Then align each subsequent layer of stickers over the last. The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. There are two ways to remove water from the DH unit, and they both work well. Your order will come with a return form with convenient instructions, or you may send your returns directly to Returns Department, Rockler Woodworking and Hardware, 4365 Willow Drive, Medina, MN 55340. When the drying is done in a kiln, the product is known as kiln-dried timber or lumber, whereas air drying is the more traditional method.. With each load I did not have the initial relative humidity rate. This allows for a more gentle kiln schedule to fully dry the timber. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. (Note: This letter designation is related to the green MC of the species. Also check that air isnt escaping around the side baffles or under the stack of lumber. In this research, a drying restraint system was evaluated as a means of warp reduction in 8- and 16-foot-long SYP lumber. However, you may need more cycles depending on the species, moisture content, and size of the timber. 0000000591 00000 n
In this paper, the effective schedules were further investigated for longer culm parts treated with boron. A lower RH setting will call for the DH to run more often. /Length 7 0 R
After two days operating only the fans and DH, I take note of the temperature. Dehumidifier suggestion: http://amzn.to/2iYZqVZThis is the first in a series of videos showing how I built a kiln for drying lumber. Every Nyle Dehumidification Dry Kiln System Example: If the WBT falls below the set parameter measures and regulates internal kiln conditions the system will turn on the spray system. Drying lumber too quickly can lead to deep end checking, warping and case hardening. Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. Dehumidification Kilns Looking at the cost-benefit analysis of a shed kiln can be enlightening. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. So, with that lengthy introduction, here is my question. My baffles hang from T-bar assemblies mounted to the ceiling. I'd like to know for my own curiosity, as well as to be able to generate SDR schedules for other species not given in the American Woodworker article, like the 6 foot long 24" wide slabs of 8/4 madrone I got this summer. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. For a kiln temperature of 140 F, sterilization takes three to five hours. Download Table of Contents. The following tables show some examples of oak schedules for steam dry kilns and dehumidification dryers. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. I prefer to empty the water tray manually and record the volume of water collected. Ideally, a lumber kiln would be large enough to dry multiple stacks of lumber. >>
If you intend to kiln dry lumber from a green state, right off the sawmill, you will need to be well-versed in airflow rates and follow a detailed drying schedule. 73. (A major source was Dry Kiln Schedules for Commercial Woods which is available from the Forest Products Society in Madison, WI.) For 4/4 hard maple, with an initial temperature of 90F and an initial relative humidity of 81%, the SDR was given as .0061 pints per hour per board foot. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. Using a piece of paper with 6 columns, write down the Schedule Step numbers in the first column on the left. The sheetrock also helps to protect the fiberglass insulation. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) Always avoid conditions that add moisture back to the lumber, especially during start-up. This problem is magnified if the lumber is thin or flatsawn. This plan allows . Forum Responses USDA, 1991) . Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. Rep. FPL-GTR-57. In-service replacement of warped 2 by 4's as wall studs or truss members is costly. If severe enough, the lumber can develop honeycomb cracks throughout. Hb```f``:A2,@!p"4|QP(y;ysc6f{f+&FfKi-L4+i`Vlf nwj2MM/E)rQ,^wm{'_B&%F`dbt JB*UWTmdIb& z P"f#*E4%
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There are two ways to remove water from the DH unit, and they both work well. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. Sign In Upload. the Dry Kiln Operator's Manual (Simpson, 1991). After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. When that is the case, I know Ill have usable lumber in just a few weeks. 44. The column on the right I added part way through is the kiln's internal RH. The velocity through the load is assumed to be between 275 and 350 fpm, except for the white woods (including maple, ash, basswood, hackberry) where higher velocities (up to 600 fpm) are desired and acceptable. Unlike general shop space, bigger is not always better for kiln design. I know your kiln is absolutely tight and perfectly sealed, but it has to vent some or it would overheat. Conventional kiln drying. Reply. Use the gridded drawings provided on the PDF, Woodworking | Blog | Videos | Plans | How To. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . Staggering the seams between the sheathing and siding layers helps avoid air infiltration. The second most common type of drying is called dehumidification drying. Dehumidification drying system. Frequently, the lumber has already air-dried for several years in a barn or outbuilding. Our approach was to build and operate a small dehumidification dry kiln. The remaining width allows for a 36-wide door and space for your drying equipment. Measure airflow over the stacks of lumber in various locations. The second temperature value is written for the 25 to 30% MC class; the third for the 20 to 25% MC class; and so on. So, if you have 100 bf in the kiln, every 12 hours you would extract (12 hours *100bf * .0061 SDR) = 7.3 pints of water. Share sensitive information only on official, secure websites. This slows the end-grain drying and limits the severity of end checking. The moisture loss, drying time and drying defects were determined. Diy dehumidifier kiln time table. Know how to choose and apply the correct schedule for the lumber. Dehumidification kilns from Nyle Systems in Brewer, Maine. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Sticker spacing can be increased to 24 apart for 5/4 or thicker hardwood. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. For single-stack kilns, stationary fans are adequate. Be sure that all of the kiln equipment is working prop-erly before lumber is loaded into the kiln. My baffles hang from T-bar assemblies mounted to the ceiling. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. For these reasons, I feel it is best to let the shed breathe, and forgo a plastic vapor barrier. Created and Presented by: Henco Viljoen and Elijah McCarty with Nyle Dry Kilns. The store will not work correctly in the case when cookies are disabled.