I like these "starter blocks" to raise the lumber a few inches off the floor. My four main baffles consist of sheets of 1 Styrofoam insulation. Also, today, we are often kiln drying No.2 Common lumber which requires a milder schedule than upper grades; in the 1950s, seldom was this lower grade lumber kiln dried.) The kiln process involves the drying of wood in a chamber where air circulation, relative humidity and temperature can be controlled so that the moisture content of wood can be reduced to a target . I use a Rockler steam generator. Adjust the baffles or fan direction to achieve good airflow. Dehumidification dry kilns operate at lower drying temperatures (typically below 150F) than do conventional kilns, which results in longer drying schedules. Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. Unlike general shop space, bigger is not always better for kiln design. Only the fans need electricity. Additionally, I have been underwhelmed by the performance of solar-operated fans. Any info or advice on using dehumidification equipment to dry out chainsaw milled lumber. The delicate blue and white color scheme c /ColorSpace /DeviceGray Measure airflow over the stacks of lumber in various locations. in the kiln to dry specific wood products at a satisfactory rate without causing objectionable drying defects. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. This kicker board will help distribute the airflow more evenly through all layers of lumber. Table 1 shows a typical drying schedule for sugar maple. endstream endobj 283 0 obj <>/Metadata 40 0 R/OCProperties<>/OCGs[294 0 R]>>/Outlines 53 0 R/PageLayout/SinglePage/Pages 280 0 R/StructTreeRoot 72 0 R/Type/Catalog>> endobj 284 0 obj <>/Font<>/Properties<>/XObject<>>>/Rotate 0/StructParents 0/Tabs/S/Type/Page>> endobj 285 0 obj <>stream When properly loaded, this kiln can dry approximately 600 board feet of 4/4" lumber. Equalizing and Conditioning Sign In Upload. Many articles have been dedicated to solar lumber kilns: everything from a simple sheet of Visqueen over a stack of lumber in the sunshine to elaborate enclosures designed for solar gain. Lay down the bead of caulking before raising the walls. If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. Ignoring for a moment the merits of a homebrew DH kiln versus a Nyle, I was curious to see that rather than referencing the standard kiln schedules (e.g. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. Khmer Kiln: quite similar to the Anagama kiln however, traditional Khmer Kilns had a flat roof. Kiln dried wood typically sells for a third more than green lumber and eliminates the need for customers to incur costs associated with drying lumber . Sticker spacing can be increased to 24 apart for 5/4 or thicker hardwood. 0000001417 00000 n This kicker board will help distribute the airflow more evenly through all layers of lumber. 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. Looking at the cost-benefit analysis of a shed kiln can be enlightening. A dehumidification kiln makes sense particularly when the lumber is air-dried first. This procedure is discussed in a following section. As a result, the kiln schedules were too severe. I know your kiln is absolutely tight and perfectly sealed, but it has to vent some or it would overheat. %PDF-1.4 % %3.3 After two days operating only the fans and DH, I take note of the temperature. Ideally, a lumber kiln would be large enough to dry multiple stacks of lumber. Sorry, preview is currently unavailable. How do I convert from the standard kiln schedules in the USDA's "Dry Kiln Schedules for Commercial Woods" and "Drying Hardwood Lumber" to an SDR-type schedule? If your lumber stack is built on starter blocks, you will need to limit airflow there as well. -. 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. I don't remember how the air flow was arranged in the kiln in the magazine, but it sounds like that could be a problem for you. Please refer to Appendix A which shows the Lumber Dry Kiln Bill of Materials. Installing a window in a kiln may seem counterintuitive at first, because windows lose more heat than an insulated wall. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. A locked padlock So, with that lengthy introduction, here is my question. Should I? This problem is magnified if the lumber is thin or flatsawn. Always use adequate samples representing both the wettest and driest lumber in the dryer. 3. There may be more depression values than required; ignore the extra depression values in this table. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. To hang the baffles, simply attach hooks to the plywood frame. Once the lumber is sterilized, it is ready for the conditioning phase. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. You can achieve top-quality results with incredible efficiency. I've been drying hardwood lumber in this Sauno dehumidification kiln for 4 years with excellent results. Consider not only the space for the lumber stacks, but extra floor space to easily load and monitor the charge of lumber. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Kiln drying is usually preceded by air drying to bring the moisture content of the wood down below 30%. . Remove samples from the stack, and cut an inch or two off one end. The dry kiln operator is fully in control, with the ability to make changes as the dry kiln schedule is executing. Soon the DH wont show much water collected in the tray. A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. 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. 73. Typical . Enter the email address you signed up with and we'll email you a reset link. Place a sticker at each end, and every 16" along the stack for 4/4 stock. WOODWEB is a registered trademark of Woodweb.com. Place a sticker at each end, and every 16 along the stack for 4/4 stock. /Type /XObject I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. Use the gridded drawings provided on the PDF, Woodworking | Blog | Videos | Plans | How To. Apply foil tape to the edges of the main baffles to help protect the Styrofoam. Milling the stickers square is advantageous over a rectangular cross-section, because no matter how you place the stickers they will form a level stack. Willie Sandry is a furniture maker and a lumber kiln operator in Camas, Washington. For the best experience on our site, be sure to turn on Javascript in your browser. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). H6`2}s=n:l)CR>/"\ 6 0 obj Our approach was to build and operate a small dehumidification dry kiln. Solar kiln drying was most effective in the summer and early fall, when kiln efficiencies were 90% to 67%, respectively, and drying times were 2 to 3/one-half/ times faster than air drying. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I won't use the auxiliary heater. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. 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. Drying lumber too quickly can lead to deep end checking, warping and case hardening. Such temperatures are high enough to kill insectsanother advantage of kiln drying over air drying. Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. A typical home center sheds floors are underbuilt for the weight of a load of lumber. Over 40 years experience building kilns. For DH kilns, use the same RH, but lower the temperature to the typical operating temperature for the compressor; raise temperature to steam values when convenient and possible. My number one priority was to build a kiln that was easy to load and easy to monitor. Two-by-four material sawn from young trees, thinnings, and stem tops contains a significant proportion of juvenile wood and is particularly notorious for warp. Place a 1x6 board on the floor behind the stack, tilted to a 45 angle. In time schedules, dry- and wet . The second most common type of drying is called dehumidification drying. Secure .gov websites use HTTPS Take the electronics out of the kiln, and continue operating the heater and fans during this phase. The last step requires a short period of high humidity to relieve the drying stresses in the boards. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. These are rough-saw red oak. << A kiln schedule is a set of temperatures and humidities that are used during kiln operation. In vacuum kiln trials, logs were heated to 56C at 70 percent log radius depth and the temperature maintained for . The T-bars are made from 1/2 galvanized pipe and are attached to the rafters with threaded pipe flanges. 7. Schedules Dry Kiln Schedules for Commercial Woods This, of course, is gross savings; we must calculate electrical costs to determine the net savings: in this case, about $62. Made in China, it exudes the classic style of Asian and Chinese cultures, featuring a unique shape that sets it apart from traditional jars. Saving money by drying your lumber may not be the answer for every woodworker, but the basics shown here demonstrate that it is within the reach and skills of the average person. Just walk out to the shed kiln and grab what you need from your custom-dried supply. Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. . Warp in dimension lumber is a significant cause for loss in grade and value. Kiln Drying . Detailed design and custom manufacture of dehumidification and chiller systems for food processing, lumber drying and industrial applications. WOODWEB is a registered trademark of Woodweb.com. 0000000710 00000 n Vacuum Kiln Drying. Dehumidification kiln schedules 145 Sterilizing, equalizing, and conditioning treatments 145 Sterilizing treatments 145 Mold 145 Fungal stain and decay 146 . Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. A variety of wood drying kiln technologies exist today: conventional, dehumidification, solar, vacuum and radio frequency. Changes in kiln temperatures and humidities are based on the MC of the lumber being dried, which in turn is determined from properly prepared kiln samples. The stickers are uniform in size and usually 3/4" or 1" square. From contributor D: My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. building the dehumidification dry kiln. %PDF-1.6 % Seems like a pretty simple way to run the kiln - once or twice a day just measure the amount of water extracted, and turn down the humidity a bit as needed. The problems with solar kilns include limited control over temperature and limited solar exposure, depending on your region and site location. 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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.. Sticker spacing can be increased to 24" apart for 5/4 or thicker hardwood. Be sure that all of the kiln equipment is working prop-erly before lumber is loaded into the kiln. I usually see a large volume of water in the DH each night when I check the kiln. Kiln Systems. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. Place the one inch sections in an oven 215F to 218F (102C to 103C) and dry - usually 18 to 36 hours depending on the oven. Another great option is to convert an existing shed or outbuilding to a lumber kiln. This publication outlines the basic construction of a small scale dehumidification dry kiln. 282 0 obj <> endobj I have sensors in the kiln for moisture levels & probes in the center of the wood attached to a lignomat moisture meter. January 27, 2007. trailer << /Size 918 /Info 891 0 R /Root 907 0 R /Prev 482770 /ID[<67858f68421814977b05bc7913f6cc23><4073af979fbabe8f1c016146fd1c21ef>] >> startxref 0 %%EOF 907 0 obj << /Pages 902 0 R /Type /Catalog /DefaultGray 903 0 R /DefaultRGB 904 0 R /Metadata 905 0 R >> endobj 916 0 obj << /S 499 /Filter /FlateDecode /Length 917 0 R >> stream But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . Adjust the baffles or fan direction to achieve good airflow. Phytosanitary heat treatments of Ceratocystis lukuohia and Ceratocystis huliohia-colonized Metrosideros polymorpha wood were evaluated using kilns. 3, a simplified transverse section of a kiln chamber with an energy recovery and dehumidification system is shown. Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. If it isn't overheating, it is leaking. You could use the dehumidifier to dry wood but it would not be part of a "kiln." Just be a different process. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. I was hoping someone could point me in the right direction or share experience. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. 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. This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. If we revisit the example of a $1,300 gross savings from a load of 540 BF of white oak lumber, and we subtract the estimated cost of $62 to kiln dry the lumber, we arrive at a net savings of $1,238 less than retail. . _0e`bd\ p@ Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. Custom Doors, Drawers & Glass Accessories, Using a Small Scale Dehumidification Kiln, Learn Woodworking Tips & Tricks with Rockler, High-quality brands and products you can trust, Expert advice and free post-purchase support, Exclusive, innovative products that help you Create with Confidence, Detailed instructions, technical specs and guides to make the most of your purchases. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. Without baffles, the top layers of lumber experience "potato chipping" with cupping, twisting or warping. I'm thinking I could vent it manually, but with the RH so high externally I am not sure if that is the right thing to do. Place some sample boards in the stack that will be easy to pull out for moisture testing later. I found that brackets for mounting rigid metal electrical conduit work best. An official website of the United States government. For a kiln temperature of 140 F, sterilization takes three to five hours. HDE small kilns feature all-aluminum construction for a long, maintenance-free life span . Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. Select a heater with an adjustable thermostat and a tip-over shutoff. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. Do not know just how the end point of moisture would compare. Standard kiln drying temperatures are low - around 120 degrees Fahrenheit or so, and drying times vary by wood size and moisture level. The first thing to consider when designing a shed kiln is size. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. An anemometer confirms that your effort constructing baffles was worthwhile. Choosing a Kiln Schedule Kiln drying normally involves temperatures in the range of 40-75 C (about 100-170 F). Whether to Wax Walnut Ends Before Steaming, Frequently Asked Questions about Widebelt Sanders. . 1. a furnace or oven for burning, baking, or drying, especially one for calcining lime or firing pottery. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. The lumber was then measured for crook, bow, and twist. Featuring lower cost drying at speeds equal to gas & steam, these kilns are continuously exceeding industry standards and changing the game. Remove samples from the stack, and cut an inch or two off one end. The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. I guess I am thinking that while I am seeing the wood's MC and the kiln's RH drop smoothly, the fact that the temperature jumps around a bit may mean that the drying rates are hard to control, hence my loss of horse chestnut. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . /Width 1628 Once the flooring deck is constructed, think about sealing the shed framing at every opportunity. This plan allows . Joining end grain to long grain forms the king of joints. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. These figures hold true for lumber up to 2 thick. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. A shed kiln has minimal venting (usually one or two gable vents) and sealed soffits. A bead of silicone caulking between the subfloor and sill plate will prevent air infiltration. Understand how kiln performance must be modified to permit the use of custom schedules for specific product applications; Be able to modify existing conventional kiln schedules to dry products in dehumidifier kilns; Recognize degrades common to various species, including hardwoods, and modify handling practices to minimize these I often buy from sawyers or homeowners at 40% to 50% of retail price. Excel Program for Modeling Lumber Dry Kiln Operations - a model for lumber dry kiln operation. A maximum 45 F depression often produces better lumber. A heavy-duty 1,500-watt space heater works fine. In the fourth column, write down the wet-bulb depressions (determined in #4 above), one for each Schedule Step, starting at the top (Schedule Step 1). This makes lightweight baffles that can be easily moved and repositioned. Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. are generally kiln dried by time scheduleswhether the wood is intended for struc-tural lumber or for appearance uses, such as furniture or millwork.
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