Virginian solar wood dryer plans, extreme woodworking machines - Review

Categories: Wood Wine Rack Plans | Author: admin 17.01.2015

One of our Members has built a solar kiln,, fer got the name at the present,, I air dry my hardwoods under the pole barn,, takes about 5 months before the moisture is down to about 11-13% Personally I would keep the major metering stuff to a last purchase once built and opperating,, and buy that stuff last,, Now I saw a design for a open air shed that had skylights in it,, not a solar kiln, but the idea of plenty of roof overhang and the skylights can get it pretty warm under there, and lots less moving parts. You will need approximately 150 feet per minute air flow through the layers to effectively dry your lumber. This is the spot to list those places Forestry Forum members have a chance to meet and to tell about it when they do. Drying wood in a controlled environment requires much less time and allows the wood to contract without warping.Solar-drying kilns are the simplest, cheapest, and safest way to dry green wood quickly, and they are good for the environment since they don’t generate CO? emissions. A solar kiln will dry the wood with a smaller chance of defects than air drying.“And they won’t dry wood too fast,” says Dr. Wintertime drying is slower and won't go quite that low.I adapted mine from a design featured in American Woodworker magazine.
I have thought about doing a Solar Kiln, with solar-cells turning computer fans for circulation placed out where the stacks of wood are getting air dried. I was also thinking I might just do a small wood stove and portable dehumidifier in an insulated box in the basement. It’s only near the end of the drying when you need to measure moisture content to determine if it’s time to stop the process and pull the wood out.”A solar kiln can also dry wood of varying shapes, sizes, or mixed species and thicknesses in the same load.
I've seen several that load from the ends but that doesn't appear to be a very good design IMHO.Also, the VT kiln has the top sized for drying Oak, one of the more difficult woods to dry due to the slow drying rate. After the kiln is loaded, only minimal vent adjustment is needed while the wood dries.Key Kiln Design FeaturesDr. The beauty of a solar kiln is that at night, the fan is shut off and as the inside of the kiln cools, the RH rises. That conditions the wood and relieves the stresses that are introduced as it dries (wood always dries from the outside-in). Although there are different solar designs on the market today, the Virginia Tech design is the kiln model considered the standard by which other kilns are built.


Woodworkers can find instructions for this model and other similar designs online.The initial investment for a solar kiln varies, depending on the size and the building materials.
However, it pays for itself in the long run.A small solar kiln normally dries anywhere from 800-1,000 board feet, although some can be downsized to dry only a few hundred board feet. A large solar kiln dries 1,500-2,000 or more board feet of lumber.The Virginia Tech solar kiln can hold up to 1,000 board feet of 1-inch thick lumber per load and dry it in about one month of moderately sunny weather in the mid-latitudes of the United States.
The kiln heats when solar energy enters the clear glazing and is absorbed on the black painted interior surfaces.As air is heated in the collector space, one or more fans circulate it through the lumber, enabling it to absorb moisture from the lumber’s surface. If the kiln has too much solar panel area, one risks the wood drying too fast, causing the wood to check and split. However, if there’s not enough solar panel area, there’s the risk of never being able to dry the wood below 15% moisture content (MC).In order to circulate air through the stack of wood, it’s necessary to install an electric fan. If used during the winter months, the angle should be increased by 10 degrees (in this case, to 55 degrees), since the angle of the sun changes from summer to winter.Moisture ReadingsSolar drying time for lumber can vary. Also, drying time for 2-inch lumber will take longer than 1-inch material.Woodworkers first learning to dry lumber, especially lumber thicker than one inch, should monitor moisture content (MC) daily to avoid drying too rapidly.
It’s important to monitor drying speed by measuring the MC of the sample boards and comparing the daily rate of moisture loss with the “safe rate” for that species.There are tables available that list the safe rates for drying 1- or 2-inch thick lumber from different species. Safe rates must be followed until lumber moisture content drops to 20%.Although moisture meters don’t work well when the MC is above 30%, the design of the kiln is such that it normally won’t allow the wood to dry too fast.
Still, when just learning to dry lumber in a solar kiln, it’s best to monitor the process to avoid any unforeseen problems.Exceeding the safe rate drying speed for a given species can cause defects in the lumber. If drying is too fast, part of the roof should be covered, or the fans turned off and the vents closed during the hottest part of the day. Although the temperature will likely rise inside the kiln, the trapped air will quickly reach 100% of its capacity to hold water and the lumber will stop drying.It’s also important to identify sample boards at the start to determine MC loss rate. These are boards that may have started out with a higher MC than the rest of the load were cut more recently than the others, or are a little thicker.“If you check the sample pieces and they’re too wet, you’re going to continue drying,” says Dr.


Wengert notes that the Virginia Tech solar kiln was designed so that it wouldn’t allow the wood to dry too fast. Otherwise, there would be too much solar input for the little amount of wood in the kiln.Moisture MetersWoodworkers should select a moisture meter that will meet their specific needs.
A pin meter measures the MC of wood by running an electrical signal between the tips of two narrow metal probes that are inserted into the wood.One advantage of pin meters (only those that use longer pins with insulated shafts) is that wood can be tested at different depths in the wood. The major disadvantages are the relatively small area tested with each insertion, their sensitivity to wood temperature, and the damage the pins do to the wood surface.
The pins can also break or give inaccurate readings when improperly inserted.Pinless meters use an electromagnetic signal to penetrate the wood surface. Wagner has models for woodworkers who need to measure wood moisture in all wood species–from the more common softwoods and hardwoods to rare tropical species.Optimum MC LevelsFor most softwoods, Dr.
However, the MC will vary if the wood is going to be exposed to rain or an outdoor sprinkler, or if it’s going to be in a dry climate such as in Albuquerque, a wet climate such as in Seattle or a coastal region. In addition, if the wood is to be used for exterior house walls where it’s protected from rain, a good average is 12% MC.SummarySolar kilns are ideal for the hobbyist or professional woodworker who wants to save money by drying his own lumber.
Additionally, they are good for the environment since they generate zero CO? emissions.Although solar kilns are designed to keep wood from drying too rapidly, it is wise to check the MC level, especially near the end of the drying cycle.
It’s also recommended that woodworkers who are new to drying lumber in a solar kiln or who are drying wood thicker than one inch frequently check the moisture levels to prevent defects later on.



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