eastern spruce, southern yellow pine, Douglas fir, redwood and other softwood-producing regions. Green dressing of material, other than timbers, has now largely been abandoned because lumber shrinks and also becomes discolored after it is surfaced, and is not acceptable to the trade. Green dressing is not adapted to stock worked to patterns because of the shrinkage which takes place during the seasoning process.”

    “Hardwood lumber is shipped chiefly in the rough. The boards are not used as a whole but are cut into smaller sizes suitable for the use of the wood-using industries. Some mill work is made at hardwood sawmill plants but this process of re-manufacture is of minor importance compared to re-manufacture at softwood plants.”

    Jimmy "B"
    Reno, NV
  2. belg

    belg Member

    Jimmy that's the stuff I've been waiting for!!!!! We were in the middle of educating me on this when operations here went screwy. I will read it thru again tonite and get back to you if I don't understand something, Thanks again Pat
  3. shamus

    shamus Registered Member

    Hi Jimmy,
    Now that what I like to read, very Informative and right on the nail. Love it and any more you can come up with.


  4. m_reusser

    m_reusser Member

  5. lassenlogger

    lassenlogger Member


    Good to see and hear from you. Have you found anything more out about the Moon Lumber Company?

    Jimmy "B"
    Reno, NV
  6. jon-monon

    jon-monon Active Member

    Great thread, Jimmy!
  7. jakejack

    jakejack New Member

    Wholesale Lumber Solutions

    Hi, I saw this advertisement about IPE and I do not know what is better for decking. any help?

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